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Sex-specific niche differentiation is common in marine vertebrates, but how this varies long-term is poorly understood. Here we investigated interannual variation in sexual segregation among breeding northern gannets Morus bassanus, wide-ranging central-place foragers with slight sexual dimorphism. Over 11 breeding seasons, we used GPS tracking and/or stable isotopes to test for sex differences in foraging trip characteristics (range, duration and timing); spatial distribution; habitat selection; and carbon and nitrogen isotopes in blood. When combining data from all years, females foraged further and for longer than males, yet despite this, the foraging areas of the sexes almost completely overlapped. Males and females selected foraging habitats that differed in terms of oceanography but not fishing vessel density. We also detected temporal segregation: females were more likely to be at sea during the day than at night, while males were more likely to be at sea during the night. However, foraging behaviour quantified by all GPS analyses varied interannually, with sex differences detected in some years but not others. Finally, males had consistently higher red blood cell δ13C and δ15N than females across all years, which was not driven by size dimorphism, instead likely by prey choice or very fine-scale habitat selection. We conclude that environmental variation influenced short-term sex differences in movement, but sex differences in stable isotopes that integrate behaviour over longer periods reveal more consistent differences. Our results suggest that inferences drawn from single-year studies may not relate to general patterns, highlighting the importance of long-term studies and combining methods.

Pelagic seabirds are important components of many marine ecosystems. The most abundant species are medium/small sized petrels (

Stable isotopes from archaic Falkland Islands wolves ( Dusicyon australis ) indicate a high trophic, marine diet. Hamley et al. argue that this is consistent with mutualism with Yaghan people. However, most D. australis had similar isotopic signatures in the European era, despite human persecution. These data therefore neither support nor refute human-mediated introduction of D. australis to the Falklands.

Funding was provided by the UK Natural Environmental Research Council (NERC) [grant number NE/M017990/1] and Fundação para a Ciência e a Tecnologia (FCT) [grant numbers MARE - UIDB/04292/2020 and UIDP/04292/2020]. Remotely-sensed data were supplied by the NERC Earth Observation Data Acquisition and Analysis Service (NEODAAS) and the Copernicus Marine Service. Support for NOFU loggers and analysis was provided through the SEATRACK project http://www.seapop.no/en/seatrack/, funded by the Norwegian Ministries of Climate and Environment, and Foreign Affairs and the Norwegian Oil and Gas Association. 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. Publisher PDF

David L. Miller was funded by OPNAV N45 and the SURTASS LFA Settlement Agreement, being managed by the U.S. Navy’s Living Marine Resources program under Contract No. N39430-17-C-1982, collaboration between Douglas B. Sigourney and David L. Miller was also facilitated by the DenMod working group (https://synergy.st-andrews.ac.uk/denmod/) funded under the same agreement. The survey that the fin whale data originate from was funded through two inter-agency agreements with the National Marine Fisheries Service: inter-agency agreement number M14PG00005 with the US Department of the Interior, Bureau of Ocean Energy Management, Environmental Studies Program, Washington, DC and inter-agency agreement number NEC-16-011-01-FY18 with the US Navy. The survey that the fulmar data originate from was funded by the UK Natural Environmental Research Council (NERC) grant NE/M017990/1. Spatial models of density and abundance are widely used in both ecological research (e.g., to study habitat use) and wildlife management (e.g., for population monitoring and environmental impact assessment). Increasingly, modellers are tasked with integrating data from multiple sources, collected via different observation processes. Distance sampling is an efficient and widely used survey and analysis technique. Within this framework, observation processes are modelled via detection functions. We seek to take multiple data sources and fit them in a single spatial model. Density surface models (DSMs) are a two-stage approach: first accounting for detectability via distance sampling methods, then modelling distribution via a generalized additive model. However, current software and theory does not address the issue of multiple data sources. We extend the DSM approach to accommodate data from multiple surveys, collected via conventional distance sampling, double-observer distance sampling (used to account for incomplete detection at zero distance) and strip transects. Variance propagation ensures that uncertainty is correctly accounted for in final estimates of abundance. Methods described here are implemented in the dsm R package. We briefly analyse two datasets to illustrate these new developments. Our new methodology enables data from multiple distance sampling surveys of different types to be treated in a single spatial model, enabling more robust abundance estimation, potentially over wider geographical or temporal domains. Publisher PDF

The work was funded by the Natural Environment Research Council (Standard Research Grant NE/H007466/1) and donations from Evan Fountain (In Memoriam donations for Issy Fountain) and Mike Matthewson. Marine vertebrates show a diversity of migration strategies, including sex differences. This may lead to differential demography, but the consequences of such between-sex variation are little understood. Here, we studied the migration of known-sex northern gannets Morus bassanus — a partial migrant with females ~8 % heavier than males. We used geolocators to determine wintering areas of 49 breeding adults (19 females and 30 males during 2010 to 2014) from 2 colonies in the northeast Atlantic (Bass Rock and Grassholm, UK). We also tested for sex-specific survival probabilities using capture−mark−recapture methods (n = 72 individuals Bass Rock, n = 229 individuals Grassholm; 2010−2018) and applied sex-specific population projection matrices (PPMs) to quantify population-level effects. Tracked gannets wintered in a range of large marine ecosystems (LMEs): Canary Current LME (CCLME; 69 %), Celtic-Biscay Shelf LME (16 %), Iberian Coastal LME (8 %), North Sea LME (4 %) or Mediterranean LME (2 %). Migratory destination differed between the sexes: 90 % of females vs. 57 % of males wintered in the CCLME. Survival was similar between the sexes at Bass Rock (mean ± 95 % CI = 0.951 ± 0.053 and 0.956 ± 0.047 for females and males, respectively). At Grassholm, there was evidence of slight sex differences in breeder survival: females had lower annual survival (0.882 ± 0.040) than males (0.946 ± 0.026). At Bass Rock, PPMs with no sex effect best fitted the observed population increase (1994−2014). Sex-specific PPMs fitted the population estimates for Grassholm (1995−2015). Our results reveal that female gannets are more likely to travel further than males to winter in the CCLME. This difference is unlikely due to morphological differences, unlike in other bird species. However, the reason for slightly higher over-winter female mortality at Grassholm is unclear. Publisher PDF

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

Small petrels are the most abundant seabirds in the Southern Ocean. However, because they breed in burrows on remote and often densely vegetated islands, their colony sizes and conservation status remain poorly known. To estimate the abundance of these species on Bird Island in the Falkland archipelago, we systematically surveyed their breeding burrow density and occupancy across this near-pristine tussac (Poa flabellata)-covered island. By modelling burrow density as functions of topography and Sentinel 2 satellite-derived Normalised Difference Vegetation Index data, we inferred habitat associations and predicted burrow abundance of the commonest species—Thin-billed Prions (Pachyptila belcheri) and Wilson’s Storm-petrels (Oceanites oceanicus). We estimate that there are 631,000 Thin-billed Prion burrows on the island (95% CI 496,000–904,000 burrows). Assuming that burrow occupancy lies between 12 and 97%, this equates to around 76,000–612,000 breeding pairs, making Bird Island the second or third largest P. belcheri colony in the world, holding approximately 3–27% of the species’ breeding population. We estimate that 8200–9800 (95% CI 5,200–18,300 pairs) pairs of Wilson’s Storm-petrels also breed on the island. Notably, the latter burrowed predominantly under and within tussac pedestals, whereas they are usually assumed to breed in rock cavities. Thin-billed Prions are declining in the Kerguelen archipelago, but their population trends in the Falklands are unknown. Given the wide confidence intervals around our own and other population estimates for these cryptic species, we recommend that their populations should be monitored regularly, at multiple sites.

