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Este artículo contiene 18 páginas, 3 figuras, 4 tablas., 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 δ13C and δ15N 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., This study was funded by the Ministerio de Economia, Industria y Competitividad from the Spanish Government (CGL2009‐11278/BOS, CGL2013‐42585‐P, CGL2013‐42203‐R, CGL2016‐78530‐R) and Fondos FEDER.

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. info:eu-repo/semantics/publishedVersion

Artificial lights at night cause high mortality of seabirds, one of the most endangered groups of birds globally. Fledglings of burrow-nesting seabirds, and to a lesser extent adults, are attracted to and then grounded (i.e., forced to land) by lights when they fly at night. We reviewed the current state of knowledge of seabird attraction to light to identify information gaps and propose measures to address the problem. Although species in families such as Alcidae and Anatidae can be grounded by artificial light, the most affected seabirds are petrels and shearwaters (Procellariiformes). At least 56 species of Procellariiformes, more than one-third of them (24) threatened, are subject to grounding by lights. Seabirds grounded by lights have been found worldwide, mainly on oceanic islands but also at some continental locations. Petrel breeding grounds confined to formerly uninhabited islands are particularly at risk from light pollution due to tourism and urban sprawl. Where it is impractical to ban external lights, rescue programs of grounded birds offer the most immediate and employed mitigation to reduce the rate of light-induced mortality and save thousands of birds every year. These programs also provide useful information for seabird management. However, these data are typically fragmentary, biased, and uncertain and can lead to inaccurate impact estimates and poor understanding of the phenomenon of seabird attraction to lights. We believe the most urgently needed actions to mitigate and understand light-induced mortality of seabirds are estimation of mortality and effects on populations; determination of threshold light levels and safe distances from light sources; documentation of the fate of rescued birds; improvement of rescue campaigns, particularly in terms of increasing recovery rates and level of care; and research on seabird-friendly lights to reduce attraction.

Nitrogen and carbon stable isotopes provide tools to investigate ecological segregation, prey choice and spatial distribution in seabirds. However, the interpretation of stable isotopes is frequently hampered by a lack of isotopic baseline data. In this study, two techniques proposed to overcome such shortages were tested: compound-specific isotope analyses of amino acids (AA-CSIA) and the analysis of hydrogen stable isotope ratios (HSIA). Feathers of two sympatric storm-petrels were compared. The two species, Black-bellied storm-petrels Fregetta tropicaand Wilson’s storm-petrels Oceanites oceanicus, moult in oceanic waters and differ in diet composition. For HSIA, a range of species with broad diet and non-breeding distribution was also investigated. Differences in carbon isotope values suggested differences in the spatial distribution and thus, in isotopic baseline values, during moult. Bulk nitrogen analyses of adult feathers did not detect species differences in trophic level. However, AA-CSIA detected clear differences in trophic levels in line with expectations: Black-bellied storm-petrels fed at a higher trophic level than Wilson‘s storm-petrels. Hydrogen values also differed between the species, but contrary to expectations were highly enriched in Black-bellied storm-petrels, but much less enriched in Wilson’s storm-petrels. Hydrogen data of seven petrel species challenge the suggestion that depleted δD values indicate a higher percentage of isosmotic fish. The present results suggest that the difference in hydrogen ratios may be explained by these petrels moulting in different ocean zones. Amino acid-specific stable isotope analyses were useful for estimating isotopic baselines and thus true trophic levels, whereas hydrogen isotopes were not. Deutsche Forschungsgemeinschaft (DFG) in the framework of the priority programme SPP1154, Qu148/16 info:eu-repo/semantics/publishedVersion

This study evaluates the trophic position of adult Yellow-legged Gulls Larus michahellis atlantis resident in the Azores archipelago in the past (1921–1928) and in the present (2009–2010), and analyses the decadal variation in the diet of breeding birds from the 1990s to the 2000s for three main colonies (Topo Islet, Baixo Islet and Mistério da Prainha). Using mixing models, we compared stable isotope signatures of nitrogen and carbon in adult breast feathers between birds from 1921 to 1928 (held in museum collections) and 2009 to 2010, jointly with both isotopic signatures of their main prey groups (fish, goose barnacles (Lepas anatifera), seabirds, mammals and refuse). The diet of breeding birds was analysed using pellets collected in 1989, 1995, 1996, 2004, 2009 and 2010. Stable isotopes analysis (SIA) results were in accordance with the results provided from the analysis of pellets, showing a relatively recent and significant change in the diet of adult gulls. In particular, SIA revealed a significant decrease in the trophic position of Yellow-legged Gulls in the Azores, over the last 89 years in response to the decrease in the consumption of seabirds and fish and, an increase in the consumption of marine invertebrates (goose barnacles) and refuse. The analysis of pellets confirmed the significant decrease in the fish ingested, whereas the ingestion of lower trophic level prey (i.e. goose barnacles, mammals and refuse) increased. Both methods reflect the feeding plasticity and opportunistic foraging behavior of this species, and are in accordance with patterns described for continental Europe. We acknowledge the support given by Fundação para a Ciência e Tecnologia, Portugal, to Patricia Pedro (SFRH/BD/ 40095/2007).

