Seabirds interact with fishing vessels to consume their discards and baits, sometimes resulting in incidental capture (bycatch) and the death of the bird, with clear conservation implications. To understand seabird-fishery interactions at large spatiotemporal scales, researchers increasingly use simultaneous seabird and fishing vessel tracking. However, vessel tracking data can contain relevant gaps due to technical issues, illicit manipulation, or the lack of adoption of tracking monitoring systems. Such hidden vessel activity might lead to underestimating the fishing effort and bycatch rates, jeopardizing the effectiveness of marine conservation management. In this work, we deployed bird-borne radar detector tags, capable to record the occurrence of radar vessels, on three shearwaters species foraging in the NW Mediterranean Sea and the Canary Current Large Marine Ecosystem. We modelled radar detections in relation to gridded AIS vessel tracking data to understand the spatiotemporal dynamics of seabird-vessels interactions and identify unreported fishing activity areas. Our models showed a moderate fit to vessel tracking data, indicating a strong association of shearwaters to fishing vessels in major fishing grounds, although in high marine traffic density regions radar detections were also driven by non-fishing vessels. Moreover, radar detector tags registered the presence of potential unregulated and unreported fishing vessels in West African waters. Overall, we showed bird-borne radar detectors can unveil the areas and periods when the association of seabirds to both, reported and unreported fishing vessels, is more intense, which should help to improve the focus of conservation efforts.

seabirds remain untracked so far, and they might be threatened by anthropogenic activities. One species which remains to be tracked during migration is the anti-tropical white-faced storm-petrel (Pelagodroma marina). Indeed, their movements and activity patterns are largely unknown, although often regarded as dispersive. In this study, we aim to identify the post-breeding movements and the daily activity patterns of the white-faced storm-petrel breeding in Cabo Verde (P. m. eadesorum). We tracked five adults with geolocators (GLS) between 2019 and 2022 and modelled their routes using Satellite Geolocation for Animal Tracking (SGAT). To understand their daily activity patterns during the non-breeding period, we programmed geolocators to record when the bird was dry or on the water. Results showed white-faced storm-petrels breeding in Cabo Verde are truly migratory, heading towards the northwest of the Atlantic in May-June and returning in October-November through the northeast towards Cabo Verde, following a clockwise movement. Birds spend the non-breeding period in areas associated with seamounts along the mid-Atlantic Ridge and south of the Azores. In addition, we found that the species is mainly active at night during the non-breeding season, suggesting they take advantage of diel vertical migration of zooplankton and nekton associated with seamounts. Their time spent on the water increases before returning to the colony, likely related to the need to complete their moult. Our data add to the growing evidence that the North Central Atlantic is a crucial location for the conservation of pelagic seabirds and highlights the need to protect these remote areas from the increasing human impact on the high seas.

Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species.

State-space models, such as Hidden Markov Models (HMMs), are increasingly used to classify animal tracks into behavioural states. Typically, step length and turning angles of successive locations are used to infer where and when an animal is resting, foraging, or travelling. However, the accuracy of behavioural classifications is seldom validated, which may badly contaminate posterior analyses. In general, models appear to efficiently infer behaviour in species with discrete foraging and travelling areas, but classification is challenging for species foraging opportunistically across homogenous environments, such as tropical seas. Here, we use a subset of GPS loggers deployed simultaneously with wet-dry data from geolocators, activity measurements from accelerometers, and dive events from Time Depth Recorders (TDR), to improve the classification of HMMs of a large GPS tracking dataset (478 deployments) of red-billed tropicbirds (Phaethon aethereus), a poorly studied pantropical seabird. We classified a subset of fixes as either resting, foraging or travelling based on the three auxiliary sensors and evaluated the increase in overall accuracy, sensitivity (true positive rate), specificity (true negative rate) and precision (positive predictive value) of the models in relation to the increasing inclusion of fixes with known behaviours. We demonstrate that even with a small informed sub-dataset (representing only 9% of the full dataset), we can significantly improve the overall behavioural classification of these models, increasing model accuracy from 0.77 ± 0.01 to 0.85 ± 0.01 (mean ± sd). Despite overall improvements, the sensitivity and precision of foraging behaviour remained low (reaching 0.37 ± 0.06, and 0.06 ± 0.01, respectively). This study demonstrates that the use of a small subset of auxiliary data with known behaviours can both validate and notably improve behavioural classifications of state space models of opportunistic foragers. However, the improvement is state-dependant and caution should be taken when interpreting inferences of foraging behaviour from GPS data in species foraging on the go across homogenous environments.

Fisheries bycatch is a critical threat to sea turtle populations worldwide, particularly because turtles are vulnerable to multiple gear types. The Canary Current is an intensely fished region, yet there has been no demographic assessment integrating bycatch and population management information of the globally significant Cabo Verde loggerhead turtle (Caretta caretta) population. Using Boa Vista island (Eastern Cabo Verde) subpopulation data from capture-recapture and nest monitoring (2013-2019), we evaluated population viability and estimated regional bycatch rates (2016-2020) in longline, trawl, purse-seine, and artisanal fisheries. We further evaluated current nesting trends in the context of bycatch estimates, existing hatchery conservation measures, and environmental (net primary productivity) variability in turtle foraging grounds. We projected that current bycatch mortality rates would lead to the near extinction of the Boa Vista subpopulation. Bycatch reduction in longline fisheries and all fisheries combined would increase finite population growth rate by 1.76% and 1.95%, respectively. Hatchery conservation increased hatchling production and reduced extinction risk, but alone it could not achieve population growth. Short-term increases in nest counts (2013-2021), putatively driven by temporary increases in net primary productivity, may be masking ongoing long-term population declines. When fecundity was linked to net primary productivity, our hindcast models simultaneously predicted these opposing long-term and short-term trends. Consequently, our results showed conservation management must diversify from land-based management. The masking effect we found has broad-reaching implications for monitoring sea turtle populations worldwide, demonstrating the importance of directly estimating adult survival and that nest counts might inadequately reflect underlying population trends.

Overfishing has been drastically changing food webs in marine ecosystems, and it is pivotal to quantify these changes at the ecosystem level. This is especially important for ecosystems with a high diversity of top predators such as the Eastern Atlantic marine region. In this work we used high-throughput sequencing methods to describe the diet of the two most abundant tuna species, the Skipjack tuna (Katsuwonus pelamis) and the Yellowfin tuna (Thunnus albacares), highly targeted by fisheries off west Africa. We also explored prey diversity overlap between these tuna species and the seabird species breeding in Cabo Verde that are most likely to share prey preferences and suffer from bycatch, the Brown booby (Sula leucogaster) and Cape Verde shearwater (Calonectris edwardsii). Overall, the diet of both tuna species was more diverse than that of seabirds. Skipjack tuna diet was dominated by prey from lower trophic levels, such as krill, anchovies, and siphonophores, while the Yellowfin tuna diet was mainly based on epipelagic fish such as flying and halfbeak fishes. Some of the most abundant prey families detected in the Yellowfin tuna diet were shared with both seabird species, resulting in a high prey diversity overlap between this tuna species and seabirds These results have implications for the management of tuna fisheries in the Eastern Tropical Atlantic, because a large decrease of both tuna species might have cascading effects on both primary and secondary consumer levels, and the decrease of these underwater predators may have implications on the viability of tropical seabird populations.

The richness and structure of symbiont assemblages are shaped by many factors acting at different spatial and temporal scales. Among them, host phylogeny and geographic distance play essential roles. To explore drivers of richness and structure of symbiont assemblages, feather mites and seabirds are an attractive model due to their peculiar traits. Feather mites are permanent ectosymbionts and considered highly host-specific with limited dispersal abilities. Seabirds harbour species-rich feather mite communities and their colonial breeding provides opportunities for symbionts to exploit several host species. To unravel the richness and test the influence of host phylogeny and geographic distance on mite communities, we collected feather mites from 11 seabird species breeding across the Atlantic Ocean and Mediterranean Sea. Using morphological criteria, we identified 33 mite species, of which 17 were new or recently described species. Based on community similarity analyses, mite communities were clearly structured by host genera, while the effect of geography within host genera or species was weak and sometimes negligible. We found a weak but significant effect of geographic distance on similarity patterns in mite communities for Cory’s shearwaters Calonectris borealis. Feather mite specificity mainly occurred at the host-genus rather than at host-species level, suggesting that previously inferred host species-specificity may have resulted from poorly sampling closely related host species. Overall, our results show that host phylogeny plays a greater role than geography in determining the composition and structure of mite assemblages and pinpoints the importance of sampling mites from closely-related host species before describing mite specificity patterns.

Speciation is a continuous and complex process shaped by the interaction of numerous evolutionary forces. Despite the continuous nature of the speciation process, the implementation of conservation policies relies on the delimitation of species and evolutionary significant units (ESUs). Puffinus shearwaters are globally distributed and threatened pelagic seabirds. Due to remarkable morphological status the group has been under intense taxonomic debate for the past three decades. Here, we use double digest Restriction-Site Associated DNA sequencing (ddRAD-Seq) to genotype species and subspecies of North Atlantic and Mediterranean Puffinus shearwaters across their entire geographical range. We assess the phylogenetic relationships and population structure among and within the group, evaluate species boundaries, and characterise the genomic landscape of divergence. We find that current taxonomies are not supported by genomic data and propose a more accurate taxonomy by integrating genomic information with other sources of evidence. Our results show that several taxon pairs are at different stages of a speciation continuum. Our study emphasises the potential of genomic data to resolve taxonomic uncertainties, which can help to focus management actions on relevant taxa, even if they do not necessarily coincide with the taxonomic rank of species.

Anthropogenic climate change is resulting in spatial redistributions of many species. We assessed the potential effects of climate change on an abundant and widely distributed group of diving birds, Eudyptes penguins, which are the main avian consumers in the Southern Ocean in terms of biomass consumption. Despite their abundance, several of these species have undergone population declines over the past century, potentially due to changing oceanography and prey availability over the important winter months. We used light-based geolocation tracking data for 485 individuals deployed between 2006 and 2020 across 10 of the major breeding locations for five taxa of Eudyptes penguins. We used boosted regression tree modelling to quantify post-moult habitat preference for southern rockhopper (E. chrysocome), eastern rockhopper (E. filholi), northern rockhopper (E. moseleyi) and macaroni/royal (E. chrysolophus and E. schlegeli) penguins. We then modelled their redistribution under two climate change scenarios, representative concentration pathways RCP4.5 and RCP8.5 (for the end of the century, 2071–2100). As climate forcings differ regionally, we quantified redistribution in the Atlantic, Central Indian, East Indian, West Pacific and East Pacific regions. We found sea surface temperature and sea surface height to be the most important predictors of current habitat for these penguins; physical features that are changing rapidly in the Southern Ocean. Our results indicated that the less severe RCP4.5 would lead to less habitat loss than the more severe RCP8.5. The five taxa of penguin may experience a general poleward redistribution of their preferred habitat, but with contrasting effects in the (i) change in total area of preferred habitat under climate change (ii) according to geographic region and (iii) the species (macaroni/royal vs. rockhopper populations). Our results provide further understanding on the regional impacts and vulnerability of species to climate change.

Over the last decades, the study of movement through tracking data has grown exceeding the expectations of movement ecologists. This has posed new challenges, specifically when using individual tracking data to infer higher-level distributions (e.g. population and species). Sources of variability such as individual site fidelity (ISF), environmental stochasticity over time, and space-use variability across species ranges must be considered, and their effects identified and corrected, to produce accurate estimates of spatial distribution using tracking data. We developed R functions to detect the effect of these sources of variability in the distribution of animal groups when inferred from individual tracking data. These procedures can be adapted for their use in most tracking datasets and tracking techniques. We demonstrated our procedures with simulated datasets and showed their applicability on a real-world dataset containing 1346 year-round migratory trips from 805 individuals of three closely related seabird species breeding in 34 colonies in the Mediterranean Sea and the Atlantic Ocean, spanning 10 years. We detected an effect of ISF in one of the colonies, but no effect of the environmental stochasticity on the distribution of birds for any of the species. We also identified among-colony variability in nonbreeding space use for one species, with significant effects of population size and longitude. This work provides a useful, much-needed tool for researchers using animal tracking data to model species distributions or establish conservation measures. This methodology may be applied in studies using individual tracking data to accurately infer the distribution of a population or species and support the delineation of important areas for conservation based on tracking data. This step, designed to precede any analysis, has become increasingly relevant with the proliferation of studies using large tracking datasets that has accompanied the globalization process in science driving collaborations and tracking data sharing initiatives.

Phenological divergence between conspecific populations breeding sympatrically is increasingly recognized as an important evolutionary process that may lead to allochronic speciation. However, the extent to which adaptation to differences in the timing of breeding may contribute to this process remains unclear. In this study, we assessed breeding phenology, population connectivity, and niche differentiation of two allochronic populations we of the Cape Verde Storm-petrel (Hydrobates jabejabe). We monitored nesting activity, marked individuals, tracked individuals during both the breeding and nonbreeding periods, and determined the trophic niche during both the breeding and nonbreeding periods. Timing of breeding for the two allochronic populations segregated into a hot (March-August) and cool (September-February) season (hereafter, hot and cool populations). These periods matched the two annual pulses of oceanic productivity around Cabo Verde, suggesting allochrony was primarily driven by a biannual cyclicity in food availability. Despite their allochronic breeding, there was, however, low differentiation between the hot and cool populations in spatial use, daily activity patterns, and trophic niche during both the breeding and nonbreeding periods. Further, the exchange of breeders between seasons, as documented through the recapture of marked individuals, may hinder seasonal adaptation by each population and ultimately, allochronic speciation. Consequently, allochrony alone may not be sufficient to drive speciation unless reproductive isolation between populations is complete or populations become strongly adapted to the environmental conditions associated with their timing of breeding.

Previous observations in Barcelona and other cities showed that approximately 40% of the food ingested by adult Monk Parakeets Myiopsitta monachus is of anthropogenic origin. Here we show that this type of food source is also used for feeding nestlings. To quantify the proportion of anthropogenic food within the diet of nestling Monk Parakeets, a non-native species in Barcelona. We analysed stable isotopes of ¹³C and ¹⁵N in feathers of Monk Parakeet nestlings collected in the Barcelona city area. We also sampled potential food sources ingested by Monk Parakeets to reconstruct the nestling diet using Bayesian mixing models with MixSIAR. Almost 30% of the nestlings’ diet was composed of anthropogenic food. Since food availability is a major factor regulating population growth, we propose educating the general public to reduce the food supply for the species and ultimately limit its population growth.

Acquiring basic knowledge such as at-sea distribution is often difficult for cryptic seabird species. Northern storm petrels (Hydrobatidae) are one family of seabirds that includes several cryptic species, including Ainley's Storm Petrel Hydrobates cheimomnestes, which appears quite similar to southern Leach's H. leucorhous and Townsend's H. socorroensis Storm Petrels when at sea. For the first time, we describe the at-sea distribution of breeding Ainley's Storm Petrels obtained using GPS tracking. We found that these birds visit waters of the eastern North Pacific between central Baja California, Mexico and southern Alta California, USA. These findings expand existing knowledge of the range of this species, which had previously been based on a few at-sea sightings and specimens.

Climate change has repeatedly been shown to impact the demography and survival of marine top predators. However, most evidence comes from single populations of widely distributed species, limited mainly to polar and subpolar environments. Here, we aimed to evaluate the influence of environmental conditions on the survival of a tropical and migratory seabird over the course of its annual cycle. We used capture-mark-recapture data from three populations of Bulwer's petrel (Bulweria bulwerii) spread across the NE Atlantic Ocean, from the Azores, Canary, and Cabo Verde Islands (including temperate to tropical zones). We also inferred how the survival of this seabird might be affected under different climatic scenarios, defined by the Intergovernmental Panel on Climate Change. Among the environmental variables whose effect we evaluated (North Atlantic Oscillation index, Southern Oscillation Index, Sea Surface Temperature [SST] and wind speed), SST estimated for the breeding area and season was the variable with the greatest influence on adult survival. Negative effects of SST increase emerged across the three populations, most likely through indirect trophic web interactions. Unfortunately, our study also shows that the survival of Bulwer's petrel will be profoundly affected by the different scenarios of climate change, even with the most optimistic trajectory involving the lowest greenhouse gas emission. Furthermore, for the first time, our study predicts stronger impacts of climate change on tropical populations than on subtropical and temperate ones. This result highlights the devastating effect that climate change may also have on tropical areas, and the importance of considering multi-population approaches when evaluating its impacts which may differ across species distributions

Three feather mite species of the genus Brephosceles Hull, 1934 (Alloptidae: Alloptinae) were found on the European storm petrel, Hydrobates pelagicus (Procellariiformes: Hydrobatidae), in the Mediterranean Sea and North-east Atlantic Ocean. Brephosceles holoplax sp. n. is described as a new species; B. pelagicus (Vitzthum, 1921) and B. longirostris (Vitzthum, 1921) comb. n. formerly known only from females are redescribed from both sexes. The latter species has been transferred from the genus Alloptes Canestrini, 1879. All descriptions are supported by DNA barcode data.

The Balearic shearwater (Puffinus mauretanicus) is the most threatened seabird in Europe and a member of the most speciose group of pelagic seabirds, the order Procellariiformes, which exhibit extreme adaptations to a pelagic lifestyle. The fossil record suggests that human colonisation of the Balearic Islands resulted in a sharp decrease of the Balearic shearwater population size. Currently, populations of the species continue to be decimated mainly due to predation by introduced mammals and bycatch in longline fisheries, with some studies predicting its extinction by 2070. Here, using a combination of short and long reads, we generate the first high-quality reference genome for the Balearic shearwater, with a completeness amongst the highest across available avian species. We used this reference genome to study critical aspects relevant to the conservation status of the species and to gain insights into the adaptation to a pelagic lifestyle of the order Procellariiformes. We detected relatively high levels of genome-wide heterozygosity in the Balearic shearwater despite its reduced population size. However, the reconstruction of its historical demography uncovered an abrupt population decline potentially linked to a reduction of the neritic zone during the Penultimate Glacial Period (~194–135 ka). Comparative genomics analyses uncover a set of candidate genes that may have played an important role into the adaptation to a pelagic lifestyle of Procellariiformes, including those for the enhancement of fishing capabilities, night vision, and the development of natriuresis. The reference genome obtained will be the crucial in the future development of genetic tools in conservation efforts for this Critically Endangered species.

Understanding the evolution of migration requires knowledge of the patterns, sources, and consequences of variation in migratory behaviour, a need exacerbated by the fact that many migratory species show rapid population declines and require knowledge-based conservation measures. We therefore need detailed knowledge on the spatial and temporal distribution of individuals across their annual cycle, and quantify how the spatial and temporal components of migratory behaviour vary within and among individuals. We tracked 138 migratory journeys undertaken by 64 adult common terns (Sterna hirundo) from a breeding colony in northwest Germany to identify the annual spatiotemporal distribution of these birds and to evaluate the individual repeatability of eleven traits describing their migratory behaviour. Birds left the breeding colony early September, then moved south along the East Atlantic Flyway. Wintering areas were reached mid-September and located at the west and south coasts of West Africa as well as the coasts of Namibia and South Africa. Birds left their wintering areas late March and reached the breeding colony mid-April. The timing, total duration and total distance of migration, as well as the location of individual wintering areas, were moderately to highly repeatable within individuals (repeatability indexes: 0.36–0.75, 0.65–0.66, 0.93–0.94, and 0.98–1.00, respectively), and repeatability estimates were not strongly affected by population-level inter-annual variation in migratory behaviour. We found large between-individual variation in common tern annual spatiotemporal distribution and strong individual repeatability of several aspects of their migratory behaviour.

Palaeoceanographic changes can act as drivers of diversification and speciation, even in highly mobile marine organisms. Shearwaters are a group of globally distributed and highly mobile pelagic seabirds. Despite a recent well-resolved phylogeny, shearwaters have controversial species limits, and show periods of both slow and rapid diversification. Here, we explore the role of palaeoceanographic changes on shearwaters' diversification and speciation. We investigate shearwater biogeography and the evolution of a key phenotypic trait, body size, and we assess the validity of their current taxonomy. Location. We generated genomic (ddRAD) data to infer a time-calibrated species tree for the shearwaters. We estimated ancestral ranges and evaluated the roles of founder events, vicariance and surface ocean currents in driving diversification. We performed phylogenetic generalised least squares to identify potential predictors of variability in body size along the phylogeny. To assess the validity of the current taxonomy, we analysed genomic patterns of recent shared ancestry and differentiation among shearwater taxa. We identified a period of high dispersal and rapid speciation during the Late Pliocene–early Pleistocene. Species dispersal appears to be favoured by surface ocean currents, and founder events are supported as the main mode of speciation in these highly mobile pelagic seabirds. Body mass shows significant associations with life strategies and local conditions. The current taxonomy shows some incongruences with the patterns of genomic divergence. A reduction of neritic areas during the Pliocene seems to have driven global extinctions of shearwater species, followed by a subsequent burst of speciation and dispersal probably promoted by Plio-Pleistocene climatic shifts. Our findings extend our understanding on the drivers of speciation and dispersal of highly mobile pelagic seabirds and shed new light on the important role of palaeoceanographic events.

Every year, billions of birds undertake extensive migrations between breeding and non-breeding areas, facing challenges that require behavioural adjustments, particularly to flight timing and duration. Such adjustments in daily activity patterns and the influence of extrinsic factors (e.g., environmental conditions, moonlight) have received much more research attention in terrestrial than marine migrants. Taking advantage of the widespread deployment in recent decades of combined light-level geolocator-immersion loggers, we investigated diel organisation and influence of the moon on flight activities during the non-breeding season of 21 migrant seabird species from a wide taxonomic range (6 families, 3 orders). Migrant seabirds regularly stopped (to either feed or rest) during migration, unlike some terrestrial and wetland birds which fly non-stop. We found an overall increase for most seabird species in time in flight and, for several species, also in flight bout duration, during migration compared to when resident at the non-breeding grounds. Additionally, several nocturnal species spent more of the day in flight during migration than at non-breeding areas, and vice versa for diurnal species. Nocturnal time in flight tended to increase during full moon, both during migration and at the non-breeding grounds, depending on species. Our study provides an extensive overview of activity patterns of migrant seabirds, paving the way for further research on the underlying mechanisms and drivers.

Light-level geolocators are popular bio-logging tools, with advantageous sizes, longevity and affordability. Biologists tracking seabirds often presume geolocator spatial accuracies between 186 and 202 km from previously innovative, yet taxonomically, spatially and computationally limited, studies. Using recently developed methods, we investigated whether assumed uncertainty norms held across a larger-scale, multispecies study. We field-tested geolocator spatial accuracy by synchronously deploying these with GPS loggers on scores of seabirds across five species and 11 Mediterranean Sea, east Atlantic and south Pacific breeding colonies. We first interpolated geolocations using the geolocation package FLightR without prior knowledge of GPS tracked routes. We likewise applied another package, probGLS, additionally testing whether sea-surface temperatures could improve route accuracy. Geolocator spatial accuracy was lower than the ~200 km often assumed. probGLS produced the best accuracy (mean ± SD = 304 ± 413 km, n = 185 deployments) with 84.5% of GPS-derived latitudes and 88.8% of longitudes falling within resulting uncertainty estimates. FLightR produced lower spatial accuracy (408 ± 473 km, n = 171 deployments) with 38.6% of GPS-derived latitudes and 23.7% of longitudes within package-specific uncertainty estimates. Expected inter-twilight period (from GPS position and date) was the strongest predictor of accuracy, with increasingly equatorial solar profiles (i.e. closer temporally to equinoxes and/or spatially to the Equator) inducing more error. Individuals, species and geolocator model also significantly affected accuracy, while the impact of distance travelled between successive twilights depended on the geolocation package. Geolocation accuracy is not uniform among seabird species and can be considerably lower than assumed. Individual idiosyncrasies and spatiotemporal dynamics (i.e. shallower inter-twilight shifts by date and latitude) mean that practitioners should exercise greater caution in interpreting geolocator data and avoid universal uncertainty estimates. We provide a function capable of estimating relative accuracy of positions based on geolocator-observed inter-twilight period.

Seabirds, particularly Procellariiformes, are highly mobile organisms with a great capacity for long dispersal, though simultaneously showing high philopatry, two conflicting life-history traits that may lead to contrasted patterns of genetic population structure. Landmasses were suggested to explain differentiation patterns observed in seabirds, but philopatry, isolation by distance, segregation between breeding and nonbreeding zones, and oceanographic conditions (sea surface temperatures) may also contribute to differentiation patterns. To our knowledge, no study has simultaneously contrasted the multiple factors contributing to the diversification of seabird species, especially in the gray zone of speciation. We conducted a multilocus phylogeographic study on a widespread seabird species complex, the little shearwater complex, showing highly homogeneous morphology, which led to considerable taxonomic debate. We sequenced three mitochondrial and six nuclear markers on all extant populations from the Atlantic (lherminieri) and Indian Oceans (bailloni), that is, five nominal lineages from 13 populations, along with one population from the eastern Pacific Ocean (representing the dichrous lineage). We found sharp differentiation among populations separated by the African continent with both mitochondrial and nuclear markers, while only mitochondrial markers allowed characterizing the five nominal lineages. No differentiation could be detected within these five lineages, questioning the strong level of philopatry showed by these shearwaters. Finally, we propose that Atlantic populations likely originated from the Indian Ocean. Within the Atlantic, a stepping-stone process accounts for the current distribution. Based on our divergence time estimates, we suggest that the observed pattern of differentiation mostly resulted from historical and current variation in sea surface temperatures.

Biological production in the oceanic zone (i.e. waters beyond the continental shelves) is typically spatially patchy and strongly seasonal. In response, seabirds have adapted to move rapidly within and between ocean basins, making them important pelagic consumers. Studies in the Pacific, Southern and Indian Oceans have shown that seabirds are relatively abundant in major frontal systems, with species composition varying by water mass. In contrast, surprisingly little was known about seabird distribution in the oceanic North Atlantic until recent tracking showed that relative abundance and diversity peak in the Sub-polar Frontal Zone, west of the Mid-Atlantic Ridge, now proposed as a Marine Protected Area. However, absolute seabird abundance, distribution, age and species composition, and their potential environmental drivers in the oceanic temperate NW Atlantic remain largely unknown. Consequently, we systematically surveyed seabirds and environmental conditions across this area by ship in June 2017, then modelled the density of common species as functions of environmental covariates, validating model predictions against independent tracking data. Medium-sized petrels (99.8%), especially Great Shearwaters (Ardenna gravis, 63%), accounted for the majority of total avian biomass, which correlated at the macroscale with net primary production and peaked at the sub-polar front. At the mesoscale, the density of each species was associated with sea surface temperature, indicating zonation by water mass. Most species also exhibited scale-dependent associations with eddies and fronts. Approximately 51, 26, 23, 7 and 1 % of the currently estimated Atlantic populations of Cory's Shearwaters (Calonectris borealis), Great Shearwaters, Sooty Shearwaters (A. grisea), Northern Fulmars (Fulmarus glacialis) and Leach’s Storm-petrels (Oceanodroma leucorhoa) occurred in the area during our survey, many of which were undergoing moult (a vital maintena nce activity). For some species, these estimates are higher than suggested by tracking, probably due to the presence of immatures and birds from untracked populations. Our results support the conclusion that MPA status is warranted and provide a baseline against which future changes can be assessed. Moreover, they indicate potential drivers of seabird abundance and diversity in the oceanic zone of the North Atlantic that should be investigated further.

The conservation of migratory marine species, including pelagic seabirds, is challenging because their movements span vast distances frequently beyond national jurisdictions. Here, we aim to identify important aggregations of seabirds in the North Atlantic to inform ongoing regional conservation efforts. Using tracking, phenology, and population data, we mapped the abundance and diversity of 21 seabird species. This revealed a major hotspot associated with a discrete area of the subpolar frontal zone, used annually by 2.9–5 million seabirds from =56 colonies in the Atlantic: the first time this magnitude of seabird concentrations has been documented in the high seas. The hotspot is temporally stable and amenable to site-based conservation and is under consideration as a marine protected area by the OSPAR Commission. Protection could help mitigate current and future threats facing species in the area. Overall, our approach provides an exemplar data-driven pathway for future conservation efforts on the high seas.

Costs of reproduction on survival have captured the attention of researchers since life history theory was formulated. Adults of long-lived species may increase survival by reducing their breeding effort or even skipping reproduction. In this study, we aimed to evaluate the costs of current reproduction on survival and whether skipping reproduction increases adult survival in a long-lived seabird. We used capture–mark–recapture data (1450 encounters) from two populations of Bulwer's petrel (Bulweria bulwerii), breeding in the Azores and Canary Islands, North Atlantic Ocean. Using a multi-event model with two different breeding statuses (breeders versus non-breeders), we calculated probabilities of survival and of transitions between breeding statuses, evaluating potential differences between sexes. Females had lower survival probabilities than males, independent of their breeding status. When considering breeding status, breeding females had lower survival probabilities than non-breeding females, suggesting costs of reproduction on survival. Breeding males had higher survival probabilities than non-breeding males, suggesting that males do not incur costs of reproduction on survival and that only the highest quality males have access to breeding. The highest and the lowest probabilities of skipping reproduction were found in breeding males from the Azores and in breeding males from the Canary Islands, respectively. Intermediate values were observed in the females from both populations. This result is probably due to differences in the external factors affecting both populations, essentially predation pressure and competition. The existence of sex-specific costs of reproduction on survival in several populations of this long-lived species may have important implications for species population dynamics.

The diversification of modern birds has been shaped by a number of radiations. Rapid diversification events make reconstructing the evolutionary relationships among taxa challenging due to the convoluted effects of incomplete lineage sorting (ILS) and introgression. Phylogenomic data sets have the potential to detect patterns of phylogenetic incongruence, and to address their causes. However, the footprints of ILS and introgression on sequence data can vary between different phylogenomic markers at different phylogenetic scales depending on factors such as their evolutionary rates or their selection pressures. We show that combining phylogenomic markers that evolve at different rates, such as paired-end double-digest restriction site-associated DNA (PE-ddRAD) and ultraconserved elements (UCEs), allows a comprehensive exploration of the causes of phylogenetic discordance associated with short internodes at different timescales. We used thousands of UCE and PE-ddRAD markers to produce the first well-resolved phylogeny of shearwaters, a group of medium-sized pelagic seabirds that are among the most phylogenetically controversial and endangered bird groups. We found that phylogenomic conflict was mainly derived from high levels of ILS due to rapid speciation events. We also documented a case of introgression, despite the high philopatry of shearwaters to their breeding sites, which typically limits gene flow. We integrated state-of-the-art concatenated and coalescent-based approaches to expand on previous comparisons of UCE and RAD-Seq data sets for phylogenetics, divergence time estimation, and inference of introgression, and we propose a strategy to optimize RAD-Seq data for phylogenetic analyses. Our results highlight the usefulness of combining phylogenomic markers evolving at different rates to understand the causes of phylogenetic discordance at different timescales.

Bycatch – a term widely used to refer to part of the catch unintentionally caught during a fishing operation, in addition to target species, and consisting of the discards and incidental catch of vulnerable species – is considered one of the most important threats to the profitability and sustainability of fisheries, as well as to the conservation of the marine environment and ecosystems. Understanding the bycatch issue and adopting effective measures in order to reduce bycatch rates are essential steps towards minimizing the impacts on vulnerable species and ensuring both a sustainable fisheries sector and healthy seas. In the Mediterranean and the Black Sea, the incidental catch of vulnerable species – namely seabirds, sea turtles, elasmobranchs, marine mammals and macrobenthic invertebrates – represents one of several challenges for the industrial, semi-industrial and small-scale fisheries that coexist in the region, as well as for the diverse and sensitive ecosystems impacted. Typically, data on this issue have been collected in an opportunistic manner and in ways that make comparisons difficult. The annual absolute values of incidental catch of vulnerable species are not available: studies cover only a small portion of the total fishing activity and often present important knowledge gaps for many types of fishing gear, countries and/or subregions, as well as on temporal scales, for example, to establish reliable baselines. The result is that little is known of the scope of the problem, despite incidental catch being a significant pressure on the populations of vulnerable species, as well as a concern for fishers.This regional review is an attempt to compile, in one single document, all available data and historical records on the incidental catch of vulnerable species in the Mediterranean and Black Sea fisheries, obtained from existing literature, databases and other grey sources, and collated in a standardized and comparable way. The main objective is to provide comprehensive baseline information, earmark the main data gaps, as well as identify the most impacting types of fishing gear by taxonomic group. This work is a reminder of the importance of standardized data collection and the need to have baseline information in order to support decision-making in the identification of appropriate bycatch mitigation techniques, thus enabling analysis of their effectiveness and comparison over time and space, as well as facilitating the implementation of relevant conservation and/or management measures at the national, subregional and regional levels.

Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.

Sexual segregation in foraging strategies has been little studied in marine species with slight Sexual Size Dimorphism (SSD), particularly regarding the role of environmental conditions and fishery activities. Sexual differences in fishery attendance are of particular concern, since uneven mortality associated to bycatch may exacerbate impacts in wildlife populations. Using a seabird species with slight SSD, the Scopoli’s shearwater (Calonectris diomedea), we assessed sexual differences in foraging strategies, and evaluated whether annual environmental conditions and fishery activity shaped such differences. We compared a four-year dataset combining bird GPS tracking, stable isotope analysis, the North-Atlantic Oscilation index (NAO, as main proxy of the annual environmental conditions), and fishing vessel positioning data (Vessel Monitoring System, VMS) from the North-Western Mediterranean, a region under intense fishery pressure. From 2012 to 2015, we tracked 635 foraging trips from 78 individual.Females showed a greater foraging effort, a lower fishery attendance, a lower trophic level and a narrower isotopic niche width than males. Moreover, in years with unfavourable environmental conditions, both sexes showed a lower fishery attendance and increased foraging effort compared to the year with most favourable conditions. Our results revealed that environmental conditions influence space use, feeding resources and fishery attendance differently between males and females, overall suggesting competitive exclusion of females by males from main foraging areas and feeding resources, particularly in unfavourable environmental conditions. We highlight the importance of evaluating sexual segregation under disparate environmental conditions, particularly in species with slight SSD, since segregation may pass otherwise unnoticed if only years with similar environmental conditions are considered. The higher fishery attendance of males likely explains the male-biased bycatch ratio for this species. Thus, inter-sexual differences in foraging strategies can lead to an unbalanced exposure of each sex to relevant threats for the conservation of long-lived species.

Whole-genome sequencing projects are increasingly populating the tree of life and characterizing biodiversity. Sparse taxon sampling has previously been proposed to confound phylogenetic inference5, and captures only a fraction of the genomic diversity. Here we report a substantial step towards the dense representation of avian phylogenetic and molecular diversity, by analysing 363 genomes from 92.4% of bird families—including 267 newly sequenced genomes produced for phase II of the Bird 10,000 Genomes (B10K) Project. We use this comparative genome dataset in combination with a pipeline that leverages a reference-free whole-genome alignment to identify orthologous regions in greater numbers than has previously been possible and to recognize genomic novelties in particular bird lineages. The densely sampled alignment provides a single-base-pair map of selection, has more than doubled the fraction of bases that are confidently predicted to be under conservation and reveals extensive patterns of weak selection in predominantly non-coding DNA. Our results demonstrate that increasing the diversity of genomes used in comparative studies can reveal more shared and lineage-specific variation, and improve the investigation of genomic characteristics. We anticipate that this genomic resource will offer new perspectives on evolutionary processes in cross-species comparative analyses and assist in efforts to conserve species.

Niche partitioning among different age, breeding status or sex classes allows resource use to be maximized while reducing intraspecific competition. Individual specialization marks the finest scale of niche partitioning where, within a species, individuals differ in their realized niches. Despite having important implications in ecology, evolution and conservation, studies simultaneously addressing the occurrence of both phenomena are scarce. We studied niche partitioning and individual specialization in foraging behaviour in relation to age, breeding status and sex using breeding, nonbreeding adult and immature Scopoli's shearwaters, Calonectris diomedea, in Minorca (Balearic Is.) during chick rearing in 2017 with GPS loggers and stable isotopes. Compared to adults, immature birds seemed to exploit a larger area at the population level, possibly to avoid competition. We found similar levels of individual specialization in immature and adult birds, which suggests the former have well-defined foraging strategies prior to prospecting the colony. For breeding status, we did not find niche partitioning or differences in individual specialization, suggesting nest attachment and pair bonds also lead to central-place foraging in nonbreeding adults. Male breeders showed greater individual specialization than female breeders in trip characteristics. At the same time, individual specialization in isotopic diet was higher in females than in males. These opposite patterns are possibly driven by a greater use of fishery discards by males, which would underlie their individual strategies of following vessels, resulting in a highly variable diet, since discarded prey types vary more than naturally accessible prey. Our results suggest that seabirds acquire individual strategies early in life and, once they are sexually mature, breeding constraints do not result in differences in feeding behaviour between breeders and nonbreeders. Finally, we showed that sexual differences in individual specialization can apparently emerge even in slightly dimorphic species sharing breeding duties.

Campylobacter spp. and Salmonella spp. are the two most frequent zoonotic bacteria involved in human enteric infections in the European Union. Both enteropathogens have been isolated from a diversity of wild birds in Northern Europe, but there is limited information about gulls as potential reservoirs in Southern Europe. A broad sampling of fledglings from nine colonies of yellow-legged gull (Larus michahellis, N = 1222) and Audouin's gull (Larus audouinii, N = 563) has been conducted in Spain and Tunisia during the late chick-rearing period. Overall, the occurrence of Campylobacter spp. and Salmonella spp. was 5.2% (93/1785, CI95%: 4.2–6.2%) and 20.8% (371/1785, CI95%: 18.9–22.7%), respectively. The most predominant Campylobacter species was C. jejuni (94.6%). A high diversity of Salmonella serovars was isolated and the most frequent were those also reported in human outbreaks, such as Salmonella Typhimurium. A high proportion of Campylobacter and Salmonella isolates showed resistance to at least one antimicrobial agent (20.2% and 51.5%, respectively), while 19.2% of Salmonella isolates were multidrug-resistant. These results show the relevance of gulls as reservoirs of Campylobacter and Salmonella by maintaining and spreading these bacteria, including resistant and multidrug resistant strains, in the environment. Our results suggest that gulls can serve as sentinel species for antibiotic pressure in the environment.

Pelagic seabird populations have declined strongly worldwide. In the North Atlantic there was a huge reduction in seabird populations following the European colonization of the Azores, Madeira and Canary archipelagos but information on seabird status and distribution for the subtropical region of Cabo Verde is scarce, unavailable or dispersed in grey literature. We compiled and compared the historical and current distribution of all seabird species breeding in the Cabo Verde archipelago, updated their relative abundance, investigated their inland habitat preferences, and reviewed their threats. Currently, the breeding seabird community in Cabo Verde is composed of Bulwer’s Petrel Bulweria bulwerii, White-faced Storm-petrel Pelagodroma marina aedesorum, Cape Verde Shearwater Calonectris edwardsii, Cape Verde Storm-petrel Hydrobates jabejabe, Cape Verde Petrel Pterodroma feae, Boyd’s Shearwater Puffinus lherminieri boydi, BrownBooby Sula leucogaster, and Red-billed Tropicbird Phaethon aethereus. One breeding species is currently extinct, the Magnificent Frigatebird Fregata magnificens. The relative abundance of Cape Verde Shearwater, Boyd’s Shearwater, Cape Verde Petrel, and Cape Verde Storm-petrel was determined from counts of their nocturnal calls in Santo Antão, São Vicente, Santa Luzia, Branco, Raso and São Nicolau. Cape Verde Petrel occurred only on mountainous islands (Santo Antão, São Nicolau, Santiago, and Fogo) from mid-to high elevations. Larger species such as the Cape Verde Shearwater and Boyd’s Shearwater exhibited a wider distribution in the archipelago, occurring close to the coastline but at lower densities on populated islands. Small procellariforms such as the CapeVerde Storm-petrel occurred at high densities only on rat-free islets and in steep areas of main islands where introduced cats and rats are unlikely to occur. The main threats to seabird populations in Cabo Verde range frompredation by introduced predators, habitat alteration or destruction, and some residual human persecution.

Seabirds inhabiting vast water masses provide numerous examples where opposing phenomena, such as natal and breeding philopatry vs. vagility have dug cryptic taxonomic boundaries among closely related taxa. The taxonomy of little shearwaters of the North Atlantic Ocean (Little–Audubon’s shearwater complex, Puffinus assimilis–lherminieri) still remains unclear, and complementary information on non-breeding distributions and at-sea behaviour becomes essential to unravel divergent local adaptations to specific habitats. Using miniaturized light-level geolocators from seven study areas in the North Atlantic, we evaluate the spatial and habitat segregation, estimate the timing of their key life-cycle events and describe the at-sea behaviour of three taxa of these little shearwaters year-round to distinguish ecological patterns and specializations that could ultimately unravel potential lineage divergences. We also assess morphometric data from birds that were breeding at each study area to further discuss potential adaptations to specific habitats. Our results show that, while birds from different taxa segregated in space and habitats, they share ecological plasticity, similar annual phenology and diel foraging behaviour. These ecological inconsistencies, while defining the evolutionary stressors faced by these taxa, do not suggest the existence of three Evolutionary Significant Units. However, they confirm the recent evolutionary divergence among the three little shearwaters of the North Atlantic.

Food is a main limiting factor for most populations. As a consequence, knowledge about the diet of invasive alien species determines the design of control measures. The Monk and Rose-ringed parakeets are two typical species of successful invasive parrots that are highly appreciated by people. Although some observations suggest that Monk parakeets rely on a higher percentage of anthropogenic food than Rose-ringed parakeets, no detailed quantitative data is available. The aim of this study was to compare the diet of the two parakeets using stable isotope analysis (SIA). We performed SIA of carbon and nitrogen in feathers collected in Barcelona, Spain. We also measured isotopic ratios for potential food sources. We reconstructed the diet of parakeets using Bayesian mixing models. The two species differed in the isotopic signatures of their feathers for both δ¹³C and δ¹⁵N. Diet reconstruction showed that Monk parakeets feed mainly on anthropogenic food (41.7%), herbaceous plants (26.9%) and leaves/seeds (22.2%), while Rose-ringed parakeets feed mainly on flowers/fruits (44.1%), anthropogenic food provided in the trap located at the museum (32.4%) and leaves/seeds (23.1%). The more detailed information we can obtain from the diet of these species is useful to develop more effective control measures for their populations. The Monk parakeet may be more susceptible to control through education local residents, given the greater use of anthropogenic food in this species compared to Rose-ringed parakeet. Our conclusions also indicate that SIA is a powerful tool in providing crucial information about the diet and informing measures to control invasive species.

The identification of geographic areas where the densities of animals are highest across their annual cycles is a crucial step in conservation planning. In marine environments, however, it can be particularly difficult to map the distribution of species, and the methods used are usually biased towards adults, neglecting the distribution of other life-history stages even though they can represent a substantial proportion of the total population. Here we develop a methodological framework for estimating population-level density distributions of seabirds, integrating tracking data across the main life-history stages (adult breeders and non-breeders, juveniles and immatures). We incorporate demographic information (adult and juvenile/immature survival, breeding frequency and success, age at first breeding) and phenological data (average timing of breeding and migration) to weight distribution maps according to the proportion of the population represented by each life-history stage. We demonstrate the utility of this framework by applying it to 22 species of albatrosses and petrels that are of conservation concern due to interactions with fisheries. Because juveniles, immatures and non-breeding adults account for 47%–81% of all individuals of the populations analysed, ignoring the distributions of birds in these stages leads to biased estimates of overlap with threats, and may misdirect management and conservation efforts. Population-level distribution maps using only adult distributions underestimated exposure to longline fishing effort by 18%–42%, compared with overlap scores based on data from all life-history stages. Synthesis and applications . Our framework synthesizes and improves on previous approaches to estimate seabird densities at sea, is applicable for data-poor situations, and provides a standard and repeatable method that can be easily updated as new tracking and demographic data become available. We provide scripts in the R language and a Shiny app to facilitate future applications of our approach. We recommend that where sufficient tracking data are available, this framework be used to assess overlap of seabirds with at-sea threats such as overharvesting, fisheries bycatch, shipping, offshore industry and pollutants. Based on such an analysis, conservation interventions could be directed towards areas where they have the greatest impact on populations.

Despite its importance for ecology and conservation, we are still far from understanding how environmentalvariability interacts with intrinsic factors and individual specialization to determine trophic strategies of long-lived taxa, mostly due to difficulties in studying the same animals over extended periods. Here, by yearlyconsistently sampling thefirst primary feather of 99 Cory’s shearwaters (Calonectris borealis) foraging in the Canary Current (CC) upwelling ecosystem, we provide robust evidence on the individual changes of isotopicratios of carbon (δ¹³C) and nitrogen (δ¹⁵N) over 17 years. We reported a slight longitudinal decline of δ¹³C values throughout 2001–2017, even after being adjusted for the marine Suess effect (linked to the increasing CO₂ emissions). Although CC is often considered to be overexploited by industrialfisheries, we could not detect adecline in Cory’s shearwater trophic level indicating a change in the trophic web structuring, as revealed by δ¹⁵N. We found negative correlations of δ¹³C and δ¹⁵15N with the CC upwelling intensity, indicating annualvariability in baseline isotopic levels propagates through the food chain and it integrates in predators’tissues.Low individual repeatabilities among years at population level indicates low long-term specialization, suggestinglong-lived individuals foraging on highly productive areas can adjust their foraging strategies and diet accordingto environmental variability. However, individual-level repeatabilities in isotopic values showed a range ofindividual specialization within the population, indicating most individuals are generalist and a few of themhighly specialized. First, although we found a clear influence of the upwelling intensity on the trophic ecology ofbirds, we could not detect any temporal trend in the trophic level of the Cory’s shearwater population, suggestinga stability in the structure of the pelagic food web of the CC over the last two decades despite thefishingpressure. Second, the existence of individual specialization highlights the importance of considering the repeatedsampling of individuals to detect small changes in the trophic ecology of a population. Finally, the coexistence ofindividuals with different degree of specialization (from extremely flexible [generalists] to highly consistent individuals [specialists] within a population can have deep implications on the capacity of populations to copewith environmental change.

Stable isotope analyses (SIAs) have been widely used in recent years to infer the diet of many species. This isotopic approach requires using diet to tissue discrimination factors (DTDFs) for each prey type and predator tissue, i.e., to determine the difference between the isotopic composition of the predator tissues and the different prey that conform its diet. Information on DTDF values in Psittaciformes is scarce. The aim of this study was to assess DTDF values for the carbon and nitrogen isotopes of the monk parakeet (Myiopsitta monachus) and the ring–necked parakeet (Psittacula krameri), two invasive alien species of concern. We fed captive birds of the two parakeet species on a single–species diet based on sunflower seeds to establish the DTDFs for the blood and feathers. In the monk parakeet (N = 9) DTDFs were Δδ¹³C 2.14 ‰ ± 0.90 and Δδ¹⁵N 3.21 ‰ ± 0.75 for the blood, and Δδ¹³C 3.97 ‰ ± 0.90 and Δδ¹⁵N 3.67 ‰ ± 0.74 for the feathers. In the ring–necked parakeet (N = 9), the DTDFs were Δδ¹³C (‰) 2.58 ± 0.90 and Δδ¹⁵N (‰) 2.35 ± 0.78 for the blood, and Δδ¹³C 3.64 ‰ ± 0.98 and Δδ¹⁵N 4.10 ‰ ± 1.84 for the feathers. DTDF values for the ring–necked parakeet blood were significantly higher than those for the monk parakeet blood. No difference was found between the two species in the DTDF for feathers. Our findings provide the first values of DTDFs for blood and feathers in these parakeets, factors that are key to infer the diet of these species based on SIA.

Insights into the year-round movements and behaviour of seabirds are essential to better understand their ecology and to evaluate possible threats at sea. The Atlantic petrel Pterodroma incerta is an Endangered gadfly petrel endemic to the South Atlantic Ocean, with virtually the entire population breeding on Gough Island (Tristan da Cunha archipelago). We describe adult phenology, habitat preferences and at-sea activity patterns for each phenological phase of the annual cycle and refine current knowledge about its distribution, by using light-level geolocators on 13 adults over 1-3 consecutive years. We also ascertained moulting pattern through stable isotope analysis (SIA) of nitrogen and carbon in feathers from 8 carcasses. On average, adults started their post-breeding migration on 25 December, taking 10 d to reach their non-breeding areas on the South American shelf slope. The pre-breeding migration started around 11 April and took 5 d. From phenological data, we found evidence of carry-over effects between successive breeding periods. The year-round distribution generally coincided with the potential distribution obtained from habitat modelling, except during the non-breeding and pre-laying exodus periods, when birds only used the western areas of the South Atlantic. Moulting occurred during the non-breeding period, when birds spent more time on the water, and results from SIA helped us to distinguish feathers grown around Gough Island from those grown in the non-breeding area. Overall, our results bring important new insights into the spatial ecology of this Endangered seabird, which should help improve conservation strategies in the South Atlantic Ocean.

The distributions of migratory species in the ocean span local, national and international jurisdictions. Across these ecologically interconnected regions, migratory marine species interact with anthropogenic stressors throughout their lives. Migratory connectivity, the geographical linking of individuals and populations throughout their migratory cycles, influences how spatial and temporal dynamics of stressors affect migratory animals and scale up to influence population abundance, distribution and species persistence. Population declines of many migratory marine species have led to calls for connectivity knowledge, especially insights from animal tracking studies, to be more systematically and synthetically incorporated into decision-making. Inclusion of migratory connectivity in the design of conservation and management measures is critical to ensure they are appropriate for the level of risk associated with various degrees of connectivity. Three mechanisms exist to incorporate migratory connectivity into international marine policy which guides conservation implementation: site-selection criteria, network design criteria and policy recommendations. Here, we review the concept of migratory connectivity and its use in international policy, and describe the Migratory Connectivity in the Ocean system, a migratory connectivity evidence-base for the ocean. We propose that without such collaboration focused on migratory connectivity, efforts to effectively conserve these critical species across jurisdictions will have limited effect.

Light-level geolocators are increasingly popular devices for tracking migratory birds. However, to ensure that data on migratory behaviour represent natural behaviour that is not affected by potentially harmful effects of carrying such a device, their effects on behaviour and fitness should be assessed. A review of studies that tested for effects of tarsus-mounted light-level geolocators on seabirds showed that results are equivocal and often difficult to interpret due to the inclusion of only few traits and/or the lack of a proper experimental design. We therefore experimentally tested whether tarsus-mounted light-level geolocators affected a long-distance migratory seabird, the Common Tern Sterna hirundo. Using a well-matched treatment and control group, including both males and females, we tested whether light-level geolocators, deployed in the second half of incubation, affected the subsequent share of incubation, provisioning rate, reproductive performance, phenology or survival of tagged birds or their partners. In the year of deployment, we found no evidence for the behaviour of tagged birds or their partners to be affected by the geolocators. Moreover, we found no effect on their reproductive performance and departure date from the breeding colony. Finally, neither local survival to the next season, nor arrival date to the breeding colony in that season differed between tagged birds or their partners and control birds. These results suggest that a year of carrying a light-level geolocator attached to the tarsus has negligible effects on Common Terns and that such a device can be used to study their migratory behaviour without causing problems or introducing bias.

This monograph revealed the most relevant areas used by the Canarian population of Bulwer’s petrel along its annual cycle. During the breeding season, petrels showed a considerable use of the waters nearby Azores (Portugal) and the waters of Morocco and Western Sahara, although always remained in oceanic waters out of the continental shelf. During the non-breeding season, most petrels concentrated mainly in Central and South Atlantic waters. Therefore, to guarantee the conservation of this species, it is essential a good environmental management of the oceanic water of these countries, as well as of the high sea territories. GPSs and geolocators used in the framework of this study were deployed mainly in breeders. However, it is important to highlight that probably more than 50% of the population is formed by immature petrels, which may show a different use of the space than breeders. Therefore, to achieve a more comprehensive view on the spatial ecology of Bulwer’s petrel, it is essential to fill this gap of knowledge by tracking juvenile and inmature birds with GPSs and geolocators. In addition, the data provided in this monograph are based on the tracked individuals from a single breeding colony of Bulwer’s petrel. Therefore, ideally similar studies should be carried out in other Canarian populations, since birds from other localities may show distinct foraging patterns. Bulwer’s petrel threats at high sea are still uncertain, however the effects of global warming on the oceans certainly is among the major ones. Knowing the actual distribution of Bulwer’s petrel populations will allow, among other things, to model the effect that the global warming would have in the distribution of this species, since the tropical species are thought to be the first to suffer the impacts of this warming.

To evaluate how avian influenza virus (AIV) circulates among the avifauna of the Antarctic and sub-Antarctic islands, we surveyed 14 species of birds from Marion, Livingston and Gough islands. A competitive enzyme-linked immunosorbent assay was carried out on the sera of 147 birds. Quantitative reverse transcription polymerase chain reaction was used to detect the AIV genome from 113 oropharyngeal and 122 cloacal swabs from these birds. The overall seroprevalence to AIV infection was 4.8%, with the only positive results coming from brown skuas (Catharacta antarctica) (4 out of 18, 22%) and southern giant petrels (Macronectes giganteus) (3 out of 24, 13%). Avian influenza virus antibodies were detected in birds sampled from Marion and Gough islands, with a higher seroprevalence on Marion Island (P = 0.014) and a risk ratio of 11.29 (95% confidence interval: 1.40–91.28) compared to Gough Island. The AIV genome was not detected in any of the birds sampled. These results confirm that AIV strains are uncommon among Antarctic and sub-Antarctic predatory seabirds, but they may suggest that scavenging seabirds are the main avian reservoirs and spreaders of this virus in the Southern Ocean. Further studies are necessary to determine the precise role of these species in the epidemiology of AIV.

Sexual segregation (SS) is widespread among animal taxa, with males and females segregated in distribution, behavior, or feeding ecology but so far, most studies on birds have focused on the breeding period. Outside this period, the relevance of segregation and the potential drivers of its persistence remain elusive, especially in the marine environment, where animals can disperse over vast areas and are not easily observed. We evaluated the degree of SS in spatio-temporal distribution and phenology, at-sea behavior, and feeding ecology during the nonbreeding period among three closely related shearwaters: Scopoli's, Cory's, and Cape Verde shearwaters (Calonectris diomedea, C. borealis , and C. edwardsii, respectively). We tracked 179 birds (92 males and 87 females) from 2008 to 2013 using geolocation-immersion loggers and collected the 13th secondary remige (molted in winter) for stable isotope analyses as a proxy of trophic level and diet. The global nonbreeding distribution did not differ between sexes for the three species, but one specific nonbreeding area was visited only by males. Cory's shearwater males remained in areas closer to the colony in a larger proportion compared to females and returned earlier to the colony, probably to defend their nests. Males presented a slightly lower nocturnal flying activity and slightly (but consistently) higher isotopic values of d13C and d15N compared to females. These differences suggest subtle sexual differences in diet and a slightly higher trophic level in males, but the extent to which sexual dimorphism in bill size can determine them remains unclear. Our study showed that SS in ecological niche in seabirds can persist year-round consistently but at a different extent when comparing the breeding and nonbreeding periods. Based on our findings, we propose that SS in these seabird species might have its origin in an ecological specialization derived from the different roles of males and females during reproduction, rather than from social dominance during the nonbreeding period.

Many generalist species are composed of individuals varying in the size of their realized niches within a population. To understand the underlying causes and implications of this phenomenon, repeated samplings on the same individuals subjected to different environmental conditions are needed. Here, we studied individual specialization of feeding strategies in breeding and nonbreeding grounds of Cory’s shearwaters (Calonectris borealis) for 2–8 years, and its relationship with fitness. Individuals were relatively flexible in nonbreeding destinations, but specialized in diet, habitat use and daily activity across years. Daily activity was also consistent throughout the year for the same individual, suggesting that it is driven by individual constraints, whereas individual diet and habitat use changed between breeding and non-breeding grounds, indicating that these specializations may be learned at each area. Moreover, individuals that were intermediate specialized in their diet tended to show higher breeding success than those with weakly and highly specialized diets, suggesting stabilizing selection. Overall, this study suggests that the development of individual specialization is more flexible than previously thought, i.e. it emerges under specific environmental conditions and can develop differently when environmental conditions vary. However, once established, individual specialization may compromise the ability of individuals to cope with environmental stochasticity.

In this study, we evaluate the main factors driving the exposure of Southern Ocean seabirds to perfluoroalkyl substances (PFASs) across a wide geographic range. Five perfluoroalkane sulfonates (PFSAs, C4–12), 10 perfluoroalkyl carboxylic acids (PFCAs, C4–13), and perfluorooctane sulfonamide (FOSA) were analyzed in plasma (n = 128) from eight species, including penguins, giant petrels, skuas, albatrosses, and shearwaters, breeding at four sites in the Antarctic, sub-Antarctic, and adjacent cool-temperate regions. Mean ?PFAS concentrations ranged from 0.53 to 53 ng/g wet weight from black-browed albatross to giant petrels, respectively. As expected due to biomagnification, greater concentrations of most PFASs were found in species near the top of marine food webs such as giant petrels. However, our results suggest that other factors, i.e., metabolic capabilities and spatial movements, can mask interspecies differences in PFASs, especially PFCAs, expected from trophic structure. For instance, trans-equatorial migratory seabirds exhibited PFAS levels and profiles that are consistent with northern hemisphere exposure, reflecting their potential biovector role in the global transport of these pollutants. Among resident species, greater concentrations of PFASs, especially long-chain PFCAs, were found in seabirds breeding or foraging north of the Antarctic Circumpolar Current (ACC) than in those restricted to Antarctic/sub-Antarctic distributions. Moreover, composition profiles of PFAS in Antarctic seabirds agree well with those expected from long-range transport. Our results confirm the importance of the ACC in protecting Antarctic food webs from water-phase-transported PFASs.

Using geolocator-immersion loggers, we tracked for the first time the migration of one Cory’s Shearwater Calonectris borealis fledgling, from its breeding colony in the Canary Islands, and along its first year of life. The juvenile bird initially followed the same migratory path as the adults but visited different areas of the Central and the South Atlantic Ocean.

Humans are inherently biased towards naming species based on morphological differences, which can lead to reproductively isolated species being mistakenly classified as one if they are morphologically similar. Recognising cryptic diversity is needed to understand drivers of speciation fully, and for accurate estimates of global biodiversity and assessments for conservation. We investigated cryptic species across the range of band-rumped storm-petrels (Hydrobates spp.): highly pelagic, nocturnal seabirds that breed on tropical and sub-tropical islands in the Atlantic and Pacific Oceans. In many breeding colonies, band-rumped storm-petrels have sympatric but temporally isolated (allochronic) populations; we sampled all breeding locations and allochronic populations. Using mitochondrial control region sequences from 754 birds, cytochrome b sequences from 69 birds, and reduced representation sequencing of the nuclear genomes of 133 birds, we uncovered high levels of genetic structuring. Population genomic analyses revealed up to seven unique clusters, and phylogenomic reconstruction showed that these represent seven monophyletic groups. We uncovered up to six independent breeding season switches across the phylogeny, spanning the continuum from genetically undifferentiated temporal populations to full allochronic species. Thus, band-rumped storm-petrels encompass multiple cryptic species, with non-geographic barriers potentially comprising strong barriers to gene flow.

Marine birds have been hypothesized to be underreported victims of harmful algal blooms (HABs). Toxic blooms of Pseudo-nitzschia spp., the primary amnesic toxin producer microalgae, domoic acid (DA) are known to cause massive mortalities of coastal seabirds and marine mammals around the world. However, these fatalities are only detected when birds die nearby the coastline and little is known about possible outbreaks of pelagic seabirds in oceanic areas. Here we aim to understand whether pelagic seabirds are exposed to amnesic shellfish poisoning (ASP) toxins. For this purpose, we tracked pelagic seabirds feeding on small epipelagic fish and squid, reported to be vectors of DA, which are obtained in high productivity zones where intense Pseudo-nitzschia blooms regularly occur. In particular, we tracked Cory’s (Calonectris borealis) and Scopoli’s (C. diomedea) shearwaters breeding in Gran Canaria (Canary Is.) and in Menorca (Balearic Is.) and feeding on the Canary Current region and the Catalonian coast, respectively. We sampled birds for blood at the recovery of the GPS (Global Positioning System) and analyzed it for DA determination by Liquid Chromatography coupled with Tandem Mass Spectrometry (LC–MS/MS). Among the 61 samples analyzed from Gran Canaria, and 87 from Menorca, 31 (50.8%) and 28 (32.2%) from each location presented detectable levels of DA ranging 1.0–10.6?ng mL-1. This work reveals that DA can be detected at variable levels in the blood of ASP-asymptomatic shearwaters and suggests a chronic exposure of shearwaters to DA, highlighting the need for further studies on DA effects. These results are of high relevance due to the vulnerability of these marine birds, which populations are in continuous decline. Since global warming is expected to alter and increase the occurrence of HABs, marine toxins might become an additional stressor for seabirds and exacerbate the already precarious conservation status of many species.

Non-breeding movement strategies of migratory birds may be expected to be flexibly adjusted to the distribution and quality of habitat, but few studies compare movement strategies among populations using distinct migration routes and wintering areas. In our study, individual movement strategies of red-necked phalaropes (Phalaropus lobatus), a long-distance migratory wader which uses saline waters in the non-breeding period, were studied using light-level geolocators. Results revealed a migratory divide between two populations with distinct migration routes and wintering areas: one breeding in the north-eastern North Atlantic and migrating ca. 10,000 km oversea to the tropical eastern Pacific Ocean, and the other breeding in Fennoscandia and Russia migrating ca. 6,000 km—largely over land—to the Arabian Sea (Indian Ocean). In line with our expectations, the transoceanic migration between the North Atlantic and the Pacific was associated with proportionately longer wings, a more even spread of stopovers in autumn and a higher migration speed in spring compared to the migration between Fennoscandian-Russian breeding grounds and the Arabian Sea. In the wintering period, van Bemmelen et al. Contrasting Movement Strategies in Phalaropes birds wintering in the Pacific were stationary in roughly a single area, whereas individuals wintering in the Arabian Sea moved extensively between different areas, reflecting differences in spatio-temporal variation in primary productivity between the two wintering areas. Our study is unique in showing how habitat distribution shapes movement strategies over the entire non-breeding period within a species.

The breeding phenology and nest site distribution of Red-billed Tropicbirds (Phaethon aethereus) was monitored from 6 June 2014 to 18 May 2016 on Parc National des Iles de la Madeleine, Senegal. During this period, this study site was visited every 15 days to record active nests and their contents (eggs or chicks). We found up to 76 nest sites but only 49 were active in 2014-2015 and 45 in 2015-2016. Red-billed Tropicbirds bred throughout the year but numbers of active nests peaked from October to January, which may be related to the seasonality of ocean upwelling. Nests were aggregated in four areas and their distribution and occupancy may be related to the direction of the wind during the seasonal peak of reproduction from October to May. The breeding success was generally high (62.9% in 2014-2015 and 47.3% in 2015-2016) compared to other colonies breeding in less productive waters. Given the singularity and small size of this population, monitoring, management and strict protection is clearly needed to guarantee its viability.

Efficiently tracking and anticipating the dynamics of infectious agents in wild populations requires the gathering of large numbers of samples, if possible at several locations and points in time, which can be a challenge for some species. Testing for the presence of specific maternal antibodies in egg yolks sampled on the colonies could represent an efficient way to quantify the exposure of breeding females to infectious agents, particularly when using an abundant and widespread species, such as the yellow-legged gull (Larus michahellis). We used such an approach to explore spatio-temporal patterns of exposure to Toxoplasma gondii, a pathogenic protozoan responsible of toxoplasmosis in humans and other warm blooded vertebrates. First, we tested the validity of this approach by exploring the repeatability of the detection of specific antibodies at the egg level using two different immunoassays and at the clutch level using an occupancy model. Then, samples gathered in 15 colonies from France, Spain and Tunisia were analysed using an immunoassay detecting antibodies specifically directed against T. gondii. Prevalence of specific antibodies in eggs was overall high while varying significantly among colonies. These results revealed that T. gondii circulated at a large spatial scale in the western Mediterranean yellow-legged gull population, highlighting its potential role in the maintenance community of this parasite. Additionally, this study illustrates how species commensal to human populations like large gulls can be used as wildlife sentinels for the tracking of infectious agents at the human-wildlife interface, notably by sampling eggs.