Cyclonic ocean eddies drive upwelling of deep waters enhanced in nutrients, which can elevate phytoplankton productivity. At mid‐latitudes in the North Atlantic, satellite images show enhanced chlorophyll‐a associated with eddies. However, surface macronutrient concentrations are often not fully depleted in this region, implying enhanced macronutrient supply is not the primary control. We conducted high resolution sampling through two mid‐latitude Atlantic eddies in late spring, located 800 and 350 km east of the Newfoundland Grand Banks. Waters outside of both eddies had unused residual macronutrients, low dissolved iron, and iron‐stressed phytoplankton. Inside both eddies, plankton biomass was higher and macronutrient concentrations lower. However, full macronutrient drawdown and an absence of iron stress were only present in the eddy nearer the continental shelf. From these two examples, iron supply and proximity to shelf iron sources appear to be important factors regulating productivity and macronutrient utilization in mid‐latitude North Atlantic cyclonic eddies.

Static (fixed-boundary) protected areas are key ocean conservation strategies, and marine higher predator distribution data can play a leading role toward identifying areas for conservation action. The Falkland Islands are a globally significant site for colonial breeding marine higher predators (i.e., seabirds and pinnipeds). However, overlap between marine predators and Falkland Islands proposed Marine Managed Areas (MMAs) has not been quantified. Hence, to provide information required to make informed decisions regarding the implementation of proposed MMAs, our aims were to objectively assess how the proposed MMA network overlaps with contemporary estimates of marine predator distribution. We collated tracking data (1999–2019) and used a combination of kernel density estimation and model-based predictions of spatial usage to quantify overlap between colonial breeding marine predators and proposed Falkland Islands MMAs. We also identified potential IUCN Key Biodiversity Areas (pKBAs) using (1) kernel density based methods originally designed to identify Important Bird and Biodiversity Areas (IBAs) and (2) habitat preference models. The proposed inshore MMA, which extends three nautical miles from the Falkland Islands, overlapped extensively with areas used by colonial breeding marine predators. This reflects breeding colonies being distributed throughout the Falklands archipelago, and use being high adjacent to colonies due to central-place foraging constraints. Up to 45% of pKBAs identified via kernel density estimation were located within the proposed MMAs. In particular, the proposed Jason Islands Group MMA overlapped with pKBAs for three marine predator species, suggesting it is a KBA hot spot. However, tracking data coverage was incomplete, which biased pKBAs identified using kernel density methods, to colonies tracked. Moreover, delineation of pKBA boundaries were sensitive to the choice of smoothing parameter used in kernel density estimation. Delineation based on habitat model predictions for both sampled and unsampled colonies provided less biased estimates, and revealed 72% of the Falkland Islands Conservation Zone was likely a KBA. However, it may not be practical to consider such a large area for fixed-boundary management. In the context of wide-ranging marine predators, emerging approaches such as dynamic ocean management could complement static management frameworks such as MMAs, and provide protection at relevant spatiotemporal scales. Fundação para a Ciência e Tecnologia - FCT info:eu-repo/semantics/publishedVersion

International audience; Southern Ocean ecosystems are under pressure from resource exploitation and climate change1,2. Mitigation requires the identification and protection of Areas of Ecological Significance (AESs), which have so far not been determined at the ocean-basin scale. Here, using assemblage-level tracking of marine predators, we identify AESs for this globally important region and assess current threats and protection levels. Integration of more than 4,000 tracks from 17 bird and mammal species reveals AESs around sub-Antarctic islands in the Atlantic and Indian Oceans and over the Antarctic continental shelf. Fishing pressure is disproportionately concentrated inside AESs, and climate change over the next century is predicted to impose pressure on these areas, particularly around the Antarctic continent. At present, 7.1% of the ocean south of 40°S is under formal protection, including 29% of the total AESs. The establishment and regular revision of networks of protection that encompass AESs are needed to provide long-term mitigation of growing pressures on Southern Ocean ecosystems.

Understanding the determinants of species’ distributions is a fundamental aim in ecology and a prerequisite for conservation but is particularly challenging in the marine environment. Advances in bio‐logging technology have resulted in a rapid increase in studies of seabird movement and distribution in recent years. Multi‐colony studies examining the effects of intra‐ and inter‐colony competition on distribution have found that several species exhibit inter‐colony segregation of foraging areas, rather than overlapping distributions. These findings are timely given the increasing rate of human exploitation of marine resources and the need to make robust assessments of likely impacts of proposed marine developments on biodiversity. Here we review the occurrence of foraging area segregation reported by published tracking studies in relation to the density‐dependent hinterland (DDH) model, which predicts that segregation occurs in response to inter‐colony competition, itself a function of colony size, distance from the colony and prey distribution. We found that inter‐colony foraging area segregation occurred in 79% of 39 studies. The frequency of occurrence was similar across the four seabird orders for which data were available, and included species with both smaller (10–100 km) and larger (100–1000 km) foraging ranges. Many predictions of the DDH model were confirmed, with examples of segregation in response to high levels of inter‐colony competition related to colony size and proximity, and enclosed landform restricting the extent of available habitat. Moreover, as predicted by the DDH model, inter‐colony overlap tended to occur where birds aggregated in highly productive areas, often remote from all colonies. The apparent prevalence of inter‐colony foraging segregation has important implications for assessment of impacts of marine development on protected seabird colonies. If a development area is accessible from multiple colonies, it may impact those colonies much more asymmetrically than previously supposed. Current impact assessment approaches that do not consider spatial inter‐colony segregation will therefore be subject to error. We recommend the collection of tracking data from multiple colonies and modelling of inter‐colony interactions to predict colony‐specific distributions.

Individual specialisations in animals are important contributors to a wide range of ecological and evolutionary processes, and have been particularly documented in relation to multiple aspects of foraging behaviours. Central-place foragers, such as seabirds, frequently exhibit pronounced specialisations and individual differences in a variety of foraging traits. In particular, the availability of fisheries discards alongside natural prey resources provides additional potential for differentiation and specialisation for opportunistically scavenging seabird species. However, the consequences of such specialisations for at-sea distributions and intraspecific interactions are not well known. Here, we investigated the links between the degree of dietary specialisation on natural or discarded prey and the foraging movements and spatial occupancy of northern gannets Morus bassanus in relation to differing intraspecific competition at 6 colonies of differing sizes. We found that, at most colonies, individuals with different dietary strategies concentrated foraging at differing levels of intraspecific competition. In addition, individuals pursuing different strategies were frequently, but not consistently, spatially separated, distinctions that were most acutely seen in females. However, this variation in individual strategy had no significant impact on current body condition. These analyses demonstrate how foraging-associated metrics need not covary within an unconstrained system. They also reveal that specialisation can have important consequences for the competitive regimes individuals experience, highlighting the complexity of examining interacting consequences at large spatial scales.

