Nathusius’ Pipistrelle

Pipistrellus nathusii

Description and identification

Nathusius’ pipistrelle looks similar at first glance to the common pipistrelle and soprano pipistrelles; however as well as having a shaggier appearance, paler underside and more furry tail, it is slightly larger, looks more robust, and has slightly broader wings than the other two species.

The teeth of Nathusius’ pipistrelle are also different from the common and soprano pipistrelles and the pattern of their wing membrane cells may also often be used to separate all three species.

As described above, the echolocation calls of Nathusius’ pipistrelle also look and sound similar to the other pipistrelles on a bat detector; however, the peak frequency (of maximum energy) of a Nathusius’ pipistrelle call is typically lower than the two more common species, at 36-41 kHz.

The social calls of ‘Nathusius’ pipistrelle are also more elaborate than those of the other two pipistrelles, and indeed more complex than most other European bat species.

Status and distribution

Nathusius’ pipistrelle is a widespread but uncommon if not rare bat species in the UK. This long-distance migrant is now known to reside in the UK; however, the number of known roosting and breeding sites for the species remains very low. Many encounters with Nathusius’ pipistrelle are in the late summer/autumn, which is the peak migration period for this species, although migrating animals may also be recorded in the spring.

Nathusius’ pipistrelle was first recorded in Nottinghamshire in September 2006 on a bat detector during an NBG bat walk at Attenborough Nature Reserve. The species was recorded there again the following autumn. Since then, the number of records of Nathusius’ pipistrelle in the NBG database has steadily increased to include records at several sites. Most records come from along the Trent Valley during mid-August to October, which indicates the importance of this river corridor for these migrating bats.

The earliest ‘in-the-hand’ record of a Nathusius’ pipistrelle in the NBG database is of a grounded female bat rescued from a water butt (and later successfully released) in Sherwood in early October 2010.

From 2014 to 2018 NBG has been significantly involved in the ‘BCT National Nathusius’ Pipistrelle Project’ (NNPP), which uses advanced survey techniques (harp traps and acoustic lures) to help us learn more about the origins and migratory patterns of Nathusius’ pipistrelles encountered in the UK. Results on the NNPP in Nottinghamshire have shown that although Nathusius’ pipistrelle can be considered a resident in the county, there is no evidence yet that it breeds here.

Roosts

Nathusius’ pipistrelle has been recorded roosting in bat boxes, cliffs, buildings and other structures in mainland Europe and is often also found roosting in trees in features such as hollows, knot-holes and bark crevices. However, in Great Britain most roost records for this species are of bats using buildings and bat boxes, with very few records of roosts in trees.

The majority of Nathusius’ pipistrelle roosts that are discovered are occupied by individual or low numbers of animals either as mating or transitional roosts, non-breeding summer roosts or, more rarely, for hibernation. Mating roosts are usually occupied in the autumn when males sing extended social calls to attract a mate.

Maternity roosts in Great Britain are very rare and those that are known are primarily in buildings. Most of these maternity roosts are also in coastal areas, particularly along the southern and eastern coastlines along likely migration routes.

Nathusius’ pipistrelle maternity roosts usually comprise at least 20 females. They can sometimes be found occupying sites with other species such as common pipistrelle, soprano pipistrelle and Brandt’s bat. Up to 350 female Nathusius’ pipistrelles have been recorded in maternity roosts in continental Europe.

The first and only confirmed record of a Nathusius’ pipistrelle roost (to date) in Nottinghamshire is a mating roost (one adult male and one adult female) in a Schwegler 1FF bat box at Attenborough Nature Reserve, which was discovered by members of NBG in September 2013.

Food and foraging

Nathusius’ pipistrelle usually feeds on small to medium-sized flying insects such as midges (particularly non-biting midges), aquatic flies, black-flies and mosquitoes, and also sometimes caddis flies, aphids and alder flies. As such, the species is most likely to be found hunting over lakes and rivers. Rivers and coastal waters may also provide hunting opportunities for Nathusius’ pipistrelle along its migration routes. This species is not exclusively associated with freshwater habitats however, and it can also be found hunting along woodland edges and rides, in woodland clearings, and also over farmland, parkland, gardens and even around street lights.

Studies of the feeding and commuting behaviour of Nathusius’ pipistrelle have indicated that the radius of the Core Sustenance Zone (CSZ) around a roost of this species is approximately 3 km, although more data are required to corroborate this.