Foraging in the Anthropocene: Feeding plasticity of an opportunistic predator revealed by long term monitoring

For centuries, human activities have altered the population dynamics of wildlife. New anthropogenic food sources provide a predictable and abundant food supply that often induces very significant changes in the size, distribution, and behaviour of many populations, with ultimate consequences on the structure and functioning of natural ecosystems. Here, we combine historical and contemporary feather samples of a population of a su-perabundant, opportunistic predator, the yellow-legged gull Larus michahellis, to assess its trophic ecology and relate it to human activities in the long term. Dietary assessments were based on stable isotope analysis of carbon, nitrogen, and sulphur (δ13C, δ15N and δ34S), and were conducted through three end-point (marine prey, waste from landfills-slaughterhouses, and terrestrial invertebrates) Bayesian mixing models. Our results suggest that gulls’ diet showed a progressive decrease in the consumption of marine prey throughout the most recent period (late 20th century onwards), linked to an increase in the consumption of meat waste and small terrestrial invertebrates. Reported dietary changes over the sampling period correlated positively with the availability of marine resources around the breeding area. We provide evidence suggesting that the ability of gulls to exploit efficiently diverse anthropogenic food subsidies likely resulted in the exponential demographic increase of this population throughout the 20th century. In addition, current regulations affecting the availability of these food resources (e.g., fishing discards and landfill waste) likely reversed this trend over the last decade. Long-term evidence of population trophic plasticity, like the one we present here, is essential to implement and support management and conservation actions that limit the availability of anthropogenic resources, especially when it comes to superabundant, problematic species.info:eu-repo/semantics/publishedVersio

Foraging in the Anthropocene: Feeding plasticity of an opportunistic predator revealed by long term monitoring

For centuries, human activities have altered the population dynamics of wildlife. New anthropogenic food sources provide a predictable and abundant food supply that often induces very significant changes in the size, distribution, and behaviour of many populations, with ultimate consequences on the structure and functioning of natural ecosystems. Here, we combine historical and contemporary feather samples of a population of a superabundant, opportunistic predator, the yellow-legged gull Larus michahellis, to assess its trophic ecology and relate it to human activities in the long term. Dietary assessments were based on stable isotope analysis of carbon, nitrogen, and sulphur (δ13C, δ15N and δ34S), and were conducted through three end-point (marine prey, waste from landfills-slaughterhouses, and terrestrial invertebrates) Bayesian mixing models. Our results suggest that gulls' diet showed a progressive decrease in the consumption of marine prey throughout the most recent period (late 20th century onwards), linked to an increase in the consumption of meat waste and small terrestrial invertebrates. Reported dietary changes over the sampling period correlated positively with the availability of marine resources around the breeding area. We provide evidence suggesting that the ability of gulls to exploit efficiently diverse anthropogenic food subsidies likely resulted in the exponential demographic increase of this population throughout the 20th century. In addition, current regulations affecting the availability of these food resources (e.g., fishing discards and landfill waste) likely reversed this trend over the last decade. Long-term evidence of population trophic plasticity, like the one we present here, is essential to implement and support management and conservation actions that limit the availability of anthropogenic resources, especially when it comes to superabundant, problematic species

Toxoplasma gondii infection in seagull chicks is related to the consumption of freshwater food resources

Understanding the spread of Toxoplasma gondii ( T . gondii ) in wild birds, particularly in those with opportunistic feeding behavior, is of interest for elucidating the epidemiological involvement of these birds in the maintenance and dissemination of the parasite. Overall, from 2009 to 2011, we collected sera from 525 seagull chicks (Yellow-legged gull ( Larus michahellis ) and Audouin ' s gull ( L . audouinii )) from 6 breeding colonies in Spain and tested them using the modified agglutination test (MAT) for the presence of antibodies against T . gondii . Chick age was estimated from bill length. Main food source of seagull chicks was evaluated using stable isotope analyses from growing scapular feathers. Overall T . gondii seroprevalence was 21.0% (IC 95% 17.5 - 24.4). A generalized linear mixed-effects model indicated that year (2009) and food source (freshwater) were risk factors associated to the individual risk of infection by T. gondii, while age (days) was close to significance. Freshwa- ter food origin was related to the highest seroprevalence levels, followed by marine origin, supporting freshwater and sewages as important routes of dispersion of T . gondii . Year dif- ferences could indicate fluctuating rates of exposure of seagull chicks to T . gondii . Age ran- ged from 4 to 30 days and seropositivity tended to increase with age (P = 0.07), supporting that seropositivity is related to T. gondii infection rather than to maternal transfer of antibod- ies, which in gulls is known to sharply decrease with chick age. This study is the first to report T . gondii antibodies in Yellow-legged and Audouin ' s gulls, thereby extending the range of intermediate hosts for this parasite and underscoring the complexity of its epidemiolog

track2KBA: An R package for identifying important sites for biodiversity from tracking data