The Sooty Shearwater Ardenna grisea, an abundant but declining petrel, is one of many seabird species that construct breeding burrows, presumably because these confer protection from predators and the elements. Little is known about the causes of variation in Sooty Shearwater burrow architecture, which can differ markedly both within and between breeding sites. We hypothesize that burrow architecture varies in response to habitat type and competition for space. To address these hypotheses, we recorded Sooty Shearwater burrow dimensions on Kidney Island, the largest Sooty Shearwater colony in the Falkland Islands, South Atlantic, and modelled these as functions of burrow density (a proxy for competition) and habitat indices. Our models suggest that Sooty Shearwaters burrow further underground in response to competition for breeding space, and that soil underlying dense tussac grass Poa flabellata is more easily excavated than other substrates, indicating how vegetation restoration could aid the conservation of this species.

Abstract Identifying and understanding patterns in movement data are amongst the principal aims of movement ecology. By quantifying the similarity of movement trajectories, inferences can be made about diverse processes, ranging from individual specialisation to the ontogeny of foraging strategies. Movement analysis is not unique to ecology however, and methods for estimating the similarity of movement trajectories have been developed in other fields but are currently under-utilised by ecologists. Here, we introduce five commonly used measures of trajectory similarity: dynamic time warping (DTW), longest common subsequence (LCSS), edit distance for real sequences (EDR), Fréchet distance and nearest neighbour distance (NND), of which only NND is routinely used by ecologists. We investigate the performance of each of these measures by simulating movement trajectories using an Ornstein-Uhlenbeck (OU) model in which we varied the following parameters: (1) the point of attraction, (2) the strength of attraction to this point and (3) the noise or volatility added to the movement process in order to determine which measures were most responsive to such changes. In addition, we demonstrate how these measures can be applied using movement trajectories of breeding northern gannets (Morus bassanus) by performing trajectory clustering on a large ecological dataset. Simulations showed that DTW and Fréchet distance were most responsive to changes in movement parameters and were able to distinguish between all the different parameter combinations we trialled. In contrast, NND was the least sensitive measure trialled. When applied to our gannet dataset, the five similarity measures were highly correlated despite differences in their underlying calculation. Clustering of trajectories within and across individuals allowed us to easily visualise and compare patterns of space use over time across a large dataset. Trajectory clusters reflected the bearing on which birds departed the colony and highlighted the use of well-known bathymetric features. As both the volume of movement data and the need to quantify similarity amongst animal trajectories grow, the measures described here and the bridge they provide to other fields of research will become increasingly useful in ecology. Significance statement As the use of tracking technology increases, there is a need to develop analytical techniques to process such large volumes of data. One area in which this would be useful is the comparison of individual movement trajectories. In response, a variety of measures of trajectory similarity have been developed within the information sciences. However, such measures are rarely used by ecologists who may be unaware of them. To remedy this, we apply five common measures of trajectory similarity to both simulated data and real ecological dataset comprising of movement trajectories of breeding northern gannets. Dynamic time warping and Fréchet distance performed best on simulated data. Using trajectory similarity measures on our gannet dataset, we identified distinct foraging clusters centred on different bathymetric features, demonstrating one application of such similarity measures. As new technology and analysis techniques proliferate across ecology and the information sciences, closer ties between these fields promise further innovative analysis of movement data.

Detecting change is necessary for effective ecosystem management, yet temporal data on key ecosystem components are lacking for many polar and subpolar regions. For example, although the Falkland Islands hosts internationally important marine and coastal bird populations, few of these were surveyed until the late twentieth century. The avifauna of one small island, Kidney Island, was surveyed between 1958 and 1963, however. This typical tussac-covered island has remained free of non-native predators, so changes in its avifauna may reflect variation in the wider marine environment. In order to obtain a rare snapshot of such changes, we re-surveyed Kidney Island’s avifauna between 2017 and 2019, counting either individuals, breeding pairs or nest sites of marine and coastal waterbirds. Waterfowl, waders and cormorant populations were broadly stable, but several populations showed profound differences over the six decades between surveys. In particular, Southern Rockhopper penguins Eudyptes chrysocome collapsed from > 3000 to 200 pairs, while Sooty Shearwaters Ardenna grisea expanded by two orders of magnitude. Due to its isolation and tight fisheries management, the Falklands marine environment is assumed to be relatively pristine. Our limited results suggest that sufficient changes may nevertheless have occurred in the region’s marine ecosystem to have detectable impacts on breeding seabirds. Fundação para a Ciência e Tecnologia - FCT info:eu-repo/semantics/publishedVersion

Group travel is a familiar phenomenon among birds but the causes of this mode of movement are often unclear. For example, flocking flight may reduce flight costs, enhance predator avoidance or increase foraging efficiency. In addition, naive individuals may also follow older, more experienced conspecifics as a learning strategy. However, younger birds may be slower than adults so biomechanical and social effects on flock structure may be difficult to separate. Gannets are wide-ranging (100s-1000s km) colonial seabirds that often travel in V or echelon-shaped flocks. Tracking suggests that breeding gannets use memory to return repeatedly to prey patches 10s–100s km wide but it is unclear how these are initially discovered. Public information gained at the colony or by following conspecifics has been hypothesised to play a role, especially during early life. Here, we address two hypotheses: (1) Flocking reduces flight costs and (2) young gannets follow older ones in order to locate prey. To do so, we recorded flocks of northern gannets commuting to and from a large colony and passing locations offshore and used a biomechanical model to test for age differences in flight speeds. Consistent with the aerodynamic hypothesis, returning flocks were significantly larger than departing flocks, while, consistent with the information gathering hypothesis, immatures travelled in flocks more frequently than adults and these flocks were more likely to be led by adults than expected by chance. Immatures did not systematically occupy the last position in flocks and had similar theoretical airspeeds to adults, making it unlikely that they follow, rather than lead, for biomechanical reasons. We therefore conclude that while gannets are likely to travel in flocks in part to reduce flight costs, the positions of immatures in those flocks may result in a flow of information from adults to immatures, potentially resulting in social learning.

Funding: UK Natural Environment Research Council (NERC Standard Grant NE/H007466/1). SB is currently funded by an ERC consolidator’s grant (310820: STATEMIG). EW is funded by the NERC (Independent Research Fellowship NE/M017990/1). Migration is a fundamental behavioral process prevalent among a wide variety of animal taxa. As individuals are increasingly shown to present consistent responses to environmental cues for breeding or foraging, it may be expected that approaches to migration would present similar among-individual consistencies. Seabirds frequently show consistent individual differences in a range of traits related to foraging and space-use during both the breeding and non-breeding seasons, but the causes and consequences of this consistency are poorly understood. In this study, we combined analysis of geolocation and stable isotope data across multiple years to investigate individual variation in the non-breeding movements and diets of northern gannets Morus bassanus, and the consequences for changes in body condition. We found that individuals were highly repeatable in their non-breeding destination over consecutive years even though the population-level non-breeding distribution spanned >35° of latitude. Isotopic signatures were also strongly repeatable, with individuals assigned to one of two dietary clusters defined by their distinct trophic (δ15N) and spatial (δ13C) position. The only non-breeding destination in which the two dietary clusters co-occurred was off the coast of northwest Africa. The majority of individuals adopted a consistent foraging strategy, as they remained within the same dietary cluster across years, with little variation in body mass corrected for size among these consistent individuals. In contrast, the few individuals that switched clusters between years were in better condition relative to the rest of the population, suggesting there may be benefits to flexibility during the non-breeding period. Our results indicate that a consistent migratory strategy can be effective regardless of wintering region or diet, but that there may be benefits to those individuals able to display flexibility. This appears to be an important behavioral strategy that may enhance individual condition. Publisher PDF

