20 results on '"Daunt, Francis"'
Search Results
2. From days to decades : short- and long-term variation in environmental conditions affect offspring diet composition of a marine top predator
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Howells, Richard J., Burthe, Sarah J., Green, Jon A., Harris, Michael P., Newell, Mark A., Butler, Adam, Johns, David G., Carnell, Edward J., Wanless, Sarah, and Daunt, Francis
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- 2017
3. Consequences of cross‐season demographic correlations for population viability.
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Layton‐Matthews, Kate, Reiertsen, Tone K., Erikstad, Kjell‐Einar, Anker‐Nilssen, Tycho, Daunt, Francis, Wanless, Sarah, Barrett, Robert T., Newell, Mark A., and Harris, Mike P.
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POPULATION viability analysis ,ANIMAL populations ,POPULATION dynamics - Abstract
Demographic correlations are pervasive in wildlife populations and can represent important secondary drivers of population growth. Empirical evidence suggests that correlations are in general positive for long‐lived species, but little is known about the degree of variation among spatially segregated populations of the same species in relation to environmental conditions. We assessed the relative importance of two cross‐season correlations in survival and productivity, for three Atlantic puffin (Fratercula arctica) populations with contrasting population trajectories and non‐overlapping year‐round distributions. The two correlations reflected either a relationship between adult survival prior to breeding on productivity, or a relationship between productivity and adult survival the subsequent year. Demographic rates and their correlations were estimated with an integrated population model, and their respective contributions to variation in population growth were calculated using a transient‐life table response experiment. For all three populations, demographic correlations were positive at both time lags, although their strength differed. Given the different year‐round distributions of these populations, this variation in the strength population‐level demographic correlations points to environmental conditions as an important driver of demographic variation through life‐history constraints. Consequently, the contributions of variances and correlations in demographic rates to population growth rates differed among puffin populations, which has implications for—particularly small—populations' viability under environmental change as positive correlations tend to reduce the stochastic population growth rate. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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4. Assessing the vulnerability of the marine bird community in the western North Sea to climate change and other anthropogenic impacts
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Burthe, Sarah J., Wanless, Sarah, Newell, Mark A., Butler, Adam, and Daunt, Francis
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- 2014
5. Hywind Scotland Ornithological Monitoring Programme: Overwintering distributions of common guillemot and razorbill populations in Eastern Scotland
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Bogdanova, Maria I., Buckingham, Lila, Newell, Mark A., Wanless, Sarah, Harris, Mike P., Andrews, Chris, Morley, Tim, Weston, Ewan, Swann, Robert, Canham, Mick, Bennett, Sophie, Cox, Nicky, Quintin, Marine, and Daunt, Francis
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seabird ,geolocation ,offshore wind developments ,at-sea distribution - Abstract
The Hywind Scotland Pilot Park located off the east coast of Scotland has been in operation since 2017 and comprises five floating wind turbines with a total generating capacity of 30 MW. Ornithological monitoring is required as part of the Marine Licence for the wind farm and is carried out in conjunction with a large-scale seabird monitoring and research programme in north-western Europe (SEATRACK) involving the deployment of geolocation loggers to obtain seabird location estimates throughout the winter. Of particular concern are two species of auks (common guillemot Uria aalge and razorbill Alca torda) known to be highly vulnerable to displacement and barrier effects from offshore renewable developments. As part of the Hywind Scotland’s ornithological monitoring, data on year-round distribution and movements of guillemots and razorbills at three major colonies along the east coast of Scotland (East Caithness SPA, Buchan Ness to Collieston Coast SPA and Isle of May National Nature Reserve) were collected over two years (2017-18 and 2018-19). In 2017, a total of 190 geolocation loggers were deployed at the three study colonies. During the 2018 breeding season, a total of 82 loggers were retrieved and 193 new data loggers were deployed. During the 2019 breeding season a total of 102 loggers were retrieved, including several deployed in the first year. We obtained reasonable sample sizes in all cases (range 11-28) except razorbills at Buchan Ness to Collieston Coast, where only five loggers were retrieved each year. The geolocation data were processed using a probabilistic method to obtain two locations per day for each bird throughout the non-breeding period. The geolocation data were analysed to determine utilisation distributions for each species at each colony in 2017-18 and 2018-19. Overlap in distributions was quantified and minimum adequate sample size of tracked birds was examined. For both species, the distribution of birds from the three study colonies was similar at a broad spatial scale, with key wintering areas located around the colonies and in the central and southern parts of the North Sea. In guillemots, among-colony spatial similarity in kernel densities was generally high throughout the non-breeding period. In razorbills, spatial similarity among colonies was highest in the post-breeding period and lowest in late winter. Our results indicate that the three populations of guillemots and razorbills had a similar overall non-breeding distribution, with extensive use of the central and southern North Sea and areas around the breeding colonies, and this was broadly consistent between years. However, in both species there were important differences among colonies in the location of hotspots during the non-breeding period. The data provide important insights into the year-round space use of these two key species at three major colonies on the east coast of Scotland and their potential interaction with offshore renewable developments.
