Leisler’s bat

Conservation status: UK Red List

GB: Near Threatened 

England: Near Threatened 

Scotland: Near Threatened 

Wales: Least Concern

Global: Least Concern

Habitat: Deciduous Woodland, Coniferous Woodland, Forest, Mixed Rural, Suburban

Description: Medium-sized bat species. Distinguishable from the noctule bat by size (forearm less than 47mm) and fur colour (darker base of fur, whereas noctule in one colour). 

Origin and distribution: Native. Widely occurring in England, Wales, and Northern Ireland, however, their distribution is often patchy. In Scotland, their main population is the south-west, north to the Highland boundary and includes the islands of Arran and Bute. Absent from the south-east of Scotland where the larger noctule bat population is larger. Precise distributions are uncertain due to the confusion with the noctule bat, particularly when identifications are based off acoustic identification. This confusion is non-existent in Northern Ireland where the noctule bat is absent.

Diet: Aerial feeder preying on a variety of insects, particularly flies (midges and dung flies), moths and beetles. Diet varies greatly according to habitat.

General ecology: The Leisler’s bat is a forest and woodland species but is adaptable and can be found in mixed rural and suburban areas. These bats emerge early (shortly before sunset) and return late to their roosts (soon after sunrise). Hibernation is mainly in trees, but occasionally use bat boxes in winter, as well as tree-like sites in buildings such as behind wooden fascias. In Northern Ireland Leisler’s bats are found in large numbers in buildings.

Breeding: Roosts and forms maternity/nursery roosts in trees. Tree holes and crevices are preferred to buildings. Species include oak, ask, beech, Scots pine and Norway Spruce. Nursery roosts are typically rot holes resulting from damage or deformation. 

Conservation status: The Leisler’s bat is classified as Near Threatened on the IUCN Red List in England, Scotland, and Great Britain. Data is deficient to comment on whether population sizes are increasing, decreasing or remaining stable, although their habitat remains stable.

Identification

Medium-sized bat species. Distinguishable from the noctule bat by size (forearm less than 47mm) and fur colour (darker base of fur, whereas noctule in one colour). Its echolocation calls can be separated by an expert from the noctule and serotine bat calls. 

Bat detector

Range: 25-54 kHz

Most energy: 29 kHz

Average duration: 8.5 ms

Confusion species

High overlap in echolocation calls with Eptesicusserotinus (Serotine Bat) and Nyctalusnoctule (Noctule Bat).