Influence of prey densities in the distribution and breeding success of Bonelli's eagle (Hieraaetus fasciatus): management implications

Abstract

Diet, prey availability, and breeding success were studied in a population of Bonelli's eagle (Hieraaetus fasciatus) in the province of Granada, SE Spain. The densities of the main prey species, European wild rabbit (Oryctolagus cuniculus), red-legged partridge (Alectoris rufa), wood pigeon (Columba palumbus), and rock dove (Columba livia), representing 90.2% of the biomass, were analysed in 19 territories occupied by pairs of Bonelli's eagles and 15 potential territories that were unoccupied but appropriate for nesting. We found no significant differences in prey density between the two types of territories. Contrary to other raptor species, we found no significant relationship between the density of their main prey species and the distance of the neighbouring pairs, either between that density and breeding success. These findings, together with the prior knowledge of nest-site selection of this eagle in the study area, can be used for proper planning of conservation strategies. These should avoid unnecessary effort to increase the eagle's food supply, and should promote the reintroduction of individuals to suitable sites for Bonelli's eagle.