Leisler's bat
Nyctalus leisleri
Leisler's bat is a medium-sized European bat characterized by narrow wings and a powerful flight. Its fur is distinctly bicolored, featuring dark brown bases and shiny golden-brown tips. It primarily inhabits forested areas, utilizing tree hollows for roosting. This species is notable for its long-distance migrations between summer and winter habitats.
Details
Identification
Bicolored fur (dark base), short ears with mushroom-shaped tragus, upper side of the forearm is hairy.
Social behavior
Social in maternity colonies; males form harems in tree hollows during the mating season.
Diet
Insectivorous; feeds on moths, dipterans (gnats, flies), and caddisflies.
Hunting strategy
Aerial hawking in open air at high altitudes, often above tree canopies or along forest edges.
Overwintering
Hibernation in tree hollows or buildings, often in larger groups.
Ecology
Ecological role
Regulator of insect populations and part of the food web for predators.
Natural predators
Owls (e.g., Tawny Owl), birds of prey, martens.
Competitor species
Common Noctule, other forest-dwelling bat species.
Ecosystem service
Biological pest control through the consumption of insects.
Threats
Loss of roosts due to intensive forestry, use of pesticides, collisions with wind turbines.
Scientific profile
Profile
Distinguishing features
Characteristic is the mushroom-shaped tragus, which is wider than it is high. The ears are short and rounded. A key feature is the hairy 'fleece' on the underside of the wing membrane along the forearm. Smaller than the Common Noctule (Nyctalus noctula), with a forearm length of 38-47 mm.
Habitat
Typical forest dweller, preferring structurally diverse deciduous and mixed forests with a high proportion of old growth and numerous tree hollows. Also found in parks, gardens, and occasionally near settlements. Often hunts over water bodies or along forest edges.
Diet
Insectivorous; feeds on small moths, dipterans (midges, flies), caddisflies, lacewings, and occasionally small beetles.
Protection & threats
Main threats
Loss of roost trees due to intensive forestry; food scarcity due to pesticide use; high collision risk at wind turbines due to open-airspace hunting behavior.
Population trend
Stable to unknown; precise monitoring is difficult due to its secretive lifestyle in tree hollows. Classified as 'vulnerable' or on the 'preliminary warning list' in Germany (depending on the federal state).
Conservation measures
Protection and preservation of old-growth stands and cavity trees; installation of bat boxes as a temporary solution; curtailment algorithms for wind turbines during peak activity periods.