Identifying important sites for biodiversity is vital for conservation and management. However, there is a lack of accessible, easily applied tools that enable practitioners to delineate important sites for highly mobile species using established criteria. We introduce the R package ‘track2KBA’, a tool to identify important sites at the population level using tracking data from individual animals based on three key steps: (a) identifying individual core areas, (b) assessing population-level representativeness of the sample and (c) quantifying spatial overlap among individuals and scaling up to the population. We describe package functionality and exemplify its application using tracking data from three taxa in contrasting environments: a seal, a marine turtle and a migratory land bird. This tool facilitates the delineation of sites of ecological relevance for diverse taxa and provides output useful for assessing their importance to a population or species, as in the Key Biodiversity Area (KBA) Standard. As such, ‘track2KBA’ can contribute directly to conservation planning at global and regional levels

Global political responsibility for the conservation of albatrosses and large petrels

Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm

Methods to detect spatial biases in tracking studies caused by differential representativeness of individuals, populations and time

Este artículo contiene 20 páginas, 6 figuras, 4 tablas.Aim: Over the last decades, the study of movement through tracking data has grown exceeding the expectations of movement ecologists. This has posed new challenges, specifically when using individual tracking data to infer higher- level distributions (e.g. population and species). Sources of variability such as individual site fidelity (ISF), en-vironmental stochasticity over time, and space-use variability across species ranges must be considered, and their effects identified and corrected, to produce accurate estimates of spatial distribution using tracking data. Innovation: We developed R functions to detect the effect of these sources of vari-ability in the distribution of animal groups when inferred from individual tracking data. These procedures can be adapted for their use in most tracking datasets and tracking techniques. We demonstrated our procedures with simulated datasets and showed their applicability on a real-world dataset containing 1346 year- round migratory trips from 805 individuals of three closely related seabird species breeding in 34 colonies in the Mediterranean Sea and the Atlantic Ocean, spanning 10 years. We detected an effect of ISF in one of the colonies, but no effect of the environmental stochasticity on the distribution of birds for any of the species. We also identified among-colony variability in nonbreeding space use for one species, with significant effects of popu-lation size and longitude. Main conclusions: This work provides a useful, much- needed tool for researchers using animal tracking data to model species distributions or establish conservation measures. This methodology may be applied in studies using individual tracking data to accurately infer the distribution of a population or species and support the deline-ation of important areas for conservation based on tracking data. This step, designed to precede any analysis, has become increasingly relevant with the proliferation of studies using large tracking datasets that has accompanied the globalization process in science driving collaborations and tracking data sharing initiatives.We thank the following institutions for funding: EU H2020 pro-gramme through grant 634495; Seventh Framework Programme (Research Executive Agency) through Marie Curie Career Integration Grant 618841 (FP7-PEOPLE-2013- CIG); ESFRI LifeWatch Project; LIFE programme of the European Commission through projects LIFE10 NAT/MT090 and LIFE11 NAT/IT/000093; Ministerio de Ciencia e Innovación/Ministerio de Economia y Competitividad (Spain) through projects CGL2009- 11278/BOS, CGL2013-42585-P, C G L 2 0 1 3 - 4 2 2 0 3 - R , C G L 2 0 16 - 7 8 5 3 0 - R a n d C G L 2 0 17- 8 52 10 - P ; Organismo Autónomo de Parques Nacionales (Spain) through pro-ject 1248/2014; Fundação para a Ciência e a Tecnologia (MCTES, Portugal) through projects MARE-UID/MAR/04292/2019; IF/00502/2013/CP1186/CT0003, PTDC/BIA-ANM/3743/2014, PTDC/MAR-PRO/0929/2014, UID/AMB/50017/2019 and UIDP/50017/2020 + UIDB/50017/2020 (to CESAM); Office Français de la Biodiversité (France), through the Programme PACOMM, Natura2000 en mer; Hellenic Bird Ringing Centre; MSDEC (Malta). VMP was supported by pre-doctoral contract BES-2014- 068025 of the Spanish Ministerio de Industria, Economía y Competitividad; MM by grant SFRH/BPD/47047/2008 from the Portuguese Foundation for Science and Technology; JMRG by Ph.D. grant AP2009-2163 from the Spanish Ministerio de Educación; GDO and MMü by Ornis italica and by the Regione Siciliana and Assessorato Risorse Agricole e Alimentari thoriugh a grant to the Ringing Unit of Palermo; VHP by grant SFRH/BPD/85024/2012 from the Portuguese Foundation for Science and Technology; VN by grant SFRH/BPD/88914/2012 from the Portuguese Foundation for Science and Technology; and JN by the Spanish National Programme Ramón y Cajal (RYC-2015- 17809); GK and SX were partially funded by the Operational Program “Environment and Sustainable Development” (EPPERAA) of the National Strategic Reference Framework (NSRF) 2007-2013, co- financed by the ERDF and Greek EDP; FdF by a Ph.D. grant from the Coordination for the Improvement of Higher Education Personnel (CAPES—Brazilian government agency; Bex Process 1307/13-4); ZZ by a PhD grant from the University of Barcelona (APIF/2012); MCF by a PhD grant from the University of Barcelona; and RR by post-doctoral contracts of the PLEAMAR programme from MINECO and Fundación Biodiversidad (2017/2349), and Ministerio de Ciencia, in-novación y Universidades (RYC-2017- 22055). This publication is part of the project I+D+i/PID2020-117155GB-I00, funded by MCIN/ AEI/10.13039/501100011033.Peer reviewe

