A medium sized bat with short blackish brown fur on its back that turns a reddish colour towards the tips and yellowish brown fur on its underside. The face, ears and wing membranes are all a blackish brown in colour. The wings are long and narrow and often have hair and the tragus is as long as it is broad with a broad rounded tip that gives it an almost mushroom appearance. The juveniles are darker in colour that the adults.
South of England and Wales.
Although woodlands are their preferred habitat, they have also been found in both parklands and urban areas. The Leisler's bat will be found roosting in buildings, provided bat boxes and trees during the summer period and building cavities and tree hollows during the winter.
Although not a direct threat from a predator, Leisler's bats are vulnerable to the loss of roost sites and any change/loss of habitat that results in a reduction in the availability of its prey. Pesticides are also a threat to the Leisler's bat, due to not only the detrimental impact they can have on its insect prey population but also due to the potential contamination of prey with fatal toxins.
Mating occurs during August/September, when a single male will pair with as many as 9 females and fertilisation occurs during the following spring. The females will form maternity roosts of between 20 and 50 bats during the summer and one offspring, known as a pup, is born during June. The pup will be weaned after about 7-8 weeks.
Leisler's bats are listed as low risk by the IUCN. Fully protected under Schedule 5 of the Wildlife and Countryside Act (1981) as amended, and by the Conservation (Natural Habitats &c.) Regulations (1994). An agreement on the Conservation of Bats in Europe (EUROBATS) under the auspices of the Bonn Convention, also known as the Convention on Migratory species (CMS) is in force, and all European bats are listed under Appendix II of the CMS.
The Leisler's bat used to be known as the hairy bat due to the long hair it has around the shoulders and back.