Winter Diet of Long-eared Owls, Asio otus (L.), in a Suburban Landscape of North-Eastern Bulgaria

Winter diet of long-eared owls in a communal roost was studied by pellet analysis containing 3,151 prey specimens. Rodents formed the majority of the food (97.0% N, 97.2% B; N = number, B = biomass), while shrews, birds and beetles constituted a negligible portion of the diet (3.0% N, 2.8% B). The staple prey consisted of inhabitants of mainly open areas like voles Microtus spp. (45.6% N, 50.8% B) and mice Apodemus spp. (20.2% N, 22.2% B) and Mus spicilegus (11.5% N, 8.2% B). The proportion pattern of the preyed taxa in pellets reflected the dominant position of the prey in the diet in combination with habitat preferences of the hunted species according to the results of principal component analysis. More frequent catch on forest and bush birds at the expense of urban birds including sparrows Passer spp. distinguished significantly the present diet from the other Bulgarian long-eared owl diets.