Global forage-fish landings are increasing, with potentially grave consequences for marine ecosystems. Predators of forage fish may be influenced by this harvest, but the nature of these effects is contentious. Experimental fishery manipulations offer the best solution to quantify population-level impacts, but are rare. We used Bayesian inference to examine changes in chick survival, body condition and population growth rate of endangered African penguins Spheniscus demersus in response to 8 years of alternating time-area closures around two pairs of colonies. Our results demonstrate that fishing closures improved chick survival and condition, after controlling for changing prey availability. However, this effect was inconsistent across sites and years, highlighting the difficultly of assessing management interventions in marine ecosystems. Nevertheless, modelled increases in population growth rates exceeded 1% at one colony; i.e. the threshold considered biologically meaningful by fisheries management in South Africa. Fishing closures evidently can improve the population trend of a forage-fish-dependent predator-we therefore recommend they continue in South Africa and support their application elsewhere. However, detecting demographic gains for mobile marine predators from small no-take zones requires experimental time frames and scales that will often exceed those desired by decision makers.

In recent years numerous studies have documented the effects of a changing climate on the world's biodiversity. Although extreme weather events are predicted to increase in frequency and intensity and are challenging to organisms, there are few quantitative observations on the survival, behaviour and energy expenditure of animals during such events. We provide the first data on activity and energy expenditure of birds, Eurasian cranes Grus grus, during the winter of 2013-14, which saw the most severe floods in SW England in over 200 years. We fitted 23 cranes with telemetry devices and used remote sensing data to model flood dynamics during three consecutive winters (2012-2015). Our results show that during the acute phase of the 2013-14 floods, potential feeding areas decreased dramatically and cranes restricted their activity to a small partially unflooded area. They also increased energy expenditure (+15%) as they increased their foraging activity and reduced resting time. Survival did not decline in 2013-14, indicating that even though extreme climatic events strongly affected time-energy budgets, behavioural plasticity alleviated any potential impact on fitness. However under climate change scenarios such challenges may not be sustainable over longer periods and potentially could increase species vulnerability.

Current fishing extraction methods often generate huge quantities of dead or dying biomass that is returned to the sea in the form of discards. This practice produces a readily available clumped resource for many scavengers such as seabirds, but in the face of declining stocks and via policy change, the amount of discards produced is set to decline in the future. To understand how discards have influenced seabird foraging in the past and how birds may respond to future change requires studies examining consistent individual foraging choices. There is increasing evidence that populations may be made up of generalist or specialist foragers and this is key to the population's ability to adapt to change. Here we test for consistent individual foraging behaviour of northern gannets Morus bassanus in relation to fishing vessels and examine consequences of scavenging behaviour in terms of foraging effort and body condition. Using a combination of bird-borne bio-logging devices (GPS and Time Depth Recorders) with high resolution GPS data acquired through vessel monitoring systems on fishing boats, we examined the overlap between birds and fisheries. We found that during repeat foraging trips in the same breeding season, gannets regularly foraged at fishing boats but there were also clear among individual differences in the extent of fisheries overlap. Furthermore, we show for the first time that these differences represent consistent strategies – individual differences in scavenging were highly repeatable across multiple trips within a period of several weeks. However, despite this finding, we found no differences in foraging effort or body condition between scavengers and non-scavengers. Moreover, scavenging strategy did not appear to influence diving behaviour or vary by sex. Scavenging on discards appears to be a strategy employed consistently by a subsection of the population and future work should examine whether these specialisations persist throughout and between years and what causes these individual differences, exploring possible demographic and fitness consequences in light of global changes to fish stocks and fisheries management.

Many established models of animal foraging assume that individuals are ecologically equivalent. However, it is increasingly recognized that some populations comprise animals whose diet and foraging behaviour differ consistently among individuals. 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 (WSLS) foraging strategy. Alternatively, it could be a consequence of other forms of individual specialisation. Pelagic seabirds are colonial central-place foragers that have classically been assumed to use flexible foraging strategies to target widely dispersed, spatiotemporally patchy prey. IFSF has been observed over days-weeks in many seabirds but it is not known whether fidelity persists over longer time scales. To test for inter-annual IFSF and examine alternative hypotheses concerning its cause, we repeatedly tracked 55 northern gannets from a large colony in the North Sea over three successive breeding seasons. Birds foraged in neritic waters, predictably structured by tidal mixing and thermal stratification but subject to stochastic wind-induced overturning. Both within and across breeding seasons, coarse to mesoscale (10s km) IFSF was significant but not absolute and foraging birds departed the colony in individually consistent directions. After accounting for sex and baseline environmental variation, nitrogen stable isotope values in gannet blood tissues were significantly repeatable, suggesting that individual dietary specialisations persist across years. At this scale individuals were also consistent in their habitat use with respect to relative sea surface temperature and some dive metrics. However, none of these factors accounted for IFSF. Moreover, within breeding seasons IFSF did not decay over time and the magnitude of IFSF across years was similar to that within years, suggesting that IFSF is not the result of WSLS foraging. Rather, we hypothesise that site familiarity, accrued early in life, causes IFSF by canalising subsequent foraging decisions. Evidence from this and other studies suggests that long-term 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.

© the authors and the University of Liverpool 2019. To successfully exploit resources, animals must be adapted to operate under phenotypic and environmental constraints. The strategies that predators use to locate prey are therefore diverse, particularly for breeding central-place foragers that must balance investment in reproduction and self-maintenance. Magnificent frigatebirds Fregata magnificens are tropical seabirds with intriguing morphology and feeding ecology, which display strikingly unequal levels of parental care (males deserting offspring months before females). These unusual traits can better help us understand the links between movement behaviour and breeding strategies in this poorly studied species. Using archival GPS, GPS-GSM loggers, bird-borne cameras and dietary data, we investigated the foraging ecology of chick-rearing magnificent frigatebirds from a breeding population in the Cayman Islands. This population engages in 2 main foraging strategies: (1) coastal trips over the continental shelf, where individuals target reef species and engage in kleptoparasitism, and (2) offshore trips during which birds feed on schooling pelagic prey. Differences in strategy use were partially linked to sex, with males (which invest less in offspring) roaming further from nests, and showing a higher propensity to forage offshore. Video data further indicated differences in social information use between strategies: foraging with conspecifics was more prevalent in coastal environments than pelagic. We suggest that observed variation in at-sea behaviour may partially be mediated by sex-based differences in parental roles, and/or size differences leading to intraspecific competition. Our study provides evidence of bimodal foraging and sheds new light on the importance of both pelagic and coastal feeding in this enigmatic species.

Interspecific competition can drive niche partitioning along multidimensional axes, including allochrony. Competitor matching will arise where the phenology of sympatric species with similar ecological requirements responds to climate change at different rates such that allochrony is reduced. Our study quantifies the degree of niche segregation in foraging areas and depths that arises from allochrony in sympatric Adélie and chinstrap penguins and explores its resilience to climate change. Three-dimensional tracking data were sampled during all stages of the breeding season and were used to parameterise a behaviour-based model that quantified spatial overlap of foraging areas under different scenarios of allochrony. The foraging ranges of the two species were similar within breeding stages, but differences in their foraging ranges between stages, combined with the observed allochrony of 28 days, resulted in them leapfrogging each other through the breeding season such that they were exploiting different foraging locations on the same calendar dates. Allochrony reduced spatial overlap in the peripheral utilisation distribution of the two species by 54.0% over the entire breeding season, compared to a scenario where the two species bred synchronously. Analysis of long-term phenology data revealed that both species advanced their laying dates in relation to October air temperatures at the same rate, preserving allochrony and niche partitioning. However, if allochrony is reduced by just a single day, the spatial overlap of the core utilisation distribution increased by an average of 2.1% over the entire breeding season. Niche partitioning between the two species by allochrony appears to be resilient to climate change and so competitor matching cannot be implicated in the observed population declines of the two penguin species across the Western Antarctic Peninsula.

© 2018 the Authors Quantitative radar studies are an important component of studying the movements of birds. Whether a bird, at a certain distance from the radar, is detected or not depends on its size. The volume monitored by the radar is therefore different for birds of different sizes. Consequently, an accurate quantification of bird movements recorded by small-scale radar requires an accurate determination of the monitored volume for the objects in question, although this has tended to be ignored. Here, we demonstrate the importance of sensitivity settings for echo detection on the estimated movement intensities of birds of different sizes. The amount of energy reflected from a bird and detected by the radar receiver (echo power) depends not only on the bird's size and on the distance from the radar antenna, but also on the beam shape and the bird's position within this beam. We propose a method to estimate the size of a bird based on the wingbeat frequency, retrieved from the echo-signal, independent of the absolute echo power. The estimated bird-size allows calculation of size-specific monitored volumes, allowing accurate quantification of movement intensities. We further investigate the importance of applying size-specific monitored volumes to quantify avian movements instead of using echo counts. We also highlight the importance of accounting for size-specific monitored volume of small scale radar systems, and the necessity of reporting technical information on radar parameters. Applying this framework will increase the quality and validity of quantitative radar monitoring.

