Key publications
Bearhop S, Bodey T, Cleasby IR, Blount J, Vigfusdottir F, MacKie K (2019). Measures of oxidative state are primarily driven by extrinsic factors in a long-distance migrant.
Biology Letters,
15, 1-4.
Full text.
Bodey TW, Cleasby IR, Bell F, Parr N, Schultz A, Votier SC, Bearhop S (2018). A phylogenetically controlled meta-analysis of biologging device effects on birds: Deleterious effects and a call for more standardized reporting of study data.
Methods in Ecology and Evolution,
9(4), 946-955.
Abstract:
A phylogenetically controlled meta-analysis of biologging device effects on birds: Deleterious effects and a call for more standardized reporting of study data
© 2017 the Authors. Methods in Ecology and Evolution © 2017 British Ecological Society the use of biologging devices continues to increase with technological advances yielding remarkable ecological insights and generating new research questions. However, as devices develop and are deployed more widely, there is a need to update our knowledge of the potential ethical impacts to allow scientists to balance these against the knowledge gained. We employed a suite of phylogenetically controlled meta-analyses on a dataset comprising more than 450 published effect sizes across 214 different studies to examine the effects of biologger tagging on five key traits in birds. Overall, we found small but significant negative effects of tagging on survival, reproduction, parental care. In addition, tagging was positively associated with foraging trip duration, but had no effect on body mass. Meta-regressions revealed that flying style, migration distance and proportional tag mass were significant influences producing these deleterious effects, with attachment type and position additionally important covariates influencing survival- and reproduction-based effect sizes. There was a positive correlation between the effects of tagging on survival and reproduction, highlighting that effects may be cumulative, with the full effects of tagging not necessarily apparent in studies focused on single traits. We discuss the tradeoff between these negative effects and the advances gained through the use of biologgers. Finally, given the number of studies from our initial literature search that lacked sufficient data for inclusion in analyses, we provide recommendations on the essential information that all biologging studies should report in order to facilitate future assessments of impacts on animals.
Abstract.
Full text.
Papastamatiou YP, Bodey TW, Friedlander AM, Lowe CG, Bradley D, Weng K, Priestley V, Caselle JE (2018). Spatial separation without territoriality in shark communities.
Oikos,
127(6), 767-779.
Abstract:
Spatial separation without territoriality in shark communities
© 2017 the Authors Spatial separation within predator communities can arise via territoriality but also from competitive interactions among and within species. However, linking competitive interactions to predator distribution patterns is difficult and theoretical models predict different habitat selection patterns dependent on habitat quality and how competition manifests itself. While models generally consider competitors to be either equal in ability, or for one phenotype to have a fixed advantage over the other, few studies consider that an animal may only have a competitive advantage in specific habitats. We used 10 years of telemetry data, habitat surveys and behavioral experiments, to show spatial partitioning between and within two species of reef shark (grey reef Carcharhinus amblyrhinchos and blacktip reef sharks C. melanopterus) at an unfished Pacific atoll. Within a species, sharks remained within small ‘sub-habitats’ with very few movements of individuals between sub-habitats, which previous models have suggested could be caused by intra-specific competition. Blacktip reef sharks were more broadly distributed across habitat types but a greater proportion used lagoon and backreef habitats, while grey reef sharks preferred forereef habitats. Grey reef sharks at a nearby atoll where blacktip reef sharks are absent, were distributed more broadly between habitat types than when both species were present. A series of individual-based models predict that habitat separation would only arise if there are competitive interactions between species that are habitat-specific, with grey reefs having a competitive advantage on the forereefs and blacktips in the lagoons and backreef. We provide compelling evidence that competition helps drive distribution patterns and spatial separation of a marine predator community, and highlight that competitive advantages may not be constant but rather dependent on habitats.
Abstract.
