Weather conditions explain variation in the diet of Long-eared Owl at winter roost in central part of European Russia

Abstract

The influence of weather conditions on the winter diet of the Long-eared Owl was studied in 2005-2013 at one roost site in Moscow, Russia. Pellets were collected every week from November to March. The diet composition of the owls included 6 rodent species, 2 in-sectivore species and 18 bird species. Common Vole was by far the most frequent prey (70.0%), followed by Ural Field Mouse (10.8%) and Brown Rat (7.5%). Among birdprey (5.3%), House Sparrow, Great Tit, Bullfinch, Tree Sparrow and Blue Tit were the most numerous species. The winter diet showed marked interannual fluctuations. In terms of weather conditions, depth of snow cover appears to be the most important factor affecting the availability of the most frequent prey species and prey groups in the diet of the Long-eared Owl. Wind speed and precipitation do not play a significant role in predating on voles and mice. The proportion of bird prey was relatively low, but increased with precipitation, indicating the high importance of birds as an alternative prey for owls. The results thus suggest that specific features of behavior and activity of prey in different weather conditions explain their proportions in the diet of the Long-eared Owl.