Spatial variation in anthropic and natural factors regulating the breeding success of the cinereous vulture (Aegypius monachus) in the SW Iberian Peninsula

Abstract

The management of the cinereous vulture (Aegypius monachus) populations, the largest bird of the Western Palæarctic and considered an umbrella species, requires the understanding of the factors limiting the breeding success. As part of a management program, we studied such factors in seven breeding colonies in Extremadura (SW Iberian Peninsula). Using a Geographic Information System and multivariate models, we analyzed the relationship of breeding success with anthropic and natural factors at the nest site and in the foraging area of the adults. We incorporated into the models density-dependent effects between pairs and the spatial autocorrelation of the environmental variables. The differences in breeding success resulted from spatial variations in natural and anthropic conditions, with present human disturbance to nests and future alteration of climate having an expected negative effect at all the sites. Management measures must set calendar restrictions for the immediate environment of the nests, mainly with respect to forestry and hunting activities. A second key element is the protection of the habitats at the nest sites and in their surrounding area, with the aim of there being both wooded areas available for the location of the nest and open environments for the availability of food. The Special Protection Areas showed a partial effectiveness of conservation measures for the species, and the need for future improvement. Lastly, in a scenario of global warming, management policies with respect to nesting habitats will have to be extended to higher altitude zones, actions that should be guided by the study of the selection of potential nesting habitat.