Bodey TW, Jessopp MJ, Votier SC, Gerritsen HD, Cleasby IR, Hamer KC, Patrick SC, Wakefield ED, Bearhop S (2014). Seabird movement reveals the ecological footprint of fishing vessels.
Curr Biol,
24(11), R514-R515.
Abstract:
Seabird movement reveals the ecological footprint of fishing vessels.
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.
Abstract.
Author URL.
Wakefield ED, Bodey TW, Bearhop S, Blackburn J, Colhoun K, Davies R, Dwyer RG, Green JA, Grémillet D, Jackson AL, et al (2013). Space partitioning without territoriality in gannets.
Science,
341(6141), 68-70.
Abstract:
Space partitioning without territoriality in gannets
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.
Abstract.
Oppel S, Beaven BM, Bolton M, Vickery J, Bodey TW (2011). Eradication of invasive mammals on islands inhabited by humans and domestic animals.
Cons Biol,
25(2), 232-240.
Abstract:
Eradication of invasive mammals on islands inhabited by humans and domestic animals.
Non-native invasive mammal species have caused major ecological change on many islands. To conserve native species diversity, invasive mammals have been eradicated from several islands not inhabited by humans. We reviewed the challenges associated with campaigns to eradicate invasive mammals from islands inhabited by humans and domestic animals. On these islands, detailed analyses of the social, cultural, and economic costs and benefits of eradication are required to increase the probability of local communities supporting the eradication campaign. The ecological benefits of eradication (e.g. improvement of endemic species’ probability of survival) are difficult to trade-off against social and economic costs due to the lack of a common currency. Local communities may oppose an eradication campaign because of perceived health hazards, inconvenience, financial burdens, religious beliefs, or other cultural reasons. Besides these social challenges, the presence of humans and domestic animals also complicates eradication and biosecurity proce- dures (measures taken to reduce the probability of unwanted organisms colonizing an island to near zero). For example, houses, garbage-disposal areas, and livestock-feeding areas can provide refuges for certain mam- mals and therefore can decrease the probability of a successful eradication. Transport of humans and goods to an island increases the probability of inadvertent reintroduction of invasive mammals, and the establishment of permanent quarantine measures is required to minimize the probability of unwanted recolonization after eradication. We recommend a close collaboration between island communities, managers, and social scien- tists from the inception of an eradication campaign to increase the probability of achieving and maintaining an island permanently free of invasive mammals.
Abstract.
Publications by year
In Press
Bodey TW, McDonald RA, Sheldon RD, Bearhop S (In Press). Absence of effects of predator control on nesting success of lapwings: implications for conservation.
IbisAbstract:
Absence of effects of predator control on nesting success of lapwings: implications for conservation
The control of generalist predator populations is increasingly adopted as a management tool to combat declines in ground-nesting bird populations. However, compensatory predation by uncontrolled species frequently occurs, and so determining the relative impacts of different predatory species, and hence the relative benefits of their control, can be difficult. Islands, with their reduced faunas, provide natural experimental units for investigating specific predator-prey interactions in detail. We studied Lapwing Vanellus vanellus breeding success on an island where feral Ferrets Mustela furo and Hooded Crows Corvus cornix were subjected to trial control regimes over two years. In both years, Lapwing hatching success was >80%, with neither Ferret nor Crow control selected as important predictors. Fledging rates in both years were 0.7 young per pair, despite highly effective predator removal, although Crow control potentially resulted in compensatory predation by Common Ravens C. corax. Neither mustelid nor corvid control produced significant immediate benefits for Lapwing. This suggests that mesopredator release of mustelids in mainland situations is unlikely to be a consistent threat to Lapwing, and provides further evidence that declines in this species are unlikely to be successfully tackled through predator management alone.
Abstract.
Bearhop S, Cleasby IR, Bodey TW, Vigfusdottir F, McDonald JL, McElwaine G, Mackie K, Colhoun K (In Press). Climatic conditions produce contrasting influences on demographic traits in a long distance Arctic migrant.