© 2018 the Zoological Society of London Understanding population dynamics requires knowledge of the differential effects of survival, productivity and dispersal on population growth. This is particularly important for the conservation of small and recently established populations, where stochastic births and deaths may result in negative growth and even extinction. Here, we investigated the population dynamics of a small population of Eurasian cranes Grus grus in the UK and the effect of a population reinforcement in population growth. We also estimated the probability that the conservation status of cranes improves in the future. We developed stochastic population models to assess the population dynamics and the effect of adding 90 individuals between 2010 and 2014. The best-supported models suggest that the crane population is self-sustaining with an annual adult survival of 0.88, but suffers from low productivity. In addition, much of the population increase has been driven by immigration of birds from continental Europe. We found that population reinforcement resulted in a 50% increase in the projected population size, from 178 to 275 breeding pairs over the next 50 years. We showed that the relative contribution of immigration to population growth declined from 43%, when the translocated birds were not considered, to 29%, when they were included in the breeding pool. Moreover, after the population reinforcement, the probability of the population improving its conservation status increased from just above zero to 32%. In light of the recent increase in translocation programs worldwide, our study highlights the need to consider population dynamics to successfully predict the increase in population size when management strategies, such as reintroductions and reinforcements, are planned.

© 2019 the Authors Understanding and predicting a species’ distribution across a landscape is of central importance in ecology, biogeography and conservation biology. However, it presents daunting challenges when populations are highly dynamic (i.e. increasing or decreasing their ranges), particularly for small populations where information about ecology and life history traits is lacking. Currently, many modelling approaches fail to distinguish whether a site is unoccupied because the available habitat is unsuitable or because a species expanding its range has not arrived at the site yet. As a result, habitat that is indeed suitable may appear unsuitable. To overcome some of these limitations, we use a statistical modelling approach based on spatio-temporal log-Gaussian Cox processes. These model the spatial distribution of the species across available habitat and how this distribution changes over time, relative to covariates. In addition, the model explicitly accounts for spatio-temporal dynamics that are unaccounted for by covariates through a spatio-temporal stochastic process. We illustrate the approach by predicting the distribution of a recently established population of Eurasian cranes Grus grus in England, UK, and estimate the effect of a reintroduction in the range expansion of the population. Our models show that wetland extent and perimeter-to-area ratio have a positive and negative effect, respectively, in crane colonisation probability. Moreover, we find that cranes are more likely to colonise areas near already occupied wetlands and that the colonisation process is progressing at a low rate. Finally, the reintroduction of cranes in SW England can be considered a human-assisted long-distance dispersal event that has increased the dispersal potential of the species along a longitudinal axis in S England. Spatio-temporal log-Gaussian Cox process models offer an excellent opportunity for the study of species where information on life history traits is lacking, since these are represented through the spatio-temporal dynamics reflected in the model.

© 2017 Migratory animals show great diversity of movement within populations, but the causes and consequences of this variability are poorly understood. Tracking a migratory seabird across its range reveals how environmental, latitudinal and demographic conditions shape migratory journeys and fitness. Migratory animals show great diversity of movement within populations, but the causes and consequences of this variability are poorly understood. Tracking a migratory seabird across its range reveals how environmental, latitudinal and demographic conditions shape migratory journeys and fitness.

© 2018 Mid-latitude (∼30-60°) seasonally stratifying shelf-seas support a high abundance and diversity of marine predators such as marine mammals and seabirds. However, anthropogenic activities and climate change impacts are driving changes in the distributions and population dynamics of these animals, with negative consequences for ecosystem functioning. Across mid-latitude shelf-seas marine mammals and seabirds are known to forage across a number of oceanographic habitats that structure the spatio-temporal distributions of prey fields. Knowledge of these and the bio-physical mechanisms driving such associations are needed to improve marine management and policy. Here, we provide a concise and easily accessible guide for both researchers and managers of marine systems on the predominant oceanographic habitats that are favoured for foraging by marine mammals and seabirds across mid-latitude shelf-seas. We (1) identify and describe key discrete physical features present across the continental shelf, working inshore from the shelf-edge to the shore line, (2) provide an overview of findings relating to associations between these habitats and marine mammals and seabirds, (3) identify areas for future research and (4) discuss the relevance of such information to conservation management. We show that oceanographic features preferentially foraged at by marine mammals and seabirds include shelf-edge fronts, upwelling and tidal-mixing fronts, offshore banks and internal waves, regions of stratification, and topographically complex coastal areas subject to strong tidal flow. Whilst associations were variable across taxa and through space and time, in the majority of cases interactions between bathymetry and tidal currents appear to play a dominant role, alongside patterns in seasonal stratification and shelf-edge upwelling. We suggest that the ecological significance of these bio-physical structures stems from a capacity to alter the densities, distributions (both horizontally and vertically) and/or behaviours of prey in a persistent and/or predictable manner that increases accessibility for predators, and likely enhances foraging efficiency. Future conservation management should aim to preserve and protect these habitats. This will require adaptive and holistic strategies that are specifically tailored to the characteristics of an oceanographic feature, and where necessary, evolve through space and time in response to spatio-temporal variability. Improved monitoring of animal movements and bio-physical conditions across shelf-seas would aid in this. Areas for future research include multi-disciplinary/trophic studies of the mechanisms linking bio-physical processes, prey and marine mammals and seabirds (which may elucidate the importance of lesser studied features such as bottom fronts and Langmuir circulation cells), alongside a better understanding of how predators perceive their environment and develop foraging strategies during immature/juvenile stages. Estimates of the importance of oceanographic habitat features at a population level should also be obtained. Such information is vital to ensuring the future health of these complex ecosystems, and can be used to assess how anthropogenic activities and future environmental changes will impact the functioning and spatio-temporal dynamics of these bio-physical features and their use by marine predators.

© 2017 the Authors. Ecology and Evolution published by John Wiley. &. Sons Ltd. 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.

© Inter-Research 2018 Inter-individual variation in behavioural traits has important implications for evolutionary and ecological processes. Site fidelity, where individuals consistently use the same foraging site, is common among marine predators. Sex differences in foraging are also well studied in marine vertebrates, but the extent to which consistent inter-individual differences in foraging vary between the sexes is poorly known. Here we quantified the effects of sex on individual foraging site fidelity (IFSF), both within and between years, in chick-brooding Campbell albatross Thalassarche impavida. Using bird-borne global positioning system loggers, we calculated route fidelity (nearest-neighbour distance), repeatability of site fidelity (terminal latitude and longitude), and foraging effort (total distance travelled and trip duration) during 2 to 10 repeat trips. Overall, Campbell albatrosses showed a high degree of site fidelity. Birds travelled to similar sites not only within the same year, but also between 2 consecutive years, suggesting that the within-year consistency is not simply in response to short-term patches of food. Moreover, within the same year, we found differences in terms of IFSF between the sexes. Females that foraged closer to the colony in neritic and shelf waters were more likely to follow similar routes on repeated foraging trips and were more consistent in their foraging effort than males. Males that foraged further offshore in pelagic waters had more repeatable foraging longitudes than females. Our study provides further evidence of the importance of IFSF among marine vertebrates. However, it also reveals that the strength of such specialisations may vary with sex.

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.

© 2016 Fisheries bycatch is a major threat to seabird populations, and understanding sex- and age-biases in bycatch rates is important for assessing population-level impacts. We analysed 44 studies to provide the first global assessment of seabird bycatch by sex and age, and used generalised models to investigate the effects of region and fishing method. Bycatch was highly biased by sex (65% of 123 samples) and age (92% of 114 samples), with the majority of samples skewed towards males and adults. Bycatch of adults and males was higher in subpolar regions, whereas there was a tendency for more immatures and females to be killed in subtropical waters. Fishing method influenced sex- and age-ratios only in subpolar regions. Sex- and age-biases are therefore common features of seabird bycatch in global fisheries that appear to be associated largely with differences in at-sea distributions. This unbalanced mortality influences the extent to which populations are impacted by fisheries, which is a key consideration for at-risk species. We recommend that researchers track individuals of different sex and age classes to improve knowledge of their distribution, relative overlap with vessels, and hence susceptibility to bycatch. This information should then be incorporated in ecological risk assessments of effects of fisheries on vulnerable species. Additionally, data on sex, age and provenance of bycaught birds should be collected by fisheries observers in order to identify regions and fleets where bycatch is more likely to result in population-level impacts, and to improve targeting of bycatch mitigation and monitoring of compliance.

© 2016 Elsevier Ltd Monitoring public perception of conservation is essential to ensure successful conservation outcomes. However, evaluating attitudes towards conservation projects presents daunting challenges because it is time consuming, expensive and open to social biases and small sample-size errors. Here, we present a recently developed approach to overcome these limitations – Internet-based methods - in particular offsite and onsite metrics. Offsite methods refer to Internet data mining tools that extract Internet search queries, such as Google Trends, while onsite methods refer to programmes that monitor traffic within websites, such as Google Analytics. We explore the potential of these methods rather than focus on the particular details of the case-studies provided to illustrate them. We used offsite methods to determine patterns in public interest in a reintroduced flagship species and in conservation awareness projects in the UK. We employed onsite metrics to assess the success in communicating a conservation outcome and to evaluate the success in online public engagement of a conservation NGO. Our results indicate that both offsite and onsite metrics are able to track changes in public interest across time and space. In particular, onsite metrics provide high levels of temporal and spatial resolution with a high degree of flexibility. These tools could add reliable information to traditional social surveys and represent an opportunity to improve our understanding of the drivers of interest in conservation.

In this Quick Guide, Votier and Sherley explain how diverse seabirds play important roles in ecosystem functioning, global nutrient cycling and climate regulation, but are declining in the face of multiple threats.

