Large-scale movement patterns in a social vulture are influenced by seasonality, sex, and breeding region.

Quantifying space use and segregation, as well as the extrinsic and intrinsic factors affecting them, is crucial to increase our knowledge of species-specific movement ecology and to design effective management and conservation measures. This is particularly relevant in the case of species that are highly mobile and dependent on sparse and unpredictable trophic resources, such as vultures. Here, we used the GPS-tagged data of 127 adult Griffon Vultures Gyps fulvus captured at five different breeding regions in Spain to describe the movement patterns (home-range size and fidelity, and monthly cumulative distance). We also examined how individual sex, season, and breeding region determined the cumulative distance traveled and the size and overlap between consecutive monthly home-ranges. Overall, Griffon Vultures exhibited very large annual home-range sizes of 5027 ± 2123 km2, mean monthly cumulative distances of 1776 ± 1497 km, and showed a monthly home-range fidelity of 67.8 ± 25.5%. However, individuals from northern breeding regions showed smaller home-ranges and traveled shorter monthly distances than those from southern ones. In all cases, home-ranges were larger in spring and summer than in winter and autumn, which could be related to difference in flying conditions and food requirements associated with reproduction. Moreover, females showed larger home-ranges and less monthly fidelity than males, indicating that the latter tended to use the similar areas throughout the year. Overall, our results indicate that both extrinsic and intrinsic factors modulate the home-range of the Griffon Vulture and that spatial segregation depends on sex and season at the individual level, without relevant differences between breeding regions in individual site fidelity. These results have important implications for conservation, such as identifying key threat factors necessary to improve management actions and policy decisions.

Cuantificar el uso y la segregación del espacio, así como los factores extrínsecos e intrínsecos que los afectan, es crucial para aumentar nuestro conocimiento de la ecología de movimientos de cada especie y diseñar medidas eficaces de gestión y conservación. Esto es especialmente relevante en el caso de especies con gran movilidad y dependientes de recursos tróficos escasos e impredecibles, como son los buitres. En este trabajo se utilizaron datos GPS de 127 buitres leonados Gyps fulvus adultos capturados en cinco regiones de cría diferentes en España para describir los patrones de movimiento (tamaño y fidelidad del área de campeo y distancia acumulada mensual). También examinamos cómo el sexo, la estación del año y la región de cría determinaban la distancia acumulada recorrida y el tamaño y solapamiento entre áreas de campeo mensuales consecutivas. En conjunto, los buitres leonados mostraron un área de campeo anual muy extensa de 5027 ± 2123 km2, una distancia acumulada mensual media de 1776 ± 1497 km y una fidelidad mensual al área de campeo del 67.8 ± 25.5%. Sin embargo, los individuos de las regiones de cría más septentrionales mostraron áreas de campeo más pequeñas y recorrieron distancias mensuales más cortas que los de las más meridionales. En todos los casos, las áreas de campeo fueron mayores en primavera y verano que en otoño e invierno, lo que podría estar relacionado con las diferencias en las condiciones de vuelo y las necesidades tróficas asociadas a la reproducción. Además, las hembras mostraron mayores áreas de campeo y menor fidelidad mensual que los machos, lo que indica que estos últimos tienden a utilizar zonas similares durante todo el año. En conjunto, nuestros resultados indican que tanto los factores extrínsecos como los intrínsecos modulan el área de campeo del buitre leonado y que la segregación espacial depende del sexo y de la estación a nivel individual, sin que existan diferencias relevantes entre las regiones de cría en cuanto a la fidelidad individual al lugar. Estos resultados podrían tener importantes implicaciones para la conservación, como la identificación de los principales factores necesarios para mejorar las medidas de gestión y las decisiones políticas.

Vultures as an overlooked model in cognitive ecology.

Despite important recent advances in cognitive ecology, our current understanding of avian cognition still largely rests on research conducted on a few model taxa. Vultures are an ecologically distinctive group of species by being the only obligate carrion consumers across terrestrial vertebrates. Their unique scavenging lifestyle suggests they have been subject to particular selective pressures to locate scarce, unpredictable, ephemeral, and nutritionally challenging food. However, substantial variation exists among species in diet, foraging techniques and social structure of populations. Here, we provide an overview of the current knowledge on vulture cognition through a comprehensive literature review and a compilation of our own observations. We find evidence for a variety of innovative foraging behaviors, scrounging tactics, collective problem-solving abilities and tool-use, skills that are considered indicative of enhanced cognition and that bear clear connections with the eco-social lifestyles of species. However, we also find that the cognitive basis of these skills remain insufficiently studied, and identify new research areas that require further attention in the future. Despite these knowledge gaps and the challenges of working with such large animals, we conclude that vultures may provide fresh insight into our knowledge of the ecology and evolution of cognition.

Too much is bad: increasing numbers of livestock and conspecifics reduce body mass in an avian scavenger.

Individual traits such as body mass can serve as early warning signals of changes in the fitness prospects of animal populations facing environmental impacts. Here, taking advantage of a 19-yr monitoring, we assessed how individual, population, and environmental factors modulate long-term changes in the body mass of Canarian Egyptian vultures. Individual vulture body mass increased when primary productivity was highly variable, but decreased in years with a high abundance of livestock. We hypothesized that carcasses of wild animals, a natural food resource that can be essential for avian scavengers, could be more abundant in periods of weather instability but depleted when high livestock numbers lead to overgrazing. In addition, increasing vulture population numbers also negatively affect body mass suggesting density-dependent competition for food. Interestingly, the relative strength of individual, population and resource availability factors on body mass changed with age and territorial status, a pattern presumably shaped by differences in competitive abilities and/or age-dependent environmental knowledge and foraging skills. Our study supports that individual plastic traits may be extremely reliable tools to better understand the response of secondary consumers to current and future natural and human-induced environmental changes.

Food predictability and social status drive individual resource specializations in a territorial vulture.

Despite increasing work detailing the presence of foraging specializations across a range of taxa, limited attention so far has been given to the role of spatiotemporal variation in food predictability in shaping individual resource selection. Here, we studied the exploitation of human-provided carrion resources differing in predictability by Canarian Egyptian vultures (Neophron percnopterus majorensis). We focussed specifically on the role of individual characteristics and spatial constraints in shaping patterns of resource use. Using high-resolution GPS data obtained from 45 vultures tracked for 1 year, we show that individual vultures were repeatable in both their monthly use of predictable and semi-predicable resources (feeding station vs. farms) and monthly levels of mobility (home range size and flight activity). However, individual foraging activities were simultaneously characterized by a high degree of (temporal) plasticity in the use of the feeding station in specific months. Individual rank within dominance hierarchy revealed sex-dependent effects of social status on resource preference in breeding adults, illustrating the potential complex social mechanisms underpinning status-dependent resource use patterns. Our results show that predictable food at feeding stations may lead to broad-scale patterns of resource partitioning and affect both the foraging and social dynamics within local vulture populations.