Year-round individual specialization in the feeding ecology of a long-lived seabird

Many generalist species are composed of individuals varying in the size of their realized niches within a population. To understand the underlying causes and implications of this phenomenon, repeated samplings on the same individuals subjected to different environmental conditions are needed. Here, we studied individual specialization of feeding strategies in breeding and non-breeding grounds of Cory's shearwaters (Calonectris borealis) for 2-8 years, and its relationship with fitness. Individuals were relatively flexible in non-breeding destinations, but specialized in diet, habitat use and daily activity across years. Daily activity was also consistent throughout the year for the same individual, suggesting that it is driven by individual constraints, whereas individual diet and habitat use changed between breeding and non-breeding grounds, indicating that these specializations may be learned at each area. Moreover, individuals that were intermediate specialized in their diet tended to show higher breeding success than those with weakly and highly specialized diets, suggesting stabilizing selection. Overall, this study suggests that the development of individual specialization is more flexible than previously thought, i.e. it emerges under specific environmental conditions and can develop differently when environmental conditions vary. However, once established, individual specialization may compromise the ability of individuals to cope with environmental stochasticity

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

Movement ecology in pelagic seabirds

[eng] Movement is a fundamental component of behaviour and thus both are inextricably linked. Variation in movement patterns usually reflects different behaviours, including those most glaring, such as foraging, dispersal, migration, social interaction, mate search or escaping from predators. The way individuals allocate their time budget to different behaviours within circadian rhythm and over the annual life cycle will ultimately provide knowledge about evolutionary processes and adaptive capacity, also important to proper conservation actions of endangered species. Among highly mobile marine megafauna, seabirds represent suitable model species to address key questions about movement and behaviour. The study of year-round movements of seabirds has been addressed over the last 20 years with the wide deployment of light-level geolocators equipped with saltwater immersion sensors. However, wet-dry data provided by such loggers seem underused so far despite their usefulness to provide important insights on a variety of dimensions of seabird ecology. The main aim of this thesis was to provide new insights into the factors shaping seabird behaviour. The thesis encompasses several aspects of seabird at-sea ecology of 4 different species spread over the Atlantic Ocean: Boyd’s shearwater (Puffinus boydi), Common tern (Sterna hirundo), Atlantic petrel (Pterodroma incerta) and Cory’s shearwater (Calonectris borealis). In Chapter 1 we reveal the timing of major events over the annual life cycle, migratory routes and place on the map the non-breeding areas of a little-known tropical seabird endemic to Cape Verde Islands, the Boyd’s Shearwater. We show that Boyd's shearwaters perform longitudinal migrations to the oligotrophic central North Atlantic Ocean for the non-breeding season, in contrast with closely-related taxa that rely on most productive waters. In Chapter 2, we show that Common terns breeding in continental Europe spread over the West African coast for wintering, but females winter further north and use offshore waters whereas males winter further south and remain nearby the coastline. Behavioural budgets of Common terns were shaped within circadian and circa-annual rhythms. In Chapter 3 we describe in detail the phenology of the Atlantic petrel, showing that breeding success likely shapes the timing of major life-history events and behavioural patterns year round. We did find evidence of carry-over effects, since failed breeders advanced their post-breeding migration, remained longer in the wintering area, and advanced pre-breeding migration comparing to successful breeders. Breeding success did not affect the selection of wintering areas, as all birds relied on the South American shelf slope during different stages of the annual cycle. In Chapter 4, we demonstrate how geolocator-immersion loggers constitute a powerful and irreplaceable source of information to study seabird behaviour. We present a novel approach to infer a diverse array of behaviours based uniquely on wet-dry data, built upon a set of state-of-the-art unsupervised machine learning algorithms that reduce multidimensional data to a bidimensional behavioural space, from which different behaviours can be drawn. We applied the protocol on