Diet of The Barn Owl (Tyto alba Scopoli 1769) From the Copiapo Valley, Atacama Desert, Chile

Abstract

he Barn Owl (Tyto alba) is a nocturnal raptor species distributed from Arica to Tierra del Fuego in Chile. The diet of this bird is the best known of any raptor of Chile; it is based on small vertebrates, particularly rodents and birds. We studied the diet of the Barn Owl, by analyzing of pellets collected in Copiapo valley, located in the hyper-arid Atacama Desert. This information was compared to available data from Chile and neighboring countries. Because of the environmental conditions of extreme aridity a low diversity of prey, typical of raptors from arid ecosystems, was expected. In the case of Tyto alba populations from the Atacama region, the most consumed species were rodents (76.7%), specially Eligmodontia dunaris (27.3%), Phyllotis darwini (24%) and Abrocoma bennetti (12.4%). Other preys corresponded to birds (17.8%) and coleopterans (3.3%). There was no significant correlation between frequency of prey and their body mass (r(2)=0.229, P=0.497) and between frequency of prey and their habitat (r(2)=0.538, p=0.088), indicating that this raptor does not select its preys by either body size or habitat. Regarding biomass, rodents contributed more significantly (95.3%) than birds (3.5%), with the largest individual contribution given by A. bennetti (60.1%) and P. darwini (26.8%). Both the Simpson (SI = 0.1683) and Shannon (H'=0.8958) indices indicate that this species consumes a low diversity of prey, which is consistent with the observations for others raptors inhabiting on arid environments.