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- 2021
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6. Modelling and mapping how common guillemots balance their energy budgets over a full annual cycle.
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Dunn, Ruth E., Green, Jonathan A., Wanless, Sarah, Harris, Mike P., Newell, Mark A., Bogdanova, Maria I., Horswill, Catharine, Daunt, Francis, and Matthiopoulos, Jason
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OCEAN temperature ,CALORIC expenditure ,ANIMAL populations ,SEVERE storms ,ENERGY budget (Geophysics) ,REPRODUCTION ,POPULATION dynamics ,BAYESIAN analysis - Abstract
The ability of individual animals to balance their energy budgets throughout the annual cycle is important for their survival, reproduction and population dynamics. However, the annual cycles of many wild, mobile animals are difficult to observe and our understanding of how individuals balance their energy budgets throughout the year therefore remains poor.We developed a hierarchical Bayesian state‐space model to investigate how key components of animal energy budgets (namely individual energy gain and storage) varied in space and time. Our model used biologger‐derived estimates of time‐activity budgets, locations and energy expenditure to infer year‐round time series of energy income and reserves. The model accounted for seasonality in environmental drivers such as sea surface temperature and daylength, allowing us to identify times and locations of high energy gain.Our study system was a population of common guillemots Uria aalge breeding at a western North Sea colony. These seabirds manage their energy budgets by adjusting their behaviour and accumulating fat reserves. However, typically during severe weather conditions, birds can experience an energy deficit over a sustained period, leading to starvation and large‐scale mortality events.We show that guillemot energy gain varied in both time and space. Estimates of guillemot body mass varied throughout the annual cycle and birds periodically experienced losses in mass. Mass losses were likely to have either been adaptive, or due to energetic bottlenecks, the latter leading to increased susceptibility to mortality. Guillemots tended to be lighter towards the edge of their spatial distribution.We describe a framework that combines biologging data, time‐activity budget analysis and Bayesian state‐space modelling to identify times and locations of high energetic reward or potential energetic bottlenecks in a wild animal population. Our approach can be extended to address ecological and conservation‐driven questions that were previously unanswerable due to logistical complexities in collecting data on wild, mobile animals across full annual cycles. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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7. Environmental heterogeneity promotes individual specialisation in habitat selection in a widely distributed seabird.
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Trevail, Alice M., Green, Jonathan A., Bolton, Mark, Daunt, Francis, Harris, Stephanie M., Miller, Peter I., Newton, Stephen, Owen, Ellie, Polton, Jeff A., Robertson, Gail, Sharples, Jonathan, and Patrick, Samantha C.