Journal of Animal Ecology Full text.
Votier SC, Fayet A, Bearhop S, Bodey T, Clark B, Grecian WJ, Guilford T, Hamer K, Jeglinski J, Morgan G, et al (In Press). Effects of age and reproductive status on individual foraging site fidelity in a long-lived marine predator.
Proceedings of the Royal Society B: Biological Sciences Full text.
Patrick SC, Bearhop S, Bodey TW, Grecian WJ, Hamer KC, Lee J, Votier SC (In Press). Individual seabirds show consistent foraging strategies in response to predictable fisheries discards.
Journal of Avian Biology,
46, 1-10.
Abstract:
Individual seabirds show consistent foraging strategies in response to predictable fisheries discards
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.
Abstract.
Wakefield ED, Cleasby IR, Bearhop S, Bodey TW, Davies R, Miller PI, Newton J, Votier SC, Hamer KC (In Press). Long-term individual foraging site fidelity – why some gannets don’t change their spots.
Ecological MonographsAbstract:
Long-term individual foraging site fidelity – why some gannets don’t change their spots
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.
Abstract.
Cleasby IR, Wakefield ED, Bodey TW, Davies RD, Patrick SC, Newton J, Votier SC, Bearhop S, Hamer KC (In Press). Sexual segregation in a wide-ranging marine predator is a consequence of habitat selection. Marine Ecology Progress Series, 518, 1-12.
Wakefield ED, Bodey TW, Bearhop S, Blackburn J, Colhoun K, Davies R, Dwyer RG, Green J, Gremillet D, Jackson AL, et al (In Press). Space partitioning without territoriality in gannets.
ScienceAbstract:
Space partitioning without territoriality in gannets
Colonial breeding is widespread among animals. Though 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 twelve neighboring colonies, forage in largely mutually exclusive areas and that these colony-specific home ranges are determined by density-dependent competition. Further, this may be enhanced by individual-level public information transfer, leading to cultural evolution and divergence among colonies.
Abstract.
Full text.
2019
Grecian WJ, Williams HJ, Votier SC, Bearhop S, Cleasby IR, Gremillet D, Hamer KC, Le Nuz M, Lescroel A, Newton J, et al (2019). Individual Spatial Consistency and Dietary Flexibility in the Migratory Behavior of Northern Gannets Wintering in the Northeast Atlantic.
FRONTIERS IN ECOLOGY AND EVOLUTION,
7 Author URL.
Full text.
Bearhop S, Bodey T, Cleasby IR, Blount J, Vigfusdottir F, MacKie K (2019). Measures of oxidative state are primarily driven by extrinsic factors in a long-distance migrant.
Biology Letters,
15, 1-4.
Full text.
2018
Bodey TW, Cleasby IR, Bell F, Parr N, Schultz A, Votier SC, Bearhop S (2018). A phylogenetically controlled meta-analysis of biologging device effects on birds: Deleterious effects and a call for more standardized reporting of study data.
Methods in Ecology and Evolution,
9(4), 946-955.
Abstract:
A phylogenetically controlled meta-analysis of biologging device effects on birds: Deleterious effects and a call for more standardized reporting of study data
© 2017 the Authors. Methods in Ecology and Evolution © 2017 British Ecological Society the use of biologging devices continues to increase with technological advances yielding remarkable ecological insights and generating new research questions. However, as devices develop and are deployed more widely, there is a need to update our knowledge of the potential ethical impacts to allow scientists to balance these against the knowledge gained. We employed a suite of phylogenetically controlled meta-analyses on a dataset comprising more than 450 published effect sizes across 214 different studies to examine the effects of biologger tagging on five key traits in birds. Overall, we found small but significant negative effects of tagging on survival, reproduction, parental care. In addition, tagging was positively associated with foraging trip duration, but had no effect on body mass. Meta-regressions revealed that flying style, migration distance and proportional tag mass were significant influences producing these deleterious effects, with attachment type and position additionally important covariates influencing survival- and reproduction-based effect sizes. There was a positive correlation between the effects of tagging on survival and reproduction, highlighting that effects may be cumulative, with the full effects of tagging not necessarily apparent in studies focused on single traits. We discuss the tradeoff between these negative effects and the advances gained through the use of biologgers. Finally, given the number of studies from our initial literature search that lacked sufficient data for inclusion in analyses, we provide recommendations on the essential information that all biologging studies should report in order to facilitate future assessments of impacts on animals.
