Stuart Bearhop

University of Exeter | UoE · Centre for Ecology and Conservation

Human−wildlife conflict is a global conservation issue, necessitating effective mitigation strategies. Hunting is a common management approach to reduce conflict, but the indirect consequences are often overlooked. Chronic hunting‐related disturbance can reduce fitness and redistribute species. In recent decades, goose−agricultural conflict has int...

Density-dependent competition for food influences the foraging behaviour and demography of colonial animals, but how this influence varies across a species’ latitudinal range is poorly understood. Here we used satellite tracking from 21 Northern Gannet Morus bassanus colonies (39% of colonies worldwide, supporting 73% of the global population) duri...

The study of animal diets and the proportional contribution that different foods make to their diets is an important task in ecology. Stable Isotope Mixing Models (SIMMs) are an important tool for studying an animal's diet and understanding how the animal interacts with its environment. We present cosimmr, a new R package designed to include covari...

The use of lead shotgun ammunition for shooting wildfowl has been restricted in England since 1999, but surveys finding lead shot in harvested birds show compliance with regulations has been low. Following the announcement in 2020 of a voluntary transition from lead to non-lead shot by UK shooting organizations, we investigated spatiotemporal varia...

Human‐modified landscapes have created opportunities for numerous taxa. Agricultural expansion has proven advantageous for several Arctic‐breeding goose species, leading to increased abundance and intensified conflict with farmers. Shooting is frequently implemented as a mitigation strategy to control population and via scaring to alter the spatial...

Top carnivores can influence the structure of ecological communities, primarily through competition and predation; however, communities are also influenced by bottom-up forces such as anthropogenic habitat disturbance. Top carnivore declines will likely alter competitive dynamics within and amongst sympatric carnivore species. Increasing intraspeci...

Conditions experienced by an individual during migration have the potential to shape migratory tactic and in turn fitness. For large birds, environmental conditions encountered during migration have been linked with survival and subsequent reproductive output, but this is less known for smaller birds, hindering our understanding of mechanisms drivi...

Gut-associated microbial communities are known to play a vital role in the health and fitness of their hosts. Though studies investigating the factors associated with among-individual variation in microbiome structure in wild animal species are increasing, knowledge of this variation at the individual level is scarce, despite the clear link between...

Wildlife populations may be the subject of management interventions for disease control that can have unintended, counterproductive effects. Social structure exerts a strong influence over infectious disease transmission in addition to other characteristics of populations such as size and density that are the primary target for disease control. Soc...

Aims Understanding the suite of environmental changes impacting migration and disentangling these from the dependencies between migratory stages is fundamental to understanding the drivers and mechanisms causing spatial shifts to migratory bird distributions. In this review, our objectives are to: (i) provide evidence of spatial change at all migra...

Researchers generally ascribe demographic drivers in a single sub-population and presume they are representative. With this information, practitioners implement blanket conservation measures across metapopulations to reverse declines. However, such approaches may not be appropriate in circumstances where sub-populations are spatiotemporally segrega...

Gut-associated microbial communities are known to play a vital role in the health and fitness of their hosts. Though studies investigating the factors associated with among-individual variation in microbiome structure in wild animal species are increasing, knowledge of this variation at the individual level is scarce, despite the clear link between...

We introduce an R package for fitting Stable Isotope Mixing Models (SIMMs) via both Markov chain Monte Carlo and Variational Bayes. The package is mainly used for estimating dietary contributions from food sources taken via measurements of stable isotope ratios from animals. It can also be used to estimate proportional contributions of a mixture fr...

Lead is a toxic heavy metal that when ingested can cause death or sub‐lethal fitness effects. Despite its toxicity, it is still widely used in recreational and management shooting globally. To reduce the impacts of lead on wildfowl, recent European Union legislation has banned the use of lead shot in and around wetlands from 2023. Understanding the...

Effective marine ecosystem monitoring is critical for sustainable management. Monitoring seabird diets can convey important information on ecosystem health and seabird–fishery interactions. The diet of breeding black-browed albatross (Thalassarche melanophris) has previously been assessed using stomach content analysis (SCA) or stable isotope analy...

