Feeding ecology of the long-eared owl (Asio otus) in northern Italy: is it a dietary specialist?

Abstract

The feeding ecology of the long-eared owl (Asio otus) in the Stupinigi Natural Park, northwestern Italy, was investigated for 1 year. Owls fed seasonally on three main prey categories. Mice (Murinae) constituted the bulk of the diet from September to March, with voles (Arvicolinae) and birds as secondary prey. During the breeding season, birds became preeminent, constituting about half of the prey ingested. Dietary overlap between the overwintering period and breeding season was low. Food-niche breadth was low in autumn and winter but increased markedly from May to August. A comparison of our results with those of eight other European studies showed that the long-eared owl in Italy has a more varied diet. The diet in Italy and Spain (southern Europe) is based on at least three prey groups and differs from that described for areas in central and northern Europe, where only species of voles are the main prey. Our results show that the long-eared owl is an adaptable predator that expands its food niche in the presence of diversified prey. This adaptability contrasts with the picture of a specialized predator.