The Patagonian Shelf Large Marine Ecosystem supports high levels of biodiversity and endemism and is one of the most productive marine ecosystems in the world. Despite the important role marine predators play in structuring ecosystems, areas of high diversity where multiple predators congregate remains poorly known on the Patagonian Shelf. Here, we used biotelemetry and biologging tags to track the movements of six seabird species and three pinniped species breeding at the Falkland Islands. Using Generalized Additive Models, we then modelled these animals’ use of space as functions of dynamic and static environmental indices that described their habitat. Based on these models, we mapped the predicted distribution of animals from both sampled and unsampled colonies and thereby identified areas where multiple species were likely to overlap at sea. Maximum foraging trip distance ranged from 79 to 1,325 km. However, most of the 1,891 foraging trips by 686 animals were restricted to the Patagonian Shelf and shelf slope, which highlighted a preference for these habitats. Of the seven candidate explanatory covariates used to predict distribution, distance from the colony was retained in models for all species and negatively affected the probability of occurrence. Predicted overlap among species was highest on the Patagonian Shelf around the Falkland Islands and the Burdwood Bank. The predicted area of overlap is consistent with areas that are also important habitat for marine predators migrating from distant breeding locations. Our findings provide comprehensive multi-species predictions for some of the largest marine predator populations on the Patagonian Shelf, which will contribute to future marine spatial planning initiatives. Crucially, our findings highlight that spatially explicit conservation measures are likely to benefit multiple species, while threats are likely to impact multiple species.

Many animal populations are thought to be in flux due to anthropogenic impacts. However, censusing organisms to understand such changes is often impractical. For example, while it is thought that over half of pelagic seabird populations are declining, most breed in burrows or on cliffs, in large, remote colonies, making them difficult to count. Burrow-nesting sooty shearwaters (Ardenna grisea) are abundant but declining in their core (South Pacific) breeding range, potentially due to introduced rodents and habitat loss. In contrast, Kidney Island, their largest colony in the Falkland Islands (Southwest Atlantic), purportedly grew by several orders of magnitude since the mid-1900s. This island is rodent-free, and native tussac grass (Poa flabellata) has increased following cessation of historical exploitation. To estimate the sooty shearwater population in the Falkland Islands, and its relationship with breeding habitat availability, we sampled burrow density and occupancy on Kidney Island and modeled these as functions of habitat. Both indices responded positively to a proxy for historical increases in tussac cover. We estimate that breeding sooty shearwaters occupy ∼140,000 (95% CI: 90,000–210,000) burrows on Kidney Island. Moreover, using additional survey data and Generalized Functional Response models to account for intra-island variation in habitat availability, we estimate that 25,000 (95% CI: 20,100 - 30,500) burrows could be occupied on nearby islands from which non-native rodents have been recently eradicated. Our study shows that habitat selection functions, generalized where necessary, not only improve population estimates but provide biological insights needed to reverse declines in seabirds and other species. Keywords: Ardenna grisea, Burrowing petrels, Habitat preference, Puffinus griseus, Resource selection function, Species distribution model

The Retrospective Analysis of Antarctic Tracking Data (RAATD) is a Scientific Committee for Antarctic Research project led jointly by the Expert Groups on Birds and Marine Mammals and Antarctic Biodiversity Informatics, and endorsed by the Commission for the Conservation of Antarctic Marine Living Resources. RAATD consolidated tracking data for multiple species of Antarctic meso- and top-predators to identify Areas of Ecological Significance. These datasets and accompanying syntheses provide a greater understanding of fundamental ecosystem processes in the Southern Ocean, support modelling of predator distributions under future climate scenarios and create inputs that can be incorporated into decision making processes by management authorities. In this data paper, we present the compiled tracking data from research groups that have worked in the Antarctic since the 1990s. The data are publicly available through biodiversity.aq and the Ocean Biogeographic Information System. The archive includes tracking data from over 70 contributors across 12 national Antarctic programs, and includes data from 17 predator species, 4060 individual animals, and over 2.9 million observed locations., Measurement(s)geographic locationTechnology Type(s)digital curationFactor Type(s)temporal interval • geographic locationSample Characteristic – OrganismAptenodytes forsteri • Lobodon carcinophaga • Eudyptes chrysolophus • Thalassarche melanophrys • Phoebetria palpebrata • Aptenodytes patagonicus • Pygoscelis adeliae • Leptonychotes weddellii • Megaptera novaeangliae • Mirounga leonina • Arctocephalus gazella • Thalassoica antarctica • Eudyptes schlegeli • Diomedea exulans • Phoebetria fusca • Diomedea chrysostoma • Procellaria aequinoctialisSample Characteristic – Environmentpolar biomeSample Characteristic – LocationAntarctica Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.11688876

The Patagonian Shelf Large Marine Ecosystem supports high levels of biodiversity and endemism and is one of the most productive marine ecosystems in the world. Despite the important role marine predators play in structuring the ecosystems, areas of high diversity where multiple predators congregate remains poorly known on the Patagonian Shelf. Here, we used biotelemetry and biologging tags to track the movements of six seabird species and three pinniped species breeding at the Falkland Islands. Using Generalized Additive Models, we then modelled these animals' use of space as functions of dynamic and static environmental indices that described their habitat. Based on these models, we mapped the predicted distribution of animals from both sampled and unsampled colonies and thereby identified areas where multiple species were likely to overlap at sea. Maximum foraging trip distance ranged from 79 to 1,325 km. However, most of the 1,891 foraging trips by 686 animals were restricted to the Patagonian Shelf and shelf slope, which highlighted a preference for these habitats. Of the seven candidate explanatory covariates used to predict distribution, distance from the colony was retained in models for all species and negatively affected the probability of occurrence. Predicted overlap among species was highest on the Patagonian Shelf around the Falkland Islands and the Burdwood Bank. The predicted area of overlap is consistent with areas that are also important habitat for marine predators migrating from distant breeding locations. Our findings provide comprehensive multi-species predictions for some of the largest marine predator populations on the Patagonian Shelf, which will contribute to future marine spatial planning initiatives. Crucially, our findings highlight that spatially explicit conservation measures are likely to benefit multiple species, while threats are likely to impact multiple species.

Many established models of animal foraging assume that individuals are ecologically equivalent. However, it is increasingly recognized that populations may comprise individuals who differ consistently in their diets and foraging behaviors. For example, recent studies have shown that individual foraging site fidelity (IFSF, when individuals consistently forage in only a small part of their population's home range) occurs in some colonial breeders. Short-term IFSF could result from animals using a win-stay, lose-shift foraging strategy. Alternatively, it may be a consequence of individual specialization. Pelagic seabirds are colonial central-place foragers, classically assumed to use flexible foraging strategies to target widely dispersed, spatiotemporally patchy prey. However, tracking has shown that IFSF occurs in many seabirds, although it is not known whether this persists across years. To test for long-term IFSF and to examine alternative hypotheses concerning its cause, we repeatedly tracked 55 Northern Gannets (Morus bassanus) from a large colony in the North Sea within and across three successive breeding seasons. Gannets foraged in neritic waters, predictably structured by tidal mixing and thermal stratification, but subject to stochastic, wind-induced overturning. Both within and across years, coarse to mesoscale (tens of kilometers) IFSF was significant but not absolute, and foraging birds departed the colony in individually consistent directions. Carbon stable isotope ratios in gannet blood tissues were repeatable within years and nitrogen ratios were also repeatable across years, suggesting long-term individual dietary specialization. Individuals were also consistent across years in habitat use with respect to relative sea surface temperature and in some dive metrics, yet none of these factors accounted for IFSF. Moreover, at the scale of weeks, IFSF did not decay over time and the magnitude of IFSF across years was similar to that within years, suggesting that IFSF is not primarily the result of win-stay, lose-shift foraging. Rather, we hypothesize that site familiarity, accrued early in-life, causes IFSF by canalizing subsequent foraging decisions. Evidence from this and other studies suggests that IFSF may be common in colonial central-place foragers, with far-reaching consequences for our attempts to understand and conserve these animals in a rapidly changing environment.