© 2016 Elsevier Ltd. Shelf-seas are highly dynamic and oceanographically complex environments, which likely influences the spatio-temporal distributions of marine megafauna such as marine mammals. As such, understanding natural patterns in habitat use by these animals is essential when attempting to ascertain and assess the impacts of anthropogenically induced disturbances, such as those associated with marine renewable energy installations (MREIs). This study uses a five year (2009–2013) passive acoustics (C-POD) dataset to examine the use of an oceanographically dynamic marine renewable energy test site by small cetaceans, dolphins (unspecified delphinids) and harbour porpoises Phocoena phocoena, in the southern Celtic Sea. To examine how temporal patterns in habitat use across the site related to oceanographic changes occurring over broad seasonal scales as well as those driven by fine scale (bi-weekly) localised processes (that may be masked by seasonal trends), separate analyses were conducted using (1) all daily animal detection rates spanning the entire five year dataset and (2) daily animal detection rates taken only during the summer months (defined as mid-June to mid-October) of 2010 (when continuous monitoring was carried out at multiple discrete locations across the site). In both instances, generalised additive mixed effects models (GAMMs) were used to link detection rates to a suite of environmental variables representative of the oceanography of the region. We show that increased harbour porpoise detection rates in the late winter/early spring (January–March) are associated with low sea surface temperatures (SST), whilst peaks in dolphin detection rates in the summer (July–September) coincide with increased SSTs and the presence of a tidal-mixing front. Moreover, across the summer months of 2010, dolphin detection rates were found to respond to small scale changes in SST and position in the spring-neap cycle, possibly reflective of a preference for the stratified waters immediately offshore of the front. Together, these findings suggest that habitat use by small cetaceans within shelf-seas is temporally variable, species specific and likely driven by complex bottom-up processes. As such, the effective conservation management of shelf-seas requires that we understand the dynamic complexities of these systems and the species that inhabit them. In particular, we emphasise the need for a good understanding of the natural drivers of habitat use by marine megafauna before the potential impacts of anthropogenically induced disturbances, such as those associated with the construction, maintenance and operation of MREIs, can be assessed.

© 2017, Dt. Ornithologen-Gesellschaft e.V. Fisheries-related mortality has been influential in driving global declines in seabird populations. Understanding the overlap between seabird distribution and fisheries is one important element in assessing bycatch risk, and may be achieved by tracking the movements of individual birds and fishing vessels. Here, we assess the spatiotemporal overlap between the vulnerable Campbell Albatross Thalassarche impavida and large (>28 m) commercial fishing boats in New Zealand’s Exclusive Economic Zone (EEZ). We used a novel analytical approach, bivariate Gaussian bridge movement modelling, to compute spatiotemporal utilization distributions of bird-borne global positioning system (GPS) loggers and data from the Vessel Monitoring System. We tracked birds for 28,815 h during incubation and chick brooding, with half of this time spent within New Zealand’s EEZ, utilizing 6.7% of the available area. However, there was no evidence that albatrosses and fishing vessels were in the same location simultaneously. We accounted for the broader ecological footprint of fishing vessels by calculating the distance between GPS-fix locations for albatrosses and fishing vessels, revealing that albatrosses were within 30 km of fishing vessels in 8.4% of foraging trips. This highlights differences in estimated fine-scale spatiotemporal overlaps which may be due to the distance between albatrosses and vessels or the methods used. Overall, the low levels of spatial overlap could be a result of Campbell Albatross’ preference for foraging in areas without fishing activity or competitive exclusion by other species. Our results reinforce the importance of multi-scale, temporally explicit, and multi-national approaches to risk assessment, as Campbell Albatrosses spend approximately half of their time foraging outside New Zealand’s EEZ.

© 2016 the Authors. Diversity and Distributions Published by John Wiley. &. Sons Ltd. Aim: the movement patterns of marine top predators are likely to reflect responses to prey distributions, which themselves can be influenced by factors such as climate and fisheries. The critically endangered Balearic shearwater Puffinus mauretanicus has shown a recent northwards shift in non-breeding distribution, tentatively linked to changing forage fish distribution and/or fisheries activity. Here, we provide the first information on the foraging ecology of this species during the non-breeding period. Location: Breeding grounds in Mallorca, Spain, and non-breeding areas in the north-east Atlantic and western Mediterranean. Methods: Birdborne geolocation was used to identify non-breeding grounds. Information on feather moult (from digital images) and stable isotopes (of both primary wing feathers and potential prey items) was combined to infer foraging behaviour during the non-breeding season. Results: Almost all breeding shearwaters (n = 32) migrated to non-breeding areas in the Atlantic from southern Iberia to the French Atlantic coast, where the majority of primary feather moult took place. Birds foraging off western Iberia yielded feather isotope ratios consistent with a diet composed largely of pelagic fishes, while the isotopic composition of birds foraging in the Bay of Biscay suggested an additional contribution of benthic prey, most likely from demersal fishery discards. Main conclusions: Combined application of geolocators and stable isotopes indicates spatial variation in dietary behaviour and interactions with fisheries. Our results imply that both pelagic fish and fisheries discards are important components of diet during the non-breeding period, which may have implications for the at-sea distribution of this migratory species. These findings will contribute to bycatch mitigation in non-breeding areas and provide baseline data that should inform future assessment of seabird responses to changing fishery practices and prey distributions.

© the Ecological Society of America Human activities have fundamentally altered the marine environment, creating a need for effective management in one of Earth's most challenging habitats. Remote camera imagery has emerged as an essential tool for monitoring at all scales, from individuals to populations and communities up to entire marine ecosystems. Here we review the use of remote cameras to monitor the marine environment in relation to human activity, and consider emerging and potential future applications. Rapid technological advances in equipment and analytical tools influence where, why, and how remote camera imagery can be applied. We encourage the inclusion of cameras within multi-method and multi-sensor approaches to improve our understanding of ecosystems and help manage human activities and minimize impacts.

© 2016 British Ornithologists' Union. Telemetry has become an important method for studying the biology and ecology of animals. However, the impact of tracking devices and their method of attachment on different species across multiple temporal scales has seldom been assessed. We compared the behavioural and demographic responses of two species of seabird, Lesser Black-backed Gull Larus fuscus and Great Skua Stercorarius skua, to a GPS device attached using a crossover wing harness. We used telemetry information and monitoring of breeding colonies to compare birds equipped with a device and harness, and control birds without an attachment. We assessed whether tagged birds have lower short-term breeding productivity or lower longer term overwinter return rates (indicative of overwinter survival) than controls. For Great Skua, we also assessed whether territory attendance within the breeding season differed between tagged and control birds. As with previous studies on Lesser Black-backed Gull, we found no short-term impacts on breeding productivity or long-term impacts on overwinter return rates. For Great Skua, there was no evidence for impacts of the device and harness on territory attendance or breeding productivity. However, as found by a previous study of Great Skuas using a different (body) harness design, there was strong evidence of reduced overwinter return rates. Consequently, a device attached using a wing harness was considered suitable for long-term deployment on Lesser Black-backed Gulls, but not on Great Skuas. These findings will inform the planning of future tracking studies.

© 2016 British Trust for Ornithology Capsule Three quarters of tracked Northern Gannets (Morus bassanus) at Grassholm gathered in rafts around the colony, concentrated within a recently designated at-sea Special Protection Area (SPA), but rafting was not correlated with foraging effort. Aims to investigate the incidence, distribution and foraging implications of Northern Gannet rafting behaviour in waters adjacent to a large colony. Methods Using bird-borne global positioning system (GPS) loggers we reconstructed at-sea movement and used a speed filter to identify rafting behaviour within 10â€
km of the colony. We mapped the spatial distribution of rafting events from 160 breeding individuals over 5 years, and investigated the relationship between foraging effort (trip duration and total distance travelled) and the presence/absence of rafting. Results on average, 74% of tracked birds engaged in rafting. of the 381 foraging trips analysed, rafting was recorded on 237 (62%). Birds were more likely to raft on outbound (224 trips, 59%), than inbound journeys (38 trips, 10%). Presence/absence of rafting did not correlate significantly with foraging trip distance or duration nor with duration of nest attendance. The majority of rafting was concentrated in a 2-km radius around the colony within a recently designated seaward SPA extension. Birds showed low individual repeatability in rafting, although there was lower variation within, than among, individuals. Conclusion Our results show that rafting is important for breeding gannets on Grassholm, and a recently designated at-sea SPA encapsulates the core distribution of rafting. Rafting did not appear to be correlated with foraging behaviour. Given the dearth of literature on rafting and the wealth of GPS tracking data for seabirds, we suggest that similar research be conducted elsewhere to further elucidate the ecological and applied significance of this behaviour.

Despite the fact that many animals live in groups, there is still no clear consensus about the ecological or evolutionary mechanisms underlying colonial living. Recently, research has suggested that colonies may be important as sources of social information. The ready availability of information from conspecifics allows animals to make better decisions about avoiding predators, reducing brood parasitism, migratory phenology, mate choice, habitat choice and foraging. These choices can play a large part in the development and maintenance of colonies. Here we review the types of information provided by colonial animals and examine the different ways in which decision-making in colonies can be enhanced by social information. We discuss what roles information might take in the evolution, formation and maintenance of colonies. In the process, we illustrate that information use permeates all aspects of colonial living.

Developments in tracking technologies have enhanced our understanding of the behaviours of many seabird species. However few studies have examined the social aspects of seabird foraging behaviour, despite the effect this might have on the distribution of foraging areas and the differences that might arise between colonies. Here we use bird-borne GPS and behavioural observation to study the social foraging behaviour and habitat use of breeding shags from three breeding colonies in the Isles of Scilly, UK. Thirteen breeding shags from three colonies (six at two colonies, and a single bird from another) were tracked in the Isles of Scilly between 2010 and 2012 and related this to observed dataobservations of on conspecific foraging aggregations (2013 - 2014) and bathymetry. Tracked shags had short foraging ranges (1.74 ± 1.6 km) mostly travelling to shallow waters between the islands. and Oobservations in these same waters revealed large that many shags foraged in largeforaging social groupsups of shags between that were consistentpersisted in time and space. There were also no clear differences in foraging distributions among the colonies – birds shared similar foraging grounds. Our finding provides important insight into the use of social information among foraging seabirds and how this may lead to shared foraging areas, as well as space partitioning.