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TOP predators ,HABITAT selection ,HETEROGENEITY ,HABITATS ,INDIVIDUAL differences - Abstract
1. Individual specialisations in behaviour are predicted to arise where divergence benefits fitness. Such specialisations are more likely in heterogeneous environments where there is both greater ecological opportunity and competition-driven frequency dependent selection. 2. Such an effect could explain observed differences in rates of individual specialisation in habitat selection, as it offers individuals an opportunity to select for habitat types that maximise resource gain while minimising competition; however, this mechanism has not been tested before. 3. Here, we use habitat selection functions to quantify individual specialisations while foraging by black-legged kittiwakes Rissa tridactyla, a marine top predator, at 15 colonies around the United Kingdom and Ireland, along a gradient of environmental heterogeneity. 4. We find support for the hypothesis that individual specialisations in habitat selection while foraging are more prevalent in heterogeneous environments. This trend was significant across multiple dynamic habitat variables that change over short time-scales and did not arise through site fidelity, which highlights the importance of environmental processes in facilitating behavioural adaptation by predators. 5. Individual differences may drive evolutionary processes, and therefore these results suggest that there is broad scope for the degree of environmental heterogeneity to determine current and future population, species and community dynamics. [ABSTRACT FROM AUTHOR]
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- 2021
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8. Improving assessments of data‐limited populations using life‐history theory.
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Horswill, Cat, Manica, Andrea, Daunt, Francis, Newell, Mark, Wanless, Sarah, Wood, Matthew, and Matthiopoulos, Jason
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COLONIES (Biology) ,SENSITIVE plant ,EFFECT of human beings on climate change ,PLANT populations ,ANIMAL populations - Abstract
Predicting how populations may respond to climate change and anthropogenic pressures requires detailed knowledge of demographic traits, such as survival and reproduction. However, the availability of these data varies greatly across space and taxa. Therefore, it is common practice to conduct population assessments by filling in missing values from surrogate species or other populations of the same species. Using these independent surrogate values concurrently with observed data neglects the life‐history trade‐offs that connect the different aspects of a population's demography. Consequently, this approach introduces biases that could ultimately lead to erroneous management decisions.We use a Bayesian hierarchical framework to combine fragmented multi‐population data with established life‐history theory and reconstruct population‐specific demographic data across a substantial part of a species breeding range. We apply our analysis to a long‐lived colonial species, the black‐legged kittiwake Rissa tridactyla, that is classified as globally Vulnerable and is highly threatened by increasing anthropogenic pressures, including offshore renewable energy development. We then use a projection analysis to examine how the reconstructed demographic parameters may improve population assessments, compared to models that combine observed data with independent surrogate values.Demographic parameters reconstructed using a hierarchical framework can be utilised in a range of population modelling approaches. They can also be used as reference estimates to assess whether independent surrogate values are likely to over or underestimate missing demographic parameters. We show that surrogate values from independent sources are often used to fill in missing parameters that have large potential demographic impact, and that resulting biases are driven in unpredictable directions thus precluding assessments from being consistently precautionary.Synthesis and applications. Our study dramatically increases the spatial coverage of population‐specific demographic data for black‐legged kittiwakes. The reconstructed demographic parameters presented can also be used immediately to reduce uncertainty in the consenting process for offshore wind development in the United Kingdom and Ireland. More broadly, we show that the reconstruction approach used here provides a new avenue for improving evidence‐based management and policy action for animal and plant populations with fragmented and error prone demographic data. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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9. Contrasting responses of male and female foraging effort to year‐round wind conditions
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Lewis, Sue, Phillips, Richard A., Burthe, Sarah J., Wanless, Sarah, and Daunt, Francis
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Male ,demographic rate ,seabird ,integumentary system ,Standard Paper ,Feeding Behavior ,Wind ,Phalacrocorax aristotelis ,Birds ,climate change ,Sex Factors ,environmental perturbation ,Scotland ,extreme weather event ,Animals ,Female ,Seasons ,Behavioural Ecology - Abstract
Summary There is growing interest in the effects of wind on wild animals, given evidence that wind speeds are increasing and becoming more variable in some regions, particularly at temperate latitudes. Wind may alter movement patterns or foraging ability, with consequences for energy budgets and, ultimately, demographic rates.These effects are expected to vary among individuals due to intrinsic factors such as sex, age or feeding proficiency. Furthermore, this variation is predicted to become more marked as wind conditions deteriorate, which may have profound consequences for population dynamics as the climate changes. However, the interaction between wind and intrinsic effects has not been comprehensively tested.In many species, in particular those showing sexual size dimorphism, males and females vary in foraging performance. Here, we undertook year‐round deployments of data loggers to test for interactions between sex and wind speed and direction on foraging effort in adult European shags Phalacrocorax aristotelis, a pursuit‐diving seabird in which males are c. 18% heavier.We found that foraging time was lower at high wind speeds but higher during easterly (onshore) winds. Furthermore, there was an interaction between sex and wind conditions on foraging effort, such that females foraged for longer than males when winds were of greater strength (9% difference at high wind speeds vs. 1% at low wind speeds) and when winds were easterly compared with westerly (7% and 4% difference, respectively).The results supported our prediction that sex‐specific differences in foraging effort would become more marked as wind conditions worsen. Since foraging time is linked to demographic rates in this species, our findings are likely to have important consequences for population dynamics by amplifying sex‐specific differences in survival rates.