A large increase in offshore wind turbine capacity is anticipated within the next decade, raising concerns about possible adverse impacts on birds as a result of collision risk. Birds' flight heights greatly influence this risk, yet height estimates are currently available only using methods such as radar- or ship-based observations over limited areas. 2. Bird-borne data-loggers have the potential to provide improved estimates of collision risk and here, we used data from Global Position System (GPS)-loggers and barometric pressure loggers to track the three-dimensional movements of northern gannets rearing chicks at a large colony in south-east Scotland (Bass Rock), located

Knowing the spatial scales at which effective management can be implemented is fundamental for conservation planning. This is especially important for mobile species, which can be exposed to threats across large areas, but the space use requirements of different species can vary to an extent that might render some management approaches inefficient. Here the space use patterns of seabirds were examined to provide guidance on whether conservation management approaches should be tailored for taxonomic groups with different movement characteristics. Seabird tracking data were synthesised from 5419 adult breeding individuals of 52 species in ten families that were collected in the Atlantic Ocean basin 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. Fil: Oppel, Steffen. Royal Society For The Protection Of Birds; Fil: Bolton, Mark. Royal Society For The Protection Of Birds; Fil: Carneiro, Ana P.B.. Birdlife International; Fil: Dias, Maria P.. Birdlife International; Fil: Green, Jonathan A.. University of Liverpool; Reino Unido Fil: Masello, Juan F.. Justus Liebig University Giessen; Fil: Phillips, Richard A.. British Antarctic Survey; Fil: Owen, Ellie. Royal Society For The Protection Of Birds; Fil: Quillfeldt, Petra. Justus Liebig University Giessen; Fil: Beard, Annalea. Environmental And Natural Resources Directorate; Fil: Bertrand, Sophie. Universidad Federal Rural Pernambuco; Brasil. Centre National de la Recherche Scientifique. Institut de Recherche pour le Développement; Francia Fil: Blackburn, Jez. British Trust For Ornithology; Fil: Boersma, P. Dee. University Of Washington, Seattle; Fil: Borges, Alder. Projecto Vitó; Fil: Broderick, Annette C.. University of Exeter; Reino Unido Fil: Catry, Paulo. Ispa - Instituto Universitário; Portugal Fil: Cleasby, Ian. Royal Society For The Protection Of Birds; Fil: Clingham, Elizabeth. Environmental And Natural Resources Directorate; Fil: Creuwels, Jeroen. Naturalis Biodiversity Center; Fil: Crofts, Sarah. Falklands Conservation; Fil: Cuthbert, Richard J.. Royal Society For The Protection Of Birds; Fil: Dallmeijer, Hanneke. Veda Consultancy; Fil: Davies, Delia. University Of Cape Town; Fil: Davies, Rachel. Marinelife; Fil: Dilley, Ben J.. University Of Cape Town; Fil: Dinis, Herculano Andrade. Parque Natural Do Fogo; Fil: Dossa, Justine. Birdlife International; Fil: Dunn, Michael J.. British Antarctic Survey; Fil: Efe, Marcio A.. Universidade Federal de Alagoas; Brasil Fil: Fayet, Annette L.. University of Oxford; Reino Unido Fil: Figueiredo, Leila. Universidade Federal de Alagoas; Brasil Fil: Frederico, Adelcides Pereira. Projecto Vitó; Fil: Gjerdrum, Carina. Environment Canada; Canadá Fil: Godley, Brendan J.. University of Exeter; Reino Unido Fil: Granadeiro, José Pedro. Faculdade de Ciências, Universidade de Lisboa; Portugal Fil: Guilford, Tim. University of Oxford; Reino Unido Fil: Hamer, Keith C.. University Of Leeds; Fil: Hazin, Carolina. Birdlife International; Fil: Hedd, April. Environment Canada; Canadá Fil: Henry, Leeann. Environmental And Natural Resources Directorate; Fil: Hernández-Montero, Marcos. Projeto Biodiversidade; Fil: Hinke, Jefferson. Noaa Fisheries Service; Fil: Kokubun, Nobuo. National Institute Of Polar Research; Fil: Leat, Eliza. Ascension Island Government; Fil: Tranquilla, Laura McFarlane. Royal Society For The Protection Of Birds; . Environmental And Natural Resources Directorate; Fil: Metzger, Benjamin. Birdlife Malta; Malta Fil: Militão, Teresa. Universidad de Barcelona; España Fil: Montrond, Gilson. Projecto Vitó; Fil: Mullié, Wim. Veda Consultancy; Fil: Padget, Oliver. University of Oxford; Reino Unido Fil: Pearmain, Elizabeth J.. Birdlife International; Fil: Pollet, Ingrid L.. Bird Studies Canada; Canadá Fil: Pütz, Klemens. Antarctic Research Trust; Fil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina Fil: Ratcliffe, Norman. British Antarctic Survey; Fil: Ronconi, Robert A.. Environment Canada; Canadá Fil: Ryan, Peter G.. University Of Cape Town; Fil: Saldanha, Sarah. Universidad de Barcelona; España Fil: Shoji, Akiko. University of Oxford; Reino Unido Fil: Sim, Jolene. Ascension Island Government; Fil: Small, Cleo. Royal Society For The Protection Of Birds; Fil: Soanes, Louise. University of Liverpool; Reino Unido Fil: Takahashi, Akinori. National Institute Of Polar Research; Fil: Trathan, Phil. British Antarctic Survey; Fil: Trivelpiece, Wayne. Noaa Fisheries Service; Fil: Veen, Jan. Veda Consultancy; Fil: Wakefield, Ewan. University of Glasgow; Reino Unido Fil: Weber, Nicola. University of Exeter; Reino Unido. Ascension Island Government; Fil: Weber, Sam. Ascension Island Government; . University of Exeter; Reino Unido Fil: Zango, Laura. Universidad de Barcelona; España Fil: González-Solís, Jacob. Universidad de Barcelona; España Fil: Croxall, John. Birdlife International