© 2016, Dt. Ornithologen-Gesellschaft e.V. Niche segregation plays a critical role in the speciation process, but determining the extent to which taxa are geographically or ecologically isolated is challenging. In this study, we use stable isotopes of carbon (δ13C), nitrogen (δ15N), hydrogen (δ2H) and oxygen (δ18O) to test for ecological differences among taxa in the Lesser Whitethroat Sylvia curruca complex. Analysis of mitochondrial DNA (mtDNA) revealed 6 distinct haplotype groups, which conform to at least 5 distinct taxa. Stable isotopes provided insight into geographical and broad-scale ecological differences among haplotypes. The most striking isotope differences were between the populations inhabiting Siberian boreal forest (S. c. blythi) from the one inhabiting semi-desert in Kazakhstan (S. c. halimodendri). It is generally assumed that these two populations form a morphological cline along a gradient from mesic to xeric habitat. Our sample includes a large proportion of morphologically intermediate individuals that appear to represent a hybrid population. However, in all of these, there is strict correspondence between haplotype and isotope signature, suggesting an ecological division on the breeding grounds between all our samples of these two taxa. The lack of ecologically intermediate individuals among our sample of morphologically intermediate ones thus speaks against the existence of a cline. The two taxa blythi and halimodendri emerge as potential models for the study of the early stages of the speciation process. While differences in stable isotopes may be largely influenced by geography, we also demonstrate how, in specific instances (such as the alleged cline reported here), they may be used to evaluate niche segregation between taxa, providing information of importance for determination of species limits.

Marine no-take zones can have positive impacts for target species and are increasingly important management tools. However, whether they indirectly benefit higher order predators remains unclear. The endangered African penguin (Spheniscus demersus) depends on commercially exploited forage fish. We examined how chick survival responded to an experimental 3-year fishery closure around Robben Island, South Africa, controlling for variation in prey biomass and fishery catches. Chick survival increased by 18% when the closure was initiated, which alone led to a predicted 27% higher population compared with continued fishing. However, the modelled population continued to decline, probably because of high adult mortality linked to poor prey availability over larger spatial scales. Our results illustrate that small no-take zones can have bottom-up benefits for highly mobile marine predators, but are only one component of holistic, ecosystem-based management regimes.

© 2015 the Authors. Unprecedented changes to the marine environment and growth of bio-logging science make detailed study of the movement ecology of threatened marine species timely. Here, we study spatial and temporal patterns of marine space use by a critically endangered seabird: the Balearic shearwater Puffinus mauretanicus. Using a suite of bio-logging systems, 67 foraging trips were recorded during incubation periods between 2011 and 2014 from one of the species' largest colonies (Sa Cella, Mallorca). Most birds followed narrow flight corridors to restricted neritic foraging grounds on the Iberian continental shelf. Productive foraging areas along the Catalan coast (NE Spain) were consistent across multiple years and between sexes, indicating extensive use of predictable resources. While our study emphasises the vulnerability of this species to anthropogenic activity in nearshore waters, consistent commuting corridors and foraging grounds represent tractable habitat for protection and offer hope for developing area-based management approaches. Preferred foraging areas showed strong overlap with recently declared Special Protection Areas, strengthening the evidence base for targeted management at these sites.

© Inter-Research 2015. Sexual segregation, common in many species, is usually attributed to intra-specific competition or habitat choice. However, few studies have simultaneously quantified sex-specific foraging behaviour 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 farther offshore and had lower δ13C 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, these results indicate that sexual segregation in gannets is driven largely by habitat segregation between mixed and stratified waters, which in turn results in sex-specific foraging behaviour and dive depths.

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. 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

In striking contrast to the general increase in diving ability with body mass in seabirds, amongst the Procellariiformes, the deepest dives appear to be by the smallest species. Here, we use recently developed, miniaturized time depth recorders to provide the first accurate measurement of dive depth and duration in two small Procellariiformes: Common (Pelecanoides urinatrix) and South Georgian diving petrel (P. georgicus), and compare their diving performance in relation to body mass with that of 58 seabirds from four orders. The 20 common and six South Georgia diving petrels in our study dived to considerable depths and for long periods (respective mean ± SD of 10.5 ± 4.6 and 18.1 ± 3.6 m, and 36.4 ± 9.1 and 44.2 ± 5.9 s). In relation to body mass, these dives are closely comparable to those of small alcids, which are considered to be diving specialists, and much greater than in closely related petrels. Previous work has shown that diving petrels and small alcids share a number of convergent morphological traits; our data reveal these are manifested in terms of diving ability. © 2014 Springer-Verlag Berlin Heidelberg.

Devices attached to flying birds can hugely enhance our understanding of their behavioural ecology for periods when they cannot be observed directly. For this, scientists routinely attach units to either birds' backs or their tails. However, inappropriate payload distribution is critical in aircraft and, since birds and planes are subject to the same laws of physics during flight, we considered aircraft aerodynamic constraints to explain flight patterns displayed by northern gannets Sula bassana equipped with (small ca. 14 g) tail- and back-mounted accelerometers and (larger ca. 30 g) tail-mounted GPS units. Tail-mounted GPS-fitted birds showed significantly higher cumulative numbers of flap-glide cycles and a higher pitch angle of the tail than accelerometer-equipped birds, indicating problems with balancing inappropriately placed weights with knock-on consequences relating to energy expenditure. These problems can be addressed by carefully choosing where to place tags on birds according to the mass of the tags and the lifestyle of the subject species.

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. © 2013 the Authors.

Aim: Demographic linkage between subpopulations plays a critical role in population processes. Metapopulation dynamics, however, remains one of the most poorly understood aspects of population biology. This is especially true for small, pelagic seabirds because their discrete subpopulations are located on offshore islands, separated by vast areas of open ocean, making monitoring logistically challenging. Seabird populations often contain large numbers of immature pre-breeders that may be important for subpopulation connectivity and demography, but are poorly studied. Here we provide evidence for intercolony movement of pre-breeding Leach's storm-petrels Oceanodroma leucorhoa among three colonies spanning the North Atlantic Ocean. We discuss their influence on metapopulation dynamics and the extinction risk of a subpopulation under threat from extreme predation. Location: North Atlantic Ocean Islands (Scotland, Canada & Iceland). Methods: We use a novel application of Bayesian stable isotope mixing models to infer recent movement of pre-breeding birds between three major breeding populations in the North Atlantic. Carbon and nitrogen stable isotope values from breeding birds (central place foragers) sampled at each colony were used as model sources and pre-breeding birds as model mixtures. Results: of 134 pre-breeding Leach's storm-petrels sampled at three colonies across the North Atlantic, five had isotope mixing model estimates dissimilar (< 25%) to their colony of capture and were instead isotopically similar to another breeding region. Nineteen further pre-breeders had highly mixed signatures (< 50% for the colony of capture), indicating possible recent movement between colonies. Main conclusions: Our findings provide evidence for interpopulation connectivity of pre-breeding Leach's storm-petrels among colonies spanning the North Atlantic. These results highlight the significance of cryptic young age-classes in metapopulation dynamics and the demographic processes. Moreover, they provide us with a better understanding of how one subpopulation remains extant, despite experiencing extreme predation rates. © 2013 John Wiley & Sons Ltd.

Vessel Monitoring System (VMS) data from 2005 to 2008 in ICES Divisions VIIe-h were used to assess the distribution and intensity of fishing activity in and around the western English Channel, one of the most intensively used marine areas on the planet. The distribution of the UK fleet of large (>15. m length) fishing vessels was analysed and clear gear-specific temporal and spatial differences in activity were found. Mobile demersal gears had the highest intensity and widest distribution of activity in the study area, and so might be expected to have the most widespread ecosystem-level impacts. The potential effects of two proposed fisheries closures; a planned wave energy testing facility (Wave Hub) and a candidate offshore Marine Protected Area (Haig Fras) are described. Maps indicate that mobile demersal gear fleets would be little affected if they were excluded from these proposed closures, but if the static gear fleets were excluded this would likely result in displacement of certain vessels, increasing fishing pressure on other rocky grounds and other fishers. Predictions concerning the effects of fisheries displacement can be improved through the use of high-resolution gear-specific activity data. This study shows that VMS can provide an invaluable source of such data, provided that gear information is made available to fisheries managers and scientists. © 2013 Elsevier Ltd.

The oceanographic drivers of marine vertebrate habitat use are poorly understood yet fundamental to our knowledge of marine ecosystem functioning. Here, we use composite front mapping and high-resolution GPS tracking to determine the significance of mesoscale oceanographic fronts as physical drivers of foraging habitat selection in northern gannets Morus bassanus. We tracked 66 breeding gannets from a Celtic Sea colony over 2 years and used residence time to identify area-restricted search (ARS) behaviour. Composite front maps identified thermal and chlorophyll-a mesoscale fronts at two different temporal scales-(i) contemporaneous fronts and (ii) seasonally persistent frontal zones. Using generalized additive models (GAMs), with generalized estimating equations (GEE-GAMs) to account for serial autocorrelation in tracking data, we found that gannets do not adjust their behaviour in response to contemporaneous fronts. However, ARS was more likely to occur within spatially predictable, seasonally persistent frontal zones (GAMs). Our results provide proof of concept that composite front mapping is a useful tool for studying the influence of oceanographic features on animal movements. Moreover, we highlight that frontal persistence is a crucial element of the formation of pelagic foraging hotspots for mobile marine vertebrates.