Bird migration studies have been increasing recently thanks to the miniaturization of tracking devices. However, for the smallest pelagic species, tracking methodologies have remained impractical and thus, important gaps in knowledge still exist. In the case of the European Storm Petrel (Hydrobates pelagicus), while Atlantic populations are thought to overwinter along the south-western African coast, the wintering grounds of Mediterranean birds remain more enigmatic. We performed stable isotope analysis (SIA) on P1, S8 and P10 feathers from 33 adult birds captured in three Atlantic colonies and 156 adult birds in seven western Mediterranean colonies to infer their wintering areas. In addition, we collated all observational field data, both from peer-reviewed publications and the grey literature, to complement our inferences from SIA. Isotopic profiles of feathers moulted at the breeding grounds (P1) differed between birds captured at northern Atlantic and Canary Islands colonies, but were similar for feathers moulted at wintering grounds (S8 and P10), indicating a low migratory connectivity. Isotopic values of feathers from western Mediterranean birds differed from those of Atlantic birds and showed Mediterranean values for all feathers, indicating that birds remain in Mediterranean waters during the winter. Variance in the isotopic values was greater in wintering than in breeding feathers, suggesting that birds disperse over larger areas. Isotopic values of feathers moulted during the non-breeding period could match a post-breeding movement towards the southern and eastern Mediterranean. This inference matches the distribution of the few winter reports, which are mainly concentrated in south-central Mediterranean, mostly in the Tunisian Platform. Our results suggest this region as the main wintering grounds for Mediterranean Storm Petrel.

Reports of enteric bacteria in Antarctic wildlife have suggested its spread from people to seabirds and seals, but evidence is scarce and fragmentary. We investigated the occurrence of zoonotic enteric bacteria in seabirds across the Antarctic and subantarctic region; for comparison purposes, in addition to seabirds, poultry in a subantarctic island was also sampled. Three findings suggest reverse zoonosis from humans to seabirds: the detection of a zoonotic Salmonella serovar (ser. Enteritidis) and Campylobacter species (e.g. C. jejuni), typical of human infections; the resistance of C. lari isolates to ciprofloxacin and enrofloxacin, antibiotics commonly used in human and veterinary medicine; and most importantly, the presence of C. jejuni genotypes mostly found in humans and domestic animals but rarely or never found in wild birds so far. We also show further spread of zoonotic agents among Antarctic wildlife is facilitated by substantial connectivity among populations of opportunistic seabirds, notably skuas (Stercorarius). Our results highlight the need for even stricter biosecurity measures to limit human impacts in Antarctica.

Studying the feeding ecology of seabirds is important not only to understand basic aspects of their ecology and threats but also for the conservation of marine ecosystems. In this regard, tropical seabirds have been relatively neglected, and in particular the trophic ecology of tropicbirds is scarcely known. We combined GPS tracking, environmental variables and sampling of regurgitates during incubation and brooding to understand the feeding ecology of red-billed tropicbirds Phaethon aethereus as well as how foraging strategies may change between 2 contrasting marine environments: a coastal island in the Canary Current upwelling (Iles de la Madeleine) and an oceanic island in the middle of the south Atlantic (St Helena). Tropicbirds breeding on the Iles de la Madeleine headed west, foraging on and beyond the shelf slope, probably to associate with subsurface predators which bring pelagic fish close to the surface. Birds from St Helena showed a greater foraging effort and a strong attraction to areas with the greatest species richness of Scombridae, possibly due to a greater difficulty in finding prey in the oligotrophic oceanic waters. Tropicbirds ranged much beyond the extension of the protected areas around their colonies, indicating that current protected areas are insufficient for these populations. We found no evidence to suspect direct mortality of tropicbirds in regional fisheries, but overexploitation of small epipelagic fish and tuna may decrease feeding opportunities and lead to competition with fisheries. The substantial differences in foraging behaviour demonstrated by individuals from both colonies indicates that caution should be taken when extrapolating foraging patterns of tropical seabirds breeding in contrasting oceanographic environments.

In predator populations, changes in foraging behaviour in response to spatio-temporal variability of prey are expected. Prey depletion might cause trophic niche widening in generalist species, but not in specialists, which are expected to increase their foraging effort without diet shifts. In sympatric species feeding on similar resources, reduced food availability can increase interspecific competition and cause trophic niche segregation. To understand these processes, we studied the spatio-temporal variability in diet and niche width in 2 sympatric gull species, the yellow-legged gull Larus michahellis and Audouin’s gull Ichthyaetus audouinii, which have experienced exponential growth in recent decades due to an increase in anthropogenic food subsidies. We sampled feathers from chicks of both species in several colonies along the western Mediterranean from 2009 to 2011 and performed stable isotope analysis of carbon, nitrogen and sulphur on these feathers. Bayesian modelling shows that both species displayed opportunistic behaviour if different types of resources were available, but could also narrow their trophic niche if 1 resource was abundant. We also provide evidence of trophic segregation between the 2 gull species, suggesting the occurrence of interspecific competition for food. Our meta-population approach provides a comprehensive view of the trophic ecology and the competitive interactions of these gull species. We emphasize the usefulness of 3-dimensional isotope analyses to correctly assess spatio-temporal variability in trophic behaviour of predator species, revealing differences that would remain hidden in single population studies or when using only the isotopic ratios of 2 elements.

Knowing the spatial scales at which effective species management can be implemented is fundamental for conservation. This is especially important for mobile species, which can be exposed to multiple threats across large geographic areas, but the space use requirements of different species can vary to an extent that might render some management approaches inefficient. We examined the space use patterns of seabirds and provide guidance on whether conservation management approaches should be tailored for taxonomic groups with different movement characteristics. We synthesised tracking data from 5419 adult breeding individuals of 52 different species in ten families that were collected in the Atlantic between 1998 and 2017. Two key aspects of spatial distribution were quantified, namely how far seabirds ranged from their colony, and to what extent individuals from the same colony used the same areas at sea. There was evidence for substantial differences in patterns of space use among the ten studied seabird families, indicating that several alternative conservation management approaches are needed. Several species exhibited large foraging ranges and little aggregation at sea, indicating that area-based conservation solutions would have to be extremely large to adequately protect such species. The results highlight that short-ranging and aggregating species such as cormorants, auks, some penguins, and gulls would benefit from conservation approaches at relatively small spatial scales during their breeding season. However, improved regulation of fisheries, bycatch, pollution and other threats over large spatial scales will be needed for wide-ranging and dispersed species such as albatrosses, petrels, storm petrels and frigatebirds.

Life history theory states that individual fitness in one stage of life is conditioned by what occurred in previous stages. In migratory species, reproductive effort during breeding has often been found to influence body condition, molt schedule, self-provisioning and migration of individuals in subsequent seasons (i.e., carryover effects of breeding). However, there is a current uncertainty in understanding how long-distance migrants trade off among such energy-demanding activities (i.e., breeding, molting and migrating). To provide evidence to the field, we experimentally reduced the parental effort of a long-lived Procellariform, the Cory's shearwater (Calonectris borealis), by inducing failure at the incubation stage. Treatment and control birds were tracked during their subsequent migration by means of light-level and immersion loggers and sampled for six specific feathers (molted at different periods along the migratory cycle) upon the recovery of the loggers 1 yr later. Feathers were used to perform stable isotope analysis (SIA) and determine corticosterone levels (CORT). By these means, we evaluated the effect of breeding effort on migratory strategy, at-sea activity patterns, molt patterns, and levels of stress experienced by birds along the non-breeding period. We did not detect any difference between birds in the induced failure group and successful breeders in terms of spatio-temporal distribution: all birds shared common foraging areas throughout the study period and the timing of major phenological events did not differ. Failed birds significantly advanced their molt, as revealed by SIA and flying activity patterns. The stress levels of failed birds, inferred through CORT concentrations in feathers, were found to be consistently lower than in successful breeders, through the end of the breeding to the non-breeding period. Thus, we provide robust evidence that the costs of reproduction can be physiologically mediated from the breeding to the non-breeding period through molting schedules and CORT levels. However, we failed to detect clear effects on migratory behavior or subsequent breeding success, suggesting that costs of breeding in long-lived species may be rapidly buffered during the post-breeding period, as would be expected from life history theory.

Feather mites are useful models for studying speciation due to their high diversity and strong degree of host specialization. However, studies to date have focused on the evolution of higher-level mite taxa while much hidden diversity likely occurs at the level of host genera and species. In this study, we examined the diversity and evolution of feather mites infesting six sympatric seabird species from six genera, breeding in the Cape Verde archipelago. We report 32 feather mite morphospecies categorized into 10 genera and three families, of which nine correspond to new, undescribed species. Molecular data corroborated morphological species descriptions, except for two morphologically-cryptic, but genetically distinct mite lineages related to Zachvatkinia oceanodromae and Laminalloptes simplex. Using these communities, we then applied a co-structure approach to test the contribution of ectosymbiont and host factors in driving feather mite evolution. Most seabird species hosted specific and unique feather mite species, even under sympatric conditions, and in general, feather mite species exhibited strong host-driven genetic structure. However, patterns of genetic differentiation were variable. That is, some mite species are more generalist than others and mite lineages/haplotypes can be shared by related seabird species. Interestingly, host-specific mites (e.g., Zachvatkinia spp.) tend to display much higher intra-specific diversity compared to more generalist mites (e.g., Microspalax and Plicatalloptes spp.). We discuss ectosymbiont and host life-history traits that might generate these patterns, such as host dispersal and breeding behavior and/or mite spatial and trophic specialization. Our findings highlight both the vast and largely unrecognized diversity of avian feather mites on seabirds, and the intrinsic complexity of the ecological processes underlying the evolution of these ectosymbionts.

The objective of the present study was to assess the presence of 17 per- and polyfluoroalkyl substances (PFAS) in blood of two closely related top predators, the Scopoli's (Calonectris diomedea) and Cory's (C. borealis) shearwaters that breed allopatrically in Mediterranean and Atlantic basins. Among PFAS, perfluorooctanesulfononic acid (PFOS) and long chain perfluorinated carboxylic acids (PFCA) were detected in all samples, highlighting somehow the ubiquity of such pollutants. Scopoli's shearwaters from the Mediterranean showed significant higher levels in all PFAS when compared with those levels determined in the colony of Cory's shearwater from the Atlantic Ocean. Moreover, significant differences also arose within the Mediterranean colonies, with the colony of the Central Mediterranean (Zembra Island in Tunisia) having the lowest levels of all PFAS. Thus, our study suggests a marked geographical pattern regarding the presence of such contaminants, and emphasizes the necessity to study PFAS accumulation in birds inhabiting temperate regions.

Studying the movements of oceanic migrants has been elusive until the advent of several tracking devices, such as the light-level geolocators. Stable isotope analysis (SIA) offers a complementary approach to infer areas used year-round, but its suitability in oceanic environments remains almost unexplored. To evaluate SIA as a tool for inferring movements of oceanic migrants, we sampled an oceanic seabird, the Bulwer’s petrel, Bulweria bulwerii, in four breeding colonies spread along its Atlantic distribution. We first studied the species moulting pattern from 29 corpses collected in the colonies. Secondly, based on this moult knowledge, we selected three feathers from tracked birds to infer their breeding and non-breeding grounds using SIA: the 1st primary (P1), the 8th secondary (S8) and the 6th rectrix (R6) feathers. Birds migrated to two main non-breeding areas, the Central or the South Atlantic Ocean. P1 showed similar isotopic values among petrels from different breeding colonies, suggesting this feather is replaced early in the non-breeding period in a common area used by most birds, the Central Atlantic. S8 and R6 feathers correctly assigned 92% and 81%, respectively, of the birds to their non-breeding areas, suggesting they were replaced late in season, when birds were settled in their main non-breeding grounds. Our results showed that the isotopic baseline levels of the Central and South Atlantic are propagated through the food web until reaching top predators, suggesting these ratios can be used to infer the movement of long-distance migrants among oceanic water masses.

High numbers of seabirds are killed annually worldwide in longline fisheries. In the Mediterranean, this mortality is seriously affecting the viability of seabird populations, in particular of the three endemic shearwaters. Even so, there is currently no specific seabird mitigation requirements for the longline fleet operating in this area. From 2013 to 2014, we assessed the efficiency and practical applicability of four mitigation measures on artisanal demersal longliners targeting European hake (Merluccius merluccius) in the western Mediterranean: night setting, tori line, weighted lines and artificial baits. We performed fifty-two pairs of experimental (with the tested mitigation measure) and control settings (without any measure), and compared their effects on seabird interactions and fish catches. In addition, we estimated the longline sink rates and the seabird access area to baited hooks in different longline configurations. Night setting reduced bycatch risk without affecting target and non-commercial fish catches. The tori line may have reduced the bycatch risk by displacing bait attacks beyond the end of the line, but at this distance shearwaters could still access to the baits and the streamers did not deter birds under calm wind conditions. Weighted lines increased sink rate, but it resulted in only a minor reduction of the seabird access window to baited hooks and led to some operational problems during the setting. Artificial baits substantially reduced commercial catches. Moreover, the seabird access to the baited hooks was influenced by the longline configuration, the setting speed and the relative position to the floats and weights. So far, night setting stands out as the best mitigation measure for reducing bycatch levels without compromising target catches in demersal longliners. Ideally, these results should be confirmed in longliners targeting species other than European hake.

Hundreds of thousands of seabirds die annually as a result of being bycaught in longline fisheries, and these rates are unsustainable for many seabird populations worldwide. To understand effects at the population level, it is essential to assess sex- and age-biased mortalities, since uneven mortalities may exacerbate bycatch impacts. In the Mediterranean, bycatch is the main cause of population declines for the 3 endemic shearwater species (Scopoli’s Calonectris diomedea, Balearic Puffinus mauretanicus and Mediterranean shearwater P. yelkouan), but little is known about population biases of the birds caught in longliners. From 2003 to 2015, we collected 639 shearwater carcasses from Spanish longliners operating in the north-western Mediterranean, determined their age and sex and examined their spatial and temporal patterns and the origin of ringed birds. Most shearwaters caught in longliners were adults, but the proportion of immatures and subadults increased in the late breeding period. Adult Scopoli’s shearwaters were mostly caught around the breeding colonies. In contrast, all Puffinus birds were caught on the Iberian shelf. Catches of Scopoli’s shearwaters were male-biased, particularly during the pre-laying period and close to the breeding colonies. Catches of Puffinus shearwaters were also male-biased during the pre-laying period, but adult catches were female-biased during chick-rearing. Ring recoveries revealed that most birds were ringed in the nearby Balearic Islands, but some Scopoli’s shearwaters ringed in France and Italy were also caught during their migration, indicating that the impacts of the Spanish longliners extend well beyond the Spanish colonies. The adult-biased and sex-biased mortality found in this study may aggravate bycatch impacts on populations and highlights the urgent need for conservation action.

Reproductive timing in many taxa plays a key role in determining breeding productivity1, and is often sensitive to climatic conditions2. Current climate change may alter the timing of breeding at different rates across trophic levels, potentially resulting in temporal mismatch between the resource requirements of predators and their prey3. This is of particular concern for higher-trophic-level organisms, whose longer generation times confer a lower rate of evolutionary rescue than primary producers or consumers4. However, the disconnection between studies of ecological change in marine systems makes it difficult to detect general changes in the timing of reproduction5. Here, we use a comprehensive meta-analysis of 209 phenological time series from 145 breeding populations to show that, on average, seabird populations worldwide have not adjusted their breeding seasons over time (-0.020?days?yr-1) or in response to sea surface temperature (SST) (-0.272?days?°C-1) between 1952 and 2015. However, marked between-year variation in timing observed in resident species and some Pelecaniformes and Suliformes (cormorants, gannets and boobies) may imply that timing, in some cases, is affected by unmeasured environmental conditions. This limited temperature-mediated plasticity of reproductive timing in seabirds potentially makes these top predators highly vulnerable to future mismatch with lower-trophic-level resources.

Given the major ongoing influence of environmental change on the oceans, there is a need to understand and predict the future distributions of marine species in order to plan appropriate mitigation to conserve vulnerable species and ecosystems. In this study we use tracking data from seven large seabird species of the Southern Ocean (black-browed albatross Thalassarche melanophris, grey-headed albatross T. chrysostoma, northern giant petrel Macronectes halli, southern giant petrel M. giganteus, Tristan albatross Diomedea dabbenena, wandering albatross D. exulans and white-chinned petrel Procellaria aequinoctialis, and on fishing effort in two types of fisheries (characterised by low or high-bycatch rates), to model the associations with environmental variables (bathymetry, chlorophyll-a concentration, sea surface temperature and wind speed) through ensemble species distribution models. We then projected these distributions according to four climate change scenarios built by the Intergovernmental Panel for Climate Change for 2050 and 2100. The resulting projections were consistent across scenarios, indicating that there is a strong likelihood of poleward shifts in distribution of seabirds, and several range contractions (resulting from a shift in the northern, but no change in the southern limit of the range in four species). Current trends for southerly shifts in fisheries distributions are also set to continue under these climate change scenarios at least until 2100; some of these may reflect habitat loss for target species that are already over-fished. It is of particular concern that a shift in the distribution of several highly threatened seabird species would increase their overlap with fisheries where there is a high-bycatch risk. Under such scenarios, the associated shifts in distribution of seabirds and increases in bycatch risk will require much-improved fisheries management in these sensitive areas to minimise impacts on populations in decline.

This publication analyses the movement ecology and at-sea behaviour of the populations of Scopoli’s and Cory’s shearwaters that breed in Spain, being both seabird species of conservation concern. Thanks to several research projects carried out by the University of Barcelona and SEO/BirdLife, a large set of remote tracking data was compiled in order to get critical knowledge to enhance conservation status of seabird populations breeding in Spain. The results included here arise from analysing part of this data set. We present the main insights found regarding ecology at-sea and year-round movements, including the identification of the foraging grounds, resting areas and commuting corridors during the breeding period, the migratory phenology, the behaviour, and the location of the wintering areas and main migratory flyways. Moreover, we provide to non-specialized readers an introduction to technical details of remote tracking systems employed in order to ensure a proper understanding of pros and cons of each methodology and a correct interpretation of results and figures. In accordance with recent phylogenetic studies and the British Ornithologists’ Union Taxonomic Committee recommendations, here we have considered the Mediterranean and the Atlantic taxa as two different species: the Scopoli’s Calonectris diomedea and the Cory’s shearwater C. borealis. This decision is also based on behavioural differences between taxa, including the migratory behaviour described in this monography, that support their consideration as different conservation units. Because of the number of individuals tracked, the amount and representativeness of colonies studied, and the set of years considered, the work presented in this book is probably the most ambitious and comprehensive effort undertaken to date to address the study of any species breeding in Spain through remote tracking systems. This book constitutes the third monography from the Migra programme (www.migraciondeaves.org), a long-term research project carried out by SEO/BirdLife since 2011, with the aim to use cutting-edge tracking technologies to unravel the movements and migration of birds breeding in Spain. Data was gathered using different remote tracking systems according to aims and limitations. Fieldwork and deployments were carried out at 13 different breeding colonies distributed across different regions of Spain: Balearic Islands (Cala Morell, Aire Islet, Pantaleu, Cabrera), Castellón (Columbretes Islands), Murcia (Palomas Islet), Almería (Terreros Islet), Chafarinas Islands, and Canary Islands (Alegranza Islet, Montaña Clara Islet, Timanfaya and Veneguera). We used ~20-25 g GPS loggers (from different manufacturers) in order to track the movements of adult individuals during the breeding period. These loggers were properly waterproofed in heat shrink tubing and attached to the back feathers using Tesa tape. Remote tracking was conducted from 2007 to 2015 and across the 13 breeding colonies referred above. We gathered 813,612 GPS locations and 1,546 foraging trips from 299 individuals. GPS data considered for the analyses correspond mainly to the chick-rearing period, but trips from prelaying and incubation were also included for birds breeding at Veneguera and Cala Morell colonies, where the most intensive fieldwork has been done. Light-level geolocation data loggers (manufactured by British Antarctic Survey and Biotrack LTd.), attached to plastic rings and deployed on tarsus, were used to study year-round movements. Many loggers were equipped with a salt-water immersion sensor, which also allowed the study of activity budgets and daily behaviour at-sea. Geolocators were deployed and recovered from 2007 to 2013 at 3 breeding colonies: Veneguera and Montaña Clara (for Cory’s shearwaters) and Pantaleu (for Scopoli’s shearwaters). This work includes data from 214 devices recovered, each working one and a half year on average. After analysing the light curves and before applying any filter, the dataset contained 203,427 geographic locations, corresponding to 309 tracks from 161 different individuals (Pantaleu: 72 trips from 46 individuals; Veneguera: 207 trips from 95 individuals; Montaña Clara: 30 trips from 20 individuals). For spatial analyses purposes, we modelled locations from geolocators in order to reduce uncertainty and get the most plausible trajectories. Through the large number of tagged individuals and breeding colonies studied, and thanks to the use of two different tracking systems, we obtained a comprehensive overview of the annual movements and at-sea behaviour of Scopoli’s and Cory’s shearwaters breeding in Spain. This allowed us to present new insights about foraging strategies, feeding grounds, migratory patterns and phenology for these populations. State-of-the-art algorithms to classify behavioural modes from GPS data were used to quantify behaviour at varying temporal and spatial scales and to build up behavioural landscapes. Furthermore, salt-water immersion data provided information to characterize individuals’ behaviour year-round, allowing us to compare performance and daily activity budgets among wintering areas. Because of the large number of individuals tracked year-round, we were also able to calculate migratory connectivity between breeding and wintering grounds. In addition, since we tracked a good amount of individuals for several years (some of them up to seven years) we also obtained new insights about spatial consistency and fidelity to wintering grounds. During breeding, some differences were found between species regarding behaviour, movement range and areas visited. Both species, but particularly colonies in the Atlantic, showed a clear preference for neritic waters far away from the colony, over the continental shelf near the mainland. However, they also used waters surrounding the colonies, in what is known as the dual foraging strategy during the chick rearing. In the Mediterranean, birds foraged along the Iberian coast from the strait of Gibraltar up to the Gulf of Lyon during the long trips, with some degree of spatial segregation among individuals from different colonies. In the case of birds at Chafarinas, birds commuted to the northern coast of Morocco, an area also used by birds from Palomas Islet. Overall, the distribution of trip length and duration values was not bimodal, which suggests that the size of the western Mediterranean basin is not large enough to promote a clear dual foraging strategy. Regarding population from the Canary Islands, birds consistently foraged along the highly productive African shelf, sometimes performing foraging trips of up to 1,000 km. Commuting flights were generally diurnal, whereas resting took place overnight. Birds were more active at sunrise and sunset, although they also foraged during the day. However, intensive foraging behaviour seems to occur in similar proportion during darkness and daylight, both in the Mediterranean and in the Atlantic. Indeed, in the Atlantic this behaviour seems to be more important during darkness in some moments, which may relate to individuals’ intrinsic factors (such as the internal state of the individuals that affects their motivation and performance to behave, e.g. physiological, neurological, etc,), the environmental conditions or the moon phase. The population of Scopoli’s shearwaters breeding in Spain spends the non-breeding period in 4 main wintering areas, sorted by importance: the Canary Current (African shelf from 14° N to 23° N), offshore waters of Angola and Namibia (from the equator to the parallel 22° S), oceanic waters of Guinea (around parallel 8° N and meridian 20° W), and off coast of Ghana (from the coast to the equator). Birds were more active during daylight across most of the wintering areas, with peaks of activity at sunrise and sunset. In the area of Guinea, however, birds were more active at night. On the other hand, Cory’s shearwaters breeding in Spain use 6 different wintering areas during the non-breeding period, sorted by importance: the Benguela Current off the coast of Namibia (from 10° S to 40° S), the Agulhas Current, the confluence between the Benguela and the Agulhas currents (around the parallel 40° S), the Canary Current (from 10° N to 25° N), the Brazil Current (from 15° S to 40° S), and the centre of the South-Atlantic (around parallel 45° S and meridian 25° W). Birds were more active during daylight, especially at sunrise and sunset, with the exception of the Canary Current where activity during daylight and darkness were similar. Both species showed some trend towards being more active during darkness with an increasing depth and distance from the coast, suggesting population plasticity in the foraging strategies to adapt to the environment of each wintering area. This population plasticity is probably related to diversity of strategies across individuals, since results indicate 75% of them use a single area repeatedly over several years and show a high degree of intra-individual overlap. As the wintering areas used by the two species differ, so do the migratory flyways. Scopoli’s shearwaters reached the wintering areas following the coastline during the postnuptial migration, but entered into the pelagic areas of the North Atlantic during the prenuptial migration on their way back to the breeding colonies. This detour was more common in individuals wintering in the southern areas. Cory’s shearwaters showed more complex migratory patterns, but overall, their complete migratory flyways -looking at prenuptial and postnuptial migration together- drew an 8-shape loop across the Atlantic, taking advantage of the prevailing winds. In both species, the prenuptial migratory corridors were weaker and more spread than the postnuptial ones. Regarding the migratory phenology, the duration of wintering period was slightly longer for Scopoli’s shearwaters, while the breeding period was longer in the case of Cory’s shearwaters. The results provided by this monography, thanks to advances in remote tracking technologies, unveil key knowledge about year-round at-sea ecology of Cory’s and Scopoli’s shearwaters, including behavioural strategies adopted throughout the year and in different areas. The insights presented here are fundamental to better define its conservation status. Nowadays Cory’s and Scopoli’s shearwaters are probably among the best-known seabird species, primarily thanks to the intensive use of remote tracking. However, there are very few marine areas proposed for the conservation of these species so far, and the majority of them are related to areas used during breeding. At national scale, the results presented in this book support largely those areas identified by SEO/BirdLife as Marine IBAs in spain (Arcos et al., 2009), which were later on included in Natura2000 network by the Spanish Government (BOE, 2014). The results also reveal the great ubiquity of these species compared to other procellariforms for which marine IBAs have been identified, since Scopoli’s shearwaters use the entire Iberian and Balearic continental shelf, and Cory’s shearwaters use the African continental shelf, from southern Morocco to the north of Mauritania, to feed during the reproductive period. At the same time, however, some degree of spatial segregation tends to occur among birds from different colonies. Both aspects have strong implications for conservation. On one side, it is important to highlight that marine protected areas are useful to develop concrete site-specific conservation actions, but these local actions necessarily need to be complemented with more relaxed actions at regional or trans-boundary (both political and ecosystem) scales. On the other side, spatial segregation of foraging grounds among colonies may allow to link impacts at sea with population trends at each breeding colony. The information regarding wintering areas and migratory flyways is even more original, since it will allow proposing new marine IBAs on international waters, outside jurisdictional Spanish waters. In fact, BirdLife has already started this process worldwide as well as in several specific areas of the Atlantic (e.g. the Canary Current, the North Atlantic, Tristan da Cunha archipelago, etc.) for which the data used in this work are an important part of the main data set. Regarding interactions with human activities, the better knowledge of spatiotemporal patterns of these populations of Cory’s and Scopoli’s shearwaters will allow us to identify overlap with potentially negative disturbances and threats (such as fishing and longlining, oil spills, etc.), guiding the design and implementation of locally adapted management actions. Overall, this information can be extremely helpful to better identify and address main threats and implement conservation and management actions at-sea that guarantee the viability of the shearwater populations. The greatest upcoming challenge is that social and political stakeholders involved in seabird and marine conservation become willing to effectively incorporate these new generation tracking tools in the conservation programs and strategies.

Despite the proliferation of seabird tracking studies, there is a relative paucity of studies on small tropical seabirds. We present for the first time the distribution and movements of the little-known Boyd’s shearwater Puffinus boydi, a Procellariiform endemic to the Cape Verde Islands. We tracked 28 birds from 2 breeding sites (Ilhéu Raso and Ilhéu de Cima) with geolocator loggers from 2007 to 2012. We also analysed stable isotopes of carbon and nitrogen in the 1st primary (P1), the 6th rectrice (R6) and the 1st (S1) and 8th (S8) secondary feathers to reveal moulting pattern and oceanic isotopic gradients. Birds migrated on average 1452 km westward, to the central Atlantic Ocean (5 to 15°N, 30 to 40°W), where they stayed on average 114 d, from May to August. Boyd’s shearwaters exploited oceanic waters year-round and showed d13C values similar to other oceanic seabird species and d15N values indicating the lowest known trophic level among all central Atlantic seabirds. Isotope values in flight feathers suggest most animals moult their P1 and R6 around the breeding ground, whereas all birds moult S1 and S8 at the non-breeding quarters. Correlations of d13C and d15N values from S8 with the longitude of the non-breeding area indicate the existence of large-scale isotopic gradients matching those known at baseline levels. Combining geolocator tracking and stable isotope analyses in feathers not only allowed us to describe in detail the annual life cycle and distribution of the species, but also the oceanic isotopic gradients in the tropical Atlantic.

With increasing pressure on the oceans from environmental change, there has been a global call for improved protection of marine ecosystems through the implementation of marine protected areas (MPAs). Here, we used species distribution modelling (SDM) of tracking data from 14 seabird species to identify key marine areas in the southwest Atlantic Ocean, valuing areas based on seabird species occurrence, seasonality and extinction risk. We also compared overlaps between the outputs generated by the SDM and layers representing important human threats (fishing intensity, ship density, plastic and oil pollution, ocean acidification), and calculated loss in conservation value using fishing and ship density as cost layers. The key marine areas were located on the southern Patagonian Shelf, overlapping extensively with areas of high fishing activity, and did not change seasonally, while seasonal areas were located off south and southeast Brazil and overlapped with areas of high plastic pollution and ocean acidification. Non-seasonal key areas were located off northeast Brazil on an area of high biodiversity, and with relatively low human impacts. We found support for the use of seasonal areas depending on the seabird assemblage used, because there was a loss in conservation value for the seasonal compared to the non-seasonal approach when using ‘cost’ layers. Our approach, accounting for seasonal changes in seabird assemblages and their risk of extinction, identified additional candidate areas for incorporation in the network of pelagic MPAs.

Technological advances in recent years have seen an explosion of tracking and stable isotope studies of seabirds, often involving repeated measures from the same individuals. This wealth of new information has allowed the examination of the extensive variation among and within individuals in foraging and migration strategies (movements, habitat use, feeding behaviour, trophic status, etc.) in unprecedented detail. Variation is underpinned by key life-history or state variables such as sex, age, breeding stage and residual differences among individuals (termed ‘individual specialization’). This variation has major implications for our understanding of seabird ecology, because it affects the use of resources, level of intra-specific competition and niche partitioning. In addition, it determines the responses of individuals and populations to the environment and the susceptibility to major anthropogenic threats. Here we review the effects of season (breeding vs. nonbreeding periods), breeding stage, breeding status, age, sex and individual specialization on foraging and migration strategies, as well as the consequences for population dynamics and conservation.

Shearwaters deprived of their olfactory sense before being displaced to distant sites have impaired homing ability but it is unknown what the role of olfaction is when birds navigate freely without their sense of smell. Furthermore, treatments used to induce anosmia and to disrupt magneto-reception in displacement experiments might influence non-specific factors not directly related to navigation and, as a consequence, the results of displacement experiments can have multiple interpretations. To address this, we GPS-tracked the free-ranging foraging trips of incubating Scopoli’s shearwaters within the Mediterranean Sea. As in previous experiments, shearwaters were either made anosmic with 4% zinc sulphate solution, magnetically impaired by attachment of a strong neodymium magnet or were controls. We found that birds from all three treatments embarked on foraging trips, had indistinguishable at-sea schedules of behaviour and returned to the colony having gained mass. However, we found that in the pelagic return stage of their foraging trips, anosmic birds were not oriented towards the colony though coastal navigation was unaffected. These results support the case for zinc sulphate having a specific effect on the navigational ability of shearwaters and thus the view that seabirds consult an olfactory map to guide them across seascapes.

Anthropogenic activities alter and constrain the structure of marine ecosystems with implications for wide-ranging marine vertebrates. In spite of the environmental importance of vast oceanic ecosystems, most conservation efforts mainly focus on neritic areas. To identify relevant oceanic areas for conservation, we assessed the year-round spatial distribution and spatio-temporal overlap of eight truly oceanic seabird species of gadfly petrels (Pterodroma spp.) inhabiting the Atlantic Ocean. Using tracking data (mostly from geolocators), we examined year-round distributions, the timing of life-cycle events, and marine habitat overlap of eight gadfly petrel species that breed in the Atlantic Ocean. We compiled 125 year-round tracks. Movement strategies ranged from non-migratory to long-distance migrant species and from species sharing a common non-breeding area to species dispersing among multiple non-breeding sites. Gadfly petrels occurred throughout the Atlantic Ocean but tended to concentrate in subtropical regions. During the boreal summer, up to three species overlapped spatio-temporally over a large area around the Azores archipelago. During the austral summer, up to four species coincided in a core area in subtropical waters around Cape Verde, and three species shared habitat over two distinct areas off Brazil. The petrels used many national Exclusive Economic Zones, although they also exploited offshore international waters. Tracking movements of highly mobile vertebrates such as gadfly petrels can provide a powerful tool to evaluate and assess the potential need for and location of protected oceanic areas. As more multispecies, year-round data sets are collected from wide-ranging vertebrates, researchers and managers will have greater insight into the location of biodiversity hotspots. These can subsequently inform and guide marine spatial planning efforts that account for both conservation and sustainable use of resources such as commercial fisheries.

