Challenges in vulture conservationinsights from movement ecology and individual spatial use

Resumen

The current phenomenon of global change can be divided into two main and antagonistic processes with respect to the use that humans make of the territory. The first and perhaps the most widespread is an intensification of human uses of territory, including an increase in the presence in landscapes of human structures such as those associated with intensive agriculture or transport networks. Alternatively, millions of hectares of land of difficult access or low productive value are being abandoned mainly in developed countries. This new scenario may imply important changes for the conservation of animal species with great movement capacities whose role in the connectivity of habitats and ecosystems is fundamental. This could be the case of vultures, species that move hundreds of kilometers and perform ecological functions and provide relevant ecosystem services by consuming the carrion generated by both wild and domestic ungulates. This thesis, through the GPS tracking of Iberian griffon vultures, evaluates how the processes of abandonment and itnensification affect some traditional aspects and generate new challenges for the conservation of vultures. The close historical relationship between humans and vultures is based on the consumption by vultures of the carrion generated by humans. Therefore, changes in the availability of carrion that imply the abandonment and intensification of human use in some areas affect the vultures mainly by modifying their trophic availability. For example, in some places, restrictive sanitary policies regarding the treatment of dead livestock result in the practical elimination of trophic resources for vultures. These emptied food areas are avoided by the vultures, which may a priori hinder their expasion and recovery as occur in Portugal (Chapter 1). Conversely, in many other areas the availability of carrion has paradoxically increased, associated with both intensification and abandonment of livestock. In the first place, areas with intensive livestock offer a strong attraction for vultures due to the amount of food associated with them. However, these areas also have abundance of human infrastructures dangerous for vultures, such as power lines and roads. This means that the mortality rate of these species in these areas is very high, which can lead to an ecological sink with unforeseeable consequences (Chapter 2). Paradoxically, abandoned areas can also lead to an increase in the availability of carrion, even if it is not quantitatively comparable to that of intensified areas. Rural abandonment implies an increase in the habitat available to wild ungulates, whose populations rapidly grow, acting as an attractant for vultures. However, this carrion is not exent of risks, as it is accompanied by an increase in other human activities such as hunting, which generate large quantities of lead-poisoned food being a threat for vulture´s health (Chapter 3). Finally, although the relationship between humans and vultures is based on food, new and more intensified human uses such as air transport also pose a new challenge for the conservation of vultures as they generate a human/fauna conflict due to the increase in collisions between aircraft and vultures which could change society’s perception of these birds, which until now has been positive (Chapter 4). In short, the increasing polarization of the landscape between abandoned and intesified areas is a complex mosaic for vultures where each area has its own risks that must be evaluated on a global scale since the great capacity of movement of these birds makes them susceptible to all these threats at the same time.