wet-dry data from Cory’s shearwater. Through these means, we can inspect in great detail and from manifold perspectives the behavioural patterns at individual and population level, highlighting how seasonal constraints shape behavioural budgets and behavioural strategies. We use data visualization tools such as actograms and behavioural landscapes to get new insights, highlighting that such tools constitute an effective method to visualize behaviour of seabirds inferred from wet-dry data from manifold perspectives. Geolocator-immersion sensors currently remain as the most cost-effective balanced tracking devices to track seabird species over the entire annual cycle while ensuring the welfare of tagged individuals. Thus, results compiled in this thesis should encourage researchers to incorporate the use wet-dry data within hypothesis-driven frameworks, which surely would contribute to increase our knowledge of seabird ecology at sea.[spa] El movimiento es un componente fundamental del comportamiento animal, estando ambos íntimamente entrelazados. Variaciones en los patrones de movimiento normalmente reflejan cambios de comportamiento, incluyendo aquellos más conspicuos como la búsqueda de alimento, la dispersión, la migración, las interacciones sociales, la búsqueda de pareja o la huida ante depredadores. La forma en la que los patrones comportamentales se ajustan en el tiempo de acuerdo a los ritmos circadianos y a lo largo del ciclo anual puede ayudarnos a entender, en última instancia, los procesos evolutivos y la capacidad de adaptación de las poblaciones animales, algo también importante de cara al desarrollo de medidas de conservación de especies amenazadas. Las aves marinas representan un modelo especialmente adecuado para el estudio de la ecología comportamental y del movimiento. Estudiar los movimientos de las aves marinas en mar abierto ha sido posible en las dos últimas décadas gracias a la normalización en el uso de geolocalizadores por niveles de luz. Aunque buena parte de los modelos de geolocalizador es capaz de registrar datos de conductividad en agua salada (seco/húmedo), esta información parece infrautilizada a la luz de la literatura publicada. Sin embargo, los datos de conductividad son enormemente útiles para el estudio de multitud de aspectos sobre la ecología de las aves marinas. Esta tesis aborda diferentes aspectos de la ecología en mar abierto de 4 especies de aves marinas del océano Atlántico: la pardela chica de Cabo Verde (Puffinus boydi), el charrán común (Sterna hirundo), el petrel atlántico (Pterodroma incerta) y la pardela cenicienta (Calonectris borealis). En el Capítulo 1 revelamos la fenología, rutas migratorias y área de invernada de una especie tropical de pequeño tamaño, la pardela de Cabo Verde, endémica de dicho archipiélago. A diferencia de especies cercanas, los individuos de esta especie realizan una migración longitudinal hasta las aguas oligotróficas del centro del Atlántico Norte. En el Capítulo 2, mostramos que los charranes comunes que crían en Europa migran hasta la costa oeste de África para invernar, aunque las hembras se quedan más al norte y en ambientes más marinos, y los machos más al sur y en ambientes costeros. El comportamiento en ambos sexos parece regulado por ritmos circadianos y anuales. En el Capítulo 3, desgranamos la fenología del petrel Atlántico, una especie endémica del archipiélago de Tristán da Cunha, mostrando que el éxito reproductor probablemente moldea la sucesión de eventos fenológicos y los patrones de comportamiento. Incluso encontramos evidencias de efectos arrastrados, puesto que los animales que fracasaron en la cría adelantaron la migración, permanecieron más tiempo en la zona de invernada, y retornaron antes a las colonias de cría. Tanto los animales que tuvieron éxito como los que fracasaron en la cría invernaron en aguas de la plataforma continental de América del Sur y Patagonia. En el Capítulo 4, presentamos un nuevo protocolo analítico basado en algoritmos de aprendizaje automático que utiliza únicamente datos de conductividad. Mediante su aplicación sobre datos de pardelas cenicientas, demostramos que los datos de conductividad constituyen una poderosa herramienta para el estudio de las aves marinas, permitiendo desglosar a un nivel sin precedentes su comportamiento a diversas escalas: espacial (de viajes cortos a migraciones anuales), temporal (de días a años) y poblacional (de individuos a poblaciones). El análisis también nos permite resaltar los diferentes elementos que moldean el comportamiento animal a diferentes escalas temporales, utilizando para ellos potentes herramientas de visualización de datos como los actogramas. El conjunto de resultados expuestos en esta tesis debe alentar a los investigadores a utilizar más frecuentemente los datos de conductividad, lo cual contribuiría a aumentar nuestro conocimiento sobre la ecología de las aves marinas