© 2014 British Ecological Society. Summary: Identifying priority areas for marine vertebrate conservation is complex because species of conservation concern are highly mobile, inhabit dynamic habitats and are difficult to monitor. Many marine vertebrates are known to associate with oceanographic fronts - physical interfaces at the transition between water masses - for foraging and migration, making them important candidate sites for conservation. Here, we review associations between marine vertebrates and fronts and how they vary with scale, regional oceanography and foraging ecology. Accessibility, spatiotemporal predictability and relative productivity of front-associated foraging habitats are key aspects of their ecological importance. Predictable mesoscale (10s-100s km) regions of persistent frontal activity ('frontal zones') are particularly significant. Frontal zones are hotspots of overlap between critical habitat and spatially explicit anthropogenic threats, such as the concentration of fisheries activity. As such, they represent tractable conservation units, in which to target measures for threat mitigation. Front mapping via Earth observation (EO) remote sensing facilitates identification and monitoring of these hotspots of vulnerability. Seasonal or climatological products can locate biophysical hotspots, while near-real-time front mapping augments the suite of tools supporting spatially dynamic ocean management. Synthesis and applications. Frontal zones are ecologically important for mobile marine vertebrates. We surmise that relative accessibility, predictability and productivity are key biophysical characteristics of ecologically significant frontal zones in contrasting oceanographic regions. Persistent frontal zones are potential priority conservation areas for multiple marine vertebrate taxa and are easily identifiable through front mapping via EO remote sensing. These insights are useful for marine spatial planning and marine biodiversity conservation, both within Exclusive Economic Zones and in the open oceans. Frontal zones are ecologically important for mobile marine vertebrates. We surmise that relative accessibility, predictability and productivity are key biophysical characteristics of ecologically significant frontal zones in contrasting oceanographic regions. Persistent frontal zones are potential priority conservation areas for multiple marine vertebrate taxa and are easily identifiable through front mapping via EO remote sensing. These insights are useful for marine spatial planning and marine biodiversity conservation, both within Exclusive Economic Zones and in the open oceans.

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 [1-3]. For example, discards of commercial capture fisheries can have both positive and negative impacts on scavengers at the population and community-level [2-6], although this is driven by individual foraging behaviour [3,7]. 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.

Intraspecific interactions have important roles in shaping foraging behaviours. For colonial species such as seabirds, intense competition for prey around colonies may drive differences in foraging behaviour between age-classes and sexes or lead to individual specialisation. While much research has focussed on understanding these differences in foraging behaviour, few studies have investigated the possibility of sub-colony foraging asymmetries within colonies. Such knowledge could improve our understanding of the ecological processes associated with colonial living. It may also have important methodological implications in studies where the foraging behaviours recorded from individuals in a small number of sub-colonies are assumed to be representative of those from the colony as a whole. Here, we use GPS loggers and stable isotope analysis of red blood cells to test for differences in foraging behaviour among 7 sub-colonies of a large northern gannet Morus bassanus colony over 3 yr. We found no instances of statistically significant differences in foraging behaviour among sub-colonies. Although complimentary in situ observations found similarities among neighbours' departure directions, these results may be attributable to wind vectors. We therefore conclude that sub-colony foraging asymmetries are either limited or absent in northern gannets. However, given the current lack of knowledge across seabird species, we urge similar studies elsewhere. © Inter-Research 2014.

The temperate waters of the North-Eastern Atlantic have a long history of maritime resource richness and, as a result, the European Union is endeavouring to maintain regional productivity and biodiversity. At the intersection of these aims lies potential conflict, signalling the need for integrated, cross-border management approaches. This paper focuses on the marine megafauna of the region. This guild of consumers was formerly abundant, but is now depleted and protected under various national and international legislative structures. We present a meta-analysis of available megafauna datasets using presence-only distribution models to characterise suitable habitat and identify spatially-important regions within the English Channel and southern bight of the North Sea. The integration of studies from dedicated and opportunistic observer programmes in the United Kingdom and France provide a valuable perspective on the spatial and seasonal distribution of various taxonomic groups, including large pelagic fishes and sharks, marine mammals, seabirds and marine turtles. The Western English Channel emerged as a hotspot of biodiversity for megafauna, while species richness was low in the Eastern English Channel. Spatial conservation planning is complicated by the highly mobile nature of marine megafauna, however they are important components of the marine environment and understanding their distribution is a first crucial step toward their inclusion into marine ecosystem management.

Commercial capture fisheries produce huge quantities of offal, as well as undersized and unwanted catch in the form of discards. Declines in global catches and legislation to ban discarding will significantly reduce discards, but this subsidy supports a large scavenger community. Understanding the potential impact of declining discards for scavengers should feature in an eco-system based approach to fisheries management, but requires greater knowledge of scavenger/fishery interactions. Here we use bird-borne cameras, in tandem with GPS loggers, to provide a unique view of seabird/fishery interactions. 20,643 digital images (one min(-1)) from ten bird-borne cameras deployed on central place northern gannets Morus bassanus revealed that all birds photographed fishing vessels. These were large (>15 m) boats, with no small-scale vessels. Virtually all vessels were trawlers, and gannets were almost always accompanied by other scavenging birds. All individuals exhibited an Area-Restricted Search (ARS) during foraging, but only 42% of ARS were associated with fishing vessels, indicating much 'natural' foraging. The proportion of ARS behaviours associated with fishing boats were higher for males (81%) than females (30%), although the reasons for this are currently unclear. Our study illustrates that fisheries form a very important component of the prey-landscape for foraging gannets and that a discard ban, such as that proposed under reforms of the EU Common Fisheries Policy, may have a significant impact on gannet behaviour, particularly males. However, a continued reliance on 'natural' foraging suggests the ability to switch away from scavenging, but only if there is sufficient food to meet their needs in the absence of a discard subsidy.

The principle of competitive exclusion postulates that ecologically-similar species are expected to partition their use of resources, leading to niche divergence. The most likely mechanisms allowing such coexistence are considered to be segregation in a horizontal, vertical or temporal dimension, or, where these overlap, a difference in trophic niche. Here, by combining information obtained from tracking devices (geolocator-immersion and time depth recorders), stable isotope analyses of blood, and conventional morphometry, we provide a detailed investigation of the ecological mechanisms that explain the coexistence of four species of abundant, zooplanktivorous seabirds in Southern Ocean ecosystems (blue petrel Halobaena caerulea, Antarctic prion Pachyptila desolata, common diving petrel Pelecanoides urinatrix and South Georgian diving petrel P. georgicus). The results revealed a combination of horizontal, vertical and temporal foraging segregation during the breeding season. The stable isotope and morphological analyses reinforced this conclusion, indicating that each species occupied a distinct trophic space, and that this appears to reflect adaptations in terms of flight performance. In conclusion, the present study indicated that although there was a degree of overlap in some measures of foraging behaviour, overall the four taxa operated in very different ecological space despite breeding in close proximity. We therefore provide important insight into the mechanisms allowing these very large populations of ecologically-similar predators to coexist.

C25 highly branched isoprenoids (HBIs) are produced by a relatively small number of diatom species, yet are common constituents of almost all marine environments. Previously, detection of HBIs in a few aquatic Arctic animals has indicated the potential use of these lipids for providing novel ecological information. In the current study, analysis of lipid extracts of livers from Leach's storm petrel (Oceanodroma leucorhoa) and Brunnich's guillemot (Uria lomvia) facilitated identification and quantification of HBI isomers. HBIs were found in the tissues of all specimens with clear differences in the abundances and distributions of individual HBI isomers both between Atlantic as well as Arctic birds. These differences are consistent with contrasting oceanographic regimes and suggests that regional differences in HBIs are reflected in the tissues of consumers. Tissue-specific assessment of HBI distributions has also revealed the presence of these lipids in muscle for the first time. This study represents the first report of HBI lipids in birds and provides evidence that these lipids are transferred across trophic levels and extends their potential use as chemical tracers beyond the ecology of aquatic organisms. © 2013 Springer-Verlag Berlin Heidelberg.

Upcoming reform of the European Union (EU) Common Fisheries Policy will be the biggest change in European fisheries management for a generation. A central plank of this reform is a proposed ban on discards, to aid the creation of economically and environmentally sustainable fisheries. This, together with a global trend for declining discards, may have unforeseen knock-on consequences for the large number of scavenging seabirds that consume this plentiful subsidy. Discards have shaped many aspects of seabird foraging, distribution and population dynamics. Here, we review these effects and consider the potential for both negative and positive impacts of discard reforms for seabirds, with particular focus on the EU, and propose recommendations for ongoing research and conservation. EU seabird scavengers are dominated by a relatively small number of large generalist taxa. Many of these occur at globally significant numbers within the EU, but may be able to buffer a decline in discards by switching to feed on alternative foods. A discard ban may have negative consequences by creating a food shortage for scavenging birds. Some species may offset this by feeding more on other birds, with potentially negative population-level impacts, or by moving into novel environments. Benefits of a discard ban may be a reduction in seabird bycatch in fishing gears, as well as a reduction in populations of large generalist species that currently dominate some seabird communities. Synthesis and applications. Reform of the Common Fisheries Policy and global discard declines are essential components towards creating sustainable fisheries, but may have both detrimental and beneficial effects on seabird communities. The nature of these impacts is still poorly understood, highlighting the need for detailed long-term seabird monitoring, as well as building resilience into populations through policy measures that incorporate remedial action on major seabird conservation priorities. Research should focus on understanding how seabird foraging, in terms of functional responses and searching behaviour, is influenced by both changing discards and natural fish prey availability, and how they impact upon fitness. It is also essential to link individual-level responses with population-, community- and ecosystem-level change. Understanding these links is fundamental to ongoing seabird management and conservation, and an ecosystem-based approach to fisheries management. © 2013 the Authors. Journal of Applied Ecology © 2013 British Ecological Society.