Recent studies have suggested that protected areas often fail to conserve target species. However, the efficacy of terrestrial protected areas is difficult to measure, especially for highly vagile species like migratory birds that may move between protected and unprotected areas throughout their lives. Here, we use a 30-y dataset of detailed demogr...

Vagrancy, where individuals occur outside of known population distributions, is a poorly understood ecological phenomenon. It can however be a key driver of site colonisation and range expansion. Evidence is emerging that presumed vagrant Siberian passerines in Western Europe, e.g. Richard’s Pipits Anthus ricardii, are colonists, with geolocator-tr...

Arctic‐breeding goose populations have increased in recent decades and their expansion into agricultural areas has caused increasing conflict with farmers due to the damage they cause. Lethal control and scaring are common management strategies of conflict mitigation. Management typically focuses on local/national scales, making addressing the impa...

Unlabelled: RATIONALE By combining precision satellite-tracking with blood sampling it has been possible to use seabirds to validate marine carbon and nitrogen isoscapes, but it is unclear whether a comparable approach using low precision light-level geolocators (GLS) and feather sampling can be similarly effective. Methods: Here we used GLS to...

1. Researchers generally ascribe demographic drivers in a single or few sub-populations and presume they are representative. With this information, practitioners implement blanket conservation measures across metapopulations to reverse declines. However, such approaches may not be appropriate in circumstances where sub-populations are spatiotempora...

Arctic-nesting geese face energetic challenges during spring migration, including ecological barriers and weather conditions (e.g., precipitation and temperature), which in long-lived species can lead to a trade-off to defer reproduction in favor of greater survival. We used GPS location and acceleration data collected from 35 greater white-fronted...

Climate change has been driving long-distance migratory birds to alter their schedules under the threat of being mismatched with their food peak at the breeding grounds. It is important to study the relative contribution of environmental, genetic and ontogenetic components in various spring timing traits in the wild in order to predict the true pot...

Species translocation is a popular approach in contemporary ecological restoration and rewilding. Improving the efficacy of conservation translocation programmes requires a combination of robust data from comparable populations, population viability modelling and post-release monitoring. Biotelemetry is becoming an ever more accessible means to col...

Animal migrations represent the regular movements of trillions of individuals. The scale of these movements has inspired human intrigue for millennia and has been intensively studied by biologists. This research has highlighted the diversity of migratory strategies seen across and within migratory taxa: while some migrants temporarily express pheno...

Deterrents against avian pest species might be more effective if they were based on some aspect of the target species' sensory salience. Sonic Nets broadcast a loud and spatially‐ focused pink noise that spans the frequency range of the target species' vocalizations, restricting interspecific communication so that it is costly for birds to remain i...

Advancements in biologging technology allow terabytes of data to be collected that record the location of individuals but also their direction, speed and acceleration. These multi-stream data sets allow researchers to infer movement and behavioural patterns at high spatiotemporal resolutions and in turn quantify fine-scale changes in state along wi...

Despite urbanisation’s general erosion of biodiversity, towns and cities provide novel opportunities for some species. During the 20th century, gulls (Laridae) colonised urban areas around the world where they flourished. At the same time, some coastal populations declined. Reasons for this difference are not fully understood, partly because little...

Few studies have assessed the influence of data quality on the predicted probability of occurrence and preferred habitat of marine predators. We compared results from four species distribution models (SDMs) for four southern-hemisphere albatross species, Buller’s (Thalassarche bulleri), Campbell (T. impavida), grey-headed (T. chrysostoma), and whit...

Releasing gamebirds in large numbers for sport shooting may directly or indirectly influence the abundance, distribution and population dynamics of native wildlife. The abundances of generalist predators have been positively associated with the abundance of gamebirds. These relationships have implications for prey populations, with the potential fo...

