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Home / Bats in Nottinghamshire / Leisler’s bat

Nyctalus leisleri

Description and identification

Leisler’s bat is a medium sized British bat, dark brown in colour with rounded ears and nose. It has a fur mane around its shoulders, which can stand on end when it is agitated44. Whilst the lower parts of its fur are dark brown, the tips are reddish, making it look glossy. The Leisler’s bat has long, narrow wings and hairy forearms/under wing, giving it the name of the ‘hairy-armed bat’. At first glance a Leisler’s bat looks like a noctule, but smaller.

The echolocation calls of Leisler’s bat can be difficult to distinguish from both noctule and serotine. The calls range from 15-45 kHz45, peaking at 25 kHz, making a chip-chop call characteristic of the two UK Nyctalus species, but are less harsh sounding than the noctule. Like the noctule, Leisler’s bat calls are very loud and can sometimes be heard from some distance with a bat detector46,47.

Status and distribution

Leisler’s bats are found throughout most of the UK but are rare; they are more common in Ireland. In England they are mainly found in the central and southern counties. There appear to be several Leisler’s bat colonies in the Sherwood Forest and Dukeries areas of Nottinghamshire, and those in the bat box schemes there attract bat enthusiasts from far and wide! Away from these core Nottinghamshire areas it is found less frequently but has a widespread distribution.

Roosts

Leisler’s bats are naturally a woodland species, with maternity colonies occupying tree holes, cracks and crevices. They are regularly found in bat box schemes at Sherwod Forest Center Parcs, Clumber Park and Budby Heath. Maternity roosts have been found in boxes at Budby and by the Forestry Commission in Elkesley Wood. Less commonly, Leisler’s bats roost in buildings, where they roost in similar positions to other crevice-dwelling bats, under tiles, roof felt or in crevices in gable ends. In Nottinghamshire, Leisler’s bat roosts have been recorded in at least 3 attics, a tree and in bat boxes.

Leisler’s bats will continue to roost in trees in winter but can also be found in cavities in buildings and occasionally in caves and tunnels, although none have been found in Nottinghamshire yet.

Food and foraging

Leisler’s bats hunt in a range of habitat types including cattle/sheep pasture, woodland, rivers, lakes and canals. They fly quite high, between 10m and 70m and swoop to catch larger prey. They also hunt around streetlights and floodlights for insects that are attracted to the light. Prey is caught and consumed in flight.

The diet of the Leisler’s bat has been investigated in Ireland, England and Germany48 where it was found that the bats eat mainly medium-sized and small insects, particularly moths and those with aquatic larvae such as caddis flies. Dung flies make up a significant part of their diet at certain times of the year.

Despite their relatively large size, Leisler’s bats will also eat much smaller swarming insects like midges and there is evidence to show that one feeding method used is to fly through swarms, filter feeding.