Abstract.
Full text.
Bodey TW, Cleasby IR, Votier SC, Hamer KC, Newton J, Patrick SC, Wakefield ED, Bearhop S (2018). Frequency and consequences of individual dietary specialisation in a wide-ranging marine predator, the northern gannet.
MARINE ECOLOGY PROGRESS SERIES,
604, 251-262.
Author URL.
Full text.
Bennison A, Bearhop S, Bodey TW, Votier SC, Grecian WJ, Wakefield ED, Hamer KC, Jessopp M (2018). Search and foraging behaviors from movement data: a comparison of methods.
Ecology and Evolution,
8(1), 13-24.
Abstract:
Search and foraging behaviors from movement data: a comparison of methods
© 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.
Abstract.
Full text.
Papastamatiou YP, Bodey TW, Friedlander AM, Lowe CG, Bradley D, Weng K, Priestley V, Caselle JE (2018). Spatial separation without territoriality in shark communities.
Oikos,
127(6), 767-779.
Abstract:
Spatial separation without territoriality in shark communities
© 2017 the Authors Spatial separation within predator communities can arise via territoriality but also from competitive interactions among and within species. However, linking competitive interactions to predator distribution patterns is difficult and theoretical models predict different habitat selection patterns dependent on habitat quality and how competition manifests itself. While models generally consider competitors to be either equal in ability, or for one phenotype to have a fixed advantage over the other, few studies consider that an animal may only have a competitive advantage in specific habitats. We used 10 years of telemetry data, habitat surveys and behavioral experiments, to show spatial partitioning between and within two species of reef shark (grey reef Carcharhinus amblyrhinchos and blacktip reef sharks C. melanopterus) at an unfished Pacific atoll. Within a species, sharks remained within small ‘sub-habitats’ with very few movements of individuals between sub-habitats, which previous models have suggested could be caused by intra-specific competition. Blacktip reef sharks were more broadly distributed across habitat types but a greater proportion used lagoon and backreef habitats, while grey reef sharks preferred forereef habitats. Grey reef sharks at a nearby atoll where blacktip reef sharks are absent, were distributed more broadly between habitat types than when both species were present. A series of individual-based models predict that habitat separation would only arise if there are competitive interactions between species that are habitat-specific, with grey reefs having a competitive advantage on the forereefs and blacktips in the lagoons and backreef. We provide compelling evidence that competition helps drive distribution patterns and spatial separation of a marine predator community, and highlight that competitive advantages may not be constant but rather dependent on habitats.
Abstract.
2015
Cleasby IR, Wakefield ED, Bodey TW, Davies RD, Patrick SC, Newton J, Votier SC, Bearhop S, Hamer KC (2015). Sexual segregation in a wide-ranging marine predator is a consequence of habitat selection.
Marine Ecology Progress Series,
518, 1-12.
Abstract:
Sexual segregation in a wide-ranging marine predator is a consequence of habitat selection
© 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.
Abstract.
Cleasby IR, Wakefield ED, Bearhop S, Bodey TW, Votier SC, Hamer KC (2015). Three-dimensional tracking of a wide-ranging marine predator: Flight heights and vulnerability to offshore wind farms.
Journal of Applied EcologyAbstract:
Three-dimensional tracking of a wide-ranging marine predator: Flight heights and vulnerability to offshore wind farms
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
Abstract.
