The Summer Diet of Barn Owl (Tyto alba) (Aves: Strigiformes) in the Southern Part of Danube Delta Biosphere Reserve

摘要

The Barn Owl (Tyto alba) is a common nocturnal predator of agro-ecosystems and it is widely distributed, especially in European countryside. A first assessment of the diet and food selection was made for the Southern part of Danube Delta Biosphere Reserve, in the summer period, in a unique wetland-grassland complex, with large areas of steppes. Mammals dominated the diet spectrum, with the shrews (Soricidae) being the most frequent (49.4%), followed by the mice (Muridae), and the voles (Arvicolinae). The mammalian component of diet is the most important also in terms of biomass (94.3%), the most important species is Sibling Vole (Microtus epiroticus) equaling 22.5% of all biomass consumed, followed by White-toothed Shrew (Crocidura suaveolens) and the Mound-building Mouse (Mus spicilegus). Birds, reptiles, amphibians and insects made up a small portion of the diet, both in terms of occurrence and of biomass. Eight species of birds were captured, the House Sparrow (Passer domesticus) being the most important. Two species of reptiles and at least four species of amphibians were recorded. Arthropods (at least 9 species) made up to 3.8% of the diet. The results suggest that the Barn Owl is a specialised feeder relying on small mammals and completing its diet with other prey only occasionally.