- Published
- 2015
10. Between-individual variation in nematode burden among juveniles in a wild host:Variation in nematode burdens of juvenile birds
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Granroth-Wilding, Hannah, Daunt, Francis, Cunningham, Emma, and Burthe, S.J.
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seabird ,dissection ,macroparasite ,demographic trait ,growth ,parasite birden ,prevalence ,endoscope ,anisakid ,Contracaecum ,host-parasite interaction ,FEC - Abstract
Parasite infection in young animals can affect host traits related to demographic processes such as survival and reproduction, and is therefore crucial to population viability. However, variation in infection among juvenile hosts is poorly understood. Experimental studies have indicated that Variation in nematode burdens of juvenile birds effects of parasitism can vary with host sex, hatching order and hatch date, yet it remains unclear whether this is linked to differences in parasite burdens. We quantified gastrointestinal nematode burdens of wild juvenile European shags (Phalacrocorax aristotelis) using two in situ measures (endoscopy of live birds and necropsy of birds that died naturally) and one non-invasive proxy Funders measure (faecal egg counts). In situ methods revealed that almost all chicks were infected (98%), NERC, The Royal Society that infections established at an early age, and that older chicks hosted more worms, but faecal egg counts underestimated prevalence. We found no strong evidence that burdens differed with host sex rank or hatch date. Heavier chicks had higher burdens, demonstrating that the relationship between burdens and their costs is not straightforward. In situ measures of infection are therefore a valuable tool in building our understanding of the role that parasites play in the dynamics of structured natural populations.
- Published
- 2017
11. Environmental heterogeneity decreases reproductive success via effects on foraging behaviour.
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Trevail, Alice M., Green, Jonathan A., Sharples, Jonathan, Polton, Jeff A., Miller, Peter I., Daunt, Francis, Owen, Ellie, Bolton, Mark, Colhoun, Kendrew, Newton, Stephen, Robertson, Gail, and Patrick, Samantha C.
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FORAGING behavior ,BEHAVIOR ,HETEROGENEITY ,BRITISH colonies ,SUCCESS - Abstract
Environmental heterogeneity shapes the uneven distribution of resources available to foragers, and is ubiquitous in nature. Optimal foraging theory predicts that an animal's ability to exploit resource patches is key to foraging success. However, the potential fitness costs and benefits of foraging in a heterogeneous environment are difficult to measure empirically. Heterogeneity may provide higher-quality foraging opportunities, or alternatively could increase the cost of resource acquisition because of reduced patch density or increased competition. Here, we study the influence of physical environmental heterogeneity on behaviour and reproductive success of black-legged kittiwakes, Rissa tridactyla. From GPS tracking data at 15 colonies throughout their British and Irish range, we found that environments that were physically more heterogeneous were associated with longer trip duration, more time spent foraging while away from the colony, increased overlap of foraging areas between individuals and lower breeding success. These results suggest that there is greater competition between individuals for finite resources in more heterogeneous environments, which comes at a cost to reproduction. Resource hotspots are often considered beneficial, as individuals can learn to exploit them if sufficiently predictable. However, we demonstrate here that such fitness gains can be countered by greater competition in more heterogeneous environments. [ABSTRACT FROM AUTHOR]
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- 2019
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12. Parasitism in early life: environmental conditions shape within-brood variation in responses to infection
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Granroth-Wilding, Hanna M V, Burthe, Sarah J., Lewis, Sue, Reed, Thomas E., Herborn, Katherine A., Newell, Mark A., Takahashi, Emi A., Daunt, Francis, and Cunningham, Emma J A
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Parasite ,Environmental variability ,Ivermectin ,Biology and Microbiology ,Brood conflict ,Host ,Individual differences ,Brood conflict, climate change, environmental variability, host, individual differences, ivermectin, nematode, parasite, seabird, sibling competition ,Climate change ,Sibling competition ,Seabird ,Ecology and Environment ,Nematode - Abstract
