Little Owl’s (Athene noctua) vertebrate food composition during breeding season with high frog dominance in grasslands

摘要

The aim of our study was to investigate the feeding of the Little Owl (Athene noctua) during the breeding period in three protected sites (Upper Kiskunság Puszta, Upper Kiskunság Lakes, Peszéradacs Meadows) in an extensively managed lowland plain area (Upper Kiskunság) of the Carpathian Basin. A further objective was to provide a detailed assessment of the vertebrate prey spectrum and dominance structure based on the analyses of pellets. Little Owl pellets were collected in September 2015 and 2016 from 20 artificial nest boxes in which successful breeding occurred in both years. Mean pellet number was calculated per individuals. Distribution of individual number and biomass of vertebrate prey taxa were also examined. The number of collected and dissected owl pellets was 2,094 in 2015 and 2,024 in 2016, respectively. The average rate of pellet regurgitation was 25.57 pellets/ind. in 2015, and 27.74 pellets/ind. in 2016. From the 40 samples (4,118 owl pellets) a total of 2,017 vertebrate preys were determined. Cumulative species richness was 21, including 12 mammalian, 1 amphibian, 4 reptile and 4 bird species. Mammals were dominant in the food (average 50.83%), and the consumption of amphibians was similar (48.06%). The consumption of birds and reptiles was not significant. Amphibians were represented by a single species, the Common Spadefoot (Pelobates fuscus) in remarkably high proportions among the prey items, followed by the Common Vole (Microtus arvalis) by approx. 37% proportion. The high proportion of the latter two species was also clearly reflected in the biomass amounts. Among the birds, the Starling (Sturnus vulgaris) proved to be the most commonly predated species apart from other species closely related to farmland habitats (Motacilla alba, M. flava, Passer montanus).