Pecularities of the Spectrum of Chick Food, Daily and Seasonal Activities of Eurasian Eagle-Owls (Bubo Bubo) During the Nesting Period on the Shore of the Kuibyshev Reservoir, Volga River

The range of food objects, daily and seasonal activity of a pair of Eurasian Eagle-Owls (Bubo bubo) in the area of their nesting on the shore of the Kuibyshev Reservoir (Ulyanovsk Region, European Russia) were studied from late April to early July 2020 during the period of feeding chicks before they left the nest. The data were obtained with help of an autonomous video surveillance system. In total, 112 prey objects brought by owls to the nest have been recorded and 22 taxa of wild vertebrates belonging to five classes of animals have been identified. The predominant feeding objects were Cricetidae rodents (39.0%), lizards (13.3%) and fish (10.5%). Waterfowl (25.6%) and fish (21.0%) predominated in terms of biomass. Daily feeding activity of owls had two distinct peaks: from 2 to 5 a.m. and from 9 to 11 p.m. Mammals and birds were important foods throughout the season of feeding the chicks. The proportion of the Sand Lizard (Lacerta agilis) in food increased in the last 10 days of May simultaneously with the appearance of fish in food, and they remained important objects until the end of observations.