Individual and environmental drivers of resource use in an endangered vultureintegrating movement, spatial and social ecology

Resumen

The study of animal movement makes possible to understand how the spatial context influences individuals and populations, something especially important for species with high movement abilities able to wander routinely over large areas and face diverse humanmediated threats at different spatial scales. Vultures are long-lived scavenging vertebrates with delayed maturity and low fecundity, often exhibiting complex social behaviours. European and most of the Old World vulture populations have been historically dependent on the spatial distribution of human-provided resources. Currently, they are endangered worldwide suffering regional dramatic declines of up to 90% mainly provoked by direct and indirect persecution, infrastructure development and decrease in food resources. Effective vulture conservation requires spatially-explicit understanding of how vultures cope with resource availability and human induced transformation. In this thesis, we used spatial data collected between 2013 and 2018 from 49 GPStagged Canarian Egyptian vultures (Neophron percnopterus majorensis). The bulk of this endemic subspecies is concentrated in Fuerteventura Island where it depends on extensive goat farms, currently changing towards semi-intensive and intensive regimes. In addition, it suffers from high mortality in power lines. Movement information is combined with individual characteristics, life-history stages, and detailed data on the spatial distribution of territories, feeding resources, and human facilities. Particularly, we examined i) drivers of the use of power lines, ii) foraging tactics according to spatiotemporal variation in food predictability and individual characteristics, iii) drivers of use of livestock farms, and iv) farmers’ perception about the target species in relation to the observed spatial behaviour. Vultures’ behaviour was influenced by the distribution, predictability and amount of feeding resources, as well as by the spatial distribution of conspecifics and sources of human disturbance. At the same time, individual attributes such as sex, age, territorial status or social rank interacted with environmental cues to shape movements. Overall, vultures somewhat avoided humans by selecting farms and electric pylons far from roads or urban areas. Importantly, the predictable food resources provided by the main feeding station determined an intensive use of electric pylons and farms in its proximity. Use of both resources were however complex according to individual traits and life-history stages. Territorial status and social position in the dominance hierarchy shaped sex-specific patterns of feeding preferences, with dominant breeding females, but not males, using predictable food more intensively and choosing to settle in nearby territories. The distribution of territories affected in turn the selection of pylons and farms by both territorial and non-breeding individuals, highlighting the close interdependency and feedback between the spatial structuring of the population and the distribution of resources. Non-territorial individuals avoided resources located close to occupied breeding territories meanwhile territorial ones preferred those close to their nest, these spatial constrains being less obvious during the non-breeding season. After disentangling how those factors influence the intensity of use electric pylons, we combined predictions combined with actual mortality showing that prioritizing mitigation measures on relatively few pylons could drastically reduce accidents. Finally, farmers perceived Egyptian vultures as the most beneficial avian scavenger in the island, but owners of larger farms, which were more visited but frequently more mechanized than smaller ones, were less aware of vulture presence in their exploitations. This suggests a potential influence of modernization in livestock practices on disconnecting people from ecosystem services provided by wildlife. Moreover, the consistency between awareness and GPS data increased when vultures were more present in farms or their surroundings, indicating that scarce and endangered species are more susceptible of suffering misperception. Our findings are important from an applied point of view in a context of rapid changes in traditional livestock practices and power development, offering sound scientific knowledge that allows to make informed management decisions. The complex network of factors and patterns should be considered in the management of electric infrastructures, predictable and semi-predictable resources, or social actions for vulture conservation. General solutions ignoring population structure and the spatial distribution of territories, feeding sources or human footprint should be avoided since those could lead to unbalanced impacts between population fractions that could compromise the effectiveness of management and conservation actions.