, Volume 56, Issue 4, pp 613-621

Dietary shifts in two vultures after the demise of supplementary feeding stations: consequences of the EU sanitary legislation

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Abstract

Among vertebrates, specialization in scavenging has appeared only in “true” Gyps vultures, which usually base their diet almost exclusively on carcasses of medium and large-sized mammals, whereas all other scavengers rely on broader ranges of prey. The availability of food for scavengers in Western Europe has not been limited during recent decades permitting the existence and growth of huge vulture populations. From 2000 onwards, however, EU sanitary legislation has progressively limited the abandonment of dead animals in the field resulting in a sudden reduction of food availability with unknown ecological and conservation consequences. Here, we examine the dietary response of a tandem of carrion eaters, the griffon vulture (Gyps fulvus) and the Egyptian vulture (Neophron percnopterus), showing different degrees of dietary specialization. Our results showed that after the reduction in numbers of supplementary feeding stations (vulture restaurants) the niche breadth of the griffon vulture has broadened and now includes significant amounts of wild rabbits (Oryctolagus cuniculus) and garbage. The diet of the Egyptian vulture, on the contrary, did not vary substantially. The diet overlap showed patterns probably conditioned by interspecific competition and the progressive exploitation of unpredictable carcasses. On a short-term scale, consequences for smaller scavengers could be negative due to the monopolization of resources by the dominant and much more abundant griffon vulture, however in the long-term all guild species would benefit from the exploitation of unpredictable carcasses, which could enhance the possibilities of coexistence.

Communicated by C. Gortázar