Unexpected role of ungulate carcasses in the diet of Golden Eagles Aquila chrysaetos in Mediterranean mountains

Abstract

Capsule Golden Eagles consumed more carrion than shown by traditional analyses. Aims To determine whether the traditional methods for diet determination in avian predators are subject to biases in relation to the consumption of carrion. Methods The consumption by Golden Eagles of ungulate carcasses supplied through sport hunting in a typical Mediterranean area of southeast Spain was monitored by camera trapping through an entire year. We simultaneously analysed the breeding diet of three Eagle pairs by conventional procedures. Results Golden Eagles regularly used ungulate carrion in the study area, benefiting from 57% of the available carcasses. Ninety percent of the territorial eagles fed on monitored carcasses, and the consumption was similar through the year. However, this source of food comprised only 1.5-9.1% of the prey items identified by traditional methods. Conclusions Our findings suggest that pellet and prey remains analyses under-represent the role of carrion in the diet of avian predators in Mediterranean ecosystems. The difficulty of quantifying scavenged material in predators' diets have probably contributed to the perception that the scavenging behaviour of species such as Golden Eagles are unimportant in the regulation and functioning of certain ecosystems. © 2010 British Trust for Ornithology.