Monteiro’s Storm-petrel (Hydrobates monteiroi) is a small seabird endemic to the Azores archipelago, where it is known to breed only on two mammal-free islets. Total breeding numbers are between 250 and 300 pairs. During the 2015 breeding season on Praia Islet, six Madeiran wall lizards (Lacerta dugesii) were observed depredating a Monteiro’s Storm-petrel chick about to fledge. In August 2015, a freshly killed chick without its head and four larger dead chicks were found. Eight other chicks had disappeared from their nests since our previous visit in early July. In 2016, there was further evidence of suspected lizard depredation. Three chicks were found predated and dragged out of their nests, and an additional 22 chicks disappeared from their nests before fledging. In 2016, Monteiro’s Storm-petrel breeding success was only 26.8%, the lowest ever recorded. We suspect that some of the chick deaths and nest failures may be attributable to these introduced lizards. All chicks were found dragged out of their nests, a behavior that is not consistent with kills from aerial predators. Lizards were suspected because they are the only possible predator on land. Therefore, we recommend evaluating the impact of Madeiran wall lizards on the two Monteiro’s Storm-petrel main colonies: Praia and baixo islets. info:eu-repo/semantics/publishedVersion

Trophic ecology and movements are critical issues for understanding the role of marine predators in food webs and for facing the challenges of their conservation. Seabird forag- ing ecology has been increasingly studied, but small elusive species, such as those forming the 'lit- tle shearwater' complex, remain poorly known. We present the first study on the movements and feeding ecology of the Barolo shearwater Puffinus baroli baroli in a colony from the Azores archi- pelago (NE Atlantic), combining global location-sensing units, stable isotope analyses of feathers (δ 13 C and δ 15 N), stomach flushings and data from maximum depth gauges. During the chick-rear- ing 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 (6 fam- ilies 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 14.8 m (range: 7.9 to 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 Barolo 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, principally on small schooling squid and fish. These traits contrast with those of 3 other Azorean Procellariiformes (Cory's shearwater Calonectris diomedea, the Madeiran storm-petrel Oceanodroma castro and Monteiro's storm-petrel O. monteiroi), indi- cating ecological segregation within the Azorean seabird community.

Studying the diet of top marine predators, such as seabirds, is important in understanding their place in the trophic network and effects of global climate change, but knowledge of the diet of several procellariiformes remains anecdotal. The diet of Bulwer's Petrel (Bulweria bulwerii) in the Azores was studied over two consecutive years using stomach flushings from 85 birds. The frequency of occurrence of prey taxa (%0) was similar in both years (χ2 = 5.396, d.f. = 5, p = 0.370), with squid being the most common. Fish and squid were of similar occurrence by number (%N) in the diet (49% and 51%, respectively) in 1998 but in 1999 fish were more numerous (62% against 38% for squid). Squid lower beaks from five families and fish otoliths from six families were identified, representing 20 taxa. The most abundant prey in both years were squid Pyroteuthis margaritifera and the mesopelagic fish Electrona risso. The maximum standard length offish and squid consumed was 7 cm and 11 cm, respectively. Given...

As on many other islands, most of the seabird species breeding in Portugal’s Azores archipelago are now restricted to tiny remnants of their former nesting range, owing in large part to the introduction of mammals by humans. Praia Islet, 0.12 km2 in size, is home to five seabird species, four of which fall under the European listing of “conservation concern.” Introduced rabbits (Oryctolagus cuniculus) on Praia had accelerated soil erosion through overgrazing, destroyed seabird nests, and competed for burrows with petrels. Restoration of seabird habitat on the islet began in 1995 and involved rabbit eradication, control of soil erosion, native plant reintroduction, and installation of artificial nests for common terns (Sterna hirundo), roseate terns (Sterna dougallii), and Madeiran storm-petrels (Oceanodroma castro). Rabbits were eradicated in 1997 using broadcast pellets containing poison. Since then, soil erosion has decreased, many of the reintroduced native plants have started to spread, and tern and Madeiran storm-petrel breeding numbers on the islet have increased by 1,548% and 43%, respectively. However, Praia Islet seabirds remain vulnerable owing to human recreational activities. This case study highlights the need to consider local conditions carefully when assessing restoration options to effect rapid mammal eradication. It also confirms the value of combining measures aimed at restoring native vegetation and improving seabird habitat quality with alien herbivore eradication.

AIM: 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 first time, the migration strategy of a small seabird, the Bulwer's petrel (Bulweria bulwerii), and provide new insights into the ecology and evolution of long-distance marine migrations. LOCATION: Subtropical and tropical Atlantic Ocean. METHODS: Using cutting-edge geolocators, we examined the year-round distribution and at-sea activity patterns of adult Bulwer's petrels sampled at five 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. RESULTS: Our results provide the first 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. MAIN CONCLUSIONS: These results indicate that specific 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. FEDER (CGL2009-11278/BOS); SEO/BirdLife (project LIFE+INDEMARES: LIFE07NAT/E/000732) info:eu-repo/semantics/publishedVersion