Parasites play key ecological and evolutionary roles through the costs they impose on their host. In wild populations, the effect of parasitism is likely to vary considerably with environmental conditions, which may affect the availability of resources to hosts for defense. However, the interaction between parasitism and prevailing conditions is rarely quantified. In addition to environmental variation acting on hosts, individuals are likely to vary in their response to parasitism, and the combined effect of both may increase heterogeneity in host responses. Offspring hierarchies, established by parents in response to uncertain rearing conditions, may be an important source of variation between individuals. Here, we use experimental antiparasite treatment across 5 years of variable conditions to test how annual population productivity (a proxy for environmental conditions) and parasitism interact to affect growth and survival of different brood members in juvenile European shags (Phalacrocorax aristotelis). In control broods, last-hatched chicks had more plastic growth rates, growing faster in more productive years. Older siblings grew at a similar rate in all years. Treatment removed the effect of environment on last-hatched chicks, such that all siblings in treated broods grew at a similar rate across environmental conditions. There were no differences in nematode burden between years or siblings, suggesting that variation in responses arose from intrinsic differences between chicks. Whole-brood growth rate was not affected by treatment, indicating that within-brood differences were driven by a change in resource allocation between siblings rather than a change in overall parental provisioning. We show that gastrointestinal parasites can be a key component of offspring's developmental environment. Our results also demonstrate the value of considering prevailing conditions for our understanding of parasite effects on host life-history traits. Establishing how environmental conditions shape responses to parasitism is important as environmental variability is predicted to increase.
- Published
- 2014
13. Reproductive performance of resident and migrant males, females and pairs in a partially migratory bird.
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Grist, Hannah, Daunt, Francis, Wanless, Sarah, Burthe, Sarah J., Newell, Mark A., Harris, Mike P., Reid, Jane M., and Bouwhuis, Sandra
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MIGRATORY birds , *FEMALES , *MALES , *LIFE , *BIRDS - Abstract
1. Quantifying among-individual variation in life-history strategies and associated variation in reproductive performance and resulting demographic structure, is key to understanding and predicting population dynamics and life-history evolution. Partial migration, where populations comprise a mixture of resident and seasonally migrant individuals, constitutes a dimension of life-history variation that could be associated with substantial variation in reproductive performance. However, such variation has rarely been quantified due to the challenge of measuring reproduction and migration across a sufficient number of seasonally mobile males and females. 2. We used intensive winter (non-breeding season) resightings of colour-ringed adult European shags (Phalacrocorax aristotelis) from a known breeding colony to identify resident and migrant individuals. We tested whether two aspects of annual reproductive performance, brood hatch date and breeding success, differed between resident and migrant males, females and breeding pairs observed across three consecutive winters and breeding seasons. 3. The sex ratios of observed resident and migrant shags did not significantly differ from each other or from 1:1, suggesting that both sexes are partially migratory and that migration was not sex-biased across surveyed areas. 4. Individual resident males and females hatched their broods 6 days earlier and fledged 0.2 more chicks per year than migrant males and females on average. Resident individuals of both sexes therefore had higher breeding success than migrants. 5. Hatch date and breeding success also varied with a pair's joint migratory strategy such that resident-resident pairs hatched their broods 12 days earlier than migrant-migrant pairs and fledged 0.7 more chicks per year on average. However, there was no evidence of assortative pairing with respect to migratory strategy: observed frequencies of migrant-migrant and resident-resident pairs did not differ from those expected given random pairing. 6. These data demonstrate substantial variation in two key aspects of reproductive performance associated with the migratory strategies of males, females and breeding pairs within a partially migratory population. These patterns could reflect direct and/or indirect mechanisms, but imply that individual variation in migratory strategy and variation in pairing among residents and migrants could influence selection on migration and drive complex population and evolutionary dynamics. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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14. Contrasting effects of GPS device and harness attachment on adult survival of Lesser Black-backed Gulls Larus fuscus and Great Skuas Stercorarius skua.
