FEEDING ECOLOGY OF TAWNY OWL (STRIX ALUCO) IN WIGRY NATIONAL PARK (NORTH EAST POLAND)

Abstract. In 19891991, the feeding ecology of Tawny Owl (Strix aluco) was studied in Wigry National Park (NE Poland). Diet composition was investigated by analysis of pellets gathered in stands under roost trees or nest boxes from April to August in 35 home ranges each year. In order to assess potential prey, small animals were caught in 28 traps. Small mammals composed 66.5 % of prey items and 78.9% of food biomass of Tawny Owl, birds 8.1 % and 13.9%, and frogs 17.4 % and 6.8 % of prey and biomass, respectively. The diet was dominated by rodents, mainly bank vole (Clethrionomys glareolus) and common vole (Microtus arvalis), which together composed 37.0 % of prey items and 37.2 % of the biomass consumed. Among birds, the most common prey was Song Thrush (Turdus philomelos). Slightly preferred prey were field mouse (Apodemus agrarius), short-tailed vole (Microtus agrestis) and bank vole. One pellet contained 111 (mean 2.34 – 0.09) prey items. Amphibians were the most numerous during May and June