2014
Patrick SC, Bearhop S, Grémillet D, Lescroël A, Grecian WJ, Bodey TW, Hamer KC, Wakefield E, Le Nuz M, Votier SC, et al (2014). Individual differences in searching behaviour and spatial foraging consistency in a central place marine predator.
Oikos,
123(1), 33-40.
Abstract:
Individual differences in searching behaviour and spatial foraging consistency in a central place marine predator
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.
Abstract.
Bodey TW, Jessopp MJ, Votier SC, Gerritsen HD, Cleasby IR, Hamer KC, Patrick SC, Wakefield ED, Bearhop S (2014). Seabird movement reveals the ecological footprint of fishing vessels.
Curr Biol,
24(11), R514-R515.
Abstract:
Seabird movement reveals the ecological footprint of fishing vessels.
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.
Abstract.
Author URL.
Bodey TW, Ward EJ, Phillips RA, McGill RAR, Bearhop S (2014). Species versus guild level differentiation revealed across the annual cycle by isotopic niche examination.
Journal of Animal Ecology,
83(2), 470-478.
Abstract:
Species versus guild level differentiation revealed across the annual cycle by isotopic niche examination
Interspecific competitive interactions typically result in niche differentiation to alleviate competition through mechanisms including character displacement. However, competition is not the sole constraint on resource partitioning, and its effects are mediated by factors including the environmental context in which species coexist. Colonial seabirds provide an excellent opportunity to investigate the importance of competition in shaping realized niche widths because their life histories lead to variation in intra- and interspecific competition across the annual cycle. Dense breeding aggregations result in intense competition for prey in surrounding waters, whereas non-breeding dispersal to larger geographical areas produces lower densities of competitors. Bayesian hierarchical models of the isotopic niche, closely aligned to the trophic niche, reveal the degree of segregation between species and functional groups during both time periods. Surprisingly, species explained far more of the variance in the isotopic niche during the non-breeding than the breeding period. Our results underline the key role of non-breeding dynamics in alleviating competition and promoting distinctions between species through the facilitation of resource partitioning. Such situations may be common in a diverse range of communities sustained by ephemeral but abundant food items. This highlights how consideration of the hierarchical grouping of competitive interactions alongside consideration of abiotic constraints across the complete annual cycle allows a full understanding of the role of competition in driving patterns of character displacement. © 2013 the Authors. Journal of Animal Ecology © 2013 British Ecological Society.
Abstract.
Bodey TW, Ward EJ, Phillips RA, McGill RAR, Bearhop S (2014). Species versus guild level differentiation revealed across the annual cycle by isotopic niche examination.
J Anim Ecol,
83(2), 470-478.
Abstract:
Species versus guild level differentiation revealed across the annual cycle by isotopic niche examination.
Interspecific competitive interactions typically result in niche differentiation to alleviate competition through mechanisms including character displacement. However, competition is not the sole constraint on resource partitioning, and its effects are mediated by factors including the environmental context in which species coexist. Colonial seabirds provide an excellent opportunity to investigate the importance of competition in shaping realized niche widths because their life histories lead to variation in intra- and interspecific competition across the annual cycle. Dense breeding aggregations result in intense competition for prey in surrounding waters, whereas non-breeding dispersal to larger geographical areas produces lower densities of competitors. Bayesian hierarchical models of the isotopic niche, closely aligned to the trophic niche, reveal the degree of segregation between species and functional groups during both time periods. Surprisingly, species explained far more of the variance in the isotopic niche during the non-breeding than the breeding period. Our results underline the key role of non-breeding dynamics in alleviating competition and promoting distinctions between species through the facilitation of resource partitioning. Such situations may be common in a diverse range of communities sustained by ephemeral but abundant food items. This highlights how consideration of the hierarchical grouping of competitive interactions alongside consideration of abiotic constraints across the complete annual cycle allows a full understanding of the role of competition in driving patterns of character displacement.
Abstract.
Author URL.
