Barn Owl Tyto alba prey in Thessaly, and evaluation of Barn Owl diets throughout Greece

Abstract

Diet composition of the Barn Owl Tyfo alba was studied in agricultural land-scapes in Thessaly, Greece, for 3 years (2003-05). A total of 852 Rattus spp. individuals were identified from 10 065 pellets, which accounted for 2.9% by fre-quency and 27.4% by biomass of 29 061 prey items. Rattus spp. were more numerous in Barn Owl pellets during winter months than in summer. We suggest that this difference was due to a shift in relative prey availability and an increased need for energy by the Barn Owl during the colder months. Com-parisons between Thessaly and 15 other areas showed differences in prey availability between islands and mainland Greece. Microtus spp. were absent from all island diets except one, and some islands had greater species richness.