The Convention on Biological Diversity aspires to designate 10% of the global oceans as Marine Protected Areas (MPAs), but so far, few MPAs protect pelagic species in the high seas. Transparent scientific approaches are needed to ensure that these encompass areas with high biodiversity value. Here we used the distribution of all globally threatened seabirds breeding in a centrally located archipelago (Tristan da Cunha) to provide guidance on where MPAs could be established in the South Atlantic Ocean. We combined year-round tracking data from six species, and used the systematic conservation-planning tool, ‘Zonation’, to delineate areas that would protect the largest proportion of each population. The areas used most intensively varied among species and seasons. Combining the sites used by all six species suggested that the most important areas of the South Atlantic are located south of South Africa, around the central South Atlantic between 30°S and 55°S, and near South America. We estimated that the longline fishing effort in these intensively used areas is around 11 million hooks on average each year, highlighting the need for improved monitoring of seabird bycatch rates and the enforcement of compliance with bird bycatch mitigation requirements by fisheries. There was no overlap between the identified areas and any of the existing MPAs in the South Atlantic. The conservation of these highly mobile, pelagic species cannot be achieved by single countries, but requires a multi-national approach at an ocean-basin scale, such as an agreement for the conservation of biodiversity beyond national jurisdiction under the United Nation Convention on the Law of the Sea.

Cape Verde petrel (Pterodroma feae) is currently considered near threatened, but little is known about its population size, breeding biology and on land threats, jeopardizing its management and conservation. To improve this situation, we captured, marked and recaptured (CMR) birds using mist-nets over 10 years; measured and sexed them; monitored up to 14 burrows, deployed GPS devices on breeders and analyzed activity data of geolocators retrieved from breeders in Fogo (Cape Verde). We set cat traps over the colony and investigated their domestic/feral origin by marking domestic cats from a nearby village with transponders, by deploying GPS devices on domestic cats and by performing stable isotope analyses of fur of the trapped and domestic cats. The population of Fogo was estimated to be 293 birds, including immatures (95% CI: 233–254, CMR modelling). Based on geolocator activity data and nest monitoring we determined the breeding phenology of this species and we found biometric differences between sexes. While monitoring breeding performance, we verified a still ongoing cat predation and human harvesting. Overall, data gathered from trapped cats without transponder, cats GPS trips and the distinct isotopic values between domestic and trapped cats suggest cats visiting the colony are of feral origin. GPS tracks from breeders showed birds left and returned to the colony using the sector NE of the islands, where high level of public lights should be avoided specially during the fledging period. Main threats for the Cape Verde petrel in the remaining breeding islands are currently unknown but likely to be similar to Fogo, calling for an urgent assessment of population trends and the control of main threats in all Cape Verde Islands and uplisting its conservation status.

Bycatch mortality in longline fisheries is considered the main threat at sea for numerous seabird species. These incidental catches occur worldwide, but mortality levels are mainly determined by the specific traits of the fishery operating in each area and the feeding behaviour and local abundance of seabirds. In the Mediterranean, demersal artisanal longliners are known to catch several seabirds, but bycatch rates and the main factors influencing both the probability and the level of seabird bycatch are poorly known. From 2011 to 2015 we studied seabird interactions with longline vessels from onboard observations across the Balearic Sea. In addition, we recorded bird catches reported by fishermen. We found an average overall bycatch rate of 0.58 birds per 1,000 hooks (0.13 – 1.37, 95%CI), which would imply a conservative estimate ranging from 274 to 2,198 seabirds caught every year on demersal longliners in the study area. The most affected species were the three endemic and threatened shearwaters of the Mediterranean (Scopoli’s Calonectris diomedea, Balearic Puffinus mauretanicus and Yelkouan shearwaters P. yelkouan), likely due to their highly aggregative behaviour and diving capabilities. Overall, the main factors influencing bycatch risk were the season (breeding stage) and the time of day (higher risk at sunrise). Other influential factors were the bait type, the wind conditions, the distance between weights, the proximity to the breeding colony and the number of hooks. Both observations onboard and information from fishermen showed a paucity of “massive” bycatch events, particularly of the two smaller and most threatened shearwaters (Puffinus spp.). This study shows that mortality caused by demersal longliners is high and may be jeopardizing the viability of the shearwater populations. Therefore, the search and implementation of mitigation measures is urgently required.

Phylogenetic relationships among species can provide insight into how new species arise. For example, careful consideration of both the phylogenetic and geographic distributions of species in a group can reveal the geographic models of speciation within the group. One such model, sympatric speciation, may be more common than previously thought. The Hydrobatinae (Aves: Procellariformes) is a diverse subfamily of Northern Hemisphere storm-petrels for which the taxonomy is unclear. Previous studies showed that Hydrobates (formally Oceanodroma) castro breeding in the Azores during the cool season is sister species to H. monteiroi, a hot season breeder at the same locations, which suggests sympatric speciation by allochrony. To test whether other species within the subfamily arose via sympatric speciation by allochrony, we sequenced the cytochrome b gene and five nuclear introns to estimate a phylogenetic tree using multispecies coalescent methods, and to test whether species breeding in the same geographic area are monophyletic. We found that speciation within the Hydrobatinae appears to have followed several geographic modes of divergence. Sympatric seasonal species in Japan likely did not arise through sympatric speciation, but allochrony may have played a role in the divergence of H. matsudairae, a cool season breeder, and H. monorhis, a hot season breeder. No other potential cases of sympatric speciation were discovered within the subfamily. Despite breeding in the same geographic area, hydrobatine storm-petrels breeding in Baja California (H. microsoma and H. melania) are each sister to a species breeding off the coast of Peru (H. tethys and H. markhami, respectively). In fact, antitropical sister species appear to have diverged at multiple times, suggesting allochronic divergence might be common. In addition, allopatry has likely played a role in divergence of H. furcata, a north Pacific breeder, and H. pelagius, a north Atlantic breeder. This study demonstrates that a variety of mechanisms of divergence have played a role in generating the diversity of the Hydrobatinae and supports the current taxonomy of the subfamily.

Fisheries provide an abundant and predictable food source for many pelagic seabirds through discards, but also pose a major threat to them through bycatch, threatening their populations worldwide. The reform of the European Common Fisheries Policy (CFP), which intends to ban discards through the landing obligation of all catches, may force seabirds to seek alternative food sources, such as baited hooks from longlines, increasing bycatch rates. To test this hypothesis we performed a combined analysis of seabird-fishery interactions using as a model Scopoli’s shearwaters Calonectris diomedea in the Mediterranean. Tracking data showed that the probability of shearwaters attending longliners increased exponentially with a decreasing density of trawlers. On-board observations and mortality events corroborated this result: the probability of birds attending longliners increased 4% per each trawler leaving the longliner proximity and bird mortality increased tenfold when trawlers were not operating. Therefore, the implementation of the landing obligation in EU waters will likely cause a substantial increase in bycatch rates in longliners, at least in the short-term, due to birds switching from trawlers to longliners. Thus the implementation of the landing obligation must be carefully monitored and counterbalanced with an urgent implementation of bycatch mitigation measures in the longlinefleet.

Host specific adaptations in parasites can lead to the divergence of conspecific populations. However, this divergence can be difficult to measure because morphological changes may not be expressed or because obvious changes may simply reflect phenotypic plasticity. Combining both genetic and phenotypic information can enable a better understanding of the divergence process and help identify the underlying selective forces, particularly in closely-related species groups. Here, we link genetic and morphometric data to understand divergence patterns within the Ornithodoros (Carios) capensis complex, a group of soft ticks (Argasidae) exploiting colonial seabirds across the globe. Species designations in this complex were historically based on larval morphology and geographic location. However, recent work has suggested that divergence within the group may be at least partially linked to host specificity. We therefore first examined population genetic structure of ticks in relation to host use and geography. These analyses revealedstrong structure in relation to host use, both when populations were sympatric and widely allopatric, with a secondary effect of geography.They also demonstrated the presence of several novel and presumably undescribed species exploiting these seabird hosts. We then used geometric morphometrics (landmark and outline analyses) to test whether host-associated genetic divergence is always accompanied by the same phenotypic changes. We found that morphological variation (size and shape) correlated well with genetic structure; tick size and shape varied strongly in relation to host type, and weakly with geography. These results support the hypothesis that speciation in this tick group has been more strongly shaped by host use than by geographic barriers per se. The revealed phenetic patterns now require detailed investigation to link them with host-specific selective forces.

We studied the temporal–spatial distribution of Common Terns Sterna hirundo along the East Atlantic Flyway. In 2009 and 2010 experienced adults from a colony on the German North Sea coast were tagged with geolocators recording light intensity and saltwater contact. Main objectives were the inter-individual temporal–spatial variation of migration routes and wintering areas, wintering site fidelity, and time spent at sea across the annual cycle. Geolocators had no effects on various traits of breeders, but their reproductive output suffered from egg breakage. This can be avoided by artificially incubating the eggs. Twelve routes of nine individuals were tracked. Transponder readings at the breeding site showed that birds left the colony 4 weeks before starting autumn migration. In spring and autumn, Common Terns stopped over around the Canary Islands. Main wintering distribution was the upwelling seas alongside the West African coast and similar between years, but different among individuals. Three females wintered further north and more offshore than six males. Pair mates wintered at different locations. Spring migration was longer (56 ± 8 days) than autumn migration (37 ± 17 days). During both migration and wintering the terns spent more time on salt water than during breeding and post-breeding. In most individuals saltwater contact was higher during the day than at night, reduced at sunrise and sunset likely due to foraging, and peaked about noon possibly related to resting or thermoregulation. Detailed ecological and behavioral studies of common terns during wintering are needed to clarify the results based on geolocators.

Upwelling regions are highly productive habitats targeted by wide-ranging marine predators and industrial fisheries. In this study, we track the migratory movements of eight seabird species from across the Atlantic; quantify overlap with the Canary Current Large Marine Ecosystem (CCLME) and determine the habitat characteristics that drive this association. Our results indicate the CCLME is a biodiversity hotspot for migratory seabirds; all tracked species and more than 70% of individuals used this upwelling region. Relative species richness peaked in areas where sea surface temperature averaged between 15 and 20°C, and correlated positively with chlorophyll a, revealing the optimum conditions driving bottom-up trophic effects for seabirds. Marine vertebrates are not confined by international boundaries, making conservation challenging. However, by linking diversity to ocean productivity, our research reveals the significance of the CCLME for seabird populations from across the Atlantic, making it a priority for conservation action.

Ardeola is the scientific journal of the Spanish Ornithological Society. We analyse historical changes in citation, topics and foreign authorship of articles published in Ardeola from its first publication in 1954 up to last year, 2015, to test to what extent the persistence of the journal during the last 61 years has been due to support of authors, Society members, readers, editors or the whole ornithological community. Analyses were done within the context of the Red Queen game played by scientific journals competing for the best and more cited articles. The impact factor of Ardeola has increased from 1985 onwards both in absolute and relative terms. Thematic changes have followed trends of the general ornithological literature, without the journal specialising in particular topics or geographical regions. Foreign authorship decreased from 1954 up to the end of the 20th century, subsequently increasing again, a trend fuelled by coverage by Current Contents and the JCR, the establishment of English as the language of publication and recent Internet access through the BioOne platform. Ardeola is a traditional scientific journal, backed by a scientific society, whose future will be guaranteed by a reputation for rigour and quality sought by authors, reviewers and editors, supported by the members of the Spanish Ornithological Society and retaining its original objective: ‘to be a journal at the level of the best…, looking for a strong collaboration with foreign authors to promote the benefit of the Ornithology’.

We studied mercury contamination in 25 seabird species breeding along a latitudinal gradient across the Southern Ocean, from Gough Island (40°S) through Marion Island (47°S) to Byers Peninsula (63°S). Total mercury concentrations in body feather samples of adults caught at breeding colonies from 2008 to 2011 were determined. Krill (Euphausia spp.) and other zooplankton consumers had low mercury concentrations (gentoo penguin Pygoscelis papua, chinstrap penguin Pseudomonas Antarctica, common diving petrel Pelecanoides urinatrix, broad-billed prion Pachyptila vittata; mean levels 308–753 ng g-1), whereas seabirds consuming squid or carrion had high mercury concentrations (ascending order: Kerguelen petrel Aphrodroma brevirostris, southern giant petrel Macronectes giganteus, soft-plumaged petrel Pterodroma mollis, sooty albatross Phoebetria fusca, Atlantic petrel Pterodroma incerta, northern giant petrel Macronectes halli, great-winged petrel Pterodroma macroptera; 10,720–28038 ng g-1). The two species with the highest mercury concentrations, northern giant petrels and great-winged petrels, bred at Marion Island. Among species investigated at multiple sites, southern giant petrels had higher mercury levels at Marion than at Gough Island and Byers Peninsula. Mercury levels among Byers Peninsula seabirds were low, in two species even lower than levels measured 10 years before at Bird Island, South Georgia. Replicate measurements after about 25 years at Gough Island showed much higher mercury levels in feathers of sooty albatrosses (by 187%), soft-plumaged petrels (53%) and Atlantic petrels (49%). Concentrations similar to the past were detected in southern giant petrels at Gough and Marion islands, and in northern giant petrels at Marion. There were no clear indications that timing of moult or migratory behavior affected mercury contamination patterns among species. Causes of inter-site or temporal differences in mercury contamination could not be verified due to a lack of long-term data related to species’ diet and trophic levels, which should be collected in future together with data on mercury contamination.

Studies on Persistent Organic Pollutants (POPs) in Antarctic wildlife are scarce, and usually limited to a single locality. As a result, wildlife exposure to POPs across the Southern Ocean is poorly understood. In this study, we report the differential exposure of the major southern ocean scavengers, the giant petrels, to POPs across a wide latitudinal gradient. Selected POPs (PCBs, HCB, DDTs, PBDEs) and related compounds, such as Dechlorane Plus (DP), were analyzed in plasma of southern giant petrels (Macronectes giganteus) breeding on Livingston (62°S 61°W, Antarctica), Marion (46°S 37°E, sub-Antarctic), and Gough (40°S 10°W, cool temperate) islands. Northern giant petrels (Macronectes halli) from Marion Island were also studied. Stable isotope ratios of C and N (d(13)C and d(15)N) were used as dietary tracers of the marine habitat and trophic level, respectively. Breeding locality was a major factor explaining petrel exposure to POPs compared with species and sex. Significant relationships between d(13)C values and POP burdens, at both inter- and intra-population levels, support latitudinal variations in feeding grounds as a key factor in explaining petrel pollutant burdens. Overall, pollutant levels in giant petrels decreased significantly with latitude, but the relative abundance (%) of the more volatile POPs increased towards Antarctica. DP was found at negligible levels compared with legacy POPs in Antarctic seabirds. Spatial POP patterns found in giant petrels match those predicted by global distribution models, and reinforce the hypothesis of atmospheric long-range transport as the main source of POPs in Antarctica. Our results confirm that wildlife movements out of the polar region markedly increase their exposure to POPs. Therefore, strategies for Antarctic wildlife conservation should consider spatial heterogeneity in exposure to marine pollution. Of particular relevance is the need to clarify the exposure of Antarctic predators to emerging contaminants that are not yet globally regulated.

The conservation status and taxonomy of the three gadfly petrels that breed in Macaronesia is still discussed partly due to the scarce information on their spatial ecology. Using geolocator and capture-mark-recapture data, we examined phenology, natal philopatry and breeding-site fidelity, year-round distribution, habitat usage and at-sea activity of the three closely-related gadfly petrels that breed in Macaronesia: Zino’s petrel Pterodroma madeira, Desertas petrel P. deserta and Cape Verde petrel P. feae. All P. feae remained around the breeding area during their non-breeding season, whereas P. madeira and P. deserta dispersed far from their colony, migrating either to the Cape Verde region, further south to equatorial waters in the central Atlantic, or to the Brazil Current. The three taxa displayed a clear allochrony in timing of breeding. Habitat modelling and at-sea activity patterns highlighted similar environmental preferences and foraging behaviours of the three taxa. Finally, no chick or adult was recaptured away from its natal site and survival estimates were relatively high at all study sites, indicating strong philopatry and breeding-site fidelity for the three taxa. The combination of high philopatry, marked breeding asynchrony and substantial spatio-temporal segregation of their year-round distribution suggest very limited gene flow among the three taxa.

Understanding the spread of Toxoplasma gondii (T. gondii) in wild birds, particularly in those with opportunistic feeding behavior, is of interest for elucidating the epidemiological involvement of these birds in the maintenance and dissemination of the parasite. Overall, from 2009 to 2011, we collected sera from 525 seagull chicks (Yellow-legged gull (Larus michahellis) and Audouin's gull (L. audouinii)) from 6 breeding colonies in Spain and tested them using the modified agglutination test (MAT) for the presence of antibodies against T. gondii. Chick age was estimated from bill length. Main food source of seagull chicks was evaluated using stable isotope analyses from growing scapular feathers. Overall T. gondii seroprevalence was 21.0% (IC95% 17.5-24.4). A generalized linear mixed-effects model indicated that year (2009) and food source (freshwater) were risk factors associated to the individual risk of infection by T. gondii, while age (days) was close to significance. Freshwater food origin was related to the highest seroprevalence levels, followed by marine origin, supporting freshwater and sewages as important routes of dispersion of T. gondii. Year differences could indicate fluctuating rates of exposure of seagull chicks to T. gondii. Age ranged from 4 to 30 days and seropositivity tended to increase with age (P = 0.07), supporting that seropositivity is related to T. gondii infection rather than to maternal transfer of antibodies, which in gulls is known to sharply decrease with chick age. This study is the first to report T. gondii antibodies in Yellow-legged and Audouin's gulls, thereby extending the range of intermediate hosts for this parasite and underscoring the complexity of its epidemiology.

Chemical signals may be the basis of interspecific recognition and speciation in many animals. To test whether a chemical label allowing recognition between closely related species exists in seabirds, we investigated two closely related taxa breeding sympatrically at some localities: Cory's and Scopoli's shearwaters. Procellariiform seabirds are ideal for this study because they have a well-developed olfactory system and unequalled associated capabilities among birds. We analysed and compared the relative volatile compounds composition of the uropygial gland secretions of Cory's and Scopoli's shearwaters. As the volatile components from uropygial secretions might also provide some critical eco-chemical information about population origin and sex, we also examined variations in the volatile compounds between populations and sexes in Cory's shearwater. The chemical data were obtained using gas chromatography–mass spectrometry techniques looking for the presence of these three particular labels: species, population and gender. We found diagnostic differences in uropygial secretions between the two species of shearwaters and smaller but significant variation between populations of Cory's shearwater in the Atlantic. No significant differences were observed between males and females. Individuals might thus use the chemical variation between species to recognize and mate with conspecifics, especially at localities where both species breed sympatrically. Geographical variation in chemical composition of uropygial secretions suggests that selective forces might vary according with locations, and might provide a key in the species recognition. Further behavioural bioassays are needed to determine whether or not these species labels are signals allowing reproductive isolation between these two taxa. Finally, one of the aims of our study was to test easier methods than freezing for storing uropygial gland secretions in the field. We describe here a new possibility for the storage of uropygial secretion samples at ambient temperature in the field, providing an alternative, simple protocols for the sampling of avian chemosignals. This article is protected by copyright. All rights reserved.

Fishing has a tremendous cultural and economic importance in the Mediterranean and the Black Sea, providing an important source of food and livelihoods for riparian countries and sustaining the traditions and the way of life of many coastal communities. However, the fisheries sector faces many challenges, including the increasing demand for fish and the potential negative effects of pollution, habitat degradation, the appearance of alien species, overfishing, and climate-driven changes on marine ecosystems. This first edition of the GFCM report on the State of Mediterranean and Black Sea fisheries includes a comprehensive analysis of the current state and past trends of fisheries in the GFCM area of application. This analysis has been carried out by different GFCM scientific bodies, the GFCM Secretariat as well as independent experts, based on different sources of information, including official data submitted by GFCM members, national reports, questionnaires, etc. The report sheds light on various aspects of fisheries, such as the extent and composition of the fishing fleet, the production and socioeconomic characteristics of fisheries, the composition and volume of discards, the incidental catch of vulnerable species and the status of stocks. Current efforts deployed by GFCM towards the governance and management of fisheries, including small-scale fisheries are also discussed, with a particular focus on accomplishments and areas for future action. The report is intended to become a flagship GFCM publication for the regular dissemination of information related to fisheries in the Mediterranean and the Black Sea and should serve as a tool to support decision-making on fisheries issues of relevance to the GFCM area of application.

According to classic niche theory, species can coexist in heterogeneous environments by reducing interspecific competition via niche partitioning, e.g. trophic or spatial partitioning. However, support for the role of competition on niche partitioning remains controversial. Here, we tested for spatial and trophic partitioning in feather mites, a diverse and abundant group of arthropods. We focused on the two dominant mite species, Microspalax brevipes and Zachvatkinia ovata, inhabiting flight feathers of the Cory’s shearwater, Calonectris borealis.We performed mite counts across and within primary and tail feathers on free-living shearwaters breeding on an oceanic island (Gran Canaria, Canary Islands). We then inves- tigated trophic relationships between the two mite species and the host using stable isotope analyses of carbon and nitrogen on mite tissues and potential host food sources. The distribution of the two mite species showed clear spatial segregation among feathers; M.brevipes showed high preference for the central wing primary feathers, whereas Z.ovata was restricted to the two outermost primaries. Morphological differences between M.brevipes and Z.ovata support an adaptive basis for the spatial segregation of the two mite species. However, the two mites overlap in some central primaries and statistical modeling showed that Z.ovata tends to outcompete M.brevipes. Isotopic analyses indicated similar isotopic values for the two mite species and a strong correlation in carbon signatures between mites inhabiting the same individual host suggesting that diet is mainly based on shared host-associated resources. Among the four candidate tissues examined (blood, feather remains, skin remains and preen gland oil), we conclude that the diet is most likely dominated by preen gland oil, while the contribution of exogenous material to mite diets is less marked. Our results indicate that ongoing competition for space and resources plays a central role in structuring feather mite communities. They also illustrate that symbiotic infracommunities are excellent model systems to study trophic ecology, and can improve our understanding of mechanisms of niche differentiation and species coexistence.

This study combined the analysis of fatty acids and stable isotopes of nitrogen and carbon to test the hypothesis that the pelagic food web of the south Catalan Sea has a wasp-waist structure supported by sardines Sardina pilchardus. If this hypo thesis were correct, most predators would be expected to have stable isotope ratios and fatty acid profiles consistent with those derived from a sardine-based diet. However, this was true only for mackerel Scomber scomber, blue butterfish Stromateus fiatola, all seabirds and oceanic loggerhead turtles Caretta caretta. The values of the DHA/EPA index of neritic loggerhead turtles and striped dolphins Stenella caeru leo alba were also consistent with a sardine/ squid diet, but their trophic positions were too high. On the other hand, the DHA/EPA index of most predatory fishes indicated that anchovies Engraulis encrasicolus and/or horse mackerel Trachurus trachurus were their main prey. Nevertheless, some amounts of low trophic level invertebrates were likely to be consumed by some predatory fishes, because their trophic positions where lower than expected from a fish-based diet only. The heterogeneous distribution of phytoplankton groups above and below the thermocline during the warm season is hypothesized to be the primary reason for this food web structure, although the strong reliance of some seabirds on sardines is the likely consequence of a massive consumption of discards from fishing boats. In short, there is little evidence for a wasp-waist structure based on sardine, which may explain why the populations of predators fluctuate less than the population of sardines.

Our current understanding of migratory strategies and the reasons for their high variability along the phylogenetic tree remains relatively poor. Most of the hypotheses relating to migration have been formulated for terrestrial taxa; classically, oceanic migrations were considered as merely dispersive because of the scarcity of observations in the open ocean. We describe for the ?rst time, the migration strategy of a small seabird, the Bulwer’s petrel (Bulwe- ria bulwerii), and provide new insights into the ecology and evolution of long- distance marine migrations. Using cutting-edge geolocators, we examined the year-round distri- bution and at-sea activity patterns of adult Bulwer’s petrels sampled at ?ve localities throughout the species’ breeding range in the Atlantic, within the Azores, Salvages, Canary and Cape Verde archipelagos. We assessed the migratory connectivity of the species and its habitat use at population and metapopulation scales. Our results provide the ?rst evidence of an oriented leapfrog migration in oceanic seabirds. Ecological niche models based on breeding-season data effectively predicted that subtropical waters of the South Atlantic would be the preferred habitat for the northern populations of Bulwer’s petrels during the non-breeding season. Habitat modelling also highlighted similarities in distributions between the breeding and non-breeding periods for the southern populations. Data on at-sea activity patterns suggested that birds from the northern and southern populations behave differently during the breeding season, as well as in the northern and southern non-breeding ranges during the non-breeding period. nThese results indicate that speci?c habitat preferences, presumably related to differences in prey availability, explain the observed distributions and hence the pattern of leapfrog migration described for Bulwer’s petrel. Our study demonstrates the utility of integrating diverse tracking data from multiple populations across international boundaries, and habitat modelling, for identifying important areas common to many marine species in the vast oceanic environments.

Two new species of the feather mite genus Promegninia Gaud & Atyeo, 1967 (Avenzoariidae: Bonnetellinae) are described from procellariids in the northeasterm Atlantic Ocean: Promegninia bulweriae n. sp. from the Bulwer’s petrel Bulweria bulwerii (Jardine & Selby) and P. calonectris n. sp. from the Cory’s shearwater Calonectris borealis (Cory) (Procellariiformes: Procellariidae). Males of P bulweriae n. sp. are most clearly distinguished from the other known species in the genus by having short legs III extending only to the level of lobar apices and short conical tarsi III with lanceolate ventral seta w; females of this species are characterised by the absence of additional sclerites at postero-lateral angles of the prodorsal shield. Males of P. calonectris differ from the other known species in having bidentate terminal lamellae on the lobar apices and the entire adanal shield; females of this species are distinguished by having well-developed pygidial shields and a hysteronotal shield encompassing the bases of setae c2. Sequence data of the mitochondrial cytochrome c oxidase subunit I gene fragment (COI) are also obtained for the new species. An updated diagnosis of Promegninia and a key to the known species are provided.

Correct species identification is a crucial issue in systematics with key implications for prioritising conservation effort. However, it can be particularly challenging in recently diverged species due to their strong similarity and relatedness. In such cases, species identification requires multiple and integrative approaches. In this study we used multiple criteria, namely plumage colouration, biometric measurements, geometric morphometrics, stable isotopes analysis (SIA) and genetics (mtDNA), to identify the species of 107 bycatch birds from two closely related seabird species, the Balearic (Puffinus mauretanicus) and Yelkouan (P. yelkouan) shearwaters. Biometric measurements, stable isotopes and genetic data produced two stable clusters of bycatch birds matching the two study species, as indicated by reference birds of known origin. Geometric morphometrics was excluded as a species identification criterion since the two clusters were not stable. The combination of plumage colouration, linear biometrics, stable isotope and genetic criteria was crucial to infer the species of 103 of the bycatch specimens. In the present study, particularly SIA emerged as a powerful criterion for species identification, but temporal stability of the isotopic values is critical for this purpose. Indeed, we found some variability in stable isotope values over the years within each species, but species differences explained most of the variance in the isotopic data. Yet this result pinpoints the importance of examining sources of variability in the isotopic data in a case-by-case basis prior to the cross-application of the SIA approach to other species. Our findings illustrate how the integration of several methodological approaches can help to correctly identify individuals from recently diverged species, as each criterion measures different biological phenomena and species divergence is not expressed simultaneously in all biological traits.

Although little studied in natural populations, the persistence of immunoglobulins may dramatically affect the dynamics of immunity and the ecology and evolution of host-pathogen interactions involving vertebrate hosts. By means of a multiple-year vaccination design against Newcastle disease virus, we experimentally addressed whether levels of speci?c antibodies can persist over several years in females of a long-lived procellariiform seabird—Cory’s shearwater—and whether maternal antibodies against that antigen could persist over a long period in offspring several years after the mother was exposed. We found that a single vaccination led to high levels of antibodies for several years and that the females transmitted antibodies to their offspring that persisted for several weeks after hatching even 5 years after a single vaccination. The temporal persistence of maternally transferred antibodies in nestlings was highly dependent on the level at hatching. A second vaccination boosted efficiently the level of antibodies in females and thus their transfer to offspring. Overall, these results stress the need to consider the temporal dynamics of immune responses if we are to understand the evolutionary ecology of host-parasite interactions and trade-offs between immunity and other life-history characteristics, in particular in long-lived species. They also have strong implications for conservation when vaccination may be used in natural populations facing disease threats.

Offspring phenotypic variation has important consequences for the future survival, reproductive success and individual ?tness of nestlings, but the sex-speci?c reproductive value and ?tness returns for parents of this variation have only rarely been explored. We analysed twelve phenotypic traits of nestling Common Terns (Sterna hirundo) in relation to their sex, age and hatching date, and explored whether sexual differences in these traits were associated with the rearing environment and survival. In addition, we studied sex-speci?c differences in offspring phenotype related to parental factors, since the existence of sexual dimorphism may re?ect differential parental investment. Bill–head length and mediated immune response varied in relation to offspring sex, with males showing larger values than females. Immune response was also affected by environmental (year), rearing (competition over 14 days old) and parental (clutch size) factors. None of the morphological, serological and immunological variables were associated with chick mortality, but female nestlings that did not survive had suffered longer periods of within-brood competition. Although some parental traits in?uenced offspring phenotype, sexual differences among nestlings did not vary in relation to parental age, mass or arrival date, which may imply that there is no great difference in cost between raising sons and raising daughters, and thus no adjustment of parental effort in relation to nestling sex. However, the evidence that immune response was higher for sons in larger clutches that were raised with siblings indicates a difference in the developmental strategies for sons and daughters, which may be related to their reproductive value. These results therefore provide evidence of certain pathways for parental sex allocation that may differentially affect sons and daughters.

In migratory birds, environmental conditions in both breeding and non-breeding areas may affect adult survival rates and hence be significant drivers of demographic processes. In seabirds, poor knowledge of their true distribution outside the breeding season, however, has severely limited such studies. This study explored how annual adult survival rates of black-legged kittiwakes Rissa tridactyla on Hornøya in the southern Barents Sea were related to temporal variation in prey densities and climatic parameters in their breeding and non-breeding areas. We used information on the kittiwakes’ spatiotemporal distribution in the non-breeding season gained from year-round light-based tracking devices (geolocators) and satellite transmitters, and kittiwake annual adult survival rates gained from a multistate capture-mark-recapture analysis of a 22 yr time series of colour-ringed kittiwakes. In the post-breeding period, kittiwakes concentrated in an area east of Svalbard, in the winter they stayed in the Grand Banks/Labrador Sea area, and in the pre-breeding period they returned to the Barents Sea. We identified 2 possible prey categories of importance for the survival of kittiwakes in these areas (sea butterflies Thecosomata in the Grand Banks/Labrador Sea area in winter and capelin Mallotus villosus in the Barents Sea in the pre-breeding season) that together explained 52 % of the variation in adult survival rates. Our results may have important implications for the conservation of kittiwakes, which are declining globally, because other populations use the same areas. Since they are under the influence of major anthropogenic activities including fisheries, international shipping and the offshore oil and gas industry, both areas should be targeted for future management plans.