2013
Wakefield ED, Bodey TW, Bearhop S, Blackburn J, Colhoun K, Davies R, Dwyer RG, Green JA, Grémillet D, Jackson AL, et al (2013). Space partitioning without territoriality in gannets.
Science,
341(6141), 68-70.
Abstract:
Space partitioning without territoriality in gannets
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.
Abstract.
2012
Bodey TW, Bearhop S, McDonald RA (2012). Invasions and stable isotope analysis – informing ecology and management. In Veitch CR, Clout MN, Towns DR (Eds.)
Island invasives: eradication and management, Gland, Switzerland.: IUCN, 148-151.
Abstract:
Invasions and stable isotope analysis – informing ecology and management
Abstract.
Stauss C, Bearhop S, Bodey TW, Garthe S, Gunn C, Grecian WJ, Inger R, Knight ME, Newton J, Patrick SC, et al (2012). Sex-specific foraging behaviour in northern gannets Morus bassanus: incidence and implications.
Marine Ecology Progress Series(457), 151-162.
Abstract:
Sex-specific foraging behaviour in northern gannets Morus bassanus: incidence and implications
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.
Abstract.
2011
Drake DR, Bodey TW, Russell JC, Towns DR, Nogales M, Ruffino L (2011). Direct Impacts of Seabird Predators on Island Biota other than Seabirds. In (Ed)
Seabird Islands: Ecology, Invasion, and Restoration.
Abstract:
Direct Impacts of Seabird Predators on Island Biota other than Seabirds
Abstract.
Drake DR, Bodey TW, Russell JC, Towns DR, Nogales M, Ruffino L (2011). Direct impacts of seabird predators on non-seabird island biota. In CPH M, Towns DR, Anderson WB, Bellingham PJ (Eds.) Seabird Islands – ecology, invasion and restoration, Oxford University Press.
Oppel S, Beaven BM, Bolton M, Vickery J, Bodey TW (2011). Eradication of Invasive Mammals on Islands Inhabited by Humans and Domestic Animals.
Conservation Biology,
25(2), 232-240.
Abstract:
Eradication of Invasive Mammals on Islands Inhabited by Humans and Domestic Animals
Non-native invasive mammal species have caused major ecological change on many islands. To conserve native species diversity, invasive mammals have been eradicated from several islands not inhabited by humans. We reviewed the challenges associated with campaigns to eradicate invasive mammals from islands inhabited by humans and domestic animals. On these islands, detailed analyses of the social, cultural, and economic costs and benefits of eradication are required to increase the probability of local communities supporting the eradication campaign. The ecological benefits of eradication (e.g. improvement of endemic species' probability of survival) are difficult to trade-off against social and economic costs due to the lack of a common currency. Local communities may oppose an eradication campaign because of perceived health hazards, inconvenience, financial burdens, religious beliefs, or other cultural reasons. Besides these social challenges, the presence of humans and domestic animals also complicates eradication and biosecurity procedures (measures taken to reduce the probability of unwanted organisms colonizing an island to near zero). For example, houses, garbage-disposal areas, and livestock-feeding areas can provide refuges for certain mammals and therefore can decrease the probability of a successful eradication. Transport of humans and goods to an island increases the probability of inadvertent reintroduction of invasive mammals, and the establishment of permanent quarantine measures is required to minimize the probability of unwanted recolonization after eradication. We recommend a close collaboration between island communities, managers, and social scientists from the inception of an eradication campaign to increase the probability of achieving and maintaining an island permanently free of invasive mammals. ©2010 Society for Conservation Biology.
Abstract.
Oppel S, Beaven BM, Bolton M, Vickery J, Bodey TW (2011). Eradication of invasive mammals on islands inhabited by humans and domestic animals.
Cons Biol,
25(2), 232-240.
Abstract:
Eradication of invasive mammals on islands inhabited by humans and domestic animals.