Climate change has profoundly altered the structure and biodiversity of marine ecosystems worldwide, and for many upper-trophic-level predators changes in lower-trophiclevel prey has been the main driver of this alteration. To better understand the nature of marine ecosystem response to global change requires detailed knowledge of predator-prey dynamics, but this is hampered by our poor understanding of spatial variation in the strength of trophic linkages. The aim of this study was to test for bottom-up effects across 4 trophic levels (phytoplankton, zooplankton, fish larvae and seabirds) over 17 yr, as well as testing for regional differences in 3 distinct marine ecosystems of the Northeast Atlantic: the Irish Sea, the Celtic Sea and the English Channel, where sea surface temperature has increased substantially in recent decades. Our results showed little evidence of bottom-up regulation from phytoplankton, zooplankton, fish larvae and seabirds, which is in contrast with the nearby North Sea, probably due to different oceanographic conditions. Despite this, we found a significant positive relationship between kittiwake productivity and the abundance of fish larvae at one colony in the Irish Sea. We speculate that during the period 1991 to 2007 these ecosystems were weakly regulated by climate change, and seabird populations in these regions might be more heavily influenced by other extrinsic factors. The spatial effects of climate change appear to vary across ecosystems, even within a relatively small geographic area. In this context, we urge complex multi-trophic-level studies to elucidate the effect of climate impacts on marine ecosystems. © Inter-Research 2013.

Colonial breeding is widespread among animals. Some, such as eusocial insects, may use agonistic behavior to partition available foraging habitat into mutually exclusive territories; others, such as breeding seabirds, do not. We found that northern gannets, satellite-tracked from 12 neighboring colonies, nonetheless forage in largely mutually exclusive areas and that these colony-specific home ranges are determined by density-dependent competition. This segregation may be enhanced by individual-level public information transfer, leading to cultural evolution and divergence among colonies.

Seabirds are well monitored and protected at their breeding grounds but spend most of their life at sea, where they are less well monitored and afforded little protection. In an attempt to address this dichotomy, attention has been directed toward establishing a network of marine reserves for seabirds, based largely on information from at-sea surveys and/or biotelemetry studies. Nevertheless, these approaches are costly, are typically only available for a limited number of locations, and not suitable for species that have either poor at-sea detectability or are unable to carry tracking devices. Here we develop a technique to identify important areas for breeding seabirds based on at-sea projections from colonies. Synthesising data from colony surveys with detailed information on population dynamics, foraging ecology and near-colony behaviour, we project colony-specific foraging distributions of the Northern gannet (. Morus bassanus) at colonies in the UK, Ireland and France. We test the ability of our models to identify at-sea hotspots through comparison with existing data from biotelemetry studies and at-sea visual surveys. These models show a positive spatial correlation with one of the most intensive at-sea seabird survey datasets. While there are limitations to estimating at-sea distributions of seabirds, implemented appropriately, we propose they could prove useful in identifying potential Marine Protected Areas for seabirds. Moreover, these models could be developed to suit a range of species or whole communities and provide a theoretical framework for the study of factors such as colony size regulation. © 2012 Elsevier Ltd.

Marine renewable energy installations harnessing energy from wind, wave and tidal resources are likely to become a large part of the future energy mix worldwide. The potential to gather energy from waves has recently seen increasing interest, with pilot developments in several nations. Although technology to harness wave energy lags behind that of wind and tidal generation, it has the potential to contribute significantly to energy production. As wave energy technology matures and becomes more widespread, it is likely to result in further transformation of our coastal seas. Such changes are accompanied by uncertainty regarding their impacts on biodiversity. To date, impacts have not been assessed, as wave energy converters have yet to be fully developed. Therefore, there is a pressing need to build a framework of understanding regarding the potential impacts of these technologies, underpinned by methodologies that are transferable and scalable across sites to facilitate formal meta-analysis. We first review the potential positive and negative effects of wave energy generation, and then, with specific reference to our work at the Wave Hub (a wave energy test site in southwest England, UK), we set out the methodological approaches needed to assess possible effects of wave energy on biodiversity. We highlight the need for national and international research clusters to accelerate the implementation of wave energy, within a coherent understanding of potential effects-both positive and negative.

Climate change has had profound effects upon marine ecosystems, impacting across all trophic levels from plankton to apex predators. Determining the impacts of climate change on marine ecosystems requires understanding the direct effects on all trophic levels as well as indirect effects mediated by trophic coupling. The aim of this study was to investigate the effects of climate change on the pelagic food web in the Celtic Sea, a productive shelf region in the Northeast Atlantic. Using long-term data, we examined possible direct and indirect 'bottom-up' climate effects across four trophic levels: phytoplankton, zooplankton, mid-trophic level fish and seabirds. During the period 1986-2007, although there was no temporal trend in the North Atlantic Oscillation index (NAO), the decadal mean Sea Surface Temperature (SST) in the Celtic Sea increased by 0.66 ± 0.02 °C. Despite this, there was only a weak signal of climate change in the Celtic Sea food web. Changes in plankton community structure were found, however this was not related to SST or NAO. A negative relationship occurred between herring abundance (0- and 1-group) and spring SST (0-group: p = 0.02, slope = -0.305 ± 0.125; 1-group: p = 0.04, slope = -0.410 ± 0.193). Seabird demographics showed complex species-specific responses. There was evidence of direct effects of spring NAO (on black-legged kittiwake population growth rate: p = 0.03, slope = 0.0314 ± 0.014) as well as indirect bottom-up effects of lagged spring SST (on razorbill breeding success: p = 0.01, slope = -0.144 ± 0.05). Negative relationships between breeding success and population growth rate of razorbills and common guillemots may be explained by interactions between mid-trophic level fish. Our findings show that the impacts of climate change on the Celtic Sea ecosystem is not as marked as in nearby regions (e.g. the North Sea), emphasizing the need for more research at regional scales.

Although oriented migrations have been identified in many terrestrial bird species, the post-breeding-season movements of seabirds are generally regarded as dispersive. We used geolocator tags to reveal post-breeding movements and winter distribution of northern gannets (Morus bassanus) at a meta-population scale. By focusing on five breeding colonies of European gannets, we show that their breeding and wintering grounds are connected by a major flyway running along the coasts of Western Europe and Africa. Moreover, maximum winter distance to colony was similar across colonies despite their wide latitudinal range. In contrast with the general opinion that large pelagic birds such as gannets have unlimited ranges beyond the breeding season, our findings strongly suggest oriented chain migration in northern gannets (a pattern in which populations move uniformly southward) and highlight the benefit of meta-population approaches for studying seabird movements. We argue that the inclusion of such processes in ocean management plans is essential to improve efforts in marine biodiversity conservation. © the Ecological Society of America.

Dramatic local population decline brought about by anthropogenic-driven change is an increasingly common threat to biodiversity. Seabird life history traits make them particularly vulnerable to such change; therefore, understanding population connectivity and dispersal dynamics is vital for successful management. Our study used a 357-base pair mitochondrial control region locus sequenced for 103 individuals and 18 nuclear microsatellite loci genotyped for 245 individuals to investigate population structure in the Atlantic and Pacific populations of the pelagic seabird, Leach's storm-petrel Oceanodroma leucorhoa leucorhoa. This species is under intense predation pressure at one regionally important colony on St Kilda, Scotland, where a disparity between population decline and predation rates hints at immigration from other large colonies. AMOVA, F(ST), Φ(ST) and Bayesian cluster analyses revealed no genetic structure among Atlantic colonies (Global Φ(ST) = -0.02 P > 0.05, Global F(ST) = 0.003, P > 0.05, STRUCTURE K = 1), consistent with either contemporary gene flow or strong historical association within the ocean basin. The Pacific and Atlantic populations are genetically distinct (Global Φ(ST) = 0.32 P < 0.0001, Global F(ST) = 0.04, P < 0.0001, STRUCTURE K = 2), but evidence for interocean exchange was found with individual exclusion/assignment and population coalescent analyses. These findings highlight the importance of conserving multiple colonies at a number of different sites and suggest that management of this seabird may be best viewed at an oceanic scale. Moreover, our study provides an illustration of how long-distance movement may ameliorate the potentially deleterious impacts of localized environmental change, although direct measures of dispersal are still required to better understand this process.

Sexual segregation in foraging and migratory behaviour is widespread among sexually dimorphic marine vertebrates. It has also been described for a number of monomorphic species, yet the underlying mechanisms are poorly understood. We examined variation among years, seasons and age-classes in sex-specific foraging and over-wintering behaviour in the northern gannet (Morus bassanus), a species with slight sexual dimorphism. Our results revealed consistent sexual differences in the stable isotope ratios of breeding birds: over three different breeding periods, adult females consistently consumed prey with significantly lower δ13C and δ15N values than adult males. Additionally, GPS tracking data showed that breeding females foraged further offshore than breeding males (a result consistent with the δ13C data), and the home ranges of the two sexes were distinct. Analyses of stable isotope ratios using a Bayesian mixing model (SIAR) revealed that breeding males consumed a higher proportion of fishery discards than females. Analysis of stable isotope ratios in red blood cells of immature gannets (aged 2-4) indicated that sexual segregation was not present in this age class. Although sample sizes were small and statistical power correspondingly low, analysis of geolocator data and of stable isotope ratios in winter-grown flight feathers revealed no clear evidence of sexual segregation during the non-breeding period. Together these results provide a detailed insight into sex-specific behaviour in gannets throughout the annual cycle and although the mechanisms remain unclear they are unlikely to be explained by slight differences in size.