Advancements in biologging technology allow terabytes of data to be collected that record the location of individuals but also their direction, speed and acceleration. These multi-stream data sets allow researchers to determine movement and behavioural patterns at high spatiotemporal resolutions and in turn quantify fine-scale changes in state alon...

Illegal killing of wildlife is a major conservation issue that, to be addressed effectively, requires insight into the drivers of human behaviour. Here we adapt an established socio-psychological model, the theory of planned behaviour, to explore reasons for hunting the Endangered Bewick's swan Cygnus columbianus bewickii in the European Russian Ar...

Long-distance migration in birds is a complex syndrome that involves high energy costs and, in some species, substantial physiological re-organisation. Such flexible migratory phenotypes are commonly associated with bird species flying non-stop across vast ecological barriers, where there are few opportunities to stop and refuel en route. Prior to...

Antarctic marine ecosystems are often considered to be pristine environments, yet wildlife in the polar regions may still be exposed to high levels of environmental contaminants. Here, we measured total mercury (THg) concentrations in blood samples from adult brown skuas Stercorarius antarcticus lonnbergi (n = 82) from three breeding colonies south...

Background Landfills are a major subsidy for some animals, with implications for their life history and demography. Gulls feed extensively on food from landfills and closures are expected to have ecological consequences, but how this influences movement ecology is virtually unknown. Methods We used GPS-tracking to quantify foraging behaviour and h...

It is increasingly important to understand animal migratory movements because climate disruption is shifting plant and animal phenology at different rates across the world. We applied a Markov state‐switching model to telemetry data of a long‐distance migrant, the barnacle goose, to detect migratory movement and relate it to three proximate environ...

Predation of wildlife by domestic cats Felis catus presents a threat to biodiversity conservation in some ecological contexts. The proportions of wild prey captured and eaten by domestic cats and thus the contributions of wild prey to cat diets are hard to quantify. This limits the understanding of any impacts of cats may have on wild animal popula...

Songbird populations are in decline all over the world, and our understanding of the causal mechanisms remains surprisingly limited. It is important to identify the extent of individual variation in migratory behaviour to better understand species' ability to respond to environmental change. We describe the annual migratory behaviour of British bre...

Symbioses are ubiquitous in the animal kingdom. However, in most cases, the role of each member is relatively fixed, and it is rare for the same species to exhibit different symbiotic behaviours throughout its ontogeny. Here, we use stable isotope analyses of food resources to identify the relationships between the spider crab Libinia ferreirae as...

Population growth rates in geese can be sensitive to small changes in survival and/or production of young and understanding which demographic rates explain more variation in population change can be crucial for implementing effective conservation actions. Here, we show that annual adult survival and production of young (assessed in winter) explaine...

Devil facial tumor disease (DFTD) is a transmissible cancer affecting Tasmanian devils Sarcophilus harrisii. The disease has caused severe population declines and is associated with demographic and behavioral changes, including earlier breeding, younger age structures, and reduced dispersal and social interactions. Devils are generally solitary, bu...

A key goal of conservation is to protect biodiversity by supporting the long-term persistence of viable, natural populations of wild species. Conservation practice has long been guided by genetic, ecological and demographic indicators of risk. Emerging evidence of animal culture across diverse taxa and its role as a driver of evolutionary diversifi...

Sex differences in diet and foraging behaviour are common in sexually dimorphic species, often driven by differences in the cost of locomotion or ability to exploit different ecological niches. However, sex-specific foraging strategies also occur in monomorphic or slightly dimorphic species where the drivers are poorly understood. Here, we study se...

Sex-specific niche differentiation is common in marine vertebrates, but how this varies long-term is poorly understood. Here we investigated interannual variation in sexual segregation among breeding northern gannets Morus bassanus, wide-ranging central-place foragers with slight sexual dimorphism. Over 11 breeding seasons, we used GPS tracking and...

Mercury (Hg) is an environmental contaminant which, at high concentrations, can negatively influence avian physiology and demography. Albatrosses (Diomedeidae) have higher Hg burdens than all other avian families. Here, we measure total Hg (THg) concentrations of body feathers from adult grey-headed albatrosses ( Thalassarche chrysostoma ) at South...

