Go to the city: urban invasions of four pipistrelle bat species in eastern Slovakia.
Until now, late summer or autumn invasions into inhabited building have been regarded as phenomenon typical for the common pipistrelle, pipistrellus pipistrellus, exclusively. During the investigation of this phenomenon in the city of Košice (eastern Slovakia), we discovered that it was not always entirely specific for this species. Dur - ing the period 2016-2018, we recorded 3 events out of 35 invasions, where small groups of common pipistrelles that invaded into inhabited buildings were also accompanied by individuals of two con-generic bat species, pipistrellus pygmaeus and pipistrellus kuhlii. Cryptic species p. pipistrellus and p. pygmaeus were determined by genetic test. In addition, in 2019, we recorded the first winter occurrence of another pipistrelle species, pipistrel - lus nathusii, in this urban environment. We conclude that areas of frequent invasive behaviour of p. pipistrellus may be sometimes associated with concomitant occurrence of other related species that share common thermal or foraging niche and such behaviour could be evidence of their urbanisation tendencies.