In recent years, a number of zoonotic flaviviruses have emerged worldwide, and wild birds serve as their major reservoirs. Epidemiological surveys of bird populations at various geographical scales can clarify key aspects of the eco-epidemiology of these viruses. In this study, we aimed at exploring the presence of flaviviruses in the western Mediterranean by sampling breeding populations of the yellow-legged gull (Larus michahellis), a widely distributed, anthropophilic, and abundant seabird species. For 3 years, we sampled eggs from 19 breeding colonies in Spain, France, Algeria, and Tunisia. First, ELISAs were used to determine if the eggs contained antibodies against flaviviruses. Second, neutralization assays were used to identify the specific flaviviruses present. Finally, for colonies in which ELISA-positive eggs had been found, chick serum samples and potential vectors, culicid mosquitoes and soft ticks (Ornithodoros maritimus), were collected and analyzed using serology and PCR, respectively. The prevalence of flavivirus-specific antibodies in eggs was highly spatially heterogeneous. In northeastern Spain, on the Medes Islands and in the nearby village of L’Escala, 56% of eggs had antibodies against the flavivirus envelope protein, but were negative for neutralizing antibodies against three common flaviviruses: West Nile, Usutu, and tick-borne encephalitis viruses. Furthermore, little evidence of past flavivirus exposure was obtained for the other colonies. A subset of the Ornithodoros ticks from Medes screened for flaviviral RNA tested positive for a virus whose NS5 gene was 95% similar to that of Meaban virus, a flavivirus previously isolated from ticks of Larus argentatus in western France. All ELISA-positive samples subsequently tested positive for Meaban virus neutralizing antibodies. This study shows that gulls in the western Mediterranean Basin are exposed to a tick-borne Meaban-like virus, which underscores the need of exploring the spatial and temporal distribution of this flavivirus as well as its potential pathogenicity for animals and humans.

Plastic debris are often ingested by marine predators and can cause health disorders and even death. We present the first assessment of plastic ingestion in Mediterranean seabirds. We quantified and measured plastics accumulated in the stomach of 171 birds from 9 species accidentally caught by longliners in the western Mediterranean from 2003 to 2010. Scopoli's shearwaters (Calonectris diomedea) showed the highest occurrence (94%) and large numbers of small plastic particles per affected bird (on average N=15.3 ±24.4 and mass=23.4±49.6mg), followed by Yelkouan shearwaters (Puffinus yelkouan, 70%, N=7.0 ±7.9, 42.1±100.0mg), Balearic shearwaters (Puffinus mauretanicus, 70%, N=3.6 ±2.9, 5.5±9.7mg) and the rest of species (below 33%, N=2.7, 113.6±128.4mg). Plastic characteristics did not differ between sexes and were not related to the physical condition of the birds. Our results point out the three endemic and threatened shearwater species are particularly exposed to plastic accumulation.

Ancient DNA has revolutionized conservation genetic studies as it allows monitoring of the genetic variability of species through time and predicting future impacts. In this study we examined temporal changes in the genetic diversity of a threatened seabird, the Cory’s shearwater (Calonectris borealis). We analysed the mitochondrial DNA control region of ancient bone samples from the late-Holocene retrieved from the Canary archipelago (NE Atlantic) together with current DNA sequences representative of the entire breeding range of the species. Our results show high levels of ancient genetic diversity in the Canaries comparable to that of the extant population. Temporal haplotype networks further revealed rare but recurrent long-distance dispersals between ocean basins. EBSP demographic analyses reveal both regional and local population size expansion events, and this is in spite of the demographic decline experienced by the species over the last millennia. Overall our findings suggest that population connectivity of the species has acted as a buffer of genetic losses and illustrate the use of ancient DNA to uncover such cryptic genetic events.

Many apical pelagic species use predictable habitats to forage, and thus their movements should signal biologically and ecologically significant areas of the marine ecosystem. Several countries are now engaged in the process to identify these areas based on animal tracking, but this is often limited to a few individuals from a single breeding population, which may result in a biased portrayal of the key marine habitats. Location: North East Atlantic Ocean. Along seven years, we tracked the foraging movements of Cory’s shearwaters (Calonectris diomedea) from multiple populations during the chick-rearing period using GPS and PTT devices. Results We obtained foraging trips from 174 shearwaters breeding on six important breeding colonies representative of the range occupied in the Macaronesian Archipelagos of Madeira, Selvagens and Canaries. Our results show that birds orient and move rapidly towards the closest neritic waters over the African continental shelf. Birds from different colonies show a substantial spatial segregation in their foraging grounds but consistently overlap in some specific foraging areas along the Canary Current characterized by their high productivity. By weighing the use of foraging grounds according to the size of each study population, we inferred the overall exploitation of such areas. Main conclusions Our meta-population approach provides a more comprehensive scenario of space use from both perspectives, the studied species and the Canary Current system, a crucial issue often neglected in conservation studies. Foraging grounds consistently used by multiple populations may not be adequately identified by tracking a single population, and therefore meta-population tracking studies reveals as a crucial tool to properly delineate key conservation areas and inform conservation planning in the marine ecosystem. Finally, we suggest pending work on the long-term stability and sustainability of identified foraging areas and propose that countries with geographical jurisdictions over the Canary Current area should work towards multilateral agreements to set management plans for this key marine ecosystem.

The energetic demands of animals change throughout their annual life cycle. In migrating birds, reproduction and migration are the two most energy demanding processes; the transition from one to the other require a number of physiological adjustments. When arriving to the breeding grounds, long-distance migratory birds need to recover from migration and prepare for reproduction. This process is crucial, since pre-breeding body condition has been established as a critical factor influencing reproductive success in several avian species. In the present study we examined the physiological condition of the Cory´s shearwater (Calonectris diomedea borealis, Cory 1881) after arrival from migration to a breeding colony, as well as its evolution throughout the pre-laying period. We weighed and took blood samples from 149 shearwaters newly arrived to their breeding colony. If found again after 10, 20, 30 or 40 days since their first capture, birds were resampled. We examined individual variation of biochemical parameters, body mass and blood oxygen transport capacity in both males and females. Our results indicate that birds were improving their condition after arrival from migration. Plasma metabolites revealed shearwaters were depositing fat and degrading muscular mass during post-migration and pre-laying, which suggest that shearwaters were remodeling their body composition in order to have more space for lipid reserves. Females started fat deposition earlier than males, probably to cope with the lipid demands of egg formation. This study shows that biochemical blood parameters are good indicators of the ecophysiological changes experienced by post-migrating and pre-breeding birds.

Adaptive sex allocation has frequently been studied in sexually size dimorphic species, but far less is known about patterns of sex allocation in species without pronounced sexual size dimorphism. Parental optimal investment can be predicted under circumstances in which sons and daughters differ in costs and/or fitness returns. In Common Terns Sterna hirundo, previous studies suggest that sons are the more costly sex to produce and rear. We investigated whether hatching and fledging sex ratio and sex-specific chick mortality correlated with the ecological environment (laying date, clutch size, hatching order and year quality) and parental traits (condition, arrival date, experience and breeding success), over 7 consecutive years. Population-wide sex ratios and sex-specific mortality did not differ from parity, but clutch size, mass of the father, maternal breeding experience and to some extent year quality correlated with hatching sex ratio. The proportion of sons tended to increase in productive years and when the father was heavier, suggesting the possibility that females invest more in sons when the environmental and the partner conditions are good. The proportion of daughters increased with clutch size and maternal breeding experience, suggesting a decline in breeding performance or a resources balance solved by producing more of the cheaper sex. No clear patterns of sex-specific mortality were found, neither global nor related to parental traits. Our results suggest lines for future studies on adaptive sex allocation in sexually nearly monomorphic species.

Prospecting allows individuals to gather information on the local quality of potential future breeding sites. In a variable and heterogeneous environment, it plays a major role in breeding habitat selection and potentially helps individuals make optimal dispersal decisions. Although prospecting movements, involving visits to other breeding sites, have been observed in many species at relatively fine spatial scales, little is known about their occurrence at larger scales. Furthermore, the adaptive value of dispersal strategies in response to environmental changes remains poorly investigated. Here, our main objective is to highlight in what ways tracking devices could constitute powerful tools to study prospecting behaviour at various spatial scales. First, we stress the importance of considering prospecting movements involved in breeding habitat selection and we detail the type of data that can be collected. Then, we review the advantages and constraints associated with the use of tracking devices in this context, and we suggest new perspectives to investigate the behavioural strategies adopted by individuals during breeding habitat selection processes and dispersal decisions. The rapid development of new powerful electronic tools for tracking individual behaviour thus opens a wide range of opportunities.More specifically, itmay allow a more thorough understanding of the role of scale-dependent dispersal behaviour in population responses to environmental changes.

Macaronesia (north-east Atlantic archipelagos) has been host to complex patterns of colonization and differentiation in many groups of organisms including seabirds such as gadfly petrels (genus Pterodroma). Considering the subspecies of widely distributed soft-plumaged petrel for many years, the taxonomic status of the three gadfly petrel taxa breeding in Macaronesia is not yet settled, some authors advocating the presence of three, two or one species. These birds have already been the subject of genetic studies with only one mtDNA gene and relatively modest sample sizes. In this study, using a total of five genes (two mitochondrial genes and three nuclear introns), we investigated the population and phylogeographical histories of petrel populations breeding on Madeira and Cape Verde archipelagos. Despite confirming complete lineage sorting with mtDNA, analyses with nucDNA failed to reveal any population structuring and Isolation with Migration analysis revealed the absence of gene flow during the differentiation process of these populations. It appears that the three populations diverged in the late Pleistocene in the last 150 000 years, that is 10 times more recently than previous estimates based solely on one mtDNA gene. Finally, our results suggest that the Madeira petrel population is ancestral rather than that from Cape Verde. This study strongly advocates the use of nuclear loci in addition to mtDNA in demographical and phylogeographical history studies.

To evaluate the avian influenza virus (AIV) circulation in Antarctic and sub-Antarctic penguins we carried out a serosurvey on six species from Livingston, Marion and Gough islands. Seropositivity against AIV was performed on serum samples using a competitive enzyme-linked immunosorbent assay and haemagglutination and neuraminidase inhibition assays. Some oropharyngeal and cloacal swabs were also assayed to detect influenza virus genomes by real time reverse transcription-polymerase chain reaction. Overall, 12.1% (n5140) penguins were seropositive to AIV. By species, we detected 5% (n519) and 11% (n518) seroprevalence in sub-Antarctic rockhopper penguins Eudyptes spp. from Gough and Marion islands, respectively, 42% (n533) seroprevalence in macaroni penguins Eudyptes chysolophus, but no positives in the three other species, gentoo Pygoscelis papua (n525) and chinstrap penguins P. antarctica (n516), from Livingston Island and king penguins Aptenodytes patagonicus (n527) from Marion Island While sero positivity reflected previous exposure to the AIV, the influenza genome was not detected. Our results indicate that AIV strains have circulated in penguin species in the sub-Antarctic region, but further studies are necessary to determine the precise role that such penguin species play in AIV epidemiology and if this circulation is species (or genus) specific.

Aim: Intraspecific variability in the migratory movements of seabirds is being revealed far more complex than hitherto recognized, and our lack of understanding undermines their effective protection. Our aim is to test whether the isotopic values of a single feather of two threatened seabirds, the Mediterranean (Puffinus yelkouan) and the Balearic (Puffinus mauretanicus) shearwaters allow the geographic assignment of birds to their non-breeding areas. Location These two species are known to use three main non-breeding areas: the NE Atlantic Ocean, the W Mediterranean and the Aegean-Black seas. Methods: We clustered in three groups the d13C and d15N values of the first primary feather (P1), inferred to be grown during the non-breeding period, of 34 Mediterranean and 56 Balearic shearwaters accidentally caught by longliners. To link the isotopic values of P1 to its corresponding non-breeding area, we performed a discriminant function analysis (DFA) based on the three clusters and applied this function to feathers of known origin: P1 from seven Mediterranean shearwaters from Hye`res Archipelago (France) tracked with geolocators and body feathers from six chicks from Balearic shearwaters. To link the moulting patterns to the areas where the feathers were grown, we applied theDFA to a sequence of primary feathers of eight Balearic and five Mediterranean shearwaters (caught by longliners). Results: Isotopic and tracking data indicate that none of the Mediterranean shearwaters migrated to the Atlantic. The cluster and discriminant function analyses revealed that 8% of Balearic and 54% of Mediterranean shearwater moulted P1 in the Mediterranean Sea. Migratory movements were reflected in the changing isotopic values of the primary sequences. Main conclusions: Stable isotope analyses (SIA) are a powerful approach to reveal the intraspecific variability in the migratory patterns of seabirds that usedistinct isotopic areas over their annual cycle. The assignment of birds to their non-breeding areas by means of SIA is a simple and effective tool that can help to evaluate the impact of human activities in remote areas not only at population but also at individual level, which is an essential knowledge for the management and conservation of threatened species.

Data about breeding populations of birds in the Antarctica are rare and fragmented. Thus, information about the status of the breeding populations of Antarctic birds is crucial given the current scenario of climate change, which is particularly acute in Antarctica. This paper presents new information about the populations of the Antarctic tern Sterna vittata, the kelp gull Larus dominicanus, the southern giant petrel Macronectes giganteus, the Antarctic skua Catharacta antarctica lonnbergi, the chinstrap penguin Pygoscelis antarctica and the gentoo penguin Pygoscelis papua on Byers Peninsula (Livingston Island, South Shetland Islands). We used line transects counts to estimate both densities and numbers of nests of the different species. We estimate that there are 398.96 birds km-2 of southern giant petrels (2793 individuals), 62.4 birds km-2 of Antarctic tern (3746 individuals) and 269.1 birds km-2 of kelp gull (1884 individuals). Furthermore, we found 15 nests of Antarctic skua in 25 km2, from which we can estimate that 60–91 birds must breed on Byers Peninsula. We also censused two colonies of gentoo penguins (3000 and 1200 pairs) and 50 pairs of chinstrap. Compared to previous estimates, gentoo penguins seem to have increased whereas chinstrap penguin have decreased. Finally, the populations of An arctic tern, southern giant petrel and kelp gull have stabilized or slightly increased.

Parasites represent ideal models for unravelling biogeographic patterns and mechanisms of diversification on islands. Both host-mediated dispersal and within-island adaptation can shape parasite island assemblages. In this study, we examined patterns of genetic diversity and structure of Ornithodoros seabird ticks within the Cape Verde Archipelago in relation to their global phylogeography. Contrary to expectations, ticks from multiple, geographically distant clades mixed within the archipelago. Trans-oceanic colonization via host movements probably explains high local tick diversity, contrasting with previous research that suggests little largescale dispersal in these birds. Although host specificity was not obvious at a global scale, host-associated genetic structure was found within Cape Verde colonies, indicating that post-colonization adaptation to specific hosts probably occurs. These results highlight the role of host metapopulation dynamics in the evolutionary ecology and epidemiology of avian parasites and pathogens.

Recent observations on the western Antarctic Peninsula have suggested that changing climatic conditions may be increasing pressure on breeding seabirds due to higher exploitation rates by the tick Ixodes uriae. Using data from 8 microsatellite markers and ticks from 6 Pygoscelis spp. colonies, we employed a population genetics approach to specifically test the hypothesis that I. uriae is expanding south-westward along the peninsula from the Subantarctic region. Contrary to expectations, tick genetic diversity was high within all colonies, and no remaining signal of colonisation events was evident. Although significant geographic genetic structure occurred among ticks from different colonies, these ectoparasites tended to belong to 2 major genetic groups, one found principally in south-western locations (Palmer Station area) and the other in more north-eastern areas (South Shetland Islands). More central colonies showed a mixture of ticks from each genetic group, suggesting that this area represents a hybridisation zone of ticks from 2 distinct origins. A subsequent clustering analysis, including ticks from 2 Subantarctic locations, did not reveal the source population for the northern peninsula group. Overall, our data refute the hypothesis of a recent south-westward expansion of I. uriae along the peninsula and suggest that this tick has been present at more southern latitudes for an extended period of time. Further studies on the distribution and genetic characteristics of this ectoparasite around Antarctica are now required to better understand the colonisation process and predict how changing environmental conditions may affect its presence and diversity in seabird colonies.

Impacts of human activities on marine top predators are acute. Our poor knowledge of the spatial and trophic ecology of these marine animals ultimately compromises the viability of their populations as well as our ability to use them as environmental biomonitors. Intrinsic biogeochemical markers, such as stable isotopes, fatty acids, trace elements and chemical pollutants are increasingly used to trace spatial and trophic ecology of marine top predators. Outstanding advances include the emergence of the first oceanographic isoscapes, the advent of compound-specific isotopic analyses, the improvements in diet reconstruction using Bayesian statistics and the analysis of tissues of tracked animals to ground-truth biogeochemical profiles. However, most researchers still focus only on a few tracers. Moreover, insufficient knowledge of the biogeochemical integration in tissues, fractionation and routing processes and geographic and temporal variability in baseline levels still hamper their resolution and potential as tracers of the spatial and feeding ecology of top predators.

Seabirds are facing a growing number of threats in both terrestrial and marine habitats, and many populations have experienced dramatic changes over past decades. Years of seabird research has improved our understanding of seabird populations and has informed a broader understanding of marine ecological processes. In an effort to encourage future research and guide seabird conservation science, seabird researchers from 9 nations identified the 20 highest priority research questions, which were organized into six general categories: (i) population dynamics, (ii) spatial ecology, (iii) tropho-dynamics, (iv) fisheries interactions, (v) response to global change, and (vi) management of anthropogenic impacts (focusing on invasive species, contaminants and protected areas). For each category, we provide an assessment of the current approaches, challenges and future directions. While this is not an exhaustive list of all research needed to address the myriad conservation challenges seabirds face, the results of this effort represent an important synthesis of current expert opinion across sub-disciplines within seabird ecology. As this synthesis highlights, research, in conjunction with direct management, education, and community engagement, can play an important role in facilitating the conservation and management of seabird populations and of the ocean ecosystems on which they and we depend.

Trophic ecology and movements are critical issues to understand the role of marine predators in food webs and face the challenges of their conservation. Seabird foraging ecology is increasingly studied, but small elusive species, such as those forming the ‘little shearwater’ complex, remain poorly known. We present the first study on the movements and feeding ecology of the Macaronesian shearwater Puffinus baroli combining global location sensing units, stable isotope analyses of feathers (d13C and d15N), stomach flushings and data from maximum depth gauges in a colony from the Azores archipelago (NE Atlantic). During the chick-rearing period, parents visited their nests most nights, foraged mainly south of the colony and fed at lower trophic levels than during the non-breeding period. Squid was the most diverse prey (six families and at least 10 different taxa), but species composition varied considerably between years. Two squid families, Onychoteuthidae and Argonautidae, and the fish family Phycidae accounted for 82.3% of ingested prey by number. On average, maximum dive depths per foraging trip reached up to 14.8 m, (range: 7.9-23.1 m). After the breeding period, birds dispersed offshore in all directions and up to 2500 km from the breeding colony and fed at higher trophic levels. Overall, our results indicate that the Macaronesian shearwater is a non-migratory shearwater feeding at the lowest trophic level among Macaronesian seabirds, showing both diurnal and nocturnal activity and feeding deeper in the water column than other seabirds do, principally on small schooling squid and fish. These traits contrast with those of three other Azorean procellariiformes (Cory’s shearwater Calonectris diomedea, the Madeiran storm-petrel Oceanodroma castro and Monteiro’s storm-petrel O. monteiroi), indicating ecological segregation within the Azorean seabird community.

An understanding of the non-breeding distribution and ecology of migratory species is necessary for successful conservation. Many seabirds spend the nonbreeding season far from land, and information on their distribution during this time is very limited. The black-legged kittiwake, Rissa tridactyla, is a widespread and numerous seabird in the North Atlantic and Pacific, but breeding populations throughout the Atlantic range have declined recently. To help understand the reasons for the declines, we tracked adults from colonies throughout the Atlantic range over the non-breeding season using light-based geolocation.

The evolution of different life-history strategies has been suggested as a major force constraining physiological mechanisms such as immunity. In some long-lived oviparous species, a prolonged persistence of maternal antibodies in offspring could thus be expected in order to protect them over their long growth period. Here, using an intergenerational vaccination design, we show that specific maternal antibodies can display an estimated half-life of 25 days post-hatching in the nestlings of a long-lived bird. This temporal persistence is much longer than previously known for birds and it suggests specific properties in the regulation of IgY immunoglobulin catabolism in such a species. We also show that maternal antibodies in the considered procellariiform species are functional as late as 20 days of age. Using a modelling approach, we highlight that the potential impact of such effects on population viability could be important, notably when using vaccination for conservation. These results have broad implications, from comparative immunology to evolutionary eco-epidemiology and conservation biology.

Trophic ecology and geographic location are crucial factors explaining OC levels in marine vertebrates, but these factors are often difficult to disentangle. To examine their relative influence, we analyzed PCBs, DDTs and stable-nitrogen isotope signatures in the blood of 10 pelagic seabird species across 7 breeding localities from the northeast Atlantic and western Mediterranean. Large scale geographic patterns emerged due to the confined character and greater historical OC inputs in the Mediterranean compared to the Atlantic basin. Spatial patterns also emerged at the regional scale within the Atlantic basin, probably associated with long-range pollutant transport. Trophic ecology, however, also was a major factor explaining OC levels. We found clear and consistent OCs differences among species regardless of the sampled locality. However, species d15N and blood OC levels were not correlated within most breeding localities. Petrel species showed significantly greater OC burdens than most shearwater species but similar trophic positions, as indicated by their similar d15N signatures. This pattern probably results from Petrel species feeding on mesopelagic fish and squid that migrate close to the sea surface at night, whereas shearwater species mainly feed on epipelagic diurnal prey. In sum, this study illustrates the lasting and unequal influence of past human activities such as PCB and DDT usage across different marine regions. In addition, our results suggest that multispecies designs are powerful tools to monitor geographic patterns of OCs and potentially useful to assess their vertical dynamics in the marine environment

Seabirds act as natural reservoirs to Lyme borreliosis (LB) spirochetes and may play a significant role in the global circulation of these pathogens. While Borrelia burgdorferi s.l. (Bbsl) has been shown to occur in ticks collected from certain locations in the North Pacific, little is known about interspecific differences in exposure within the seabird communities of this region. We examined the prevalence of anti-Bbsl antibodies in 805 individuals of nine seabird species breeding across the North Pacific. Seroprevalence varied strongly among species and locations. Murres (Uria spp.) showed the highest antibody prevalence and may play a major role in facilitating Bbsl circulation at a worldwide scale. Other species showed little or no signs of exposure, despite being present in multispecific colonies with seropositive birds. Complex dynamics may be operating in this wide scale, natural host-parasite system, possibly mediated by the host immune system and host specialization of the tick vector.

Determining migratory strategies of seabirds is still a major challenge due to their relative in accessibility. Small geolocators are improving this knowledge, but not all birds can be tracked. Stable isotope ratios in feathers can help us to understand migration, but we still have insufficient baseline knowledge for linking feather signatures to movements amongst distinct water masses. To understand the migration strategies of kittiwakes Rissa tridactyla and the link between stable isotopes in feathers and the areas in which these were grown, we tracked 6 kittiwakes from Hornøya (N Norway) with light level geolocators over one year. Then we analysed the stable isotopes of carbon and nitrogen in their 1st and 7th primary feathers as well as in the 1st, 3rd, 5th, 7th and 10th primaries of 12 birds found freshly dead in the same breeding colony. After breeding, all tracked birds moved east of the Svalbard archipelago and subsequently migrated to the Labrador Sea. Thereafter, birds showed individual variation in migration strategies; three travelled to the NE Atlantic, whereas the others remained in the Labrador Sea until the end of the wintering period. Changes in stable isotope signatures from the 1st to the 10th primary feathers corresponded well to the sequence of movements during migration, and the area in which we inferred that each feather was grown. Thus, by combining information on moult patterns and tracking data, we demonstrate that stable isotope analysis of feathers can be used to trace migratory movements of seabirds.

PAHs were analyzed in the liver of 5 species of pelagic seabirds (Procellariiformes) from the northeast Atlantic and the Mediterranean. The main objective was to assess the trophic and geographic trends of PAHs in seabirds to evaluate their suitability as bioindicators of chronic marine pollution by these compounds. Although higher levels of PAHs have been described in the Mediterranean compared to other oceanic regions, we did not find significant spatial patterns and observed only minor effects of the geographic origin on seabird PAHs. However, we found significant higher PAH levels in petrel compared to shearwater species, which could be related to differences in their exploitation of mesopelagic and epipelagic resources, respectively, and the vertical dynamic of PAHs in the water column. Overall, although this study enhances the need of multi-species approaches to show a more comprehensive evaluation of marine pollution, seabirds emerged as poor indicators of pelagic chronic PAH levels.

Offspring of long-lived species should face costs of parental trade-offs that vary with overall energetic demands encountered by parents during breeding. If sex differences exist in how parents make the trade-off, sex-specific differences may exist in the contribution of each parent to those costs. Adaptations of offspring facing such costs are not well understood, but the hormone corticosterone probably plays a role. We manipulated breeding effort in Cory’s shearwaters (Calonectris diomedea) to increase costs to offspring and used an integrated measure of corticosterone from chick feathers to investigate how experimental variation in parental investment influences offspring physiology. Average foraging trip duration and foraging efficiency (FE) of breeding pairs were not related to chick corticosterone, but sex biases in FE were. Adult male investment was more strongly related to chick corticosterone than was female investment. Importantly, we show for the first time suppression of adrenocortical activity in nestling Procellariiform seabirds, and explain how our results indicate an adaptive mechanism invoked by chicks facing increased costs of parental trade-offs.

Feeding ecology and geographic location are 2 major factors influencing animal stable isotope signatures, but their relative contributions are poorly understood, which limits the usefulness of stable isotope analysis in the study of animal ecology. To improve our knowledge of the main sources of isotopic variability at sea, we determined ?15N and ?13C signatures in the first primary feather of adult birds from 11 Procellariiform species (n = 609) across 16 northeast Atlantic localities, from Cape Verde (20° N) to Iceland (60° N). Post-breeding areas (where the studied feather is thought to be grown) were determined using light-level geolocation for 6 of the 11 species. Isotopic variability was geographically unstructured within the mid-northeast Atlantic (Macaronesian archipelagos), but trophically structured according to species and regardless of the breeding location, presumably as a result of trophic segregation among species. Indeed, the interspecific isotopic overlap resulting from combining ?15N and ?13C signatures of seabirds was low, which suggests that most species exploited exclusive trophic resources consistently across their geographic range. Species breeding in north temperate regions (Iceland, Scotland and Northern Ireland) showed enriched ?15N compared to the same or similar species breeding in tropical and subtropical regions, suggesting some differences in baseline levels between these regions. The present study illustrates a noticeable trophic segregation of northeast Atlantic Procellariiformes. Our results show that the isotopic approach has limited applicability for the study of animal movements in the northeast Atlantic at a regional scale, but is potentially useful for the study of long-distance migrations between large marine systems.

Carotenoids, as pigments with antioxidant and immunoregulatory properties, play a crucial role in developing chicks. Carotenoids must be acquired through diet and are relatively scarce, suggesting that their availability is a limiting factor leading to a trade-off between colour displays and physiological functions. However, potential differences in this trade-off between male and female chicks have been little studied. We manipulated carotenoid availability in 9 days old common tern Sterna hirundo chicks by supplementing their fish diet with four carotenoids during 9 days. Our aim was to examine sex-specific responses to the experimental increase of dietary carotenoids on plasma circulation, physiological and condition variables and successful fledging. Furthermore, to explore the functional and evolutionary basis of the trade-off, we studied the relationships among carotenoid concentration, mediated immune response and foot colouration. After treatment, control chicks showed decreasing plasma levels for most carotenoid types, whereas supplemented chicks had strong increases. Colour luminosity and saturation increased in both treatment groups, while hue only changed significantly towards redder feet in supplemented females.

Identifying markers that are indicative of individual state, related to fitness, and which could be used to study life-history tradeoffs in wild populations is extremely difficult. Recently, it has been suggested that telomeres, the ends of eukaryote chromosomes, might be useful in this context. However, little is known of the link between telomere length and fitness in natural populations and whether it is a useful indicator of biological state. We measured average telomere length in red blood cell samples taken from a wide age range of individuals of a very long-lived and highly sexually dimorphic seabird, the southern giant petrel (Macronectes giganteus). We examined the relationship with age, sex, and subsequent survival over an 8-year period. Telomere length was longer in chicks than adults. Within the adult group, which ranged in age from 12 to 40 years, telomere length was not related to age. For the first time in birds, there was some evidence of a sex difference. Male giant petrels, which are substantially larger than females, had significantly shorter telomere lengths than females. This difference was evident from an early stage in life and is likely to relate to differences in growth trajectories. Those adults that died during the 8-year time window following the telomere length measurement had significantly shorter telomere lengths than those that survived this period, irrespective of age or sex, neither of which were significant predictors of survival. These results show that relatively short telomere length is related to future life expectancy at any adult age, demonstrating its usefulness as a state variable. Key words: giant petrel, life span, sex differences, survival, telomere dynamics.

The loss of species during the Holocene was, dramatically more important on islands than on continents. Seabirds from islands are very vulnerable to human-induced alterations such as habitat destruction, hunting and exotic predators. For example, in the genus Puffinus (family Procellariidae) the extinction of at least five species has been recorded during the Holocene, two of them coming from the Canary Islands.

In long-lived seabirds, intermittent nonbreeding years in an adult life, the so called ‘sabbatical years’, are common. However, proximal causes that make animals decide whether to breed or not to breed are poorly known. In this study we assessed different components of the physiological state of a long-lived pelagic seabird, the Cory's shearwaters Calonectris diomedea, during the pre-laying period to understand which components are influencing breeding decisions. We analyzed plasma biochemistry, haematocrit, leukocyte counts and stable isotope (?15N and ?13C) values in blood and claws. We also recorded body mass, ectoparasite loads and fault bars in primary and tail feathers. All parameters were compared between breeders and sabbaticals and between males and females. Among all biochemical variables analyzed we found triglyceride levels in plasma to be significantly greater in breeders than in sabbaticals and in females than males. H/L ratio was lower in breeders than in sabbaticals and greater in males than females. These results suggest the ability to store fat and the immunological condition are important components compromising breeding decisions. Our study also suggests that H/L ratio can be used as a good predictor of the breeding decisions.

Ecological studies on food webs rarely include parasites, partly due to the complexity and dimensionality of host-parasite interaction networks. Multiple co-occurring parasites can show different feeding strategies and thus lead to complex and cryptic trophic relationships, which are often difficult to disentangle by traditional methods. We analyzed stable isotope ratios of C (13C/12C, ?13C) and N (15N/14N, ?15N) of host and ectoparasite tissues to investigate trophic structure in 4 co-occurring ectoparasites: three lice and one flea species, on two closely related and spatially segregated seabird hosts (Calonectris shearwaters). ?13C isotopic signatures confirmed feathers as the main food resource for the three lice species and blood for the flea species. All ectoparasite species showed a significant enrichment in ?15N relatively to the host tissue consumed (discrimination factors ranged from 2 to 5‰ depending on the species). Isotopic differences were consistent across multiple host-ectoparasite locations, despite of some geographic variability in baseline isotopic levels. Our findings illustrate the influence of both ectoparasite and host trophic ecology in the isotopic structuring of the Calonectris ectoparasite community. This study highlights the potential of stable isotope analyses in disentangling the nature and complexity of trophic relationships in symbiotic systems.

Although seabirds have been proposed as useful biomonitors for organochlorine contaminants (OCs) in marine environments, their suitability is still unclear. To understand the geographic variability and the influence of seabird trophic ecology in OC levels, we analyzed PCBs, DDTs, ?13C, and ?15N in the blood of adult Calonectris shearwaters throughout a vast geographic range within the northeast Atlantic Ocean (from Cape Verde to Azores) and the Mediterranean Sea (from the Alboran Sea to Crete). OC concentrations were greater in birds from the Mediterranean than in those from the Atlantic colonies, showing higher and lower chlorinated PCB profiles, respectively. This large-scale patternmayreflect theinfluenceof historicalEuropean runoffs in the Mediterranean basin and diffused sources for OCs in remote Atlantic islands. Spatial patterns also emerged withintheAtlanticbasin,probablyassociatedwithpollutantlongrange transport and recent inputs of DDT in the food webs of shearwaters from Cape Verde and the Canary islands. Moreover, a positive association of OC concentrations with ?15N within each locality points out diet specialization as a major factor explaining differences in OCs at the intraspecific level. Overall, this study highlights wide range breeding seabirds, such as Calonectris shearwaters, as suitable organisms for biomonitoring large geographic trends of organochlorine contamination in the marine environment.

