One of Austria’s rarest bat species. Occurrance was documented during periods of migration and breeding and in hibernation sites. Maternity roosts were found in three areas, all of them in nest boxes. Hibernating individuals were found in towns. In contrast to sources from the 19th century, Nyctalus leisleri was almost entirely found outside the Alps at a sealevel of below 800 metres, than within the alpine area at very high sealevels.