Non-native invasive mammal species have caused major ecological change on many islands. To conserve native species diversity, invasive mammals have been eradicated from several islands not inhabited by humans. We reviewed the challenges associated with campaigns to eradicate invasive mammals from islands inhabited by humans and domestic animals. On these islands, detailed analyses of the social, cultural, and economic costs and benefits of eradication are required to increase the probability of local communities supporting the eradication campaign. The ecological benefits of eradication (e.g. improvement of endemic species’ probability of survival) are difficult to trade-off against social and economic costs due to the lack of a common currency. Local communities may oppose an eradication campaign because of perceived health hazards, inconvenience, financial burdens, religious beliefs, or other cultural reasons. Besides these social challenges, the presence of humans and domestic animals also complicates eradication and biosecurity proce- dures (measures taken to reduce the probability of unwanted organisms colonizing an island to near zero). For example, houses, garbage-disposal areas, and livestock-feeding areas can provide refuges for certain mam- mals and therefore can decrease the probability of a successful eradication. Transport of humans and goods to an island increases the probability of inadvertent reintroduction of invasive mammals, and the establishment of permanent quarantine measures is required to minimize the probability of unwanted recolonization after eradication. We recommend a close collaboration between island communities, managers, and social scien- tists from the inception of an eradication campaign to increase the probability of achieving and maintaining an island permanently free of invasive mammals.
Abstract.
Bodey TW, Bearhop S, McDonald RA (2011). Localised control of an introduced predator: creating problems for the future?.
Biol Invasions,
13(12), 2817-2828.
Abstract:
Localised control of an introduced predator: creating problems for the future?
Introduced mammalian predators have had significant impacts on many native prey species. Although control of such predators for conservation management is becoming increasingly commonplace, it is often undertaken at a relatively small scale in relation to the overall predator population. Processes such as immigration mean that it remains difficult to determine the effectiveness of control measures. We investigated the impacts of feral ferret Mustela furo removal on the entire feral ferret population on Rathlin Island, UK. Removal of ferrets prior to breeding led to a substantial increase in the post-dispersal population through the enhanced survival of juveniles. Despite increased numbers, overwinter survival remained high, potentially aided by the reduced territoriality shown by this feral species compared to wild carnivores. The response of this ferret population to control is a further illustration of the complex ecological processes and outcomes arising from the disruption of wildlife populations. It highlights how partial or localised management may prove ineffective, and at worst might exacerbate the problems that management was designed to avert.
Abstract.
Jones HP, Towns DR, Bodey TW, Miskelly CM, Ellis JC, Rauzon MJ, Kress SW, McKown MW (2011). Recovery and restoration of seabird islands. In CPH M, Towns DR, Anderson WB, Bellingham PJ (Eds.) Seabird Islands – ecology, invasion and restoration, Oxford University Press.
Bodey TW, Bearhop S, McDonald RA (2011). The diet of an invasive alien predator the feral ferret Mustela furo: implications for the conservation of ground nesting birds.
Eur J Wildl Res,
57, 107-117.
Abstract:
The diet of an invasive alien predator the feral ferret Mustela furo: implications for the conservation of ground nesting birds.
Introduced carnivores have had a significant impact on the fauna of a number of countries, particularly on islands. In the British Isles, several offshore islands holding internationally important aggregations of seabirds and shorebirds support self-sustaining feral ferret Mustela furo populations, often as the top terrestrial predator. However, little is known about the interactions between ferrets and both native and nonnative prey in these locations. We examined the diet of feral ferrets on Rathlin Island, Northern Ireland. We determined the frequency of occurrence of prey items and constructed energetic models to determine their potential impact on both native and introduced prey. Rabbits Oryctolagus cuniculus occurred in 75% of scats, while birds, carrion, and brown rats Rattus norvegicus were important secondary items. There was little difference between the diets of males and females. Estimates of the energy requirements of the population at current, and with hypothetically reduced, rabbit availability revealed the potential for carrion to maintain the ferret population over winter. Management options could thus focus on reducing anthropogenic food sources as an immediate way of mitigating the threat to ground-nesting birds, while other strategies, including eradication, are considered.