Satellite transmitters and geographic-positioning-system devices often add substantial mass to birds to which they are attached. Studies on the effects of such instruments have focused on indirect measures, whereas the direct influence of extra mass on pelagic behavior is poorly known. We used 2.5-g geolocators to investigate the effect of extra mass on the pelagic behavior of Cory’s Shearwaters (Calonectris diomedea) by comparing the traits of a single foraging trip among a group carrying 30-g weights, a group carrying 60-g weights, and a control group. The weights were attached to the birds’ backs using typical techniques for attaching satellite transmitters to seabirds. The extra mass increased the duration of the birds’ trips and decreased their foraging efficiency and mass gained at sea. These indirect effects may be related to foraging traits: weighted birds showed a greater search effort than control birds, traveled greater distances, covered a greater foraging area, and increased the maximum foraging range. Furthermore, the time spent on the sea surface at night was greater for weighted than for control groups, which showed that the extra mass also affected activity patterns. Our results underline the need to quantify the effects of monitoring equipment commonly used to study the pelagic behavior of seabirds. We suggest that geolocators can be used to obtain control data on foraging-trip movements and activity patterns.

To test the potential effects of winds on the migratory detours of shearwaters, transequatorial migrations of 3 shearwaters, the Manx Puffinus puffinus, the Cory’s Calonectris diomedea, and the Cape Verde C. edwardsii shearwaters were tracked using geolocators. Concurrent data on the direction and strength of winds were obtained from the NASA SeaWinds scatterometer to calculate daily impedance models reflecting the resistance of sea surface winds to the shearwater movements. From these models we estimated relative wind-mediated costs for the observed synthesis pathway obtained from tracked birds, for the shortest distance pathway and for other simulated alternative pathways for every day of the migration period. We also estimated daily trajectories of the minimum cost pathway and compared distance and relative costs of all pathways. Shearwaters followed 26 to 52% longer pathways than the shortest distance path. In general, estimated wind-mediated costs of both observed synthesis and simulated alternative pathways were strongly dependent on the date of departure. Costs of observed synthesis pathways were about 15% greater than the synthesis pathway with the minimum cost, but, in the Cory’s and the Cape Verde shearwaters, these pathways were on average 15 to 20% shorter in distance, suggesting the extra costs of the observed pathways are compensated by saving about 2 travelling days. In Manx shearwaters, however, the distance of the observed synthesis pathway was 25% longer than that of the lowest cost synthesis pathway, probably because birds avoided shorter but potentially more turbulent pathways. Our results suggest that winds are a major determinant of the migratory routes of seabirds.

The spatial ecology of seabirds has greater precedence today than ever before because of impacts on the marine environment from human exploitation, pollution, and climate change. Specific life history traits make seabirds particularly sensitive to these impacts, currently driving many species to unsustainable population declines. To evaluate the risk posed by human activities, we need integrative studies on seabird abundance, distributions, and movements in relation to the biophysical marine environment. Also interpreting the limits of these relationships is fundamental to understanding historical constraints and behavioural adaptations of seabirds that are shaped by evolutionary processes. In this Theme Section, we assembled 4 review papers and 10 case studies that highlight some of the latest techniques to study seabird spatial ecology. This includes the application of tracking tags, ship-based surveys, and remotely sensed environmental data, to characterize seabird movement patterns, fine scale behaviour, and overall distribution combined with measures of the oceanic habitats to enhance our understanding of the functional role that seabirds play. Overall, this knowledge is crucial for understanding and predicting the impacts that fisheries, climate change and pollution are exerting on marine ecosystems and will provide opportunities for developing marine protected areas, conservation action plans and species management.

Migratory marine vertebrates move annually across remote oceanic water masses crossing international borders. Many anthropogenic threats such as overfishing, bycatch, pollution or global warming put millions of marine migrants at risk especially during their long-distance movements. Therefore, precise knowledge about these migratory movements to understand where and when these animals are more exposed to human impacts is vital for addressing marine conservation issues. Because electronic tracking devices suffer from several constraints, mainly logistical and financial, there is emerging interest in finding appropriate intrinsic markers, such as the chemical composition of inert tissues, to study long-distance migrations and identify wintering sites. Here, using tracked pelagic seabirds and some of their own feathers which were known to be grown at different places and times within the annual cycle, we proved the value of biogeochemical analyses of inert tissue as tracers of marine movements and habitat use. Analyses of feathers grown in summer showed that both stable isotope signatures and element concentrations can signal the origin of breeding birds feeding in distinct water masses. However, only stable isotopes signalled water masses used during winter because elements mainly accumulated during the long breeding period are incorporated into feathers grown in both summer and winter. Our findings shed new light on the simple and effective assignment of marine organisms to distinct oceanic areas, providing new opportunities to study unknown migration patterns of secretive species, including in relation to human-induced mortality on specific populations in the marine environment.

The Patagonian Sea is the oceanic ecosystem of the South-Western Atlantic. Exposed to the ecological effects of the fronts created by the Brazil and Malvinas currents, it is a unique, highly productive ocean which is plentiful in species of high aesthetic, ecological and economic value, but it is also vulnerable. Albatrosses, petrels, penguins, sea lions and elephant seals are top predators and charismatic species of the Patagonian Sea. They require considerable space and resources and are vulnerable to many human activities. This makes them good indicators of the status of conservation of the ecosystem; ensuring their protection will also be beneficial for many other species. However, current conservation measures, which comprise relatively few impact mitigation actions and limited protection of coastal breeding areas, are insufficient. There is an urgent need to identify and protect the open sea environments where turtles, seabirds and marine mammals forage. This Atlas of the Patagonian Sea. Species and Spaces is a summary of information on the use made of the ecosystem of the Patagonian Sea by 16 species of top predators: Wandering Albatross, Black-browed Albatross, Grey-headed Albatross, Northern Royal Albatross, Light-mantled Albatross, Southern Giant Petrel, Northern Giant Petrel, White-chinned Petrel, Magellanic Penguin, Southern Rockhopper Penguin, King Penguin, Gentoo Penguin, South American Sea Lion, South American Fur Seal, Antarctic Fur Seal and Southern Elephant Seal. Identification of the principal foraging areas for these species was made possible by the use of tracking methods that allow the movements of individuals in the ocean to be closely observed and accurately described. The key coastal areas involved are the waters adjacent to the Malvinas Islands, the Staten Island and the Diego Ramírez Islands, and the Valdés Peninsula as far as the northern end of the Gulf of San Jorge. These areas have been recognised as being significant for the biological diversity of the Patagonian Sea. Far from the coast, and therefore out of sight, pelagic environments are less well known and thus tend to be ignored. The data included in this publication suggest as important areas for top predators the oceanographic front associated with the slope area of the Patagonian Shelf, the ocean environment adjacent to the Malvinas Islands, the shelf-slope area at the latitude of the Gulf of San Jorge and areas influenced by the outflow of the Río de la Plata. Also important are the waters to the east of the Burdwood Bank and those of the polar front in the far south-east of the Patagonian Sea. A coastal-pelagic corridor between the Valdés Peninsula and the slope appears to be particularly important for migratory movements from the coast to the deep sea. Among the spatial tools for protecting the open sea are the creation of marine areas under special management. Any definition on the use of resources in these areas should embody the concept of integrated ecosystem management in the conservation of the diversity of species and ecological functions. The ecological requirements of top predators are rarely taken into account when defining management actions, except when evidence has been produced of potentially irreversible impact. This Atlas helps to identify those marine environments for which considerations of integrated management are urgently needed. The Patagonian Sea is not pristine. The unsustainable exploitation of its resources means that numerous human activities pose threats to biodiversity. These include overfishing, fishing discards, the bycatch of seabirds and marine mammals, the introduction of non-native species, the degradation of coastal and marine environments, and the contamination associated with the extraction of oil, or caused by urban and industrial waste. The current situation of the seas of the world, under even greater threat as a result of climate change, cannot tolerate any further inaction. The biological diversity and functionality of the world’s ecosystems are of extraordinary importance for the future of humankind. However, the “biodiversity crisis” that could bring about the collapse and extinction of certain animal populations clearly exists, and appropriate solutions have yet to be found. The detailed analysis contained in this Atlas of the Patagonian Sea provides useful basic scientific information essential for implementing the vision of integrated ecosystem management. In particular it suggests that there is a need to create a network of marine areas, under special considerations of biodiversity management, which will incorporate those open sea environments which are linked to key coastal areas.

Migratory routes and wintering areas of Cory’s shearwaters Calonectris diomedea from es Pantaleu (Mallorca). Here we show the migratory trips through the Atlantic Ocean of 8 Cory’s shearwaters breeding at es Pantaleu islet (P.N. de sa Dragonera, Majorca) during the winter of 2002-2003. The majority of the birds preferred the coasts of the Sahara and of Mauritania and to a lesser extent those of Namibia, corresponding to two zones of oceanic upwelling of cold and very productive waters (Canary and Benguela currents respectively). One of the birds behaved more in keeping with those from the Atlantic colonies, wintering in the confluence of the Brazilian and Malvinas currents off the coasts of southern Brazil and Uruguay, a straight-line distance of some 9000 km from es Pantaleu. Another spent the winter in the equatorial waters of the gulf of Guinea. Most of the birds made a loop-migration return through the northern sub-equatorial Atlantic, avoiding the calm areas. One of them reached the coasts of the Small Antilles, in the Caribbean. Key words: Cory’s shearwaters, Calonectris diomedea, migratory routes, wintering areas, es Pantaleu (Mallorca). Paraules clau: virot gros, Calonectris diomedea, rutes migratòries, àrees d’hivernada, es Pantaleu (Mallorca).

On 21 March 2007, while catching Fea’s Petrels Pterodroma feae on Fogo, Cape Verde Islands, Jacob Gonzalez-Solis noticed an odd individual amongst 17 birds trapped for ringing which showed an overall grey cast to the entire underparts. In spring 2008 and 2009, respectively, a further 18 and 19 were trapped but none showed any anomalous coloration.

Trophic segregation has been proposed as a major mechanism explaining the coexistence of closely related animal taxa. However, how such segregation varies throughout the annual cycle is poorly understood. Here, we examined the feeding ecology of the two subspecies of Cory’s shearwater, Calonectris diomedea diomedea and Calonectris diomedea borealis, breeding in sympatry in a Mediterranean colony. To study trophic segregation at different stages, we combined the analysis of isotope values (d15N, d13C) in blood obtained during incubation and in feathers moulted during chick-rearing and wintering periods with satellite-tracking data during the chick-rearing period. Satellite-tracking and stable isotope data of the first primary feather revealed that C. d. borealis foraged mainly in the Atlantic whereas C. d. diomedea foraged exclusively in the Mediterranean. This spatial segregation could reflect the foraging behaviour of the C. d. borealis individuals before they arrived at the Mediterranean colony. Alternatively, greater wing loading of C. d. borealis individuals may confer the ability to fly across the strong winds occurring at the at the Gibraltar strait. Isotope values of the eighth secondary feather also support segregation in wintering areas between the two forms: C. d. diomedea wintered mainly in association with the Canary current, whereas C. d. borealis wintered in the South African coast. Overall, our results show that spatial segregation in foraging areas can display substantial variation throughout the annual cycle and is probably a major mechanism facilitating coexistence between closely related taxa.

Increasing evidence suggests oceanic traits may play a key role in the genetic structuring of marine organisms. Whereas genetic breaks in the open ocean are well known in fishes and marine invertebrates, the importance of marine habitat characteristics in seabirds remains less certain. We investigated the role of oceanic transitions versus population genetic processes in driving population differentiation in a highly vagile seabird, the Cory’s shearwater, combining molecular, morphological and ecological data from 27 breeding colonies distributed across the Mediterranean (Calonectris diomedea diomedea) and the Atlantic (C. d. borealis). Genetic and biometric analyses showed a clear differentiation between Atlantic and Mediterranean Cory’s shearwaters. Ringingrecovery data indicated high site fidelity of the species, but we found some cases of dispersal among neighbouring breeding sites (<300 km) and a few long distance movements (>1000 km) within and between each basin. In agreement with this, comparison of phenotypic and genetic data revealed both current and historical dispersal events. Within each region, we did not detect any genetic substructure among archipelagos in the Atlantic, but we found a slight genetic differentiation between western and eastern breeding colonies in the Mediterranean. Accordingly, gene flow estimates suggested substantial dispersal among colonies within basins. Overall, genetic structure of the Cory’s shearwater matches main oceanographic breaks (Almería-Oran Oceanic Front and Siculo-Tunisian Strait), but spatial analyses suggest that patterns of genetic differentiation are better explained by geographic rather than oceanographic distances. In line with previous studies, genetic, phenotypic and ecological evidence supported the separation of Atlantic and Mediterranean forms, suggesting the 2 taxa should be regarded as different species.

The value of stable isotope analysis in tracking animal migrations in marine environments is poorly understood, mainly due to insufficient knowledge of isotopic integration into animal tissues within distinct water masses. We investigated isotopic and moult patterns in Cory’s shearwaters to assess the integration of different stable isotopes into feathers in relation to the birds’ transoceanic movements. Specimens of Mediterranean Cory’s shearwater Calonectris diomedea diomedea caught accidentally by Catalan longliners were collected and the signatures of stable isotopes of C (d13C), N (d15N) and S (d34S) were analysed in 11 wing and two tail feathers from 20 birds, and in some breast feathers. Based on isotopic signatures and moult patterns, the feathers segregated into two groups (breeding and wintering), corresponding to those grown in the Mediterranean or Atlantic regions, respectively. In addition, feathers grown during winter, i.e. moulted in Atlantic waters, were grouped into two isotopically distinct profiles, presumably corresponding to the two main wintering areas previously identified for Mediterranean Cory’s shearwater in tracking studies. N signatures mainly indicated the Mediterranean-to-Atlantic migration, whereas C and S signatures differed according to the Atlantic wintering area. Our results indicate that isotopic signatures from distant oceanic regions can integrate the feathers of a given bird and can indicate the region in which each feather was grown. This study thus underscores how stable isotope analysis can link marine animals to specific breeding and wintering areas, and thereby shed new light on studies involving assignment, migratory connectivity and carry-over effects in the marine environment.

Global wind patterns influence dispersal and migration processes of aerial organisms, propagules and particles, which ultimately could determine the dynamics of colonizations, invasions or spread of pathogens. However, studying how wind?mediated movements actually happen has been hampered so far by the lack of high resolution global wind data as well as the impossibility to track aerial movements. Using concurrent data on winds and actual pathways of a tracked seabird, here we show that oceanic winds define spatiotemporal pathways and barriers for large?scale aerial movements. We obtained wind data from NASA SeaWinds scatterometer to calculate wind cost (impedance) models reflecting the resistance to the aerial movement near the ocean surface. We also tracked the movements of a model organism, the Cory’s shearwater (Calonectris diomedea), a pelagic bird known to perform long distance migrations. Cost models revealed that distant areas can be connected through “wind highways” that do not match the shortest great circle routes. Bird routes closely followed the low?cost “wind?highways” linking breeding and wintering areas. In addition, we found that a potential barrier, the near surface westerlies in the Atlantic sector of the Intertropical Convergence Zone (ITCZ), temporally hindered meridional trans?equatorial movements. Once the westerlies vanished, birds crossed the ITCZ to their winter quarters. This study provides a novel approach to investigate wind?mediated movements in oceanic environments and shows that large?scale migration and dispersal processes over the oceans can be largely driven by spatiotemporal wind patterns.

Despite the advent of devices to track seabird movements, the extent to which productive areas and oceanic winds influence foraging strategies is still not fully understood. We investigated the main environmental determinants of foraging strategies in Cory’s shearwaters Calonectris diomedea. We combined satellite-tracking information from 14 birds breeding on Canary Island with concurrent data on chlorophyll concentrations and oceanic winds. Additionally, we took a blood sample at the end of each foraging trip and analysed stable isotope signatures to examine the use of trophic resources. All birds showed a commuting type of trip, concentrating foraging activity exclusively on the African continental shelf. Foraging locations showed a strong association with chlorophyll concentrations, suggesting birds select foraging areas according to prey availability. In contrast with other breeding colonies where Cory’s shearwaters use a dual-foraging strategy, birds showed a unimodal strategy and did not show differences in C and N isotope signatures in plasma, confirming that close proximity to highly productive areas strongly influence foraging strategies. In addition, birds tracked during two consecutive trips foraged on the same area, suggesting high resource availability promotes fidelity to feeding grounds also at coarse-scales. Commuting trips followed a consistent clockwise movement, heading southwest when birds foraged along the continental shelf. Trade winds consistently blow from northeast over the study period, suggesting that birds used tail winds to reduce their flying costs. In summary, our results corroborate that oceanographic conditions in the vicinity of the breeding colony have a strong effect on foraging strategies of pelagic seabirds. KEY WORDS: chlorophyll a, foraging movements, oceanic productivity, oceanic wind, satellite-tracking, stable isotopes.

Seabird moult is poorly understood because most species undergo moult at sea during the non-breeding season. We scored moult of wings, tail and body feathers on 102 Mediterranean Cory’s Shearwaters accidentally caught by longliners throughout the year. Primary renewal was found to be simple and descendant from the most proximal (P1) to the most distal (P10) feather. Secondaries showed a more complex moulting pattern, with three different asynchronous foci: the first starting on the innermost secondaries (S21), the second on the middle (S5) and the latest on the outermost secondaries (S1). Rectrix moult started at a later stage and was simple and descendant from the most proximal feather (R1) expanding distally. Although a few body feathers can be moulted from pre-laying to hatching, moult of ventral and dorsal feathers clearly intensified during chick rearing. Different moulting sequences and uncoupled phenology between primary and secondary renewal suggest that flight efficiency is a strong constraint factor in the evolution of moulting strategies. Moreover, moult of Cory’s Shearwaters was synchronous between wings and largely asynchronous between tail halves, with no more than one rectrix moulted at once. This result is probably related to the differential sensitivity of wings and the tail on flight performance, ultimately derived from different aerodynamic functions. Finally, Cory’s Shearwater females renewed feathers earlier and faster than males, which may be related to the lower chick attendance of females.

Contamination in marine foodwebs is nowadays of great environmental concern owing to the increasing pollution levels in marine ecosystems from different anthropogenic sources. Seabirds can be used as indicators of regional contaminant patterns across large temporal and spatial scales. We analysed mercury, selenium and lead levels as well as stable isotope ratios of carbon and nitrogen in breeding- and winter-season feathers on males and females of two related shearwater species, providing information on spatiotemporal patterns of contaminants as well as the influence of the trophic ecology of these seabirds on contaminant levels. During the breeding season, selenium and lead concentrations were highest at Cape Verde archipelago, showing no differences among the other colonies or between the sexes. However, mercury levels varied among colonies, being highest in the Mediterranean, probably resulting from the larger emissions and fallout of this pollutant in Europe. Feathers grown during breeding also showed sexual differences in mercury concentrations and D13C. Differences in mercury concentration between sexes are mainly due to egg-laying decontamination in females. In contrast, differences in mercury among colonies are probably related to differences in trophic ecology, as indicated by D13C and D15N measurements. Contaminant concentrations in winter-grown feathers did not show any relationship with stable isotope values but were affected by contaminant loads associated with the breeding season. These findings suggest that the interpretation of contaminant levels of migratory species from feathers moulted out of the breeding season should be made with caution because those values could reflect exposures to contaminants acquired during the breeding season. We conclude that other factors than feeding ecology may play an important role in the interpretation of contaminant levels and their annual dynamics at several spatial scales. Consideration of the relevant temporal context provided by isotopic signatures and contaminant concentrations is important in deciphering contaminant information based on various tissues.

The bill is a sexually dimorphic structure in many bird species implicated in numerous functions. Sexual differences may arise from sexual selection or ecological divergence. Here, we tested the relationship between sexual dimorphism and trophic niche segregation in Cory’s shearwaters. For the first time in avian morphological studies, we combined linear measurements and geometric morphometric methods to examine sexual differences in bill size and shape. We also investigated feeding ecology by tracking foraging movements during the breeding period and by analysing stable isotope signatures in blood during the breeding and in feathers grown during the non breeding period. Bill traits were all sexually dimorphic, both in absolute and relative terms, and scaled hypermetrically with body mass in several characters in males. However, males and females did not differ in their feeding areas or isotopic signatures and no significant correlation was observed between these traits and bill dimorphism. Therefore, we discard the foraging-niche divergence hypothesis, and suggest that sexual dimorphism in bill size in this species is more likely driven by sexual selection related to antagonistic interactions.

Parasite communities can be structured at different spatial scales depending on the level of organization of the hosts; hence, examining this structure should be a multiscale process. We investigated ectoparasite community structure composed by three lice (Halipeurus abnormis, Austromenopon echinatum and Saemundssonia peusi) and one flea species (Xenopsylla gratiosa) at the infra-, component and regional community levels in three closely related seabird hosts, the Mediterranean Cory’s shearwater (Calonectris d.diomedea), the Atlantic Cory’s shearwater (C.d.borealis) and the Cape Verde shearwater (C.edwardsii). We examined temporal and spatial structuring of infracommunities, the influence of host aggregation and body condition on the component community, and the effect of genetic and geographic connectivity among host populations on the regional community. Ectoparasite infracommunities showed a substantial species overlap in temporal patterns of abundance but species were spatially segregated within the host body. Within component communities, abundance of all ectoparasite species showed an aggregated distribution. However, aggregation patterns and its relationship with the spatial distribution of hosts within the breeding colony differed among ectoparasite species, mainly reflecting ecological differences between fleas and lice. At regional scale, similarity in ectoparasite communities correlated with geographic distances among host colonies, but not with genetic distances. This result suggests differences in climate and habitat characteristics among host localities as a major determinat of regional communities, rather than host connectivity. Our results highlight the importance of the geographic distribution of host breeding colonies and the spatial segregation within the host body as key factors in determining ectoparasite community structure in Calonectris shearwaters.

The knowledge of ecophysiological responses in relation to foraging effort is crucial to understanding feeding strategies, survival and reproductive trade-offs, as well as to obtain reliable indicators of an excessive workload. We present an integrative approach that examines a suite of ecophysiological parameters in relation to increased workload. We experimentally increased wing loading of 10 Cory's shearwaters Calonectris diomedea, a medium-sized pelagic seabird, by adding 45 g extra weight and compared their ecophysiological responses with 10 control birds. Among all the parameters analysed, the only significant response to overloading was a longer foraging trip, a lower rate of mass gain whilst at sea, and an increase in plasma levels of creatine kinase and lactate dehydrogenase activity indicating muscular damage. The analyses on these muscular enzymes open new opportunities to measure the impact of instruments on birds and to understand physiological responses in relation to foraging activity.

We examined whether the two giant petrel species segregate by gender and species in relation to the stage of the annual cycle. We tracked the individual foraging behavior of 14 male and 11 female northern giant petrels (Macronectes halli) and 13 male and 15 female southern giant petrels (M.giganteus) breeding at South Georgia over one year by using geolocators (Global Location System loggers). Males of both species showed a flexible foraging strategy, switching from coastal to pelagic habits, probably governed by spatiotemporal changes in carrion availability. In contrast, marine areas exploited by females were more consistent over the year and similar between the two species, with most foraging locations concentrated over the same pelagic waters. This study provides support for the differences in foraging between sexes as the main mechanism to reduce intraspecific competition. Although the two species are morphologically similar and can easily access each other’s foraging habitat, they differ in the foraging areas exploited. Thus, interspecific competition seems mainly relaxed by spatial segregation, particularly between males in winter, probably mediated by different competitive abilities and physical tolerances to temperature and winds. Foraging southern giant petrels from South Georgia were not restricted to the areas within the line of equidistance to other colonies, but their foraging range overlapped with feeding grounds of conspecifics breeding in the Falkland Islands and the Antarctic Continent. Taken together, these findings suggest that foraging selection on marine habitat heterogeneity reduces interspecific competition, whereas carrion availability reduces intersexual competition, in giant petrels.

The importance of sympatric speciation (the evolution of reproductive isolation between codistributed populations) in generating biodiversity is highly controversial. Whereas potential examples of sympatric speciation exist for plants, insects and fishes, most theoretical models suggest that it requires conditions that are probably not common in nature, and only two possible cases have been described for tetrapods. One mechanism by which it could occur is through allochronic isolation - separation of populations by breeding time. Oceanodroma castro (the Madeiran or band-rumped storm-petrel) is a small seabird that nests on tropical and subtropical islands throughout the Atlantic and Pacific Oceans. In at least five archipelagos, different individuals breed on the same islands in different seasons. We compared variation in five microsatellite loci and the mitochondrial control region among 562 O. castro from throughout the species’ range. We found that sympatric seasonal populations differ genetically within all five archipelagos, and have ceased to exchange genes in two. Population and gene trees all indicate that seasonal populations within four of the archipelagos are more closely related to each other than to populations from the same season from other archipelagos; divergence of the fifth sympatric pair is too ancient for reliable inference. Thus, seasonal populations appear to have arisen sympatrically at least four times. This is the first evidence for sympatric speciation by allochrony in a tetrapod, and adds to growing indications that population differentiation and speciation can occur without geographic barriers to gene flow.

We compared patterns of mitochondrial DNA differentiation in three host-specific lice (Halipeurus abnormis, Austromenopon echinatum and Saemundssonia peusi) and one generalist flea (Xenopsylla gratiosa), parasitizing 22 colonies of Calonectris. The three closely related hosts: the Atlantic and the Mediterranean Cory’s (Calonectris d. diomedea and C. d. borealis) and the Cape Verde (C. edwardsii) shearwaters show distinct phylogeographic structure. The host-specific lice appeared undifferentiated among the three Calonectris taxa, whereas the more generalist flea displayed significant levels of population differentiation. Neither genetic distances among host populations, nor their spatial distribution explained the patterns of genetic variability observed in the ectoparasites. The lack of differentiation among lice is unexpected, given that seabird lice show high levels of cospeciation with their hosts, and have an elevated rate of mitochondrial DNA evolution. We discuss the implications of these findings.

In birds, parents adjust their feeding behaviour to the breeding duties, which ultimately may lead to seasonal adjustments in nutritional physiology and hematology over the breeding season. Although avian physiology has been widely investigated in captivity, few studies integrate individual changes in feeding and physiological ecology throughout the breeding season in wild birds. To study relationships between feeding ecology and nutritional ecophysiology in Cory’s shearwaters (Calonectris diomedea), we weighed and took blood samples at pre-laying, egg-laying, mid incubation, hatching and chick rearing of 28 males and 19 females. In addition, we instrumented 6 birds with geolocators to track their foraging movements throughout the reproductive period. Thus, we examined individual changes in (a) nutritional condition (biochemistry metabolites); (b) oxygen carrying capacity (hematology) and; (c) feeding areas and foraging effort (stable isotopes and foraging movements). Geolocators revealed a latitudinal shift in main feeding areas towards more southern and more neritic waters throughout the breeding season, which is consistent with the steady increase in ?13C signatures found in blood. Geolocators also showed a decrease in foraging effort from egg-laying to hatching, reflecting the activity decrease associated to the incubation duties. Plasma metabolites, body mass and oxygen carrying capacity were associated to temporal changes in nutritional state and foraging effort, in relation to the recovery after migration, egg formation, fasting shifts during incubation and chick provisioning. This study shows that combining physiological and ecological approaches can help understanding the influence of breeding duties on feeding ecology and nutritional physiology in wild birds.

It has been suggested that sexual size dimorphism (SSD) may influence sex ratios at different life stages. Higher energy requirements during growth associated with larger body size could lead to a greater mortality of the larger sex and ultimately to an overproduction of the smaller sex. To explore the associations between SSD and hatching and fledging sex ratio we performed a species-level and a phylogenetically controlled analysis, based on 83 bird species. Overall, there was a significant inverse relationship between the degree of SSD and the proportion of males at hatching and fledging. Sex-specific mortality related to SSD showed a weak but persistent negative tendency, suggesting a mortality bias towards the larger sex. These results suggest that changes in relation to SSD may take place mainly at the conception stage, but could be adjusted during growth. However, conclusions should be cautiously treated since these relationships weaken when additional variables are considered.

Longline fisheries, oil spills and offshore wind mills are some of the major threats increasing seabird mortality at sea, but the impact of these threats on specific populations have been difficult to determine so far. We tested the use of molecular markers, morphometric measures, and stable isotope (?15N and ?13C) and trace element concentrations in the first primary feather (grown at the end of the breeding period) to assign the geographic origin of Calonectris shearwaters. Overall, we sampled birds from three taxa: 13 Mediterranean Cory’s shearwater (Calonectris d. diomedea), 10 Atlantic Cory’s shearwater (Calonectris d. borealis) and one Cape Verde shearwater (C. edwardsii) breeding sites. Assignments rates were investigated at three spatial scales: breeding colony, breeding archipelago and taxa levels. Genetic analyses based on the mitochondrial control region (198 birds from 21 breeding colonies) correctly assigned 100% of birds to the three main taxa, but failed in detecting geographic structuring at lower scales. Discriminant analyses based on trace elements composition achieved the best rate of correct assignment to colony (77.5%). Body measurements or stable isotopes mainly succeed assigning individuals among taxa (87.9 and 89.9%, respectively) but failed at colony level (27.1 and 38.0%, respectively). Combining all three approaches (morphometrics, isotopes and trace elements on 186 birds from 15 breeding colonies), substantially improved correct classifications (86.0, 90.7 and 100% among colonies, archipelagos and taxa, respectively). Validations using two independent data sets and Jackknife cross-validation confirmed the robustness of the combined approach in the colony assignment (62.5, 58.8 and 69.8% for each validation test, respectively). A preliminary application of the discriminant model based on stable isotopes ?15N and ?13C values and trace elements (219 birds from 17 breeding sites) showed that 41 Cory’s shearwaters caught in the western Mediterranean longliners came mainly from Menorca (48.8%), Ibiza (14.6%) and Crete (31.7%) breeding colonies. Our findings show that combining analyses of trace elements and stable isotopes on feathers can achieve high rates of correct geographic assignment of birds in the marine environment, opening new prospects to the study of seabird mortality at sea.

Despite the increasing interest in long distance migration, the wintering areas, migration corridors and population mix in winter quarters of most pelagic marine predators are unknown. Here we present the first study to track migration movements of shearwaters throughout the complete nonbreeding period. We used geolocators (global location sensing (GLS) units based on ambient light levels) to track 22 Cory’s shearwaters Calonectris diomedea, breeding in three different areas. Most birds wintered in one or more of three relatively small areas, all clearly associated with major coastal upwelling systems of the tropical and south Atlantic. Transequatorial movements were dominated by prevailing trade winds and westerlies and avoided calm oligotrophic areas. Breeding populations clearly differed in their main preference amongst the three major wintering areas but showed substantial mixing. This illustrates the exceptional value of GLS not only for describing and determining the influence of oceanographic features on migration patterns, but also to determine population mix in winter quarters. This knowledge is essential to assess the impact of population level threats, such as longlining, offshore windfarms and oil spills, to multiple breeding sites and ultimately critical in devising conservation policies that guarantee the sustainable exploitation of the oceans.

A central point in life history theory is that parental investment in current reproduction should be balanced by the costs in terms of residual reproductive value. Long-lived seabirds are considered fixer investors, that is, parents fix a specific level of investment in their current reproduction independent to the breeding requirements. We tested this hypothesis analyzing the consequences of an experimental increase in flying costs on the foraging ecology, body condition and chick condition in Cory’s shearwaters Calonectris diomedea. We treated 28 pairs by reducing the wing surface in one partner and compared them with 14 control pairs. We monitored mass changes and incubation shifts and tracked 19 foraging trips per group using geolocators. Furthermore, we took blood samples at laying, hatching and chick-rearing to analyse the nutritional condition, haematology, muscle damage and stable isotopes. Eighty day old chicks were measured, blood sampled and challenged with PHA immune assay. In addition, we analysed the effects of handicap on the adults at the subsequent breeding season. During incubation, handicapped birds showed a greater foraging effort than control birds, as indicated by greater foraging distances and longer periods of foraging, covering larger areas. Eighty days old chicks reared by treated pairs were smaller and lighter and showed a lower immunity than those reared by control pairs. However, oxygen demands, nutritional condition and stable isotopes did not differ between control and handicapped birds. Although handicapped birds had to increase their foraging effort, they maintained physical condition by reducing parental investment and transferred the experimentally increased costs to their partners and the chick. This result supports the fixed investment hypothesis and is consistent with life history theory.