Forty-one microsatellite loci were found to be polymorphic in the Leach's storm-petrel Oceanodroma leucorhoa when characterised in 24 unrelated individuals sampled from a population located at Gull Island, Newfoundland, Canada. Sequence homology was used to assign a predicted chromosome location for 39 of the polymorphic loci. Four polymorphic microsatellite loci were Z-linked based on the typing of known sex individuals and/or sequence homology. The set of 37 autosomal markers will be suitable for population and parentage studies of the Leach's storm-petrel (combined first parent non-exclusion probability

Preserved and archived organic material offers huge potential for the conduct of retrospective and long-term historical ecosystem reconstructions using stable isotope analyses, but because of isotopic exchange with preservatives the obtained values require validation. The Continuous Plankton Recorder (CPR) Survey is the most extensive long-term monitoring program for plankton communities worldwide and has utilised ships of opportunity to collect samples since 1931. To keep the samples intact for subsequent analysis, they are collected and preserved in formalin; however, previous studies have found that this may alter stable carbon and nitrogen isotope ratios in zooplankton. A maximum ~0.9‰ increase of δ(15) N and a time dependent maximum ~1.0‰ decrease of δ(13) C were observed when the copepod, Calanus helgolandicus, was experimentally exposed to two formalin preservatives for 12 months. Applying specific correction factors to δ(15) N and δ(13) C values for similarly preserved Calanoid species collected by the CPR Survey within 12 months of analysis may be appropriate to enable their use in stable isotope studies. The isotope values of samples stored frozen did not differ significantly from those of controls. Although the impact of formalin preservation was relatively small in this and other studies of marine zooplankton, changes in isotope signatures are not consistent across taxa, especially for δ(15) N, indicating that species-specific studies may be required.

Seabird populations contain large numbers of immatures-in some instances comprising >50% of the fully grown adults in the population. These birds are significant components of marine food webs and may contribute to compensatory recruitment and dispersal, but remain severely understudied. Here, we use GPS-PTTs, radio-tracking and analysis of stable carbon (δ13C) and nitrogen (δ15N) isotopes to investigate the movements and foraging ecology of immature seabirds. Our study focussed on immature northern gannets Morus bassanus aged 2-4 attending non-breeding aggregations alongside a large breeding colony. GPS-PTT tracking of five birds revealed that immatures have the ability to disperse widely during the breeding season, with some individuals potentially prospecting at other colonies. Overall, however, immatures were faithful to the colony of capture. During returns to the focal colony, immatures acted as central place foragers, conducted looping and commuting flights, and analysis of the variance in first-passage time revealed evidence of area-restricted search (ARS) behaviour. In addition, stable carbon (δ13C) and nitrogen (δ15N) isotope analyses indicate that immatures were isotopically segregated from breeders. Our findings provide insights into the foraging, prospecting and dispersal behaviour of immature seabirds, which may have important implications for understanding seabird ecology and conservation. © 2010 Springer-Verlag.

Entanglement with plastic debris is a major cause of mortality in marine taxa, but the population-level consequences are unknown. Some seabirds collect marine debris for nesting material, which may lead to entanglement. Here we investigate the use of plastics as nesting material by northern gannets Morus bassanus and assess the associated levels of mortality. On average gannet nests contained 469.91 g (range 0-1293 g) of plastic, equating to an estimated colony total of 18.46 tones (range 4.47-42.34 tones). The majority of nesting material was synthetic rope, which appears to be used preferentially. On average 62.85 ± 26.84 (range minima 33-109) birds were entangled each year, totalling 525 individuals over eight years, the majority of which were nestlings. Although mortality rates are high, they are unlikely to have population-level effects. The use of synthetic fibres as nesting material is a common strategy among seabirds, but the impacts of entanglement warrants further investigation.

One potential approach to combat the impacts of climate change is the expansion of renewable energy installations, leading to an increase in the number of wave-powered marine renewable energy installations (MREIs). The consequences of increased use of these devices for birds are unknown. Here we describe the wave-powered energy- generating devices currently either operational or in development and review the potential threats and benefits of these to marine birds, their habitats and prey. Direct neg- ative effects include risk of collision, disturbance, displacement and redirection during construction, operation and decommissioning. Above-water collision is a particular con- cern with wind-powered devices, but, because of their low profiles, the collision risk asso- ciated with wave-powered devices is likely to be much lower. Conversely, wave devices also pose the novel threat of underwater collision. Wave-energy-generating devices may indirectly impact marine birds by altering oceanographic processes and food availability, with implications for trophic cascades. Through appropriate mitigation, wave-powered MREIs offer the potential to enhance habitats. Direct positive effects may include provision of roosting sites, and indirect positive effects may include prey aggregation due to suitable substrates for sessile organisms or because they act as de facto protected areas. The cumulative effect of these could be the improvement and protection of foraging opportunities for marine birds. Recent studies have been critical of the methods used in the assessment of wind-powered MREI impacts, which lack sufficient sample sizes, controls or pre-development comparisons. Here we suggest solutions for the design of future studies into the effects of MREIs. Wave-powered MREIs are certain to become part of the marine environment, but with appropriate planning, mitigation and monitor- ing they have the potential to offer benefits to marine birds in the future.

1. The geographical range sizes of individual species vary considerably in extent, although the factors underlying this variation remain poorly understood, and could include a number of ecological and evolutionary processes. A favoured explanation for range size variation is that this result from differences in fundamental niche breadths, suggesting a key role for physiology in determining range size, although to date empirical tests of these ideas remain limited. 2. Here we explore relationships between thermal physiology and biogeography, whilst controlling for possible differences in dispersal ability and phylogenetic relatedness, across 14 ecologically similar congeners which differ in geographical range extent; European diving beetles of the genus Deronectes Sharp (Coleoptera, Dytiscidae). Absolute upper and lower temperature tolerance and acclimatory abilities are determined for populations of each species, following acclimation in the laboratory. 3. Absolute thermal tolerance range is the best predictor of both species' latitudinal range extent and position, differences in dispersal ability (based on wing size) apparently being less important in this group. In addition, species' northern and southern range limits are related to their tolerance of low and high temperatures respectively. In all cases, absolute temperature tolerances, rather than acclimatory abilities are the best predictors of range parameters, whilst the use of independent contrasts suggested that species' thermal acclimation abilities may also relate to biogeography, although increased acclimatory ability does not appear to be associated with increased range size. 4. Our study is the first to provide empirical support for a relationship between thermal physiology and range size variation in widespread and restricted species, conducted using the same experimental design, within a phylogenetically and ecologically controlled framework.

An emerging consequence of global climate change is its potential effect on the timing of seasonal biological events. Analysis of long-term datasets reveals a high degree of plasticity in the nature of phenological responses both within and among species, and understanding these differences is central to understanding the mechanisms and implications of climate-related change. We investigated factors influencing timing of breeding (median laying date) in a colonial nesting seabird, the common guillemot Uria aalge, over 23 breeding seasons between 1973 and 2008. There was a trend for earlier laying over this period, and earlier laying was associated with higher average breeding success. Multiple regression models (with de-trended explanatory variables to control for linear trends over time) indicate that the timing of breeding is positively correlated with a wide-scale climatic driver, the winter North Atlantic Oscillation (WNAO), and negatively correlated with population size: guillemots lay later in years with high WNAO indices and earlier in years with larger populations. Responses to environmental conditions are probably related to indirect effects on timing or abundance of food availability, direct effects of weather or both. The mechanism(s) leading to a possible relationship between laying date and population size are less clear. They may be related to Allee-type effects associated with social stimulation, improved foraging efficiency or a densitydependent increase in breeding site quality. Given the correlative nature of these results, we are cautious about the role of non-climatic (intrinsic) factors, but we cannot exclude that they play a role alongside climatic (extrinsic) factors in influencing reproductive phenology. © 2009 Inter-Research.

Capsule Leach's Storm-petrels Oceanodroma leucorhoa may be depredated by endemic St Kilda Field Mice Apodemus sylvaticus hirtensis. © 2009 British Trust for Ornithology.

Arctic regions are expected to experience pronounced changes in climate during the current century. Large numbers of waterfowl breed in these regions, and any climate induced changes are likely to have consequences for their demographics. Moreover, environmental changes experienced during migration and on the wintering grounds may also have impacts but remain poorly understood. We investigate the role of climate variation during breeding, migration and wintering, while controlling for possible effects of mammalian predation and density dependence on the reproduction of Svalbard breeding barnacle geese Branta leucopsis using 40 years of observations. Breeding success was significantly positively correlated with temperature on both the wintering grounds (Scotland) and breeding grounds (Svalbard), but negatively correlated with the number of days of strong cross-winds during the northward migration period. These factors remained significant when controlling for a strong negative effect of population size. Goose reproduction on Svalbard was also linked to fluctuations in arctic fox Alopex lagopus populations occurring elsewhere in the arctic. This reveals the importance of mammalian predation, which may vary as a non-linear function of conditions within the wider arctic region. Climate predictions were used to project barnacle goose reproduction and hence the population until 2050. These simulations suggest the population will grow at between 1% and 2.7% per year, in response to increasing temperatures. However, it is harder to predict how changes in other factors, such as reductions in sea ice, may impact on arctic breeding birds. © 2009 Oikos.