Sexual segregation, common in many species, is usually attributed to intra-specific competi- tion or habitat choice. However, few studies have simultaneously quantified sex-specific foraging be- haviour and habitat use. We combined movement, diving, stable isotope and oceanographic data to test whether sexual segregation in northern gannets Morus bassanus results from sex-specific habitat use. Breeding birds foraging in a seasonally stratified shelf sea were tracked over 3 consecutive breeding seasons (2010�2012). Females made longer trips, foraged far- ther offshore and had lower δ 13 C values than males. Male and female foraging areas overlapped only slightly. Males foraged more in mixed coastal waters, where net primary production (NPP) was relatively high (>3 mg C m �2 d �1 ) and sea-surface temperature (SST) was relatively low ( 15°C) more than females, possibly as a consequence of foraging in productive mixed waters over offshore banks. Females foraged most frequently in stratified offshore waters, of intermediate SST (12�15°C), but exhibited no consistent response to NPP. Sex-specific differences in diving behaviour corresponded with differences in habitat use: males made more long and deep U- shaped dives. Such dives were characteristic of inshore foraging, whereas shorter and shallower V-shaped dives occurred more often in offshore waters. Heavier birds attained greater depths during V-shaped dives, but even when controlling for body mass, females made deeper V-shaped dives than males. Together

Background:\ud \ud Albatrosses and other large seabirds use dynamic soaring to gain sufficient energy from the wind to travel large distances rapidly and with little apparent effort. The recent development of miniature bird-borne tracking devices now makes it possible to explore the physical and biological implications of this means of locomotion in detail. Here we use GPS tracking and concurrent reanalyzed wind speed data to model the flight performance of wandering albatrosses Diomedea exulans soaring over the Southern Ocean. We investigate the extent to which flight speed and performance of albatrosses is facilitated or constrained by wind conditions encountered during foraging trips.\ud Results:\ud \ud We derived simple equations to model observed albatross ground speed as a function of wind speed and relative wind direction. Ground speeds of the tracked birds in the along-wind direction varied primarily by wind-induced leeway, which averaged 0.51 (± 0.02) times the wind speed at a reference height of 5 m. By subtracting leeway velocity from ground velocity, we were able to estimate airspeed (the magnitude of the bird’s velocity through the air). As wind speeds increased from 3 to 18 m/s, the airspeed of wandering albatrosses flying in an across-wind direction increased by 0.42 (± 0.04) times the wind speed (i.e. ~ 6 m/s). At low wind speeds, tracked birds increased their airspeed in upwind flight relative to that in downwind flight. At higher wind speeds they apparently limited their airspeeds to a maximum of around 20 m/s, probably to keep the forces on their wings in dynamic soaring well within tolerable limits. Upwind airspeeds were nearly constant and downwind leeway increased with wind speed. Birds therefore achieved their fastest upwind ground speeds (~ 9 m/s) at low wind speeds (~ 3 m/s).\ud Conclusions:\ud \ud This study provides insights into which flight strategies are optimal for dynamic soaring. Our results are consistent with the prediction that the optimal range speed of albatrosses is higher in headwind than tailwind flight but only in wind speeds of up to ~ 7 m/s. Our models predict that wandering albatrosses have oval-shaped airspeed polars, with the fastest airspeeds ~ 20 m/s centered in the across-wind direction. This suggests that in upwind flight in high winds, albatrosses can increase their ground speed by tacking like sailboats.

Population-level estimates of species' distributions can reveal fundamental ecological processes and facilitate conservation. However, these may be difficult to obtain for mobile species, especially colonial central-place foragers (CCPFs; e.g., bats, corvids, social insects), because it is often impractical to determine the provenance of individuals observed beyond breeding sites. Moreover, some CCPFs, especially in the marine realm (e.g., pinnipeds, turtles, and seabirds) are difficult to observe because they range tens to ten thousands of kilometers from their colonies. It is hypothesized that the distribution of CCPFs depends largely on habitat availability and intraspecific competition. Modeling these effects may therefore allow distributions to be estimated from samples of individual spatial usage. Such data can be obtained for an increasing number of species using tracking technology. However, techniques for estimating population-level distributions using the telemetry data are poorly developed. This is of concern because many marine CCPFs, such as seabirds, are threatened by anthropogenic activities. Here, we aim to estimate the distribution at sea of four seabird species, foraging from approximately 5,500 breeding sites in Britain and Ireland. To do so, we GPS-tracked a sample of 230 European Shags Phalacrocorax aristotelis, 464 Black-legged Kittiwakes Rissa tridactyla, 178 Common Murres Uria aalge, and 281 Razorbills Alca torda from 13, 20, 12, and 14 colonies, respectively. Using Poisson point process habitat use models, we show that distribution at sea is dependent on (1) density-dependent competition among sympatric conspecifics (all species) and parapatric conspecifics (Kittiwakes and Murres); (2) habitat accessibility and coastal geometry, such that birds travel further from colonies with limited access to the sea; and (3) regional habitat availability. Using these models, we predict space use by birds from unobserved colonies and thereby map the distribution at sea of each species at both the colony and regional level. Space use by all four species' British breeding populations is concentrated in the coastal waters of Scotland, highlighting the need for robust conservation measures in this area. The techniques we present are applicable to any CCPF.

Search behavior is often used as a proxy for foraging effort within studies of animal movement, despite it being only one part of the foraging process, which also includes prey capture. While methods for validating prey capture exist, many studies rely solely on behavioral annotation of animal movement data to identify search and infer prey capture attempts. However, the degree to which search correlates with prey capture is largely untested. This study applied seven behavioral annotation methods to identify search behavior from GPS tracks of northern gannets (Morus bassanus), and compared outputs to the occurrence of dives recorded by simultaneously deployed time–depth recorders. We tested how behavioral annotation methods vary in their ability to identify search behavior leading to dive events. There was considerable variation in the number of dives occurring within search areas across methods. Hidden Markov models proved to be the most successful, with 81% of all dives occurring within areas identified as search. k‐Means clustering and first passage time had the highest rates of dives occurring outside identified search behavior. First passage time and hidden Markov models had the lowest rates of false positives, identifying fewer search areas with no dives. All behavioral annotation methods had advantages and drawbacks in terms of the complexity of analysis and ability to reflect prey capture events while minimizing the number of false positives and false negatives. We used these results, with consideration of analytical difficulty, to provide advice on the most appropriate methods for use where prey capture behavior is not available. This study highlights a need to critically assess and carefully choose a behavioral annotation method suitable for the research question being addressed, or resulting species management frameworks established.

Marine protected areas (MPAs) underpin the sustainable management of marine ecosystems but require accurate knowledge of species distributions. Recently, advances in tracking technology and habitat modelling have enabled the production of large-scale species distribution models (SDM), which provide the basis for hotspot mapping. In the UK, hotspot mapping to inform seabird MPA identification has involved converting observed or predicted distributions to polygons using either Maximum Curvature or Getis-Ord (Gi*) analysis. Here, we apply both mapping techniques to UK-wide, breeding season SDM predictions for four seabird species (Black-legged Kittiwakes Rissa tridactyla, Common Guillemots Uria aalge, Razorbills Alca torda and European Shags Phalacrocorax aristotelis) in order to compare their performance and inform seabird MPA. When using Maximum Curvature, grid cells within the identified maximum curvature boundaries were defined as hotspots. For Getis-Ord analysis, we defined hotspots as either (1) grid cells containing the top 1% or (2) the top 5% Gi* scores or (3) cells in which Gi* scores were statistically significant. Hotspots based upon Maximum Curvature or statistically significant Gi* scores covered the greatest area and were generally larger than current marine Special Protection Areas. Hotspots based on the top 1% or top 5% of Gi* scores were smaller and were concentrated around the largest breeding colonies. All hotspot methods consistently identified several high-density areas that should be prioritised for seabird conservation. Ultimately, the choice of hotspot identification method should be informed by considering species ecology alongside conservation goals to ensure hotspots are of sufficient size to protect target populations.

