Poison-related mortality effects in the endangered Egyptian vulture (Neophron percnopterus) population in Spain

Abstract

A total of 211 poisoning incidents registered over the period 1990–2007 and affecting 294 Egyptian vultures (Neophron percnopterus) were studied to address the impact of poison-related mortality in the Spanish population. Poison-related mortality mainly affected the birds on an individual level, with low numbers of individuals being found in each incident (mean 1.39) with 94.9% being adults. Deaths were largely recorded (81.8%) during the breeding season, with mortality peaking during May and June (52.1%). In contrast with other raptor species, a high proportion of adult individuals (74.2%) were found in the nest or its surroundings. Age-related differences in the poisoning rate are probably related with different feeding and behavioral strategies between age classes. The illegal use of poison to control predators was the main cause of mortality (93.8%), and particularly in small hunting reserves (74.9%), since the kind of food resources that adults exploit are coincident with the type of baits employed to illegally control predators and the preferred habitat coincides with areas of small game hunting. Our results suggest that poisoning is probably one of the main causes of Egyptian vulture mortality in Spain. The eradication of the illegal use of poisoning and supplementary feeding in specific territories to provide safe food seems priority for its conservation.