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Thaxter, Chris B., Ross‐Smith, Viola H., Clark, Jacquie A., Clark, Nigel A., Conway, Greg J., Masden, Elizabeth A., Wade, Helen M., Leat, Eliza H. K., Gear, Sheila C., Marsh, Mike, Booth, Chris, Furness, Robert W., Votier, Steve C., Burton, Niall H. K., and Daunt, Francis
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GLOBAL Positioning System ,HARNESSES ,GREAT black-backed gull ,TELEMETRY ,SEA birds - Abstract
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. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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15. Weak large-scale population genetic structure in a philopatric seabird, the European Shag Phalacrocorax aristotelis.
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BARLOW, EMILY J., DAUNT, FRANCIS, WANLESS, SARAH, ÁLVAREZ, DAVID, REID, JANE M., and CAVERS, STEPHEN
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SHAG (Bird) ,BIRDS ,GENETICS ,PHILOPATRY ,MITOCHONDRIAL DNA ,CLUSTER analysis (Statistics) ,BIOLOGICAL divergence - Abstract
Quantifying population genetic structure is fundamental to testing hypotheses regarding gene flow, population divergence and dynamics across large spatial scales. In species with highly mobile life-history stages, where it is unclear whether such movements translate into effective dispersal among discrete philopatric breeding populations, this approach can be particularly effective. We used seven nuclear microsatellite loci and mitochondrial DNA ( ND2) markers to quantify population genetic structure and variation across 20 populations (447 individuals) of one such species, the European Shag, spanning a large geographical range. Despite high breeding philopatry, rare cross-sea movements and recognized subspecies, population genetic structure was weak across both microsatellites and mitochondrial markers. Furthermore, although isolation-by-distance was detected, microsatellite variation provided no evidence that open sea formed a complete barrier to effective dispersal. These data suggest that occasional long-distance, cross-sea movements translate into gene flow across a large spatial scale. Historical factors may also have shaped contemporary genetic structure: cluster analyses of microsatellite data identified three groups, comprising colonies at southern, mid- and northern latitudes, and similar structure was observed at mitochondrial loci. Only one private mitochondrial haplotype was found among subspecies, suggesting that this current taxonomic subdivision may not be mirrored by genetic isolation. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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16. A new method to quantify prey acquisition in diving seabirds using wing stroke frequency.
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Sato, Katsufumi, Daunt, Francis, Watanuki, Yutaka, Takahashi, Akinori, and Wanless, Sarah
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SHAG (Bird) , *PISCIVOROUS birds , *FORAGING behavior , *BIRDS , *CORMORANTS , *ACCELEROMETERS , *SPEED-indicators , *ISLANDS - Abstract
To understand the foraging strategies of free-ranging diving animals, time series information on both foraging effort and foraging success is essential. Theory suggests that wing stroke frequency for aerial flight should be higher in heavier birds. Based on this premise, we developed a new methodology using animal-borne accelerometers to estimate fine-scale temporal changes in body mass of a pursuit-diving, piscivorous seabird, the European shag, Phalacrocorax aristotelis. We hypothesized that variations in body mass determined from changes in wing stroke frequency before and after a series of dives would be related to the amount of prey captured. The estimated net gain in body mass during a foraging trip was highly variable, ranging from -30 to 260 g, values that were extremely similar to food loads obtained from shags on the Isle of May in previous years using water-offloading and nest balances. Load sizes estimated using the wing stroke method were strongly and positively related to both cumulative flight time and return flight time. At the trip level, load size was unrelated to cumulative dive bout duration and the total amount of time spent underwater. However, highly significant relationships were apparent at the individual bout level, with birds showing bigger mass gains following longer dive bouts. Results from this study are therefore extremely encouraging and suggest that changes in body mass determined from changes in wing stroke frequency may provide a reliable method of obtaining short- to medium-term information on foraging effort and success of diving seabirds. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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17. Incorporating density‐dependent regulation into impact assessments for seabirds.