International audience; Consistent intra-population variability in foraging behaviour is found among a wide range of taxa. Such foraging specialisations are common among marine vertebrates, yet it is not clear how individuals repeatedly locate prey or foraging sites at ocean-wide scales. Using GPS and time-depth loggers we studied the fine-scale foraging behaviour of central-place northern gannets Morus bassanus at two large colonies. First, we estimated the degree of consistency in individual foraging routes and sites across repeated trips. Second, we tested for individual differences in searching behaviour in response to environmental covariates using reaction norms, estimated from mixed effect models. Adult gannets tracked over multiple foraging trips showed repeatable between-individual differences in terminal points and departure angles of foraging trips, but low repeatability in trip duration and trip length. Importantly, individual birds showed highly repeatable dive locations, with consistently different environmental conditions (such as copepod abundance), suggesting a high degree of foraging site specialisation. Gannets also showed between-individual differences in searching behaviour along environmental gradients, such that individuals intensified searching under different conditions. Together these results suggest that widespread individual foraging consistency may represent specialisation and be linked with individual responses to environmental conditions. Such divergent searching behaviour could provide a mechanism by which consistent foraging behaviour arises and is maintained among animals that forage across large spatial scales.

This is the first comprehensive study of at-sea activity patterns of albatrosses during the nonbreeding period, based on data from combination geolocator-immersion loggers deployed on the wandering albatross Diomedea exulans, black-browed albatross Thalassarche melanophris, grey- headed albatross T. chrysostoma and light-mantled albatross Phoebetria palpebrata from South Georgia (54° 00' S, 38° 03' W). Differences in behaviour among species observed during the breeding season were maintained during the nonbreeding period, suggesting a high degree of foraging niche specialisation. Wandering albatrosses exhibited longer flight bouts, and spent more time on the water during daylight, than any of the smaller species. Light-mantled albatrosses were the most active nocturnally. During daylight, grey-headed albatrosses were the most aerial and black-browed albatrosses had the shortest flight bouts. Although all species still engaged in foraging behaviour predominantly during daylight, they spent a greater proportion of time on the water (presumably resting) during the nonbreeding period compared with the breeding period, suggesting that they could more readily meet their energy demands when no longer subject to central place constraints. There was no evidence from activity patterns that might suggest that wing feather moult handicaps flight capability during the nonbreeding period. Individuals of all species engaged in rapid east-west commutes, when considerably higher proportions of time were spent in flight than while resident, in particular during daylight, possibly because birds are unable to navigate effectively during complete darkness. Despite consistency in individual dispersal patterns, there were year-to-year differences in the nocturnal behaviour of black-browed albatrosses, probably attributable to prey variability.

By extracting energy from the highly dynamic wind and wave fields that typify pelagic habitats, albatrosses are able to proceed almost exclusively by gliding flight. Although energetic costs of gliding are low, enabling breeding albatrosses to forage hundreds to thousands of kilometers from their colonies, these and time costs vary with relative wind direction. This causes albatrosses in some areas to route provisioning trips to avoid headwind flight, potentially limiting habitat accessibility during the breeding season. In addition, because female albatrosses have lower wing loadings than males, it has been argued that they are better adapted to flight in light winds, leading to sexual segregation of foraging areas. We used satellite telemetry and immersion logger data to quantify the effects of relative wind speed, sex, breeding stage, and trip stage on the ground speeds (Vg) of four species of Southern Ocean albatrosses breeding at South Georgia. Vg was linearly related to the wind speed component in the direction of flight (Vwf), its effect being greatest on Wandering Albatrosses Diomedea exulans, followed by Black-browed Albatrosses Thalassarche melanophrys, Light-mantled Sooty Albatrosses Phoebatria palpebrata, and Gray-headed Albatrosses T. chrysostoma. Ground speeds at Vwf = 0 were similar to airspeeds predicted by aerodynamic theory and were higher in males than in females. However, we found no evidence that this led to sexual segregation, as males and females experienced comparable wind speeds during foraging trips. Black-browed, Gray-headed, and Light-mantled Sooty Albatrosses did not engage in direct, uninterrupted bouts of flight on moonless nights, but Wandering Albatrosses attained comparable Vg night and day, regardless of lunar phase. Relative flight direction was more important in determining Vg than absolute wind speed. When birds were less constrained in the middle stage of foraging trips, all species flew predominantly across the wind. However, in some instances, commuting birds encountered headwinds during outward trips and tail winds on their return, with the result that Vg was 1.0–3.4 m/s faster during return trips. This, we hypothesize, could result from constraints imposed by the location of prey resources relative to the colony at South Georgia or could represent an energy optimization strategy.

Colonial seabirds are relatively easy to observe, count, measure and manipulate, and consequently have long been used as models for testing ecological hypotheses. A combination of ani- mal tracking and satellite imagery has the potential to greatly inform such efforts, by allowing seabird-environment interactions to be observed remotely. We review how this can be achieved by applying innovative statistical techniques to quantify habitat use and preferences. Seabird move- ments are now observable at scales of meters using GPS loggers, and up to several years using light- based geolocation, while satellite remote sensing systems, at resolutions of km, are capable of char- acterizing the millions of km 2 of habitat that are accessible to seabirds. Physical forcing and biological processes result in a hierarchical, patchy distribution of prey. Hence, analyses of seabird movements should be conducted at appropriate scales. Variation in habitat accessibility should also be consid- ered: this declines with distance from the colony during the breeding season, when seabirds are cen- tral place foragers, and may be limited in the nonbreeding period by migration corridors that are defined by wind patterns. Intraspecific competition can further modify spatial usage, leading to spa- tial segregation of birds foraging from different colonies. We recommend that spatial usage be mod- eled as a function of habitat preference, accessibility and, potentially, competition. At the population level, this is currently best achieved using an empirical approach (e.g. using mixed-effects general- ized additive models). At the individual level, more mechanistic models (e.g. state-space models) are more appropriate and have the advantage of modeling location errors explicitly. Contribution to the Theme Section 'Spatiotemporal dynamics of seabirds in the marine environment' OPEN

Many pelagic seabirds are thought to regulate reproductive effort by adopting a dual foraging strategy, alternating or mixing short foraging trips over local shelf waters (maximising provi- sioning rates) with longer trips over distant oceanic water (allowing restoration of lost condition). Many species also respond to chick condition, decreasing food supply to over-fed, and sometimes increasing it to under-fed chicks. Analysis of tracking data from 4 albatross species breeding at South Georgia provided evidence that adults responded to prevailing environmental conditions, but did not provide evidence for a dual foraging strategy. Trip durations and maximum foraging ranges tended to follow a positively skewed, unimodal distribution, with the exception of the light-mantled albatross for which no significant modes were apparent. Individual distributions deviated from this, but none were strongly bimodal or showed regular alternation of trip lengths, trip distance or predominant bathy- metric regime. There were significant relationships between meal mass and trip duration, time since the last feed and chick condition on return, reflecting responses to current rather than predicted chick needs. On average, adults returned with smaller meals after 1 to 2 d trips, but otherwise stayed away until a threshold payload was obtained; consequently, provisioning rate (g d -1 ) was much greater after shorter trips. Lack of dual foraging may reflect the diversity of foraging zones available in this highly productive region. By inference, this would mean that adoption of dual foraging elsewhere is a con- sequence of greater heterogeneity in resource availability in waters surrounding those colonies.

