Nyctalus leisleri

Medium sized dark brown bat with rounded ears and muzzle. This species is smaller than the other Nyctalus species and has darker coloured fur. The fur is two-colored, the base of the hair is dark black-brown and the tips are red-brown. The dorsal side is darker than the ventral. The skin areas are black-brown. The wings are long and narrow.

Echolocation calls are between 45 – 15 kHz, the peak frequencies are around 25 kHz.

Leisler’s bat is a typical woodland bat, more rarely found in orchards and parks. On the Canary Islands and Madeira it is found in subtropical laurel forests, in the Mediterranean – in oak woodlands and in Central Europe – in mixed beach woodlands. This species is seasonally migratory. The roosts are changed between 2 – 4 days at a distance of up to 1,7 km.

Roosts are found in naturally developed tree holes and woodpecker holes. They can be found in roof spaces in Ireland, the Canary islands and Madeira and at some places in Germany. Winter roosts are in tree holes but also in buildings and rarely in rock crevices. There is no available data for winter roosts in Bulgaria.

Mating takes place from the end of July to September in mating groups. The males form small groups of up to 12 animals and one male lures up to 10 females, principally with a song flight, or more rarely from the roost entrance. Nursery colonies usually comprise of 20 – 50 females. Between the beginning and end of June, 1 – 2 young are born. They reach sexual maturity in their first autumn.

The flight is fast above and below the canopy of trees and also over larger water bodies and around street lamps. On the Canary Islands and Madeira, Leisler’s bats are also active in winter. The food consists of moths, Diptera, caddis flies and beetles.

Habitat loss, loss of roosts because of the clearing of old mature trees are the main threat to this species. Wind farms have recently been recognised as a significant threat during migration.

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”.