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Merrall, Eve, Green, Jonathan A., Robinson, Leonie A., Butler, Adam, Wood, Matt J., Newell, Mark A., Black, Julie, Daunt, Francis, and Horswill, Catharine
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POPULATION viability analysis , *ENVIRONMENTAL impact analysis , *POPULATION dynamics , *PRECAUTIONARY principle , *WEIBULL distribution - Abstract
Many industries are required to perform population viability analysis (PVA) during the consenting process for new developments to establish potential impacts on protected populations. However, these assessments rarely account for density‐dependent regulation of demographic rates. Excluding density‐dependent regulation from PVA‐based impact assessments is often assumed to provide a maximum estimate of impact and therefore offer a precautionary approach to assessment. However, there is also concern that this practice may unnecessarily impede the development of important industries, such as offshore renewable energy. In this study, we assess density‐dependent regulation of breeding success in 31 populations of seabird. We then quantify the strength and form of this regulation using eight different formulations. Finally, we use PVA to examine how each formulation influences the recreation of observed dynamics (i.e. model validation), as well as the predicted absolute and relative population response to an extrinsic threat (i.e. model projection). We found evidence of both negative (n = 3) and positive (n = 5) regulation of seabird breeding success. In populations exhibiting negative regulation, excluding density‐dependent regulation from PVA‐based impact assessment allowed uncontrolled population growth, such that model outcomes became biologically implausible. By contrast, in populations exhibiting positive regulation, excluding density‐dependent regulation provided an appropriate reconstruction of observed dynamics, but population decline was underestimated in some populations. We find that multiple formulations of density dependence perform comparably at the detection, validation and projection stages of analysis. However, we tentatively recommend using a log‐linear or Weibull distribution to describe density‐dependent regulation of seabird breeding success in impact assessments to balance accuracy with caution. Finally, we show that relative PVA metrics of impact assessment cannot necessarily be used to overcome PVA misspecification by assuming density independence in positively regulated populations. Synthesis and applications: We suggest that a density‐dependent approach when performing PVA‐based assessments for seabird populations will prevent biologically unrealistic, unconstrained population growth and therefore ensure meaningful PVA metrics in populations experiencing negative regulation. It will also maintain a precautionary approach for populations experiencing positive regulation, crucial when estimating impacts for these more vulnerable populations. These conclusions have immediate international application within the consenting processes for marine industries. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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18. Effects of body size, sex, parental care and moult strategies on auk diving behaviour outside the breeding season.
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Dunn, Ruth E., Wanless, Sarah, Green, Jonathan A., Harris, Michael P., and Daunt, Francis
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BODY size ,MOLTING ,POPULATION dynamics ,ANIMAL sexual behavior ,BEHAVIOR - Abstract
Information on seabird foraging behaviour outside the breeding season is currently limited. This knowledge gap is critical as this period is energetically demanding due to post‐fledging parental care, feather moult and changing environmental conditions. Based on species' body size, post‐fledging parental strategy and primary moult schedule we tested predictions for key aspects of foraging behaviour (maximum dive depth (MDD), daily time submerged (DTS) and diurnal dive activity (DDA)) using dive depth data collected from three seabird species (common guillemot Uria aalge, razorbill Alca torda and Atlantic puffin Fratercula arctica) from the end of the breeding season (July) to mid‐winter (January). We found partial support for predictions associated with body size; guillemots had greater MDD than razorbills but MDD did not differ between razorbills and puffins, despite the former being 35% heavier. In accordance with sexual monomorphism in all three species, MDD did not differ overall between the sexes. However, in guillemots and razorbills there were sex‐specific differences, such that male guillemots made deeper dives than females, and males of both species had higher DTS. In contrast, there were no marked sex differences in dive behaviour of puffins in July and August in accordance with their lack of post‐fledging parental care and variable moult schedule. We found support for the prediction that diving effort would be greater in mid‐winter compared to the period after the breeding season. Despite reduced daylight in mid‐winter, this increase in DTS occurred predominantly during the day and only guillemots appeared to dive nocturnally to any great extent. In comparison to diving behaviour of these species recorded during the breeding season, MDD was shallower and DTS was greater during the non‐breeding period. Such differences in diving behaviour during the post‐breeding period are relevant when identifying potential energetic bottlenecks, known to be key drivers of seabird population dynamics. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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19. Among-year and within-population variation in foraging distribution of European shags Phalacrocorax aristotelis over two decades: Implications for marine spatial planning.
