Small bat like the Common Pipistrelle bat but a little bigger. The dorsal fur is brown, the ventral side is scarcely delineated, somewhat paler grey-brown. The face, ears and the membranes are dark brown. The wings are relatively long. The tail membrane is furred on the upper side to about half of the length. The fifth finger is longer than 43 mm.
Up to 12 ms long QFC calls with peak frequencies of 38 – 43 kHz. When obstacles are close, FM – QCF calls are with peak frequencies of 38 – 43 kHz.
Forest habitat: deciduous and mixed forests, can be seen in parks and gardens. Often near water bodies – big rivers and lakes. Hunting grounds are in forests and forest edges, over water bodies. They are around 6,5 km from the roost and can extend to 20 km2. Nathusius’ Pipistrelle bat is a seasonal long-distance (1000 km) migrant.
Summer and winter roosts are in tree holes, under tree barks, in crevices of buildings and cliffs. Nathusius’ Pipistrelle bat does not hang upside down like the other species.
The copulation occurs during the fall. Before the copulation the males occupy individual territories and they make display calls that attract passing females. Nursery colonies form in April – May and they are small, but after the birth of the pups the number increases. The nursery roosts are changed regularly. Females can give birth to twins, rarely even triplets. The nursery roosts are already abandoned by the end of July.
The flight is rapid and direct, 5 – 15 m above the ground. Nathusius’ Pipistrelle Bat hunts at the edges of forests, over waterways and around street lamps. The food consists of flying insects and other small insects.
Wind farms during migration of the species, pesticide use and loss of roosts.
Christian Dietz and Andreas Kiefer (2014), “Bats of Britain and Europe”;
Vasil Popov, Atila Sedefchev (2003), “Mammals in Bulgaria”;
Vasil Popov, Nikolay Spasov, Teodora Ivanova, Borqna Mihaylova and Kiril Georgiev (2007), “Mammals important for conservation in Bulgaria”.