Multi-colony approaches to study migratory and foraging strategies in pelagic seabirds

[eng] Movement is a widespread characteristic in the animal kingdom —occurring at many spatiotemporal scales— with consequences at an individual, population, species, and even ecosystem level. It is a very diverse character, with many different drivers that stem from the way in which individuals interact with their environment. Of these, one of the most important is the distribution of resources, particularly for migratory and foraging movements. In migration, the search for an optimal environment involves movement at large spatiotemporal scales, following seasonal changes in resource distribution. In foraging movements, the search for resources happens at small spatiotemporal scales, and involves different strategies to optimise the search and capture of food, including the ability to obtain foraging cues from conspecifics. In seabirds, movement —at large and local scales— has deep repercussions in their life-history traits, evolutionary history, morphology, physiology and behaviour, which makes them a very valuable study group to understand the role, the causes and consequences of migratory and foraging movements in the ecology of marine top- predators. The study of migratory and foraging movements has been revolutionised by the development of smaller, cheaper and better tracking devices, promoting multi-colony, population and even species approaches to the study of animal movement, but which also come with a set of methodological challenges that have to be addressed in order to make unbiased inferences of space and habitat use at population or species level from individual movement data. In this thesis, we develop methods to test the possible biases introduced by the use of individual tracking data to infer distribution at a population or species level. we then apply these tools to a multi-colony dataset of non-breeding locations of Cory’s (Calonectris borealis), Scopoli’s (C. diomedea) and Cape Verde (C. edwardsii) shearwaters, to study their migratory connectivity and non-breeding habitat segregation at the colony, population and species level. Lastly, we apply state-of-the-art spatial models to study foraging distributions of three neighbouring colonies of Cory’s shearwaters, detect the segregation among them and unravel the environmental and behavioural drivers of this segregation. I developed several functions in the R environment aimed at the detection of the effects of individual site fidelity and temporal variability in the inference of spatial use at a colony or population level, and to calculate the degree in which the movements of a single population can be representative of those of the entire species. These tools are applicable to individual movement data regardless of the species or tracking device. we also used these tools to demonstrate the spatial and ecological segregation between the non-breeding distributions of three taxa of Calonectris shearwaters studied, as well as detecting a stronger degree of migratory connectivity at a population than at a colony level, indicating that individuals of different colonies within a population mix in the non-breeding areas, but birds from different populations do not, which has important implications for their population dynamics and for their conservation and management. Lastly, we demonstrated segregation among the foraging distributions of three neighbouring colonies of Cory’s shearwaters, both in the waters surrounding the colony and in distant, foraging grounds, finding evidences of both environmental and behavioural drivers behind this segregation, and suggesting a mechanism through which transfer of information between individuals can be shaping the distributions of foraging seabirds. The results of this thesis provide relevant tools for the field of movement ecology, as they can be used for analysing movements of mobile species, regardless of species, tracking device or spatiotemporal scale. In addition, they are relevant for the field of seabird ecology as they provide insights into the causes of space and habitat use in long-ranging pelagic seabirds.[cat] El moviment és una característica omnipresent en el regne animal, a les més diverses escales espacio-temporals i amb conseqüències a diferents nivells (individual,. poblacional, específic i fins i tot ecosistèmic). La força impulsora del moviment més predominant i generalitzada és distribució dels recursos en el medi, important tant a gran escala (moviments migratoris) com en els moviments diaris de recerca d’aliment a escala petita. En les aus marines en particular, el moviment té repercussions profundes en les seves característiques morfològiques i de comportament, en la seva història de vida, i la seva història evolutiva. El desenvolupament de dispositius de seguiment més petits, barats i precisos ha promocionat la proliferació d’estudis del moviment animal des d’un punt de vista multi- colònia, de població i fins i tot d’espècie. En aquesta tesi, desenvolupo diferents funcions per testar els biaixos introduïts en l’estudi del moviment, a través de dades de seguiment individual, a nivell de població o espècie. Posteriorment, utilitzo aquestes eines per a analitzar la connectivitat migratòria i la segregació dels hàbitats d’hivernada, des d’un punt de vista multi-colònia, de les baldrigues cendroses de l’Atlàntic (Calonectris borealis), del Mediterrani (C. diomedea), i de Cap Verd (C. edwardsii). Per últim, aplico un mètode innovador de modelatge espacial per a estudiar les distribucions d’alimentació de baldrigues cendroses de l’Atlàntic criant en tres colònies veïnes, per detectar-ne la segregació i descobrir-ne les causes, tant ambientals com comportamentals, incloent com els diferents mecanismes de transferència d’informació entre individus poden afectar a aquestes distribucions. Els resultats d’aquesta tesi tenen rellevància per a la ecologia del moviment en general, ja que són aplicables a dades de moviment individual de qualsevol espècie, independentment de l’aparell de seguiment utilitzat, i en el camp de l’ecologia de les aus marines, ja que proporciona nous coneixements sobre els diferents factors afectant la distribució i l’ús de l’espai, tant durant la cria com durant la hivernada, en aus pelàgiques