Abstract.
2010
Bodey TW, Bearhop S, Roy SS, Newton J, McDonald RA (2010). Behavioural responses of invasive American mink Neovison vison to an eradication campaign, revealed by stable isotope analysis.
Journal of Applied Ecology,
47(1), 114-120.
Abstract:
Behavioural responses of invasive American mink Neovison vison to an eradication campaign, revealed by stable isotope analysis
1. The detrimental impacts of invasive, non-native species on islands are widely acknowledged and it is often best to act rapidly against such species, even where uncertainty exists over the best way to proceed. If management actions are evaluated and refined, using information learnt from the biology of culled animals, this uncertainty can be gradually reduced, increasing the likelihood of a successful outcome.
2. American mink Neovison vison carcasses were collected as part of an eradication campaign on several islands of the Outer Hebrides, Scotland, and stable isotope analysis was used to describe ecological variation in this invasive non-native predator.
3. Isotope profiles from individual mink whiskers demonstrated how behaviour at a population level changed markedly over time. As the eradication campaign progressed, mink increased their reliance on marine food sources and focused their activity on the coastline. Stable isotope analyses also demonstrated sex-related changes in foraging and ranging behaviour in relation to food resource availability on the two main island complexes.
4. Synthesis and applications. Our findings contribute to the refinement of a campaign to extend the successful eradication of mink from Uist and Harris, to the whole of the Outer Hebrides archipelago, UK. They also highlight the potential for stable isotope approaches to provide more detailed postmortem information that can inform adaptive management of wildlife populations for conservation objectives.
Abstract.
Bodey TW, Smart J, Smart MA, Gregory RD (2010). Reducing the impacts of predation on ground-nesting waders: a new landscape-scale solution?.
Aspects Appl Biol,
100, 167-174.
Abstract:
Reducing the impacts of predation on ground-nesting waders: a new landscape-scale solution?
Breeding waders have undergone substantial population declines, and high predation levels may prevent recovery. Manipulating habitats could benefit waders through habitat improvement while potentially buffering against predation. We examined two trial manipulations, ‘wet’ and ‘sward’, designed to encourage lapwing Vanellus vanellus to nest at higher densities further from field edges, as such patterns lead to higher nest survival. We also monitored their impact on breeding redshank Tringa totanus. Nest distribution shifted towards field centres in ‘wet’ fields, but improvements in nest survival were limited. Nest survival increased in ‘sward‘ fields, and there was a positive effect on small mammal populations. Such management can, therefore, increase nesting success, and we discuss potential mechanisms driving these improvements. These manipulations could be incorporated into agri-environment options, allowing further study of the underlying factors and, for the first time, providing an effective landscape-scale solution that both enhances breeding habitat suitability and decreases predator impacts.
Abstract.
2009
Bodey TW, McDonald RA, Bearhop S (2009). Mesopredators constrain a top predator: competitive release of ravens after culling crows.
Biol Lett,
5(5), 617-620.
Abstract:
Mesopredators constrain a top predator: competitive release of ravens after culling crows.
Although predator control programmes rarely consider complex competitive interactions among predators, it is becoming clear that removal of larger 'superior' competitors often releases the 'inferior' ones and can precipitate trophic cascades. In contrast, our study indicates that culling hooded crows Corvus cornix appears to release a larger competitor, the common raven Corvus corax. Ravens ranged more widely, and the predation of artificial nests was significantly faster (although total predation was similar), after the removal of crows. Our study provides evidence of a novel reversal of competitive release where a larger species was freed from constraints imposed on its distribution and behaviour by a smaller species, and emphasizes the importance of considering community and ecosystem effects of predator manipulations when undertaken for conservation or game management.
Abstract.
Author URL.