Movement ecology in pelagic seabirds

Movement is a fundamental component of behaviour and thus both are inextricably linked. Variation in movement patterns usually reflects different behaviours, including those most glaring, such as foraging, dispersal, migration, social interaction, mate search or escaping from predators. The way individuals allocate their time budget to different behaviours within circadian rhythm and over the annual life cycle will ultimately provide knowledge about evolutionary processes and adaptive capacity, also important to proper conservation actions of endangered species. Among highly mobile marine megafauna, seabirds represent suitable model species to address key questions about movement and behaviour. The study of year-round movements of seabirds has been addressed over the last 20 years with the wide deployment of light-level geolocators equipped with saltwater immersion sensors. However, wet-dry data provided by such loggers seem underused so far despite their usefulness to provide important insights on a variety of dimensions of seabird ecology. The main aim of this thesis was to provide new insights into the factors shaping seabird behaviour. The thesis encompasses several aspects of seabird at-sea ecology of 4 different species spread over the Atlantic Ocean: Boyd’s shearwater (Puffinus boydi), Common tern (Sterna hirundo), Atlantic petrel (Pterodroma incerta) and Cory’s shearwater (Calonectris borealis). In Chapter 1 we reveal the timing of major events over the annual life cycle, migratory routes and place on the map the non-breeding areas of a little-known tropical seabird endemic to Cape Verde Islands, the Boyd’s Shearwater. We show that Boyd's shearwaters perform longitudinal migrations to the oligotrophic central North Atlantic Ocean for the non-breeding season, in contrast with closely-related taxa that rely on most productive waters. In Chapter 2, we show that Common terns breeding in continental Europe spread over the West African coast for wintering, but females winter further north and use offshore waters whereas males winter further south and remain nearby the coastline. Behavioural budgets of Common terns were shaped within circadian and circa-annual rhythms. In Chapter 3 we describe in detail the phenology of the Atlantic petrel, showing that breeding success likely shapes the timing of major life-history events and behavioural patterns year round. We did find evidence of carry-over effects, since failed breeders advanced their post-breeding migration, remained longer in the wintering area, and advanced pre-breeding migration comparing to successful breeders. Breeding success did not affect the selection of wintering areas, as all birds relied on the South American shelf slope during different stages of the annual cycle. In Chapter 4, we demonstrate how geolocator-immersion loggers constitute a powerful and irreplaceable source of information to study seabird behaviour. We present a novel approach to infer a diverse array of behaviours based uniquely on wet-dry data, built upon a set of state-of-the-art unsupervised machine learning algorithms that reduce multidimensional data to a bidimensional behavioural space, from which different behaviours can be drawn. We applied the protocol on wet-dry data from Cory’s shearwater. Through these means, we can inspect in great detail and from manifold perspectives the behavioural patterns at individual and population level, highlighting how seasonal constraints shape behavioural budgets and behavioural strategies. We use data visualization tools such as actograms and behavioural landscapes to get new insights, highlighting that such tools constitute an effective method to visualize behaviour of seabirds inferred from wet-dry data from manifold perspectives. Geolocator-immersion sensors currently remain as the most cost-effective balanced tracking devices to track seabird species over the entire annual cycle while ensuring the welfare of tagged individuals. Thus, results compiled in this thesis should encourage researchers to incorporate the use wet-dry data within hypothesis-driven frameworks, which surely would contribute to increase our knowledge of seabird ecology at sea.El movimiento es un componente fundamental del comportamiento animal, estando ambos íntimamente entrelazados. Variaciones en los patrones de movimiento normalmente reflejan cambios de comportamiento, incluyendo aquellos más conspicuos como la búsqueda de alimento, la dispersión, la migración, las interacciones sociales, la búsqueda de pareja o la huida ante depredadores. La forma en la que los patrones comportamentales se ajustan en el tiempo de acuerdo a los ritmos circadianos y a lo largo del ciclo anual puede ayudarnos a entender, en última instancia, los procesos evolutivos y la capacidad de adaptación de las poblaciones animales, algo también importante de cara al desarrollo de medidas de conservación de especies amenazadas. Las aves marinas representan un modelo especialmente adecuado para el estudio de la ecología comportamental y del movimiento. Estudiar los movimientos de las aves marinas en mar abierto ha sido posible en las dos últimas décadas gracias a la normalización en el uso de geolocalizadores por niveles de luz. Aunque buena parte de los modelos de geolocalizador es capaz de registrar datos de conductividad en agua salada (seco/húmedo), esta información parece infrautilizada a la luz de la literatura publicada. Sin embargo, los datos de conductividad son enormemente útiles para el estudio de multitud de aspectos sobre la ecología de las aves marinas. Esta tesis aborda diferentes aspectos de la ecología en mar abierto de 4 especies de aves marinas del océano Atlántico: la pardela chica de Cabo Verde (Puffinus boydi), el charrán común (Sterna hirundo), el petrel atlántico (Pterodroma incerta) y la pardela cenicienta (Calonectris borealis). En el Capítulo 1 revelamos la fenología, rutas migratorias y área de invernada de una especie tropical de pequeño tamaño, la pardela de Cabo Verde, endémica de dicho archipiélago. A diferencia de especies cercanas, los individuos de esta especie realizan una migración longitudinal hasta las aguas oligotróficas del centro del Atlántico Norte. En el Capítulo 2, mostramos que los charranes comunes que crían en Europa migran hasta la costa oeste de África para invernar, aunque las hembras se quedan más al norte y en ambientes más marinos, y los machos más al sur y en ambientes costeros. El comportamiento en ambos sexos parece regulado por ritmos circadianos y anuales. En el Capítulo 3, desgranamos la fenología del petrel Atlántico, una especie endémica del archipiélago de Tristán da Cunha, mostrando que el éxito reproductor probablemente moldea la sucesión de eventos fenológicos y los patrones de comportamiento. Incluso encontramos evidencias de efectos arrastrados, puesto que los animales que fracasaron en la cría adelantaron la migración, permanecieron más tiempo en la zona de invernada, y retornaron antes a las colonias de cría. Tanto los animales que tuvieron éxito como los que fracasaron en la cría invernaron en aguas de la plataforma continental de América del Sur y Patagonia. En el Capítulo 4, presentamos un nuevo protocolo analítico basado en algoritmos de aprendizaje automático que utiliza únicamente datos de conductividad. Mediante su aplicación sobre datos de pardelas cenicientas, demostramos que los datos de conductividad constituyen una poderosa herramienta para el estudio de las aves marinas, permitiendo desglosar a un nivel sin precedentes su comportamiento a diversas escalas: espacial (de viajes cortos a migraciones anuales), temporal (de días a años) y poblacional (de individuos a poblaciones). El análisis también nos permite resaltar los diferentes elementos que moldean el comportamiento animal a diferentes escalas temporales, utilizando para ellos potentes herramientas de visualización de datos como los actogramas. El conjunto de resultados expuestos en esta tesis debe alentar a los investigadores a utilizar más frecuentemente los datos de conductividad, lo cual contribuiría a aumentar nuestro conocimiento sobre la ecología de las aves marinas

