Bats and Swifts as food of the European Kestrel (Falco tinnunculus) in a small town in Slovakia

Abstract

Bats (Chiroptera) and Common Swifts (Apus apus) are excellent fliers that use buildings as roosts and breeding sites in urban areas. Some predators have recently become adapted to hunting formerly unavailable prey. One such urban predator is the European Kestrel (Falco tinnunculus). We analyzed the diet and foraging behaviour of this species in Bardejov, North-Eastern Slovakia. In several observed breeding pairs, some bird began to hunt bats using novel foraging behaviour: sit-and-wait above ventilation channels of building facades where bats roosted, using ambush and perching tactics. Kestrel pairs that specialised in hunting bats also hunted Swifts. We did not find significant differences between Kestrel sexes in hunting bats and Swifts, but Kestrels preying on bats and Swifts had significantly higher breeding success than those that did not. Recently, Kestrels and their novel prey, bats and Swifts, have become endangered by rapidly-improved insulation of building facades in Central Europe. This intervention simultaneously destroys breeding and roosting places and potentially causes the collapse of urban populations of the European Kestrel.