Diet of Barn Owl Tyto alba in Central South Bulgaria as influenced by landscape structure

Abstract

This study of the diet of Barn Owl Tyto alba analyzed pellets containing 18,810 prey specimens. Small mammals (98.2% by number, 97.5% by biomass) dominated, while birds, reptiles, amphibians, and insects constituted a negligible portion of the diet (1.8% by number, 2.5% by biomass). Voles (Microtus spp.) were the most numerous prey (35.3 ± 14.4%, range 14.6%-67.1%) in 9 localities (69.2%, n = 13 individually studied localities) and dominated the biomass in all diets (51.4 ± 14.1%, range 27.4%-78.2%). The lesser white-toothed shrew (Crocidura suaveolens) (20.8 ± 7.6%, range 7.3%-32.8%) was the most frequent prey in the other 4 localities (30.8%). The breeding localities with more similar proportions of habitats in their hunting territories had significantly higher diet overlaps (r = 0.336, P < 0.01). The amount of wetlands and the indices of habitat heterogeneity and topographic relief among the landscape characteristics of the hunting territories significantly influenced diet composition according to redundancy analysis. Larger areas of wetlands correlated with higher predation on wetland mammal species, as well as the European pine vole (Microtus subterraneus) and white-toothed shrews, and thus with broader food niche breadth.