Movement ecology in pelagic seabirds

Movement is a fundamental component of behaviour and thus both are inextricably linked. Variation in movement patterns usually reflects different behaviours, including those most glaring, such as foraging, dispersal, migration, social interaction, mate search or escaping from predators. The way individuals allocate their time budget to different behaviours within circadian rhythm and over the annual life cycle will ultimately provide knowledge about evolutionary processes and adaptive capacity, also important to proper conservation actions of endangered species. Among highly mobile marine megafauna, seabirds represent suitable model species to address key questions about movement and behaviour. The study of year-round movements of seabirds has been addressed over the last 20 years with the wide deployment of light-level geolocators equipped with saltwater immersion sensors. However, wet-dry data provided by such loggers seem underused so far despite their usefulness to provide important insights on a variety of dimensions of seabird ecology. The main aim of this thesis was to provide new insights into the factors shaping seabird behaviour. The thesis encompasses several aspects of seabird at-sea ecology of 4 different species spread over the Atlantic Ocean: Boyd’s shearwater (Puffinus boydi), Common tern (Sterna hirundo), Atlantic petrel (Pterodroma incerta) and Cory’s shearwater (Calonectris borealis). In Chapter 1 we reveal the timing of major events over the annual life cycle, migratory routes and place on the map the non-breeding areas of a little-known tropical seabird endemic to Cape Verde Islands, the Boyd’s Shearwater. We show that Boyd's shearwaters perform longitudinal migrations to the oligotrophic central North Atlantic Ocean for the non-breeding season, in contrast with closely-related taxa that rely on most productive waters. In Chapter 2, we show that Common terns breeding in continental Europe spread over the West African coast for wintering, but females winter further north and use offshore waters whereas males winter further south and remain nearby the coastline. Behavioural budgets of Common terns were shaped within circadian and circa-annual rhythms. In Chapter 3 we describe in detail the phenology of the Atlantic petrel, showing that breeding success likely shapes the timing of major life-history events and behavioural patterns year round. We did find evidence of carry-over effects, since failed breeders advanced their post-breeding migration, remained longer in the wintering area, and advanced pre-breeding migration comparing to successful breeders. Breeding success did not affect the selection of wintering areas, as all birds relied on the South American shelf slope during different stages of the annual cycle. In Chapter 4, we demonstrate how geolocator-immersion loggers constitute a powerful and irreplaceable source of information to study seabird behaviour. We present a novel approach to infer a diverse array of behaviours based uniquely on wet-dry data, built upon a set of state-of-the-art unsupervised machine learning algorithms that reduce multidimensional data to a bidimensional behavioural space, from which different behaviours can be drawn. We applied the protocol on wet-dry data from Cory’s shearwater. Through these means, we can inspect in great detail and from manifold perspectives the behavioural patterns at individual and population level, highlighting how seasonal constraints shape behavioural budgets and behavioural strategies. We use data visualization tools such as actograms and behavioural landscapes to get new insights, highlighting that such tools constitute an effective method to visualize behaviour of seabirds inferred from wet-dry data from manifold perspectives. Geolocator-immersion sensors currently remain as the most cost-effective balanced tracking devices to track seabird species over the entire annual cycle while ensuring the welfare of tagged individuals. Thus, results compiled in this thesis should encourage researchers to incorporate the use