Foraging in the Anthropocene: Feeding plasticity of an opportunistic predator revealed by long term monitoring

10 pages, 4 figures, 4 tables, supplementary data https://doi.org/10.1016/j.ecolind.2021.107943For centuries, human activities have altered the population dynamics of wildlife. New anthropogenic food sources provide a predictable and abundant food supply that often induces very significant changes in the size, distribution, and behaviour of many populations, with ultimate consequences on the structure and functioning of natural ecosystems. Here, we combine historical and contemporary feather samples of a population of a superabundant, opportunistic predator, the yellow-legged gull Larus michahellis, to assess its trophic ecology and relate it to human activities in the long term. Dietary assessments were based on stable isotope analysis of carbon, nitrogen, and sulphur (δ13C, δ15N and δ34S), and were conducted through three end-point (marine prey, waste from landfills-slaughterhouses, and terrestrial invertebrates) Bayesian mixing models. Our results suggest that gulls’ diet showed a progressive decrease in the consumption of marine prey throughout the most recent period (late 20th century onwards), linked to an increase in the consumption of meat waste and small terrestrial invertebrates. Reported dietary changes over the sampling period correlated positively with the availability of marine resources around the breeding area. We provide evidence suggesting that the ability of gulls to exploit efficiently diverse anthropogenic food subsidies likely resulted in the exponential demographic increase of this population throughout the 20th century. In addition, current regulations affecting the availability of these food resources (e.g., fishing discards and landfill waste) likely reversed this trend over the last decade. Long-term evidence of population trophic plasticity, like the one we present here, is essential to implement and support management and conservation actions that limit the availability of anthropogenic resources, especially when it comes to superabundant, problematic speciesThis work was supported by FAU2008-00012-C02-01 from INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Spain), CGL2009-11278/BOS from Ministerio de Ciencia e Innovación from the Spanish Government, Fondos FEDER, 2017/2349 of the PLEAMAR programme with the collaboration of the Fundación Biodiversidad, from the Ministerio para la Transición Ecológica (Spain), cofounded by the EMFF (European Union), and REN2003-07050 Aplicación de biomarcadores a la gestión de una especie problemática (Larus cachinnans). CERCA Programme from Generalitat de Catalunya is also acknowledged. RR was supported by a postdoctoral Ramón y Cajal contract (RYC-2017-22055) and VMP was supported by a pre-doctoral contract BES-2014-068025 both from the Spanish Ministerio de Economía, Industria y CompetitividadWith the institutional support of the ‘Severo OchoaCentre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe

Multi-isotopic assessments of spatio-temporal variability of diet: the case of two sympatric gulls in the Western Mediterranean.

