Factors influencing the breeding density of Bearded Vultures, Egyptian Vultures and Eurasian Griffon Vultures in Catalonia (NE spain): management implications

摘要

Using multivariate analyses we examined differences in breeding density of the Bearded Vulture Gypaetus barbatus, the Eurasian Griffon Vulture Gyps fulvus and the Egyptian Vulture Neophron percnopterus in NE Spain (Catalonia) in relation to trophic, orographic-landscape and anthropic variables. Sampling units used were regional divisions (comarques). High density of Bearded Vulture was principally linked to areas with scant vegetation and low human population density. In contrast, high densities of both the Egyptian and Eurasian Griffon Vultures were associated with availability of trophic resources (sheep and goats). Positive effects were detected in relation to low density of inhabitants (Egyptian Vulture) and altitudes between 1,000-2,000 m and landscape with low tree cover (Eurasian Griffon Vulture). The Bearded Vulture seemed to be the most selective species in relation to environmental characteristics while the Eurasian Griffon and the Egyptian Vultures displayed a higher degree of ecological plasticity. Future conservation actions should bear these results in mind in order to optimise management. Food resources from extensive livestock farming, in particular, seem fundamental for the conservation of scavenger species. Preference monitoring and conservation efforts are needed in the regions with highest vulture densities (Alta Ribagorca, Pallars Jussa and Alt Urgell), while regions with low vulture populations should be managed in order to favour the geographical expansion and recolonisation of zones currently not occupied by these species. Conservation priorities should be based on favouring extensive livestock practices, and as an alternative to muladares (traditional animal carcass disposal sites) farmers should be encouraged to leave animal carcasses in the field, while ensuring compliance with health regulations.