Case report and prey analysis of ground-nesting eagle owls ( <i>Bubo bubo</i> ) in Slovakia

Abstract In current ornithological literature, there is a general consensus that the eagle owl ( Bubo bubo ) is a breeder of rocky habitats in Slovakia, especially on cliffs and quarry walls, but little research to date has concentrated on cases of ground-nesting in the lowland areas of the country. This study provides an overview of the documented cases of eagle owls breeding in lowland forests, a relatively unusual method of breeding for this species. The authors also report a recent case of an eagle owl breeding on the ground in a floodplain forest at the small settlement of Sedín near the forest edge in the western part of the Danube Lowlands. The nest was located in a shallow basin at the base of a large white poplar ( Populus alba ) tree, just 3 m from an oxbow lake. The site was visited three times between 12 April and 12 May 2024, and three young birds were observed in the nest, all of which likely fledged successfully. Prey remains from the nest were analysed and the results are presented here together with those of five other eagle owl nests from the lowlands of Slovakia and the Czech Republic. In the nest near Sedín, the common hamster ( Cricetus cricetus ) was the predominant prey species, in contrast to a location near Vojčice in the East Slovak Lowlands in which the brown rat ( Rattus norvegicus ) predominated or nest sites in Southern Moravia and the Třeboňsko region of the Czech Republic where larger birds were the main prey.