Cellular immune response (CMI) has been widely studied in relation to different individual and fitness components in birds. CMI is usually measured by tissue swelling resulting from T-lymphocyte production after injection of phytohemagglutinin-P. However, few studies have simultaneously examined individual, social factors and habitat-mediated variance in the immune response of chicks and adults from the same population and in the same breeding season. We investigated ecological and physiological variance in CMI response of male and female fledglings and adults in a breeding population of Cory’s Shearwaters, Calonectris diomedea, in the Mediterranean Sea. Explanatory variables included individual traits (body condition, carbon and nitrogen stable isotope ratios, ?15N and ?13C, plasma total proteins, triglycerides, uric acid, osmolarity and ß-hydroxy-butyrate, erythrocyte mean corpuscular diameter, hematocrit and hemoglobin) as well as burrow traits (temperature, isolation and physical structure). During incubation, immune response in adults was significantly greater in males than in females. Fledglings exhibited a lower immune response than adults. Ecological and physiological factors affecting immune response differed between adults and fledglings. GLM models showed that immune response in adult males was positively associated with burrow isolation, suggesting that males breeding at higher densities suffer a suppression of their immune system. In contrast, immune response in fledglings was positively associated with body condition and plasma triglyceride levels. Therefore adult immune response seems partly associated with social stress whereas in fledglings a trade-off between immune function and fasting capability may exist. Our results and those from previous studies, provide support for an asymmetric influence of ecological and physiological factors on the health of different age and sex groups within a bird population as well as for the importance of simultaneously considering individual and population characteristics in intraspecific studies of immune response.

We investigated phylogenetic relationships and the biogeographic history of the Calonectris species complex, using both molecular and biometric data from one population of the Cape Verde shearwater Calonectris edwardsii (Cape Verde Islands), one from the streaked shearwater C. leucomelas (western PaciWc Ocean) and 26 from Cory’s shearwater populations distributed across the Atlantic (C. d. borealis) and the Mediterranean (C. d. diomedea). The streaked shearwater appeared as the most basal and distant clades, whereas the genetic divergences among the three main clades within the Palearctic were similar. Clock calibrations match the Wrst speciation event within Calonectris to the Panama Isthmus formation, suggesting a vicariant scenario for the divergence of the PaciWc and the Palearctic clades. The separation between the Atlantic and Mediterranean clades would have occurred in allopatry by range contraction followed by local adaptation during the major biogeographic events of the Pleistocene. The endemic form from Cape Verde probably evolved as a result of ecological divergence from the Mediterranean subspecies. Finally, one Mediterranean population (Almeria) was unexpectedly grouped into the Atlantic subspecies clade, both by genetic and by morphometric analyses,pointing out the Almeria-Oran oceanographic front (AOOF) as the actual divide between the two Cory’s shearwater subspecies. Our results highlight the importance of oceanographic boundaries as potentially eVective barriers shaping population and species phylogeographical structure in pelagic seabirds.

We investigated trophic ecology variation among colonies as well as sex- and age-related differences in diet in the southern giant petrel (Macronectes giganteus), a long-lived seabird that is sexually dimorphic in size. We measured stable-isotopes (δ13C, δ15N) in the blood samples collected during breeding at Bird Island (South Georgia, Antarctica) in 1998 and at two colonies in the Argentinean Patagonia in 2000 and 2001. Individuals from South Georgia showed lower δ13C and δ15N values than in Patagonia, as expected from the more pelagic location and the short length of the Antarctic food web. Males and females showed significant differences in the isotopic signatures in both localities. These differences agree with the sexual differences in diet found in previous studies, which showed that both sexes rely mainly on penguin and seal carrion, but females also feed extensively on marine prey, such as fish, squid and crustaceans. However, in the Patagonia males showed significantly higher δ15N and δ13C values than females and the reverse trend was observed at South Georgia. This opposite trend is probably related to the different trophic level of carrion between locations: whereas penguins and pinnipeds in Patagonia rely mainly on fish and cephalopods, in South Georgia they rely mainly on krill. Stable isotope values of male and female chicks in Patagonia did not differ but both attained high values, similar to adult males but higher than adult females, suggesting that parents do not provision differentially their single offspring in relation to sex but instead provide higher proportion of carrion, probably a higher quality and more abundant food, than they consume themselves. Stable isotopes at South Georgia were not affected by age of adults. We have add new information on intraspecific segregation in the diet in a seabird species and also underline the importance of considering food web structure to study intraspecific variability in trophic ecology.

Bias in sex ratios at hatching and sex specific post hatching mortality in size dimorphic species has been often detected, and is usually skewed towards the production and survival of the smaller sex. Since common terns show a limited sexual size dimorphism, with males being only about 1-6% larger than females in a few measurements, we would expect to find small or no differences in production and survival of sons and daughters. To test this prediction, we carried out a two-year observational study on sex ratio variation in common terns at hatching and on sex specific post hatching mortality. Sons and daughters hatched from eggs of similar volume. Post hatching mortality was heavily influenced by hatching sequence. In addition, we detected a sex specific mortality bias towards sons. Overall, hatching sex ratio and sex specific mortality resulted in fledging sex ratios 8% biased towards females. Thus, other reasons than body size may be influencing the costs of rearing sons. Son mortality was not homogeneous between brood sizes but greater for two-chick broods. Since adults rearing two-chick broods were younger, lighter and bred consistently later than those rearing three-chick broods, it is suggested that lower capacity of two-chick brood parents adversely affected offspring survival of sons. Though not significantly, two-chick broods tended to be female biased at hatching, perhaps to counteract the greater male-biased nestling mortality. Thus, population bias in secondary sex ratio is not limited to strongly size dimorphic species, but species with a slight sexual size dimorphism can also show sex ratio bias through a combination of differential production and mortality of sons and daughters.

We analyzed offspring sex ratio variation in Mediterranean Cory’s Shearwater (Calonectris d. diomedea) during two consecutive breeding seasons in two colonies. We test for differential breeding conditions between years and colonies looking at several breeding parameters and parental condition. We then explored the relationship between offspring sex ratio and parental condition and breeding parameters. This species is sexually dimorphic with males larger and heavier than females; consequently we expected differential parental cost in rearing sexes, or a greater sensitivity of male chicks to adverse conditions, which may lead to biased sex ratios. Chicks were sexed molecularly by the amplification of the CHD genes. Offspring sex ratio did not differ from parity, either at hatching or fledging, regardless of the colony or year. However, parental body condition and breeding parameters such as egg size and breeding success were different between years and colonies. Nevertheless neither nestling mortality nor body condition at fledging varied between years or colonies, suggesting that male nor female chicks were probably not differentially affected by variability in breeding conditions.

We investigated the possible effects of a 12-g data-logger attached to a darvic ring on the performance of Cory s shearwater (Calonectris diomedea, 600–850 g) from two different colonies in the western Mediterranean Sea. We compared return rates, current breeding success and body condition between equipped and unequipped birds. Effects on feeding ecology during winter and breeding period was also evaluated through the measurement of stable isotopes of carbon ( 13C) and nitrogen ( 15N) in one of the colonies. We found no evidence of negative effects of loggers on demographic parameters analysed or in feeding ecology. Power analyses suggested a high power to detect medium effect size, but a low power to detect small changes. Despite the non-significant results we could only exclude medium to strong effects of the devices on one of these parameters. We detected some short-term negative effects on body condition for the equipped birds, but these were unlikely to have had important consequences. Results suggest that the use of loggers is an adequate methodology to obtain information from seabirds at sea, but data should be carefully interpreted with regard to potential biases during severe environmental conditions.

The two sibling species of giant petrels, (northern Macronectes halli and the southern M.giganteus), the dominant scavengers of the subantarctic and Antarctic environment, are one of the best examples of sexual segregation in avian foraging and feeding ecology. During breeding, males and females feed mainly on penguin and seal carrion, but females also feed extensively on marine prey such as cephalopods, fish and krill. Sexual differences in diet are reflected not only in analyses of regurgitations, but also in the isotopic composition of carbon and nitrogen, as well as in their heavy metal burdens. Direct observations and tracking of pelagic movements showed that males of both species usually forage closer to the breeding grounds, exploiting carcasses on beaches, whereas females show more pelagic habits. In consequence, foraging effort, foraging efficiency, predictability of resources exploited, optimum foraging time and activity budgets differ between sexes. During winter, however, studies on activity and pelagic movements suggest more similar feeding habits between sexes. Overall, differences in foraging and feeding ecology are probably related to the substantial sexual size dimorphism; males of both species are 16-35% heavier and have disproportionately larger bills than females. The importance of size in contest competition to access carrion may explain their large body size as well as the competitive exclusion of females from coastal habitats, reducing intraspecific competition for food. Ultimately, a differential exploitation of carrion probably increased sexual dimorphism not only in body size but also in the feeding structures such as bill size. The apparently greater profitability of the feeding strategies of males compared to females suggests that giant petrels reflect an evolutionary process that benefits each sex differently.

BACKGROUND AND INTRODUCTION Seabirds belonging to the order Procellariiformes (albatrosses and petrels) are amongst the most pelagic of seabirds and occur in all of the world’s oceans. They are, therefore, excellent potential indicators of the state of marine ecosystems, especially high seas. The status and trends of albatross breeding populations are well documented and, with 19 of 21 species now globally threatened and the remainder Near Threatened (BirdLife International 2004a); albatrosses have become the bird family most threatened with extinction. Many petrel species are also globally threatened. Although albatross and petrel species face many threats at their breeding sites, the main problems they encounter currently relate to the marine environment, particularly involving interactions with fisheries, notably the many thousands of birds killed annually by longline fishing. Many of the solutions to these problems require accurate knowledge of the distributions of albatrosses and petrels throughout their annual and life cycles. Such data are also invaluable for understanding many aspects of the ecology and demography of these species and their role in the functioning of marine systems—including their potential susceptibility to changes in these. In terms of remote-tracking to reveal their at-sea distribution (a key to understanding how they function in marine ecosystems), albatrosses (and giant-petrels) are the most studied of all marine species. Given the substantial potential of these data for conservation applications, including for marine analogues of terrestrial Important Bird Areas (IBAs), pioneered by BirdLife since the 1980s, BirdLife convened an evaluation workshop to explore the data and concepts with the main dataholders. This report presents the results of the workshop. AIMS The main strategic aims of the workshop were: 1. To assess how at-sea distribution data from remotetracking studies of seabirds can contribute to: i. the development of criteria for defining Important Bird Areas (IBAs) in the marine environment; ii. current initiatives for the establishment of high seas Marine Protected Areas (MPAs) especially by IUCN. 2. To scope the extent to which these data can be used to quantify overlap between marine areas used by albatrosses and the location of fishing effort, especially longline: i. to identify areas of higher risk, especially for the development of appropriate mitigation measures for the fisheries involved; ii. to identify the Regional Fishery Management Organisations (RFMOs) with prime responsibility for the management of fisheries with significant risk of incidental bycatch of globally threatened nontarget species, especially albatrosses and petrels. 3. To establish a Geographic Information System database to maintain detailed information on remote-recorded range and distribution of seabirds, as an international conservation tool. RESULTS Data and methods • Over 90% of all extant albatross and petrel tracking data was submitted to the workshop, representing 16 species of albatross, both species of giant-petrel and Whitechinned Petrel. A GIS database was developed to facilitate analysis, visualisation and interpretation of these data. • Standard analytical procedures were developed and applied to the satellite tracking (PTT) data from raw data records submitted by dataholders. • Consistent procedures were developed for the presentation of geolocator tracking (GLS) data—the main source of information for distributions in nonbreeding seasons. • Appropriate analytical procedures were agreed for transforming location data into density distributions, a crucial step in the visualisation, analysis and interpretation of multiple data sets. • Protocols for data access and use, acknowledging the need to make available information to the international conservation community while safeguarding the proprietary rights of the individual data contributors and data users, were agreed. Analysis and case-histories The data available allowed the demonstration of a variety of properties relating to albatross and petrel ecology and distribution, including: • The nature and variation in range and distribution, for breeding birds, in relation to stage of breeding season, gender (sex) and year (i.e. interannual variation). • Differences in range and distribution of breeding birds from different colonies within the same population (island group). • Similarities and differences in range and distribution of breeding birds from different populations of the same species, using data for the two species (wandering albatross, black-browed albatross) with the most comprehensive data, which provide compelling evidence of the insights that can be generated by applying common and consistent approaches to data from a variety of studies and sites. • Regional syntheses for providing clear indications of the potential (and challenges) for using data across a range of albatross and petrel species to identify areas of key habitat common to different species. • Similarities and differences in range and distribution of breeding and non-breeding birds at the same time of year. • The spectacular journeys and far-distant destinations (comprising migratory routes, staging areas and wintering ranges) of some species of albatross and petrel during the non-breeding season. These represent very significant achievements, some indicating interesting aspects and avenues for future research, others identifying potential biases and concerns relating to analysis and interpretation of data, yet others revealing key gaps in viii our knowledge. Nevertheless, all indicate the potential of such data to address important questions relating to albatross and petrel ecology and conservation. Strategic aims and applications Definition of Important Bird Areas (IBAs) and contribution to high seas Marine Protected Areas • Tracking data for albatrosses and petrels will make a key contribution to attempts to identify areas of critical habitat for marine organisms and hotspots of biodiversity in coastal and pelagic marine ecosystems. • Characterising density distributions and combining (weighting) these with estimates of source population size, will be fundamental approaches for marine taxa. • The extent to which existing definitions of IBAs, developed for terrestrial species and systems, can be extended to marine contexts requires considerable further investigation for which the albatross and petrel data are uniquely suited; however, approaches which combine data from different groups of marine animals (e.g. fish, seabirds, marine mammals) are likely to be essential in longer-term approaches to issues of marine habitat conservation. • The albatross and petrel data represent a uniquely coherent and comprehensive data set, covering large areas of marine habitat, and are therefore especially suitable for further investigation, perhaps particularly in high seas contexts. Interactions with fisheries and fishery management organisations • Examples of overlap between albatross distribution (both breeding and on migration) and fishing effort illustrate the considerable importance and potential of approaches to match data on the distribution (and abundance) of albatrosses and petrels with data on fishing effort, particularly for longline fisheries. • Difficulties in obtaining data for appropriate scales and times, even for the better documented fisheries, may constrain what can be achieved, especially in terms of analysis seeking to estimate bycatch rates and/or their impact on source populations of albatrosses. • Nevertheless, even existing data are adequate to provide broad characterisation of the location (and timing) of potential interactions between albatross species and different longline fisheries; this is a high priority task. • These data are used to provide a preliminary identification of the responsibilities of RFMOs for environmentally sensitive management of albatrosses and their habitat based on overlap of ranges and jurisdictions. For the Southern Hemisphere this provides very clear indications of the critical role of, in preliminary priority order, Commission for the Conservation of Southern Bluefin Tuna (CCSBT), Western and Central Pacific Fisheries Commission (WCPFC), Indian Ocean Tuna Commission (IOTC), International Commission for the Conservation of Atlantic Tunas (ICCAT) and Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). • A similar initial review, in relation to Exclusive Economic Zones (EEZs), is also provided. • Combined with data on overlap with fishing operations, these will enable preliminary identification of the times, places and fisheries where adverse interactions are most likely and, thereby, allow the identification of mitigation measures appropriate to the circumstances. Maintaining the database as an international conservation tool Participants agreed to maintain the tracking database, assembled for the purposes of this workshop, beyond the meeting and production of its report. • The database should be maintained and reconstituted by re-submission of data on the basis of the agreed policy on data access and use. • A policy and practice for data access and use (based on principles developed for the Census of Marine Life Ocean Biogeographic Information Service (OBIS) – SEAMAP Programme) was agreed. • BirdLife International offered, at least as an interim measure, to house and manage the database at its Secretariat headquarters in Cambridge, UK. • The offer was accepted in principle. However the need to maintain and augment the data, to facilitate interactive and collaborative use, to link the albatross and petrel and tracking data to other, analogous, data sets and to the latest information on the physical and biological marine environment was recognised. Possibilities for linking, or possibly migrating, the Procellariiform Tracking Database from BirdLife to an organisation or institution specialising in the management and analysis of data on marine systems and biogeography should be investigated. FUTURE WORK Existing data • All data submitted to the workshop should be resubmitted to the new database, managed by BirdLife, and subject to the agreed data access and use procedures. • Other extant data, especially for Antipodean and Waved Albatrosses, and Westland Petrel Procellaria westlandica, should be requested from relevant dataholders and data owners. • New data should be requested as it becomes available. New data Priorities are: • For breeding birds, more data (and in most cases from more individuals) are needed for some stages of the breeding cycle (particularly incubation), for sexed birds and for sufficient years to assess the consistency of basic distribution patterns, for additional populations (island groups) and from more colonies within populations. • For most species, data on the distribution of adults when not breeding. • For almost every species, data on the distribution of immatures and early life-history stages. Methods • Evaluation of the potential biases of using the different types (and where appropriate different duty cycling) of existing data (e.g. PTT, GLS) in different kinds of analysis and on the use of appropriate spatial statistics to create density distributions from the different kinds of tracking data. Environment • Need to facilitate easy access to appropriate data sets on the physical and biological environment at appropriate scales, including detailed bathymetry, sea surface temperature, marine productivity, sea-ice etc. Tracking ocean wanderers: the global distribution of albatrosses and petrels – Executive summary Links to other tracking/sighting data on pelagic marine taxa • Facilitate links to analogous sets of data on other petrels, penguins, marine mammals, sea turtles and migratory fish. • Encourage and support links with initiatives like the Marine Mammal Tracking Database and programmes like the Census of Marine Life’s Tagging Of Pacific Pelagics which are trying to assemble similar data on a collaborative basis. • Investigate the feasibility and utility of combining remote tracking and survey data sets. Prime candidate areas for pilot studies to do this with seabird data would include the north-east Pacific, tropical east Pacific, south-west Atlantic and parts of the Indian Ocean. Links to data from fisheries Compare and analyse the distribution data for albatrosses/ petrels and fishing effort to: • Identify times and places where potential exists for adverse interactions between fisheries and albatrosses/ petrels. This would enable: i. Specification of mitigation measures appropriate to these circumstances; ii. Approaches to RFMOs with appropriate jurisdictions, singly or in combination, to seek to develop the necessary regulations to apply the mitigation measures. • Estimate bycatch rates of albatrosses/petrels for appropriate areas and at appropriate scales and for extrapolation to areas where bycatch data from fisheries are currently lacking. • Assist modelling of seabird-fishery interactions with implications for fisheries (taking financial losses through bycatch into account in cost-benefit analyses) and for seabird populations. IBAs and Marine Protected Areas • Identify and relate areas of core habitat to population estimates and threatened status to evaluate in detail the implications of different criteria for helping define marine IBAs. • Develop this approach further by choosing suitable systems/areas in which to link to remote-tracking data on other seabirds (especially penguins) and to at-sea survey data. This is especially relevant for coastal and shelf systems (i.e. within EEZs). • Develop this further relative to Marine Protected Areas in conjunction with data on other marine taxa (e.g.marine mammals, sea turtles) and on resource use (e.g. fisheries, hydrocarbons). This is relevant both to EEZs and to high seas. Agreement on the Conservation of Albatrosses and Petrels (ACAP) • The applications envisaged of the albatross and petrel tracking database are highly relevant to the conservation aims of ACAP. The database is likely to be a key tool for furthering the work of ACAP.

It has been suggested that breeding performance differs between young and old birds due to the appearance and disappearance of phenotypes through differential survival (selection hypothesis) or differential recruitment (delayed breeding hypothesis) of high-quality individuals, but each bird may show constant breeding performance over its life. We tested constant egg-volume and laying date by modelling their variability on the basis of the 109 known-age females of common tern Sterna hirundo with data available from 1 to 9 years. Longitudinal analyses showed a significant advancement of laying date, as well as a steady increase in egg-volume, in young age classes from 2 to 5–7 years old, indicating individual intrinsic changes in performance with age. In our model, female effect accounted for 74% and 8% of variance in egg-volume and laying date, respectively, suggesting that if correlation between breeding performance and survival or recruitment exists, population patterns of age-specific performance may emerge. However, we found no evidence that birds that did not return to breed during young age classes laid later or smaller eggs than returned breeders. Likewise, we found no evidence that recruiting birds laid earlier or larger eggs than same aged birds recruited in preceding years. Thus, this study shows that age-specific patterns in timing of breeding and egg-size in common terns result from individuals intrinsic changes, and we reject the selection and the delayed breeding hypotheses as a major factor shaping age-specific patterns at population level.

Northern giant petrels (Macronectes halli) are among the largest and most sexually size dimorphic species of seabirds, with females being only 80% the mass of males. Both sexes scavenge on seal and penguin carrion in the sub-Antarctic ecosystem, but during the breeding season females also feed extensively on other marine food resources and show more pelagic habits than males. The outstanding sexual segregation in foraging and feeding ecology in northern giant petrels suggests that mechanisms maintaining sexual size dimorphism by ecological factors may be operating. I evaluated this possibility by examining ecological correlates with body size and by static allometry analyses. Proportion of male fledglings was 0.36 (n=33 fledglings). There was no assortative mating by size neither association between the male size with the breeding performance. By contrast, smaller females raised their chick in better condition. Moreover, bill size showed a size dimorphism beyond that expected by body size dimorphism, i.e. when controlling for body mass, males showed relatively longer bill than females. This trait did not deviate from isometry with respect to body size and its phenotypic variability was low, suggesting that the disproportionately large bill of males is related to their more scavenging life style compared to females. In general, the increase and maintenance of sexual size dimorphism in giant petrels is more consistent with an ecological causation rather than a result of sexual selection.

In most seabird species incubation shifts shorten when hatching approaches, a behavioural response allowing the chick to be fed soon after hatching. Three mechanisms have been proposed to explain these shortened absences: endogenous timing; a response to embryo signals or, a seasonal increase in food availability. I tested these hypotheses by cross-fostering eggs between two sibling species: the northern Macronectes halli and the southern M.giganteus giant petrels, the former normally breeding 5-6 weeks earlier than the latter but both have an incubation period of 60 days. The length of the last trip before hatching was unaffected by the timing of hatching, suggesting that trip length was not related to the increase in food availability with the progress of the season. Moreover, northern giant petrels reduced their last trip lengths regardless of whether or not they were incubating their own developed or the southern undeveloped egg (with embryos not developed enough to signal). Parents presumably, therefore, possess endogenous control allowing them to predict hatching date and to reduce trip duration accordingly, regardless of the communication with the embryo. Nevertheless, shorter last trips before hatching in southern giant petrels incubating northern giant petrel eggs suggest that embryo signals are used by parents for a fine tuning synchronisation of the internal timer to the natural variability in the length of the incubation period.

The concentrations of PCBs, DDTs, HCHs, HCB and OCS were determined in sediments and associated biota, both invertebrates (Physella acuta, Hirudo medicinalis, chironomid larvae, Hydrous pistaceus, Helochares lividus) and vertebrates (Rana perezi), in a temporary aquatic system, a rice-field in the Ebro Delta (NE Spain). The qualitative and quantitative distribution of organochlorine compounds in sediments and aquatic biota has been explained by two mechanisms: equilibrium partitioning and/or biomagnification through the trophic web. Nevertheless, bioaccumulation processes are by far more complex, since several biotic and abiotic factors contribute to the observed pollutant loads in the organisms. In this respect, the biological characteristics of the organisms considered (e.g. species, age, lipid contents, feeding habits, etc.), as well as ecological factors (e.g. the habitat of the species and vertical distribution), have been shown to account for the organochlorine levels observed.

Black rat Rattus rattus populations can reach high densities in the Mediterranean islands, as it has been the case in Chafarinas Islands (Western Mediterranean coast) in the last decade. This archipelago holds the second largest breeding population of Audouin's gull Larus audouinii and an important population of yellow-legged gull Larus cachinnans. Circumstantial evidences of rat predation upon Audouin's gull eggs led to conservation concerns over the impact of rat predation on gull productivity. We studied the impact of rats on gull nests experimentally by building artificial nests into the breeding area of yellow-legged gulls. Two kinds of eggs were placed in the artificial nests: manipulated eggs, in which the shell was previously opened, and entire (unmanipulated) eggs. Rats preyed extensively on opened eggs but only once on entire eggs, apparently due to lack of skills to prey on entire eggs, suggesting that rats do not normally have access to fresh gull eggs. Rats inhabiting breeding areas of gulls can scavenge on broken eggs rolled out of the nest or on eggs with softened shells after nest desertion, but it is unlikely that they prey on natural gull nests guarded by parents. We suggest that introduced black rats in Mediterranean islands can only marginally affect the productivity of gulls owing to egg predation.

The impact of Yellow-legged gulls on Audouin's gulls was studied through observations from a blind, at the Ebro Delta, the Chafarinas Islands and the Columbretes Islands colonies, during different stages of the Audouin's gull breeding season. The rates of predation (upon eggs and chicks) and kleptoparasitism (aerial and on courtship and chick-feeding regurgitates) were recorded to assess this impact. Kleptoparasitism and predation rates recorded at the three colonies may be considered low when compared with similar studies dealing with other gull species. It seems that the interactions did not represent a threat to population dynamics of Audouin’s gulls in any of the three colonies. The highest rates of aerial kleptoparasitism, courtship feeding and chick mortality were recorded at the Columbretes Islands, whereas the lowest at the Ebro Delta. The ratio of number of Yellow-legged gulls to number of Audouin’s gulls seems to influence the rate of disturbances. Food availability is also likely to play an important role in the number of interactions, which increased when food was in shorter supply. The study at the Ebro Delta and Chafarinas was restricted to some subcolonies and results may not be necessarily representative of the entire colonies. The existence of some Yellow-legged Gull individuals specialized as predators were recorded. Finally, we discuss the suitability of several conservation measures commonly applied in colonies where both species breed syntopically.

Interactions between yellow-legged Larus cachinans and Audouin's Larus audouinii gulls and fisheries operating around the Chafarinas Islands, located 4.5 km off the Moroccan Mediterranean coast, are reviewed. At the Chafarinas archipelago two distinct types of fisheries operate: trawlers and purse seines. Gulls take advantage of both fisheries. They scavenge trawler discards and congregate around shoals of fish attracted to the surface by the purse-seine lamps. When both trawlers and purse-seine boats are in operation, the diet of both gull species is similar, with epipelagic fish accounting for over 60% of the biomass, partially collected in association with the purse-seine fishery. When only trawlers operated yellow-legged gulls, but not Audouin's gulls, augmented their diet mainly with human waste from refuse dumps, suggesting that competition for food between the two species is mainly limited to the periods when resources made available by fishery activities are abundant. Likewise, when only trawlers operated, there was an increase in the predation pressure on eggs and chicks of Audouin’s gulls. In particular, during the week of celebrations for the holy lamb festival when neither fishery operated, egg losses of Audouin’s gull increased dramatically, suggesting that severe food shortage caused by the cessation of fishing can result in an increased predation pressure by yellow-legged gulls, affecting Audouin’s gull productivity. These results suggest a novel socio-ecological link between gulls, fisheries and local feasts.

We analysed concentrations of cadmium, lead, mercury and selenium in blood from males and females of the 2 sibling species of giant petrels, the northern Macronectes halli and the southern M. giganteus, breeding sympatrically at Bird Island (South Georgia, Antarctica). Blood samples were collected in 1998 during the incubation period, from 5 November to 10 December. Between species, cadmium and lead concentrations were significantly higher for northern than for southern giant petrels, which probably resulted from northern giant petrels wintering in more polluted areas (mainly on the Patagonian shelf and Falkland Islands) compared to southern giant petrels (wintering mainly around South Georgia and the South Sandwich Islands). Between sexes, cadmium concentrations were significantly higher for females than for males in both species, corresponding to the more pelagic habits of females compared to the more scavenging habits of males. Lead and cadmium concentrations in circulating blood decreased significantly over the incubation period, suggesting that when breeding at Bird Island, exposure to the source of pollution had ended, and these metals had been cleared from the blood and excreted, or rapidly transferred to other tissues. Association of lead and cadmium with a common source of pollution was further corroborated by a significant positive correlation between the levels of the 2 elements found. Mercury levels were similar between the species, but showed an opposite trend between sexes, with males showing higher levels than females in northern giant petrels, and the opposite was true in southern giant petrels, with no changes throughout incubation. Selenium levels were similar between sexes, but significantly greater for northern than for southern giant petrels. Moreover, there was a significant increase in the selenium levels over the incubation period in northern giant petrels. Age of adult birds did not affect metal concentrations. Coefficients of variation of metal levels were consistently lower for northern than for southern giant petrels, particularly for mercury, suggesting that the former species is more dietary specialised than the latter. Contaminant analyses, when combined with accurate information on seabird movements, obtained through geolocation or satellite tracking, help us to understand geographic variation of pollution in the marine environment.

We studied the mercury contamination of 13 species of seabirds breeding on Bird Island, South Georgia, in 1998. Total mercury concentrations in body feather samples of birds caught at their breeding colonies were determined. Among the species, Grey-headed Albatross (8,933 ng g-1) and Southern Giant Petrel (7,774 ng g-1) showed highest, and Gentoo Penguin (948 ng g-1) lowest, body feather mercury concentrations. Mercury levels were negatively correlated with the proportion of crustaceans (mainly krill) in the species’ diets, suggesting that the trophic level is the most important factor in explaining the variation of mercury concentrations in Antarctic seabirds. In four species studied for age effects among adult birds (Grey-headed and Black-browed Albatross, Northern and Southern Giant Petrel), no age dependent variation in mercury levels was found. Sex differences were also assessed: female Gentoo Penguins had lower mercury levels than males, which may be related to the elimination of part of the mercury body burden by females into eggs. In contrast, Northern Giant Petrel males had lower levels than females, which may be related to a higher consumption by males of carrion from Antarctic fur seals. In Grey-headed Albatrosses, mercury levels were 113% higher than 9 years before (1989) when this species was investigated at the same site, indicating a possible increase in mercury pollution of the Southern Ocean during the last decade.

We investigated courtship feeding and copulatory behaviour of common terns Sterna hirundo in relation to age. We found a significant positive correlation between the total number of courtship feedings delivered to females and the total number of mountings. Moreover, both courtship feeding and mounting rates were positively correlated with female and male age. Also, the number of cloacal-contacts per mounting increased significantly with male or female age, which may indicate an increase in copulatory ability with age. The number of mountings for older birds was up to 3 times the number for younger birds. Presuming that transfer of sperm is proportional to the number of cloacal contacts, older birds may have transferred up to 6 times more sperm than younger birds during the pre-laying and laying period. These results may account for the preference of young females for older mates as well as for older extra-pair mates.

We analysed and compared the diet of Audouin's gulls Larus audouinii between their two largest breeding sites in the world: the Ebro Delta and the Chafarinas Islands (northwestern Mediterranean). These two localities showed marked differences in the features of commercial fishing fleet: in the Ebro Delta area a large fishing fleet produced large amounts of discards, while in the Chafarinas the fleet discarded smaller amounts of fish and marine invertebrates, due to the lower number of vessels. It is also likely that percentage of discards from total catches is also lower around the Chafarinas than at the Ebro Delta. We distinguished two types of fishing to compare diet compositions: diurnal (only trawling activity) and diurnal and nocturnal (trawling and purse-seine activity, respectively). We also differentiated regurgitates from young nestlings (up to 20 days old) and from older nestlings or adult birds. At the two localities, fish was the main food of Audouin's gulls, with epipelagic prey (mainly clupeoids) being more important when both diurnal and nocturnal fisheries were operating. This confirms that epipelagic prey either caught actively by the gulls or linked to fisheries was particularly important in the feeding habits of Audouin's gulls. Nevertheless, differences between the two colonies appear mainly when only trawlers operated: while at the Ebro Delta gulls showed higher consumption of benthic-mesopelagic prey (probably linked to a higher trawler discard availability), gulls from the Chafarinas Islands consumed higher biomass of epipelagic prey probably caught actively by night. When both fleets operated around the two colonies, the average biomass of prey in a regurgitate of younger chicks was significantly higher at the Ebro Delta than at Chafarinas, and the opposite trend was recorded for older nestlings and adults. Niche width was broader in Chafarinas than in the Ebro Delta for both age classes and for any fishing fleet schedule, suggesting again that the exploitation of discards was higher at the Ebro Delta than at the Chafarinas, where gulls show a more varied diet. Despite that availability of discards was probably higher at the Ebro Delta than at Chafarinas, the per capita availability was not so different at both localities due to the increasing seabird community population at the Ebro Delta, which ca. doubled that at Chafarinas in the last decade.

