Dynamics of Asio otus L., 1758 (Aves: Strigiformes) winter-spring trophic regime in Western Plain (Romania)

Abstract

The trophic regime of Asio otus is dominated by Microtus arvalis . In both areas the proportion of this species in the long-eared owl's food presents an important seasonal variation. In winter it moves usually through tunnels under the snow, thus being less frequently hunted. When the main prey is scarce, alternative food resources are exploited, in these areas mice, which become dominant as a group. A significant variation is recorded also by the mean biomass of preys of Asio otus from Satu Mare. The average body mass increases with one third from January to March, when the efficiency of hunt is maximum.