Stable-hydrogen isotope signatures of feathers from a first-winter Baikal Teal Anas formosa collected in Essex in January 1906 reveal marked differences between juvenile feathers, grown on the breeding grounds, and post-juvenile feathers, grown on the wintering grounds.The natal-area signatures were consistent with a Siberian origin and the wintering-area signatures were consistent with a west European origin.This suggests that the Essex bird originated within the normal breeding range of Baikal Teal and that its occurrence in Britain was the result of natural vagrancy. © British Birds 102 · December 2009.

1. In long-lived animals with delayed maturity, the non-breeding component of the population may play an important role in buffering the effects of stochastic mortality. Populations of colonial seabirds often consist of more than 50% non-breeders, yet because they spend much of their early life at sea, we understand little about their impact on the demographic process. 2. Using multistate capture-mark-recapture techniques, we analyse a long-term data set of individually identifiable common guillemots, Uria aalge Pont. to assess factors influencing their immature survival and two-stage recruitment process. 3. Analysis of the distribution of ringed common guillemots during the non-breeding season, separated by age classes, revealed that all age classes were potentially at risk from four major oil spills. However, the youngest age class (0-3 years) were far more widely spread than birds 4-6 years old, which were more widely spread than birds aged 6 and over. Therefore the chance of encountering an oil spill was age-dependent. 4. A 2-year compound survival estimate for juvenile guillemots was weakly negatively correlated with winter sea-surface temperature, but was not influenced by oil spills. Non-breeder survival did not vary significantly over time. 5. In years following four oil spills, juvenile recruitment was almost double the value in non-oil-spill years. Recent work from Skomer Island showed a doubling of adult mortality associated with major oil spills, which probably reduced competition at the breeding colony, allowing increased immature recruitment to compensate for these losses. We discuss the implications of compensatory recruitment for assessing the impact of oil pollution incidents.

Large skuas and gulls are top predators in marine ecosystems, feeding on shoaling fish, fishery discards and facultatively on smaller seabirds. As generalist predators they may have deleterious impacts on prey populations of seabirds, particularly when alternative foods are scarce. Declines in discards and lipid-rich shoaling fish may result in these large scavenging birds turning to prey on seabirds to meet their nutritional needs, yet we know relatively little about seabird predator-prey dynamics. Declines in Black-legged Kittiwakes Rissa tridactyla in the UK are attributed to reductions in Sandeel Ammodytes marinus availability, but may also be due to predation by Great Skuas Stercorarius skua in some parts of their range. We investigate whether variation in two demographic parameters (breeding success and population growth rate) of Kittiwake colonies across Shetland are explained by skua population density at increasing spatial scales (rings with radii of 0-5, 5-10, 10-15, 15-20, 20-25 and 25-30 km) and Kittiwake population density. These explanatory variables do not explain a significant amount of the variation in annual population growth rate (lambda), but our estimate of population change is highly conservative and we cannot exclude the possibility of type II errors. Kittiwake breeding success is positively correlated with Sandeel availability and negatively correlated with the number of Kittiwakes at the focal colony. Having controlled for these effects the number of Great Skuas also has an influence on breeding success, being negatively correlated at the scale of 5-10 and 20-25 km, but positively correlated at the scale of 10-15 km. In addition, analysis of Kittiwake populations subdivided into exposed or protected cliffs reveals that exposed sub-colonies declined more steeply than protected ones - presumably as a function of differences in susceptibility to Skua predation. We propose that comparing differences in demographic rates may be useful in unravelling seabird predator-prey dynamics, but only where there is a comprehensive demographic dataset, where it is possible to correct for confounding factors such as food availability, and information on habitat-predation interactions. © 2008 the Authors.

Fatty acid signatures (FAS) were determined in plasma and adipose tissue of great skuas Stercorarius skua from Shetland in order to test the applicability of this biomarker in estimating diets of wild scavenging seabirds. The plasma FAS were compared with those of captive herring gulls Larus argentatus, which were fed typical Northeast Atlantic demersal and pelagic fish. The individual fatty acids that showed the largest proportional changes in FAS due to changes of dietary fish in herring gulls also varied the most in wild great skuas, suggesting a dietary origin of these changes in FAS. Thus, great skuas that had recently been feeding largely on a demersal or terrestrial diet were distinguished from individuals feeding mainly on a pelagic diet. Pronounced variation in the plasma FAS of great skuas suggests either very flexible feeding behaviour or individual dietary specialisation, which concurs with previous studies based on pellets. Individuals that regurgitated pellets consisting only of demersal fish, bird or rabbit showed larger values of a specific polyunsaturated fatty acid ratio (20:4n-6/18:3n-3+18:4n-3+20:5n-3) than birds whose pellets also contained remains of pelagic fish. Although pellet data showed a clear dominance of demersal fish in the summer diet of the great skua, the large proportions of long-chain monounsaturated fatty acids (e.g. 20:1n-9 and 22:1n-11) in adipose tissue of the great skua suggest that a considerable part of fat accumulated outside the breeding season comes from fatty pelagic fish. © Inter-Research 2006.

There have been numerous recent observations of changes in the behavior and dynamics of migratory bird populations, but the plasticity of the migratory trait and our inability to track small animals over large distances have hindered investigation of the mechanisms behind migratory change. We used habitat-specific stable isotope signatures to show that recently evolved allopatric wintering populations of European blackcaps Sylvia atricapilla pair assortatively on their sympatric breeding grounds. Birds wintering further north also produce larger clutches and fledge more young. These findings describe an important process in the evolution of migratory divides, new migration routes, and wintering quarters. Temporal segregation of breeding is a way in which subpopulations of vertebrates may become isolated in sympatry.

There have been numerous recent observations of changes in the behavior and dynamics of migratory bird populations, but the plasticity of the migratory trait and our inability to track small animals over large distances have hindered investigation of the mechanisms behind migratory change. We used habitat-specific stable isotope signatures to show that recently evolved allopatric wintering populations of European blackcaps Sylvia atricapilla pair assortatively on their sympatric breeding grounds. Birds wintering further north also produce larger clutches and fledge more young. These findings describe an important process in the evolution of migratory divides, new migration routes, and wintering quarters. Temporal segregation of breeding is a way in which subpopulations of vertebrates may become isolated in sympatry.

Oil spills often spell disaster for marine birds caught in slicks. However, the impact of oil pollution on seabird population parameters is poorly known because oil spills usually occur in wintering areas remote from breeding colonies where birds may be distributed over a wide area, and because it is difficult to separate the effects of oil pollution from the effect of natural environmental variation on seabird populations. Using a long-term data set we show that over-winter survival of adult common guillemots (Uria aalge) is negatively affected by both the incidence of four major oil-spills in their wintering grounds and high values of the North Atlantic Oscillation (NAO) index. After controlling for the effect of the NAO index, we show that winter mortality of adult guillemots is doubled by major oil pollution incidents. Our results demonstrate that oil pollution can have wide-scale impacts on marine ecosystems that can be quantified using populations of marked individuals to estimate survival.

The numbers of American Wigeons Anas americana recorded in Britain and Ireland have increased significantly since the establishment of BBRC in 1958, and records ceased to be considered by the Committee from 1st January 2002. The status and distribution of the species is analysed here, and its identification discussed. Although male American Wigeon in breeding plumage is very distinctive, the identification of other plumages is much more problematic.

By switching great skuas Catharacta skua from one isotopically distinct diet to another, we measured diet-tissue discrimination factors and tested the assumption that dietary nitrogen and carbon isotope signatures are incorporated into blood and feathers at similar rates. We also examined the effects of metabolic rate and looked for evidence of isotopic routing. We found that blood delta(15)N and delta(13)C signatures altered after the diet switch at similar rates (14.4 d and 15.7 d, respectively). Qualitative analyses imply that the same was true with feathers. Mass balance calculations suggest that only a small amount of lipid is likely to be involved in the synthesis of blood and feathers. Differences in diet-tissue discrimination factors before and after the diet switch may mean that toward the end of the experiment, some of the nutrients for blood synthesis had been coming from stores. Repeated measures mixed models provided evidence that increases in metabolic rate might accelerate fractional turnover rates in blood. There is a need for more laboratory-based experimental isotope studies in order to address further questions that this study has raised.

Winter 1995/96 saw a huge influx of Common Redpolls Carduelis flammea and Arctic Redpolls C. hornemanni into Britain and Western Europe. Two forms of redpoll were involved, the nominate race of Common Redpoll C.f.flammea ('Mealy Redpoll') and the Eurasian race of Arctic Redpoll C. h. exilipes, and there is no evidence of any arrivals from other than northern Eurasian populations. Three main influxes were recorded in the north and east of Britain. The first two, in early and mid November, were immediately preceded by or coincided with substantial movements through Utsira in southwest Norway, Heligoland off the northwest coast of Germany, and Falsterbo in southern Sweden; the last of the three arrivals occurred in early December and was associated with the onset of very cold weather, but not with large movements farther north and east. On the British east coast, numbers were the largest since 1975. The irruption was absorbed in Britain, and no significant movements were recorded through bird observatories on southern and western coasts. Return spring migration was heavy through southern North Sea sites (which experienced little of the autumn arrival), but was much less apparent farther north.

The Chestnut Bunting Emberiza rutila has been recorded only five times in autumn in Western Europe, including once in Britain. It is potentially a more numerous vagrant to Britain and Ireland, but detailed information on non-adult-male plumage is lacking. This paper rectifies this situation and discusses the species' separation from other similar buntings, in particular the far more commonly recorded Yellow-breasted Bunting E. aureola.