- Author
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Bogdanova, Maria I., Wanless, Sarah, Harris, Michael P., Lindström, Jan, Butler, Adam, Newell, Mark A., Sato, Katsufumi, Watanuki, Yutaka, Parsons, Matt, and Daunt, Francis
- Subjects
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BIRD populations , *SHAG (Bird) , *OCEAN zoning , *BIRD food , *SEXUAL behavior in birds , *FORAGING behavior - Abstract
Highlights: [•] We identified key foraging areas of breeding European shags over a 23-year period. [•] 8years’ data captured over 90% of the foraging area used during the study period. [•] Over 60% of this area was captured with just 2years’ data. [•] Foraging range varied with sex, environmental conditions and population density. [•] Foraging locations of birds from different sub-colonies were spatially segregated. [Copyright &y& Elsevier]
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- 2014
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20. Breeding phenology and its effects on reproductive success in seabirds
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Keogan, Katharine, Phillimore, Albert, Daunt, Francis, and Walling, Craig
- Subjects
meta-analysis ,seabird ,Trophic mismatch ,phenology - Abstract
The timing of reproduction is important for fitness, and has been used to measure the effect of widespread environmental change across ecosystems globally. Across trophic levels, species occupying higher levels of a food web are generally adjusting their timing of breeding in response to environmental change at a slower rate than their prey (Poloczanska et al., 2013; Thackeray et al., 2010). This may lead to a trophic mismatch between the energy requirements of consumers and the timing of peak availability of resources during the crucial reproductive period, potentially negatively impacting on fitness. However, the effects of environmental change have not been uniform across populations, species, or regions of the world. This makes it difficult to predict how different populations will adjust their response to environmental change and the consequences of this for fitness. Marine species are generally underrepresented in studies of environmental change, and seabirds are a group of marine organisms that may be particularly at risk. They generally occupy higher trophic levels, are long-lived, and reproduce slowly, meaning they may lack the evolutionary capacity to adapt if the timing of key resources shifts rapidly under climate change. However, the disconnected nature of previous studies of the trends and drivers of seabird breeding phenology and the effects of trophic mismatch on seabird fitness has precluded a global understanding of the extent to which seabirds will respond to climate-mediated environmental change. In this thesis, I make use of resources contributed by a global network of collaborators to first establish the global average trends in seabird breeding phenology over time and in response to sea surface temperature. I then identify which seabird populations may be at higher risk of mismatch with prey by characterising sources of variance around these phenological trends (e.g. due to differences in phylogeny, biogeographic region, or life history traits). I go on to explore the scales at which phenology is correlated across breeding North Atlantic seabird populations, to understand whether it is likely that phenology is driven by conditions experienced by populations at the breeding grounds, overwintering locations, or across multiple spatial scales. Finally, I examine the fitness consequences of trophic mismatch between the resource and consumer in two ways. I first use 30+ years of data from the long-term monitored population of European shags Phalacrocorax aristotelis on the Isle of May, Scotland, to identify the impact of trophic mismatch on population- and individual-level fitness over time and in relation to changes in SST and diet. My final data chapter expands the focus on the effects of mismatch on population level breeding success back to the global scale. In the absence of detailed information on prey availability and phenology, I develop on an existing framework that allows us to predict when phenological change may impact on population level fitness to identify whether trophic mismatch is both present in a population and getting worse over time. I use these criteria to compare relationships across populations, regions and life history traits to identify the prevalence of trophic mismatch across populations on a global scale.
- Published
- 2019
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