wet-dry data within hypothesis-driven frameworks, which surely would contribute to increase our knowledge of seabird ecology at sea.El movimiento es un componente fundamental del comportamiento animal, estando ambos íntimamente entrelazados. Variaciones en los patrones de movimiento normalmente reflejan cambios de comportamiento, incluyendo aquellos más conspicuos como la búsqueda de alimento, la dispersión, la migración, las interacciones sociales, la búsqueda de pareja o la huida ante depredadores. La forma en la que los patrones comportamentales se ajustan en el tiempo de acuerdo a los ritmos circadianos y a lo largo del ciclo anual puede ayudarnos a entender, en última instancia, los procesos evolutivos y la capacidad de adaptación de las poblaciones animales, algo también importante de cara al desarrollo de medidas de conservación de especies amenazadas. Las aves marinas representan un modelo especialmente adecuado para el estudio de la ecología comportamental y del movimiento. Estudiar los movimientos de las aves marinas en mar abierto ha sido posible en las dos últimas décadas gracias a la normalización en el uso de geolocalizadores por niveles de luz. Aunque buena parte de los modelos de geolocalizador es capaz de registrar datos de conductividad en agua salada (seco/húmedo), esta información parece infrautilizada a la luz de la literatura publicada. Sin embargo, los datos de conductividad son enormemente útiles para el estudio de multitud de aspectos sobre la ecología de las aves marinas. Esta tesis aborda diferentes aspectos de la ecología en mar abierto de 4 especies de aves marinas del océano Atlántico: la pardela chica de Cabo Verde (Puffinus boydi), el charrán común (Sterna hirundo), el petrel atlántico (Pterodroma incerta) y la pardela cenicienta (Calonectris borealis). En el Capítulo 1 revelamos la fenología, rutas migratorias y área de invernada de una especie tropical de pequeño tamaño, la pardela de Cabo Verde, endémica de dicho archipiélago. A diferencia de especies cercanas, los individuos de esta especie realizan una migración longitudinal hasta las aguas oligotróficas del centro del Atlántico Norte. En el Capítulo 2, mostramos que los charranes comunes que crían en Europa migran hasta la costa oeste de África para invernar, aunque las hembras se quedan más al norte y en ambientes más marinos, y los machos más al sur y en ambientes costeros. El comportamiento en ambos sexos parece regulado por ritmos circadianos y anuales. En el Capítulo 3, desgranamos la fenología del petrel Atlántico, una especie endémica del archipiélago de Tristán da Cunha, mostrando que el éxito reproductor probablemente moldea la sucesión de eventos fenológicos y los patrones de comportamiento. Incluso encontramos evidencias de efectos arrastrados, puesto que los animales que fracasaron en la cría adelantaron la migración, permanecieron más tiempo en la zona de invernada, y retornaron antes a las colonias de cría. Tanto los animales que tuvieron éxito como los que fracasaron en la cría invernaron en aguas de la plataforma continental de América del Sur y Patagonia. En el Capítulo 4, presentamos un nuevo protocolo analítico basado en algoritmos de aprendizaje automático que utiliza únicamente datos de conductividad. Mediante su aplicación sobre datos de pardelas cenicientas, demostramos que los datos de conductividad constituyen una poderosa herramienta para el estudio de las aves marinas, permitiendo desglosar a un nivel sin precedentes su comportamiento a diversas escalas: espacial (de viajes cortos a migraciones anuales), temporal (de días a años) y poblacional (de individuos a poblaciones). El análisis también nos permite resaltar los diferentes elementos que moldean el comportamiento animal a diferentes escalas temporales, utilizando para ellos potentes herramientas de visualización de datos como los actogramas. El conjunto de resultados expuestos en esta tesis debe alentar a los investigadores a utilizar más frecuentemente los datos de conductividad, lo cual contribuiría a aumentar nuestro conocimiento sobre la ecología de las aves marinas