We studied foraging activity of giant petrels during the incubation period, by simultaneously deploying activity recorders and satellite transmitters on northern (Macronectes halli) and southern giant petrels (Macronectes giganteus) at Bird Island (South Georgia, Antarctica) between 29 October and 26 December 1998 . Satellite tracking showed two types of trips: (1) coastal trips, all undertaken by male northern giant petrels, to the nearby South Georgia mainland, presumably foraging on seal and penguin carcasses on beaches, and (2) pelagic trips, foraging at sea for marine prey or potentially scavenging on distant archipelagos (e.g. South Sandwich, Falkland or South Orkney Is.). Activity recorder data were consistent with the types of trip defined by the satellite tracking data, with median wet activity (time spent at the sea surface) during pelagic trips being 41%, but only 14% on coastal trips. On pelagic trips, there was a significant negative correlation between the duration of wet periods and the speed of travel between satellite uplinks. Mean travelling speed between uplinks was greater during day than night for both types of trips, suggesting that giant petrels prefer to travel during daylight and are less active at night. The scarcity of wet periods during the night in giant petrels foraging to the South Georgia coast (median 3%, range 1-9 %) indicates that such birds spent almost all night on land. Likewise, the scarcity of wet periods at night for three birds foraging 700-1000 km south of Bird Island, where there is no land but abundant icebergs, suggests these birds were resting on the icebergs at night. In addition to the adaptations to scavenging on carrion, pelagic trips by giant petrels contain elements similar to those of albatrosses, indicating a complexity to giant petrel lifestyle hitherto unrecognised.

Over the breeding season, courtship feedings in pairs of common terns were estimated to range from 0 to over 150 and copulations from 0 to over 50 per pair, based on a daylength of 17 h. The numbers of both were negatively correlated with laying date, suggesting that late breeding was a consequence of poor-quality males unable to provision their females adequately. Although there was not usually a temporal link between courtship feedings and copulations, overall they were strongly correlated, suggesting that females copulate repeatedly with the same male to gain food. High food availability, as indicated by low tide, was associated with high levels of courtship feeding and few copulations, and vice versa, whereas we did not detect any pattern associated with the time of day. Three of 272 courtship feedings, and two of 76 copulation attempts, were extrapair. Only one of 34 broods contradicted the assumption that broods contained only true siblings, in accordance with the high levels of sexual fidelity observed.

We performed a line transect survey (352.4 km) of primates in the Serra de Paranapiacaba, at one of the largest relatively undisturbed fragments of the Atlantic rainforest of Southeastern Brazil (ca. 1400 km2), in August 1998. The brown capuchin, Cebus apella nigritus, was the most common species found in the area (20 groups, density estimate: 5.31+-2.05 individuals per km2, mean+-SE). Nine groups of the brown howler monkey, Alouatta guariba clamitans, and eight of the woolly spider monkey, Brachyteles arachnoides arachnoides, were also recorded, with preliminary density estimates of 0.79+-0.40 and 2.33+-1.37 individuals per km2, respectively. Density estimates for these species in other fragments of Atlantic rainforest are reviewed, showing that densities in Paranapiacaba are among the lowest reported. It is suggested that the higher densities reported for isolated populations in small forest patches (<50 km2) is related to the absence of main primate predators, the density compensation phenomenon and the ecological plasticity of some primate species. In contrast, local extinction in many small patches is probably related to hunting pressure. Given the important primate populations found in the Paranapiacaba fragment, conservation strategies for the studied species should give priority to effective protection of the largest remnant fragments from illegal hunting and deforestation, rather than translocation of individuals or captive breeding programs to introduce monkeys in small forest fragments vulnerable to hunting and of uncertain future.

From 1992 to 1999, we used subcutaneously injected transponders, enabling remote and automatic annual identification with the aim of performing an integrated population study of a Common Tern Sterna hirundo colony. Within a few years, population parameters and their inter-year variation could be calculated with a high degree of accuracy (adult return rate 91%, subadult return rate 35%, breeding success 1.3 fledglings pair-1y-1, mean recruitment age 3y). Data on condition, fate, reproductive performance and output were gathered year by year and contributed greatly towards the detailed study of many questions in behavioural and population ecology, such as individuals' quality, prospecting and recruitment. The arrival time of prospectors and recruitment age were related to body condition. The high body mass of adults increased their reproductive performance and output. Divorce rate was low (18.9%) and increased with arrival asynchrony of mates. Divorced terns tended to change territories, whereas territory fidelity in general was high. The future focus of this ongoing study is reproductive value, senescence, lifetime reproductive success, fitness, and questions related to genealogy.

El marcaje individual de animales mediante la implantación de transponders es permanente, de identificación inequívoca, con pocas pérdidas si se realiza adecuadamente, y sin efectos importantes sobre los portadores. Mediante este método se pueden recolectar datos a nivel individual a lo largo de toda la vida de un animal. Ello hace de los transponders una herramienta adecuada para estudios a largo plazo de la dinámica poblacional así como distintos aspectos de la ecología del comportamiento. Su mayor inconveniente reside en el coste inicial de los lectores, solo al alcance de grandes proyectos. Desde 1992, marcamos con transponders 101 adultos y todos los pollos que volaron de una colonia de charranes en Wihelmshaven (Alemania), lo que nos permitió la identificación por control remoto y automática de los individuos. En unos pocos años, los parámetros poblacionales y su variación interanual se pudieron calcular con precisión (tasa adulta de retorno 91%, subadulta 35%, éxito reproductor 1,3 pollos por pareja y año, edad mediana de reclutamiento 3 años). Datos sobre los parámetros reproductores de los individuos marcados se recolectaron año tras año. La combinación del sistema de identificación de los transponders con balanzas de precisión situadas en los posaderos permitió recolectar datos precisos sobre la condición de las aves a lo largo de la estación reproductora. Asimismo, algunos individuos marcados con transponders fueron pintados mediante aerosoles activados por control remoto, para facilitar estudios mediante observación directa, como por ejemplo la fidelidad sexual. Todo ello, permitió un estudio detallado sobre la calidad individual, los procesos de prospección y reclutamiento, el sistema de apareamiento, el significado de las puestas de reposición, la fidelidad al lugar del nido, etc. La fecha de llegada de los prospectores y el reclutamiento parece estar relacionado con la condición física. Una masa corporal elevada incrementa las posibilidades de una reproducción con éxito. La tasa de divorcio fue baja (18,9%) y se incremento con la asincronía de llegada a la colonia de los miembros de una pareja. La fidelidad al lugar del nido fue alta, tanto entre años como entre dos reproducciones en un mismo año, aunque fue menos para aves divorciadas o enviudadas.

During the Audouin's Gull's breeding season at the Ebro Delta in 1993, 24 fresh eggs from eight three-egg clutches (modal clutch-size) were collected at the peak of the laying period. Eggs were processed to obtain formalin-fixed yolks, which were halved and stained using the potassium dichromate method. Digitized images of the yolks were examined to assess the daily rates of yolk deposition. We used these data in combination with egg compositional analysis to build a model of energy demands during the formation of an average clutch in Audouin's Gull. To show how the different parameters of clutch formation affect the daily energy investment peak, we performed a simulation analysis in which the rapid yolk development (RYD) period, the follicle triggering interval (FTI), the laying interval (LI) and the albumen synthesis period (ASP) were allowed to vary simultaneously. In our sample, the mean RYD period was seven days with a range from six to eight days. There were no significant differences in yolk volume among eggs in a clutch, but albumen volume was significantly smaller in third eggs. According to our model the albumen synthesis of the a-egg coincides with the energy demand peak for clutch formation. This peak represents an increase by ca. 42% in female energy requirements. Values obtained from the simulation analysis showed that only the ASP of the a-egg and the RYD durations of the second and third follicles produced noticeable reductions in peak energy investment. We predict that in gulls, whose laying intervals seem to be kept constant, significant increases of the durations of the RYD periods of second and third eggs, or even significant reductions of yolk size of these eggs, may operate simultaneously to match the energy demands during clutch formation to the prevailing food conditions.

We satellite-tracked the foraging trips of males and females of the 2 sibling species of giant petrels, Macronectes halli and M. giganteus, breeding sympatrically at Bird Island (South Georgia, Antarctica), during the incubation period (November-December). Size of the activity range in addition to speed and distance covered on foraging trips were similar between the species, but were lower for males than for females in both species. Sex-specific differences agree with previous observations on diets and on attendance at seal carcasses, suggesting that females mainly forage at sea, whereas males mainly scavenge on the coast. Overall, however, the foraging ecology of both species seems very similar. Interspecific and intersexual competition may be reduced by the limited overlap in the at-sea range, with southern giant petrels foraging further south than did northern giant petrels, and females further west than males, suggesting some spatial partitioning in foraging areas. Male northern giant petrels foraged almost exclusively on the South Georgia coast; their strong dependence during the brooding and chick-rearing period on Antarctic fur seals, whose population has increased exponentially in recent years, may be reflected in the recent population increase of northern giant petrels at South Georgia. Foraging areas of giant petrels overlapped extensively with longline fishery distribution, highlighting their susceptibility to being caught on longline hooks. Females were at higher risk during the study period since they made longer trips and foraged further west than males, into areas where local longline fisheries are more active.

Giant petrels (Macronectes spp.) are the most sexually dimorphic of all seabirds. We used satellite-tracking and mass change during incubation to investigate the influence of sexual size dimorphism, in terms of the intersexual food competition hypothesis, on foraging and fasting strategies of northern giant petrels at South Georgia. Females foraged at sea whereas males foraged mainly on the South Georgia coast, scavenging on seal and penguin carcasses. Foraging effort (flight speed, distance covered, duration of foraging trips) was greater for females than for males. In contrast, foraging efficiency (proportionate daily mass gain while foraging) was significantly greater for males than for females. Females were significantly closer to the desertion mass threshold than males and could not compensate for the mass loss during the incubation fast while foraging, suggesting greater incubation costs for females than for males. Both sexes regulated the duration and food intake of foraging trips depending on the depletion of the body reserves. In males the total mass gain was best explained by mass at departure and body size. We suggest that sexual segregation of foraging strategies arose from size-related dominance at carcasses, promoting sexual size dimorphism. Our results indicate that sex-specific differences in fasting endurance, contest competition over food and flight metabolic rates are key elements in maintenance of sexual size dimorphism, segregating foraging strategies and presumably reducing competition between sexes.

In long-lived seabirds with low annual reproductive output, the renesting decision after breeding failure is critical, and the parents have to weigh benefits of replacement clutches against possible future reproductive costs. In this study, we investigated factors influencing renesting decisions in common terns (Sterna hirundo) and compared aspects of breeding biology and body mass between two breeding attempts by the same pairs in each of 4 years of heavy losses due to predation. Renesting birds were characterized by early laying dates and by a high age. Among early breeders, high egg mass reduced the probability of renesting. A long relaying interval coincided with low mass of replacement eggs in one year, and short intervals with high egg mass in another. Further, egg mass decreased and relaying intervals increased the later the predation events occurred. Evidence of high levels of parental care of replacement clutches came from body mass data: female mass increase prior to egg laying was higher in the second attempt than in the first, whereas male mass was lower during the second courtship period than during the first. Male mass also affected relaying intervals and mass of replacement eggs. We conclude that common terns expend high levels of parental care of replacement clutches. Intrinsic factors related to individual quality (age, body condition) seemed most important for renesting decisions and for the degree of parental care, but foraging conditions seemed to have modifying effects.

The diet of the viperine snake was compared with food availability in the Ebro Delta, a wetland largely occupied by rice fields, in 1990 and 1991. Snake selection of prey type and size was studied seasonally and by snake group: males, females and immature snakes. Overall, feeding activity (percentage of individuals with prey and number of prey per stomach) increased with food availability. Diet analysis showed that viperine snakes mainly foraged on the green frog Rana perezi (adults and tadpoles) and the carp Cyprinus carpio. Conversely, viperine snakes rejected the mosquito fish Gambusia holbroki which is the most abundant species in autumn, when Natrix maura has a low feeding activity. Statistical comparisons between viperine snake diet and prey availability showed that males selected small carp, immature snakes selected tadpoles and, in spring, females selected frogs. The selection of small carp by males may reflect a sexual divergence of trophic niche related to sexual size dimorphism, as females are larger than males. As tadpoles are presumably easier to catch than fish, tadpole selection by immature individuals may reflect variance in capture abilities. In spring, the selection of frogs by females overlapped with vitellogenesis, suggesting that females compensate for the cost of reproduction by selecting green frogs, which have a greater biomass and higher energy content than fish. Carps eaten in spring were smaller than in summer. Moreover, in summer viperine snakes selected smaller carp than the available mean size. This divergent tendency between carp size selection and carp size availability reveals how seasonal diet shifts in prey size selection may be a response to an increase in prey size.

The seasonal decline in egg-volume on the basis of the individual changes in 35 known-age female Common Terns Sterna hirundo was studied with data available for 3-6 years. Interindividual differences were significant for both laying dates and egg-volume. Thus, to examine whether the decline was an effect of an assortment of females with the timing of breeding according to their individual egg-volume, the individual values of laying date were correlated with egg-volume. Correlation was not significant, suggesting that seasonal decline in egg-volume was not due to interindividual differences. Instead, egg-volume showed a gradual decrease with the progress of the season at intraindividual level i.e. the later an individual female laid in the season the smaller was the egg-volume. Moreover, the seasonal decline in egg-volume was not due to a simultaneous increase in egg-volume with an advancement of the timing of breeding with age, since the rate of seasonal decrease in egg-volume was similar for young and old birds. Individual average of laying date accounted for 22% of the individual average of fledgling production whereas egg-volume was not significantly correlated with fledging production. Thus, it is suggested that seasonal decline in egg-volume is a non-adaptive consequence of physiological effect of condition on both timing of breeding and egg-volume.

We investigated which of three hypotheses (better option, incompatibility or asynchronous arrival) best explains divorce in the common tern. One partner did not return the next year in 18.5% of 150 pairs. Among the 106 pairs in which both mates returned, the divorce rate was 18.9%. We found no significant differences in: breeding performance or condition in relation to the probability of divorce; quality of previous mates and new mates, mean age in relation to pair bond status; breeding success before and after divorce nor did this differ from breeding success of reunited pairs. Hence the better option and incompatibility hypotheses were not supported. However, divorce was more likely in pairs in which mates arrived asynchronously on the breeding grounds, supporting the asynchronous arrival hypothesis. Median arrival asynchrony for divorced pairs was 7.5 days and for reunited pairs 2 days; mates arriving more than 16 days apart always split up. About 20% of divorced birds lost breeding status in the year of divorce, probably as a consequence of their late arrival. Our results suggest that terns search for a new mate as soon as they arrive on the breeding grounds and that mates remain faithful to each other to avoid the costs of searching for a new partner. Thus, synchrony in arrival facilitates pair bond maintenance rather than asynchrony promoting divorce, since divorce appears to be a side-effect of asynchrony and not an active decision.

We studied nest-site and mate fidelity in renesting Common Terns (Sterna hirundo), from 1993 to 1997, in a Common Tern colony breeding on six small artificial islands in the harbour area in Wilhelmshaven (German North Sea coast). Implanted transponders made possible individual recognition of the adults throughout their lifetime. We compared intra-season rates of nest-site and mate fidelity with between-year rates. Intra-season divorce was never observed. On the other hand, inter-year divorce was estimated at about 25%, suggesting that the costs of intra-season divorce are higher or opportunities for divorce are lower than between years. For 75% of 26 pairs that renested within the same season, the distance moved was less than 4.3 m. For 75% of 57 faithful pairs between two consecutive seasons, the distance moved was less than 1.25 m. Dispersal distances between and within years did not differ significantly but were clearly shorter than a paired random distribution of nests. Most of the birds changed the nest-site either when renesting or between years, but most of the new scrapes can be considered as lying within the original territory. Thus, failure of the first breeding attempt increased neither divorce nor nest-site dispersal as compared with between-year rates. We also studied the influence of parental age and the date of breeding failure on distances moved in renesting birds. Late renesting pairs did not change the nest-site. A multiple regression analysis revealed that the longer the duration of the first breeding attempt and the older the pair, the shorter the nest dispersal distance.

From 1993 to 1995 we analysed the influence of purse-seine and trawler fisheries on the activity cycle of Audouin's Larus audouinii and Yellow-legged Gull L.cachinnans at the Chafarinas Islands (Moroccan coast). Yellow-legged Gulls showed an activity cycle mainly diurnal. However, they take advantage of the fish attracted to the surface by purse-seine boats during the night and dawn. Purse-seine fisheries use powerful lamps that aid the gulls in localizing and exploiting schools of fish concentrated around lamps. Audouin's gull did not show any activity peak either during the day or at night. Although Audouin's Gulls showed conspicuous activity peaks depending on the trawler time-table in other colonies, the difficulty of predicting trawling fishery discards at Chafarinas Islands probably underlies the absence of clear peaks of activity linked to this fishery. Data suggest that parents foraged and relieved each other continuously. The capacity to maintain a continuous trophic activity, day and night, could be an additional advantage when the energetic costs increase during the reproductive period.

Migration costs are usually evaluated in terms of energy expenditure or risk of predation. Although parasitism has been widely recognized as an important potential factor for fitness, few studies have dealt with the relationships between migration and parasitism. From 1991 to 1997, birds in the surroundings of Santa Susanna village (Catalan Maditerranean coast) were regularly mist-netted and ringed. Blood smears from 13 common passerines species were collected during the reproductive period and examined to detect the presence of blood parasites. Migratory status of these species was assigned according to the analysis of captures and recaptures over the year. Some dipterous samples were also collected with a Malaise trap installed near the ringing station and determined to species level. Five bird species were classified as a partial or total migrants and 8 species were classified as a residents. Of the five migrant species, four presented at least one individual infected by haematozoan parasite. Only one species showed infected individuals among the eight species classified as residents. At least three dipterous species were identified in the study area as a potential vector for haematozoan haemoproteids. We suggest two ways to explain these results. 1.- The habitat-heterogeneity hypothesis: the degree of exposure of host species to parasite vectors has been reported as the main factor to explain parasite prevalences. In spite of the presence of some potential vectors in the study area, haematozoan parasite species seem to be absent from the area. Migrant species were parasitized outside of the study area, in the winter quarters or during the stop-overs in migration. 2.- The immunosuppressive hypothesis: immunosupressive effects of large energy investment of host species can increase the level of infection. Resident species are not so stressed as migrant species. Resident species, although infected, can mantain parasite infection below the detectability level or they can recover from infections. Migrant species are more likely to develop acute infections as a consequence of the migratory effort.

It is hypothesized that birds will retain the nest site after successful breeding performance but will move to another nest site after breeding failure. Similarly, improvement in the breeding performance has been suggested as a benefit of nest site fidelity. Although breeding success and nest site fidelity can also be influenced by age and duration of pair bond, few studies have analyzed the interactions of these variables with nest site fidelity. From 1992 to 1996, Common Terns Sterna hirundo of a colony at Wilhelmshaven fitted with transponders, were studied and their nest sites, mates and reproductive performace were checked each year. The nest distance between year n and year n+1 was measured for individually identified females. The potential causes of nest site fidelity were analyzed by relating fledging success in the year n, laying date in the year n+1, arrival date in the year n+1 and body condition in the year n+1 with nest site fidelity. The potential benefits were investigated by relating the breeding performance in the year n+1 (i.e. laying date, egg volume, clutch size, hatching success and fledging success) with nest site fidelity. When age and pair bond are not considered, it appears that the timing of breeding is the cause of nest site fidelity, and a greater success is the benefit. However, when age and pair bond status are included in the multiple regression analysis, it reveals that these variables are more likely to determine nest site fidelity than the mentioned above. Older and faithful birds showed a higher nest site fidelity than younger divorced or widowed birds. Mechanisms which could influence the ability of older and faithful birds to occupy the same nest site year after year are discussed.

A significant decrease in the body size of Audouin's Gulls Larus audouinii breeding at the Chafarinas Islands is reported. The decrease in linear measurements in the current breeding population ranged from 2.5% to 5.6% in males and from 0.61% to 4.4% in females. This was detected when assessing the reliability of a sex-discriminating function derived for the same colony 13 years earlier. When applied to the current population, this function failed to predict the sex of a large proportion of males (44%). The relative decrease in mean size was significantly greater in males than in females for culmen, nalospi and tarsus lengths, while for bill depth at culmen, wing length and body mass the relative decrease was similar in both sexes. Since the extent of differences depended on sex, these differences cannot be attributed to a systematic between-observer bias. Mean body size reduction might be either the result of a greater proportion of small breeding birds in the current population, because of increased availability of nesting sites (competition relaxation hypothesis), or an outcome of environmental factors affecting growth parameters (environmental constraint hypothesis). According to the first hypothesis, the changes observed would be associated with higher variability values. Conversely, if the second is true, the degree of variability should be similar. Since there are no significant differences in the degree of variability shown in the two data sets, our results support the second hypothesis. The environmental constraint acting via growth parameters is probably related to the increase in the number of Audouin's Gull breeding pairs while food availability was depleted. Our data suggest that changes in the duration of the growth period, rather than in the growth rates themselves, are involved in the body size differences found.

The diets of two potential competitor species, Audouin's Larus audouinii and yellow-legged gulls Larus cachinnans, were examined while they bred at the Chafarinas Islands during 1993, 1994, and 1995. Data were collected during two commercial fishing regimes: (1) trawling and purse seine fisheries, and (2) diurnal trawlers only. Since the food supply for the gulls in this area was heavily reliant on the activity of purse seine fisheries, these contrasting situations allowed us to analyze short-term effects, induced by daily changes in food supply, on niche width, dietary shift, and niche overlap between the two species. Overall, both species relied mainly on fish for food, especially Clupeiforms, in the case of Audouin's gull irrespective of the fishing situation, and in the case of the yellow-legged gull, only when purse seine fishing was in operation. When purse seine boats did not operate (food shortage), yellow-legged gulls broadened their niche, consuming equal amounts of all the feeding resources, and they showed a dietary shift toward a greater consumption of prey from refuse tips. In contrast, Audouin's gulls did not change their niche width, but showed a slight dietary shift away from the consumption of epipelagic fish, compensated by an increase in reliance on benthic-mesopelagic resources. Niche overlap was clearly higher on days when both fishing fleets operated, probably because a superabundant food resource facilitates high overlap without affecting coexistence between the two species. Since our study was developed on the basis of daily variations in food supply, and competition effects are to be expected on a longer-term basis, these changes can be seen as the outcome of the coexistence of two species in stable competitive equilibrium.

We examined blood smears of 38 adult Corys Shearwaters Calonectris diomedea (O. Procellariformes) from Chafarinas Is. (Moroccan Mediterranean coast). Although the presence of the haemoproteid vector at this locality (Ruiz et al. 1995), no Shearwater was infected. Pelagic habits of most Procellariiformes are an unsuitable environment for potential vectors of haemoproteids.

We analyzed five different types of food samples from Audouin's Gull (Larus audouinii), collected during the breeding seasons of 1994 and 1995 at its two main breeding colonies, the Ebro Delta and the Chafarinas Islands. These food samples included spontaneous regurgitates, dry boli containing partially digested food, food remains, pellets, and prey identified during direct observations of chick provisioning. We compared estimates of biomass, levels of taxonomic determination allowed by each kind of food sample, and the associated potential biases to assess which sampling method provides the best estimate of diet in gulls. Regurgitates allowed identification of most prey to species level and reliable biomass estimates, but their collection was time-consuming and invasive. Dry boli provided almost the same information as regurgitates at order level and were easy to collect. However, both underestimated soft-bodied prey and prey with large, hard parts. Food remains provided an estimate of diet composition that was highly biased towards prey with large distinctive hard parts. However, food remains were a good complement to dry boli, enhancing biomass estimates for food items that had a good relationship of weight and linear measurements of prey hard parts. Direct observation allowed identification of prey only to upper taxonomic categories, and is useful when only a broad categorization of prey types is required. Pellets showed important biases towards fish with robust otoliths, and inaccurate conversion to biomass, but they can be useful for monitoring variations in the consumption of certain prey items. Several factors such as time spent collecting, sample availability, disturbance to animals, and the status of the species studied need to be considered when deciding on a method of diet assessment sampling.

Predatory and (or) kleptoparasitic interactions are greatly facilitated in mixed-species gulleries, particularly when one of the species is larger than the others. Larus audouinii, the Audouin's gull, is a threatened species breeding in sympatry with the larger L. cachinnans, the yellow-legged gull, throughout the Mediterranean. The yellow-legged gull has often been cited as the main threat to the Audouin's gull. On the Chafarinas Islands, the second largest breeding place for Audouin's gulls in the world, both gull species depend largely on commercial fisheries for food. We analyze the influence of food availability, assessed through fishery activity, on the frequency and intensity of interaction pressure by yellow-legged gulls upon Audouin's gulls during the breeding season. We studied five different types of interaction: (1) flyovers of yellow-legged gulls; (2) ground intrusions; (3) egg predation; (4) chick predation, and (5) aerial kleptoparasitism. Moreover, intensity of interaction pressure was assessed using logistic regression analysis to build a model of the relationship between Audouin's gulls' response to yellow-legged gull flyovers as a dependent variable and fishing fleet activity as an independent variable. All interactions except aerial kleptoparasitism were significantly more frequent during days without sardine fishery activity. However, chick predation is significantly higher only during the period when yellow-legged gull has fledglings. Overall, the results of the estimated logistic model indicate a positive association between depleted food and the response by Audouin's gulls to aerial intrusions.

The diet and feeding ecology of breeding Audouin's Gull Larus audouinii were examined at the Ebro Delta (NW Mediterranean) during 1993, 1994 and 1995 and found to depend on the activity of the commercial fisheries operating within the foraging range of the birds in the colony. One of the largest fishing fleets in the Mediterranean operates in this area, both diurnal inshore trawlers and nocturnal purse-seine boats. Since 1991, a trawler moratorium has coincided with the breeding season of the gull, which has affected its feeding ecology in the area. Data were collected under four commercial fishing regimes: diurnal trawling only, diurnal trawling and purse-seine fishing at night, night fishing only, and no fishing. Although Audouin's Gull usually feeds mainly on epipelagic fish (65% by biomass on average), in our study they depended largely on trawler discards (benthonic fish represented up to 73% by biomass when only trawlers operated) because they are a food source with a high energetic value and are predictable in space and time. The active capture of clupeiform fish significantly increased when trawlers were not operating, and the gull has also broadened its foraging niche to feed in rice fields, in ecotonic habitats and occasionally on refuse tips, suggesting that the clupeiform population was not large enough to meet the food demands of the colony. The presence of some discard prey in the diet when trawlers were not operating indicated that some breeding gulls were able to travel beyond the area affected by the moratorium (more than 110 km from the colony). The frequency of incubation changeovers did not change significantly when trawlers were not operating, but marked changes brought about by the moratorium were recorded during the chick-rearing stage. Chick feeding frequency significantly decreased during the trawler moratorium, although the number of prey per regurgitate delivered to chicks did not vary. When trawlers did not operate, adults seemed to compensate for the lower food availability by carrying larger prey items to the chicks. In contrast, chicks occasionally did not accept the regurgitated food, especially when trawler discards were available. The trawler moratorium affected not only the diet of Audouin's Gull but also the adult time budgets and the provisioning rates of chicks, although the species showed some ability to buffer against low food availability.

We analyze the dynamics of the gastropod community living in the Ebro Delta ricefields in relation to the cultivation cycle. We found six bassommatophoran species, three of which form more than 97% of total: Physella acuta (Drapamaud), Planorbis planorbis (L.), and Lymnaea ovata (L.). Colonization of ricefields by freshwater pulmonates started in June, with populations increasing until the harvest in October, when the bulk of gastropods showed a decline. Populations recovered quickly and, in some cases reached their yearly maximum of abundance in Autumn. P. acuta predominates over all other species except in May and June, when P. planorbis takes over. L. ovata is always the least abundant of the three main species. The analysis of size classes suggests that there are two breeding seasons for P. acuta and P. planorbis, the first at the end of Summer, with a total replacement of the population, and the second in October-November, without replacement. Conversely, L. ovata shows a wide array of size classes throughout the rice cultivation cycle. This suggests that this species breeds earlier and outside the ricefields. The variations in population numbers of each species in relation to environmental changes induced by rice cultivation suggest that P. planorbis better exploits the algal cover or other food available at the ricefield bottoms, while P. acuta forages mainly on epiphytic vegetation and adventitious plants. Gastropod secondary production and turnover ratios in the Ebro Delta fall within the range of natural freshwater systems, but are situated in the zone of higher values.

Differences in diet between chicks and adults of Audouin's Gull (Larus audouinii) were examined in the Chafarinas Islands (SW Mediterranean) during the breeding seasons of 1993 and 1994. The major food type for chicks on the Chafarinas Islands were fish, both epipelagic (some of them coming from purse-seine activity) and benthonic (coming from trawler discards), forming a minimum 70% by biomass. The amount of fish fed to young increased with chick age, up to 95% by biomass. Adults also consumed mainly fish (75% by number and 90% by biomass), mostly clupeiforms, Sardina Sardina pilchardus and Gilt Sardine Sardinella aurita. Terrestrial prey were especially given to youngest chicks, probably because of requirements to increase the feeding rates of these chicks. Shorter foraging trips to the near Moroccan coast to feed on terrestrial prey (chiefly arthropods and isopods) may allow adults especially to guard/brood small chicks, and eventually to increase the feeding rates. Feeding rates significantly decreased with brood size, and also decreased with chick age, although this effect was not significant. Weight and size of food items fed to chicks increased with chick age, and fledglings were fed with larger items than those consumed by adults. This was probably related to the increase in gape width with chick age, and the trade-off between food load carried to feed chicks and the distance traveled to catch the fish.

The Ebro Delta ricefields are used by waterbirds mainly as foraging habitats, since other uses, such as nesting, are restricted to a few species. The availability of freshwater wetlands in the Ebro Delta depends chiefly on the hydrological cycle derived from rice culture. We present data on seasonal variation in availability of potential waterbird prey items (macroinvertebrates and vertebrates) in the Ebro Delta ricefield system, and discuss their relevance for waterbird populations living there during an annual cycle. Biomass/length predictive equations are presented for those prey items more relevant to waterbird populations

Data on haematozoan parasitemias in Laridae are scarce and, since blood parasites may influence birds fitness, it is important to report their incidence in threatened species such as Audouin's Gull. Blood smears of 90 Audouin's Gulls caught during incubation at their two main breeding sites, the Ebro Delta and the Chafarinas Islands, were examined for Haemoproteus lari parasitemia. Overall prevalence of the parasite was 92.1% for the Chafarinas Is. and 28.9% for the Ebro Delta. To our knowledge, prevalences reported in this study are the highest ever recorded for Laridae. Differences in prevalence between localities were significant, but not differences between the sexes within each locality. Males were more intensely parasitized than females in Chafarinas, and gulls from Chafarinas were more intensely parasitized than those from the Ebro Delta. Differences in intensity were also checked using data from sympatric Yellow-legged Gulls, L. cachinnans, and only the factor locality was significant. There was no significant relationship between body condition and intensity of parasitemia in males or females in either locality. These data indicate higher susceptibility to H. lari for gulls breeding at the Chafarinas Islands.

This paper deals with two factors affecting density and distribution of nests of Yellowlegged Gull in the Medes Islands colony, both the habitat and the culling. Nest density was significantly lower on coastal cliffs than on the other parts of the islands. Vegetated areas, when suitable, allowed higher nest density. Clutch size was not different among the study areas. The colony size does not seem to have decreased since the last census in 1991 (Fortia and Hontangas 1991). However, we recorded a significant decrease in the nest density in Borne study areas.

Stomach contents of nine adult Herons coming from the Ebro Delta have been analyzed: four of Little Egret (Egretta garzetta), four of Grey Heron (Ardea cinerea) and one of Night Heron (Nycticorax nycticorax). Results show that, these Little Egrets fed mainly in brackish waters, whereas Grey Herons and Night Herons caught preys in freshwater masses.

The gastric contents of 92 Song Thrushes caught in Majorca (n = 47) and Montsia (n = 45) during October 1986 have been analyzed. Diet composition is given for taxonomice and typological prey-types. Song Thrushes of Majorca consumed high quality resources homogeneously, whereas those of Montsia used suboptimal resources heterogeneously. Trofic differences found between ecomorphotypes need further studies to be adequately interpreted. The energy conversion of prey types clearly show that olives are the most song thrushes' profitable prey. The need of animal prey consumption related to protein deficit and the alternative coevolutive hypothesis are discussed. Estimations of the costs of Song Thrush feeding activity during the winter to olive harvest are given.