Billions of vertebrates migrate to and from their breeding grounds annually, exhibiting astonishing feats of endurance. Many such movements are energetically costly yet there is little consensus on whether or how such costs might influence schedules of survival and reproduction in migratory animals. Here we provide a global analysis of associations...

Age‐related changes in diet have implications for competitive interactions and for predator–prey dynamics, affecting individuals and groups at different life stages. To quantify patterns of variation and ontogenetic change in the diets of Tasmanian devils Sarcophilus harrisii , a threatened marsupial carnivore, we analyzed variation in the stable i...

Anthropogenic climate disruption, including temperature and precipitation regime shifts, has been linked to animal population declines since the mid‐20th century. However, some species, such as Arctic‐breeding geese, have thrived during this period. An increased understanding of how climate disruption might link to demographic rates in thriving spe...

Monitoring postrelease establishment and movement of animals is important in evaluating conservation translocations. We translocated 39 wild pine martens Martes martes (19 females, 20 males) from Scotland to Wales. We released them into forested areas with no conspecifics in 2015, followed by a second release in 2016, alongside the previously relea...

Global anthropogenic changes are significantly impacting the ecology and evolution of many species. Among temperate taxa, changes to reproductive phenology as a result of warming springs are apparent. However, how such responses to abiotic change interact with biotic impacts resulting from human management interventions are less clear. Here we exam...

Physiological processes, including those that disrupt oxidative balance, have been proposed as key to understanding fundamental life‐history trade‐offs. Yet, examination of changes in oxidative balance within wild animals across time, space and major life‐history challenges remains uncommon. For example, migration presents substantial physiological...

Predators can shape the distributions and dynamics of their prey through direct and indirect mechanisms. Where prey animals are regarded as pests, the augmentation of predator populations might offer a potential tool in their management. Declines in invasive non‐native grey squirrel Sciurus carolinensis populations in Ireland and Scotland have been...

Diet analyses can reveal important changes in seabird foraging ecology and, by inference, resource availability and predator–prey dynamics within the wider marine ecosystem. Here, we analysed stomach contents of 1544 grey-headed albatross Thalassarche chrysostoma (GHA) and black-browed albatross T. melanophris (BBA) chicks from Bird Island, South G...

Identifying and understanding patterns in movement data are amongst the principal aims of movement ecology. By quantifying the similarity of movement trajectories, inferences can be made about diverse processes, ranging from individual specialisation to the ontogeny of foraging strategies. Movement analysis is not unique to ecology however, and met...

Ecologists quantify animal diets using direct and indirect methods, including analysis of faeces, pellets, prey items and gut contents. For stable isotope analyses of diet, Bayesian stable isotope mixing models (BSIMMs) are increasingly used to infer the relative importance of food sources to consumers. Although a powerful approach, it has been har...

Migration is a fundamental behavioral process prevalent among a wide variety of animal taxa. As individuals are increasingly shown to present consistent responses to environmental cues for breeding or foraging, it may be expected that approaches to migration would present similar among-individual consistencies. Seabirds frequently show consistent i...

Marine vertebrates show a diversity of migration strategies, including sex differences. This may lead to differential demography, but the consequences of such between-sex variation are little understood. Here we studied the migration of known-sex northern gannets Morus bassanus – a partial migrant with females ~8% heavier than males. We used geoloc...

Killing protected species mistaken for morphologically similar quarry species, or species with weaker protection, can hinder their conservation. Despite policy aims to reduce threats from illegal killing, information is lacking on susceptible species, conservation impacts and the identification accuracy of hunters. We examined the ability of hunter...

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 hi...

Understanding the rich social lives of animals benefits international conservation efforts

Oxidative stress is a likely consequence of hard physical exertion and thus a potential mediator of life-history trade-offs in migratory animals. However, little is known about the relative importance of intrinsic and extrinsic stres-sors on the oxidative state of individuals in wild populations. We quantified the relationships between air temperat...