Year-round movements of a small seabird and oceanic isotopic gradient in the tropical Atlantic

Despite the proliferation of seabird tracking studies, there is a relative paucity of studies on small tropical seabirds. We present for the first time the distribution and movements of the little-known Boyd's shearwater Puffinus boydi, a Procellariiform endemic to the Cape Verde Islands. We tracked 28 birds from 2 breeding sites (Ilhéu Raso and Ilhéu de Cima) with geolocator loggers from 2007 to 2012. We also analysed stable isotopes of carbon and nitrogen in the 1st primary (P1), the 6th rectrice (R6) and the 1st (S1) and 8th (S8) secondary feathers to reveal moulting pattern and oceanic isotopic gradients. Birds migrated on average 1452 km westward, to the central Atlantic Ocean (5 to 15°N, 30 to 40°W), where they stayed on average 114 d, from May to August. Boyd's shearwaters exploited oceanic waters year-round and showed δ13C values similar to other oceanic seabird species and δ15N values indicating the lowest known trophic level among all central Atlantic seabirds. Isotope values in flight feathers suggest most animals moult their P1 and R6 around the breeding ground, whereas all birds moult S1 and S8 at the non-breeding quarters. Correlations of δ13C and δ15N values from S8 with the longitude of the non-breeding area indicate the existence of large-scale isotopic gradients matching those known at baseline levels. Combining geolocator tracking and stable isotope analyses in feathers not only allowed us to describe in detail the annual life cycle and distribution of the species, but also the oceanic isotopic gradients in the tropical Atlantic

Year-round movements of a small seabird and oceanic isotopic gradient in the tropical Atlantic

Despite the proliferation of seabird tracking studies, there is a relative paucity of studies on small tropical seabirds. We present for the first time the distribution and movements of the little-known Boyd's shearwater Puffinus boydi, a Procellariiform endemic to the Cape Verde Islands. We tracked 28 birds from 2 breeding sites (Ilhéu Raso and Ilhéu de Cima) with geolocator loggers from 2007 to 2012. We also analysed stable isotopes of carbon and nitrogen in the 1st primary (P1), the 6th rectrice (R6) and the 1st (S1) and 8th (S8) secondary feathers to reveal moulting pattern and oceanic isotopic gradients. Birds migrated on average 1452 km westward, to the central Atlantic Ocean (5 to 15°N, 30 to 40°W), where they stayed on average 114 d, from May to August. Boyd's shearwaters exploited oceanic waters year-round and showed δ13C values similar to other oceanic seabird species and δ15N values indicating the lowest known trophic level among all central Atlantic seabirds. Isotope values in flight feathers suggest most animals moult their P1 and R6 around the breeding ground, whereas all birds moult S1 and S8 at the non-breeding quarters. Correlations of δ13C and δ15N values from S8 with the longitude of the non-breeding area indicate the existence of large-scale isotopic gradients matching those known at baseline levels. Combining geolocator tracking and stable isotope analyses in feathers not only allowed us to describe in detail the annual life cycle and distribution of the species, but also the oceanic isotopic gradients in the tropical Atlantic

Safe Operating Space for Penguins (SOSPEN) initiative: a global effort towards the IUCN-Penguin Specialist Group vision of "penguins in perpetuity"

