Bat predation by tawny owls Strix aluco in differently human-transformed habitats

Differences in the frequency with which bats feature in the diet of tawny owls Strix aluco were studied, as these relate to types of habitat occupied (i.e. urban park, suburban forest, non-urban land outside forest, and non-urban forest as divided into forest edge or forest interior). The pellets collected at 152 sites in central and north-eastern Poland in the years 1990-2008 comprised 17,908 items of vertebrate prey, of which 115 (0.64%) were bats. Tawny owls caught 11 bat species, most frequently Nyctalus noctula, Plecotus auritus and Eptesicus serotinus. The analysis revealed habitat-related differences to the proportions of all tawny owl prey items accounted for by bats, being the highest in urban habitats (2.0%) and suburban forests (0.8%), and the lowest in forest interiors (0.1%). Bat frequency in the diet of tawny owls correlated negatively with that of other mammals pooled together with amphibians. Myotis nattereri and "aerial hawkers" (vs. "gleaners") were taken significantly more often in habitats associated with a large city (parks and suburban forests), and P. auritus in non-urban habitats.