Peer-reviewed. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Current Biology. To access the final edited and published work see doi:10.1016/j.cub.2014.04.041, Exploitation of the seas is currently unsustainable, with increasing demand for marine resources placing intense pressure on the Earth’s largest ecosystem [1]. The scale of anthropogenic effects varies from local to entire ocean basins 1, 2 and 3. For example, discards of commercial capture fisheries can have both positive and negative impacts on scavengers at the population and community-level 2, 3, 4, 5 and 6, although this is driven by individual foraging behaviour 3 and 7. Currently, we have little understanding of the scale at which individual animals initiate such behaviours. We use the known interaction between fisheries and a wide-ranging seabird, the Northern gannet Morus bassanus [3], to investigate how fishing vessels affect individual birds’ behaviours in near real-time. We document the footprint of fishing vessels’ (≥15 m length) influence on foraging decisions (≤11 km), and a potential underlying behavioural mechanism, by revealing how birds respond differently to vessels depending on gear type and activity. Such influences have important implications for fisheries, including the proposed discard ban [8]), and wider marine management.

Animal populations are frequently limited by the availability of food or of habitat. In central-place foragers, the cost of accessing these resources is distance-dependent rather than uniform in space. However, in seabirds, a widely studied exemplar of this paradigm, empirical population models have hitherto ignored this cost. In part, this is because non-independence among colonies makes it difficult to define population units. Here, we model the effects of both resource availability and accessibility on populations of a wide-ranging, pelagic seabird, the black-browed albatross Thalassarche melanophris. Adopting a multi-scale approach, we define regional populations objectively as spatial clusters of colonies. We consider two readily quantifiable proxies of resource availability: the extent of neritic waters (the preferred foraging habitat) and net primary production (NPP). We show that the size of regional albatross populations has a strong dependence, after weighting for accessibility, on habitat availability and to a lesser extent, NPP. Our results provide indirect support for the hypothesis that seabird populations are regulated from the bottom-up by food availability during the breeding season, and also suggest that the spatio-temporal predictability of food may be limiting. Moreover, we demonstrate a straightforward, widely applicable method for estimating resource limitation in populations of central-place foragers.

This Is the Place Bats, bees, seals, and many seabirds practice central-place foraging, leaving a central home site, such as a hive or a rookery, to forage in a specific territory. Such species also share the challenge of competing for local resources with individuals from separate colonies. Using satellite tags, Wakefield et al. (p. 68 , published online 6 June; see the Perspective by Weimerskirch ) followed over 180 northern gannets to determine potential drivers of foraging territory division. Boundaries among colonial territories arose as a result of competition with individuals from other territories. Individuals from the same colony appeared to share information about foraging sites, presumably contributing to the establishment and maintenance of specific, long-term colonial territories.

Telemetry methods and remote sensing now make it possible to record the spatial usage of wide-ranging marine animals and the biophysical characteristics of their pelagic habitats. Furthermore, recent statistical advances mean that such data can be used to test ecological hypotheses and estimate species' distributions. Black-browed Albatrosses Thalassarche melanophrys are highly mobile marine predators with a circumpolar breeding and foraging distribution in the Southern Hemisphere. Although they remain relatively abundant, increased fisheries bycatch has led to their listing as endangered by conservation bodies. We satellite-tracked 163 breeding Black-browed Albatrosses and eight closely related Campbell Albatrosses T. impavida from nine colonies. We then quantified habitat usage, and modeled population-level spatial distribution at spatiotemporal scales >50 km and 1 month, as a function of habitat accessibility, habitat preference, and intraspecific competition, using mixed-effects generalized additive models (GAMM). During incubation, birds foraged over a wider area than in the post-brood chick-rearing period, when they are more time constrained. Throughout breeding, the order of habitat preference of Black-browed Albatrosses was for neritic (0-500 m), shelf-break and upper shelf-slope (500 1000 m), and then oceanic (>1000 m) waters. Black-browed Albatrosses also preferred areas with steeper (>3 degrees) bathymetric relief and, in addition, during incubation, warmer sea surface temperatures (peak preference similar to 16 degrees C). Although this suggests specialization in neritic habitats, incubation-stage Black-browed Albatrosses from South Georgia also foraged extensively in oceanic waters, preferring areas with high eddy kinetic energy (>250 cm(2)/s(2)), especially the Brazil-Malvinas Confluence, a region of intense mesoscale turbulence. During chick-rearing, this species had a more southerly distribution, and following the seasonal retreat of sea ice, birds from some populations utilized neritic polar waters. Campbell Albatrosses showed similar bathymetric preferences but also preferred positive sea level anomalies. Black-browed Albatross foraging areas were partially spatially segregated with respect to colony and region, with birds preferring locations distant from neighboring colonies, presumably in order to reduce competition between parapatric conspecifics. At the global scale, the greatest concentrations of breeding Black-browed Albatrosses are in southern South American neritic, shelf-break, and shelf-slope waters. These regions also hold large fisheries and should therefore be a priority for introduction of bycatch mitigation measures.

Despite the recent burgeoning in predator tracking studies, few report on seabird activity patterns, despite the potential to provide important insights into foraging ecology and distribution. In the first year-round study for any small petrel, we examined the activity patterns of the white-chinned petrel Procellaria aequinoctialis based on data from combination geolocator-immersion loggers deployed on adults at South Georgia. The petrels were highly nocturnal, flying for greater proportions of darkness than any large procellarid studied so far, except the light-mantled albatross Phoebetria palpebrata. Flight bout durations were short compared with other species, suggesting a dominant foraging mode of small-scale searching within large prey patches. When migrating, birds reduced the proportion of time on the water and increased flight bout duration. Activity patterns changed seasonally: birds flew least during the nonbreeding period, and most frequently during chick-rearing in order to meet higher energy demands associated with provisioning offspring. The degree of their response to moonlight was also stage dependent (greatest in nonbreeding, and weakest in incubating birds), a trait potentially shared by other nocturnal petrels which will have repercussions for feeding success and prey selection. For the white-chinned petrel, which is commonly caught in longline fisheries, these results can be used to identify periods when birds are most susceptible to bycatch, and therefore when use of mitigation and checking for compliance is critical.

The seas above mid-ocean ridges are biodiversity hotspots in an otherwise largely oligotrophic environment, but the nature and extent of linkage between these offshore regimes and coastal ecosystems remains uncertain. Using a combination of GPS and geolocation tracking data, we show that a male fulmar, breeding on the Scottish coast, foraged over areas of persistent thermal fronts along the Charlie-Gibbs Fracture Zone (CGFZ) of the Mid-Atlantic Ridge during the incubation period. The bird travelled over 6200km in 14.9 days. First-passage time analysis identified seven areas of restricted search, four on the shelf and three in the vicinity of the Mid-Atlantic Ridge. Previous studies of incubation foraging trip durations at this site suggest that a trip of this duration is unusual, and further work is required to assess the extent to which different individuals use these offshore resources. Nevertheless, these data highlight the potential importance of high sea areas beyond the limits of national jurisdiction when considering the management and conservation of seabirds breeding in NW Europe, and raises the potential for even greater linkage between the CGFZ and seabirds breeding colonies in other regions.