11th International Penguin Conference, 4-9 September 2023, Viña del Mar, ChileThirteen of the world¿s 18 penguin species are under conservation threat in the IUCN Red List. Penguins deserve conservation priority. A crucial step towards the IUCN Penguin Specialist Group (PSG) vision of ¿penguins in perpetuity¿ is improving their resilience to climate change by identifying key marine areas for penguins. Efforts for managing and mitigating the impacts on penguins are directed towards an IUCN PSG initiative for a Safe Operating Space for Penguins (SOSPEN). Based on broad partnerships, SOSPEN aims to (i) assemble available tracking datasets for penguins; (ii) incorporate tracking data to identify key marine areas for individual penguin species; (iii) further develop the analyses of the spatial distribution of the major climate and human threats facing penguins; and (iv) incorporate this information within an operational Marine Ecosystem Model, to simulate past and future scenarios based on climate projections under the IPCC scenarios. The SOSPEN initiative will build on penguins¿ tracking datasets provided to the Retrospective Analysis of Antarctic Tracking Data project and acknowledges the contributions of the data providers. We seek colleagues to join us in this initiative by providing their penguin tracking data and by becoming partners in the analysis and publication process. SOSPEN partners will retain full ownership of their datasets, which will be used solely to pursue the research objectives of SOSPEN. This initiative aims to be at the forefront of collaborative efforts in creating effective conservation strategie

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

Year-round individual specialization in the feeding ecology of a longlived seabird

Este artículo contiene 12 páginas, 5 figuras, 1 tabla.Many generalist species are composed of individuals varying in the size of their realized niches within a population. To understand the underlying causes and implications of this phenomenon, repeated samplings on the same individuals subjected to different environmental conditions are needed. Here, we studied individual specialization of feeding strategies in breeding and non-breeding grounds of Cory’s shearwaters (Calonectris borealis) for 2–8 years, and its relationship with fitness. Individuals were relatively flexible in non-breeding destinations, but specialized in diet, habitat use and daily activity across years. Daily activity was also consistent throughout the year for the same individual, suggesting that it is driven by individual constraints, whereas individual diet and habitat use changed between breeding and non-breeding grounds, indicating that these specializations may be learned at each area. Moreover, individuals that were intermediate specialized in their diet tended to show higher breeding success than those with weakly and highly specialized diets, suggesting stabilizing selection. Overall, this study suggests that the development of individual specialization is more flexible than previously thought, i.e. it emerges under specific environmental conditions and can develop differently when environmental conditions vary. However, once established, individual specialization may compromise the ability of individuals to cope with environmental stochasticity.L. Zango was supported by a PhD grant from the Spanish government (Formación de Profesorado Universitario; FPU15/01927). J.M. Reyes-González was supported by a PhD grant from the Spanish government (Formación de Profesorado Universitario; AP2009–2163). T. Militão was supported by a Ph.D. Grant (SFRH/BD/47467/2008) from Fundação para a Ciência e Tecnologia (Portugal). R. Ramos was supported by postdoctoral contracts of the PLEAMAR (2017/2349) and Ramón y Cajal (RYC-2017–22055) programs from the European Maritime and Fisheries Fund (EMFF) and the Spanish Ministerio de Educación y Ciencia, Ministerio de Ciencia e Innovación (MINECO), respectively. Z. Zajková was supported by a PhD Grant from University of Barcelona (APIF/2012). We would like to thank everyone that participated in fieldwork in Veneguera and Montaña Clara from 2007 to 2015: R. Arizmendi, N. Pérez, A. Vulcano, M. Codina, J. Moreno, L. Stefan, E. Gómez-Díaz, J. Navarro, M. López, E. Rodríguez, I. De Diego, A. Soriano, M. Heus, M. Pastor, R. Manzano, H. Dinis, C. Astals, M. Smyrli, P. Serrano, J. Ferrer-Obiol, N. Gomes and I. García, I. Díaz, M. Cruz and C. Soria. Pascual Calabuig and Loly Estévez provided invaluable logistic support every year in Gran Canaria. We are especially grateful with V. Morera-Pujol, Daniel Sol and Pascual López-López for their support and contribution at different stages of this work and Fernanda De Felipe for the molecular sexing analyses. This study was funded by MINECO, Ministerio de Economía y Competitividad (CGL2006-01315/BOS, CGL2009-11278/BOS, CGL2013-42585-P and CGL2016-78530-R) from the Spanish government and Fondos FEDER, and Research Executive Agency (European Commission, FP7- PEOPLE-2013-CIG, 618841).Peer reviewe