In predator populations, changes in foraging behaviour in response to spatio-temporal variability of prey are expected. Prey depletion might cause trophic niche widening in generalist species, but not in specialists, which are expected to increase their foraging effort without diet shifts. In sympatric species feeding on similar resources, reduced food availability can increase interspecific competition and cause trophic niche segregation. To understand these processes, we studied the spatio-temporal variability in diet and niche width in 2 sympatric gull species, the yellow-legged gull Larus michahellis and Audouin's gull Ichthyaetus audouinii, which have experienced exponential growth in recent decades due to an increase in anthropogenic food subsidies. We sampled feathers from chicks of both species in several colonies along the western Mediterranean from 2009 to 2011 and performed stable isotope analysis of carbon, nitrogen and sulphur on these feathers. Bayesian modelling shows that both species displayed opportunistic behaviour if different types of resources were available, but could also narrow their trophic niche if 1 resource was abundant. We also provide evidence of trophic segregation between the 2 gull species, suggesting the occurrence of interspecific competition for food. Our meta-population approach provides a comprehensive view of the trophic ecology and the competitive interactions of these gull species. We emphasize the usefulness of 3-dimensional isotope analyses to correctly assess spatio-temporal variability in trophic behaviour of predator species, revealing differences that would remain hidden in single population studies or when using only the isotopic ratios of 2 elements

Disentangling environmental from individual factors in isotopic ecology: A 17-year longitudinal study in a long-lived seabird exploiting the Canary Current

Este artículo contiene 13 páginas, 5 figuras, 3 tablasDespite its importance for ecology and conservation, we are still far from understanding how environmental variability interacts with intrinsic factors and individual specialization to determine trophic strategies of longlived taxa, mostly due to difficulties in studying the same animals over extended periods. Here, by yearly consistently sampling the first primary feather of 99 Cory’s shearwaters (Calonectris borealis) foraging in the Canary Current (CC) upwelling ecosystem, we provide robust evidence on the individual changes of isotopic ratios of carbon (δ13C) and nitrogen (δ15N) over 17 years. We reported a slight longitudinal decline of δ13C values throughout 2001–2017, even after being adjusted for the marine Suess effect (linked to the increasing CO2 emissions). Although CC is often considered to be overexploited by industrial fisheries, we could not detect a decline in Cory’s shearwater trophic level indicating a change in the trophic web structuring, as revealed by δ15N. We found negative correlations of δ13C and δ15N with the CC upwelling intensity, indicating annual variability in baseline isotopic levels propagates through the food chain and it integrates in predators’ tissues. Low individual repeatabilities among years at population level indicates low long-term specialization, suggesting long-lived individuals foraging on highly productive areas can adjust their foraging strategies and diet according to environmental variability. However, individual-level repeatabilities in isotopic values showed a range of individual specialization within the population, indicating most individuals are generalist and a few of them highly specialized. First, although we found a clear influence of the upwelling intensity on the trophic ecology of birds, we could not detect any temporal trend in the trophic level of the Cory’s shearwater population, suggesting a stability in the structure of the pelagic food web of the CC over the last two decades despite the fishing pressure. Second, the existence of individual specialization highlights the importance of considering the repeated sampling of individuals to detect small changes in the trophic ecology of a population. Finally, the coexistence of individuals with different degree of specialization (from extremely flexible [generalists] to highly consistent individuals [specialists]) within a population can have deep implications on the capacity of populations to cope with environmental change.We also thank the Spanish Ministry of Economy, Industry and Competitiveness (MINECO; CGL2009-11278/BOS, CGL2013-42585-P, CGL2016-78530-R), FEDER Funds and the European Union (FP7- PEOPLE-2013-CIG, 618841) for funding this research, and Pascual Calabuig, Loly Estévez, Joan Navarro, Verónica Cortés, Raphaël Coppola, Marianne Bosch, Joan Ferrer, Fernanda De Felipe and many students for their help at various stages of the work. RR was supported by a postdoctoral Ramón y Cajal contract of the Spanish MINECO (RYC- 2017-22055), JMRG was supported by Spanish Ministry of Education, Culture and Sports FPU program (AP2009-2163), VMP was supported by a predoctoral contract of the Spanish MINECO programme for the training of research staff (BES-2014-068025), and ZZ was supported by a PhD grant of University of Barcelona (APIF 2012).Peer reviewe