Pipistrellus Bats

Pipistrellus pipistrellus

Common Pipistrelle

Description and identification

Common pipistrelles are one of the smallest bats found in the UK, and are the ones that you are most likely to see flying at dusk. A small brown bat, the common pipistrelle has short ears, and weighs only 4-8gms – about the same as a pound coin! The ‘common pip’ normally (but not always) has a black band across the face, leading to their nickname of ‘the bandits’. They are quite recognisable when in the air, with a characteristic jerky flight pattern as they hunt for insects.

The common pipistrelle, the most common species of bat in Europe, was only confirmed to actually be two species through molecular genetics50 after two distinctive echolocation frequencies were established51. The separation of these two bats through the application of mitochondrial sequence analyses was one of the first among European mammals.

Status and distribution

The common pipistrelle is our most widespread bat species, present throughout Great Britain and Ireland. It is generally accepted that there were significant historical declines in pipistrelles (and other bat species) from at least the beginning of the 20th century53, if not earlier. There are now signs that the population is starting to increase again. The latest report from BCT shows that there has been an 82.1% increase in numbers since the baseline year of monitoring in 1999.

The common pipistrelle is the only species to have been recorded in all of the 36 hectads of Nottinghamshire.

Conservation

Protected in the UK under the Wildlife and Countryside Act, 1981. European Protected Species under Annex IV of the European Habitats Directive.

Roosts

In summer, common pipistrelles are likely to be found roosting in building crevices – under roof coverings, in soffits and fascias, or under hanging tiles. Females will gather in groups of around 50 bats, sometimes in greater numbers but usually fewer than 200, to give birth to a single pup. Once the young are able to fly, the colony often breaks up and the animals roost in smaller numbers. They often return to the same maternity site year after year. Individual bats, especially males may also be found in low numbers in rock crevices or under tree bark.

Little is known about where common pipistrelles hibernate in Nottinghamshire or anywhere else in the UK for that matter! They are known to hibernate in underground cellars, tunnels and caves and occasionally in cavity walls but are only ever found in low numbers. They need cool, stable and humid temperatures to remain torpid.

Food and foraging

The common pipistrelle eats a variety of different flies, as well as aquatic midges and mosquitos – in fact they have been recorded eating up to 3000 midges in a night! If you’re listening to a pipistrelle on a heterodyne bat detector then listen out for a sound like a raspberry, or a ‘zip’; this is the sound made when the bat homes in on its prey. As the bat gets closer to its prey, its calls also get closer together, producing what is called a ‘feeding buzz’.

The common pipistrelle is very much a generalist bat species and being adaptable it is found across the country in both urban, suburban and rural areas. It is often seen hunting for food in urban parks and gardens and around street lamps where flying insects have been attracted to the light.

NBG have a dedicated team of bat carers who take in bats found by members of the public. Many have injuries or are young bats which have found themselves in trouble on one of their first flights away from the roost.

The common pipistrelle is the species we recieve the most calls about which perhaps shows that this species has adapted well to the modern urban environment.

Soprano Pipistrelle

Pipistrellus pygmaeus

Description and identification

Soprano pipistrelles, along with common pipistrelles, are the bats that you are most likely to see at dusk in the UK. In wooded areas near water the soprano pipistrelle is usually the most abundant bat species. Although it has a paler, more rounded face and is typically slightly smaller, the soprano pipistrelle looks very much like its ‘common’ relative, although it does typically smell a bit more! The soprano pipistrelle is more likely to be seen hunting for food over water than the common pipistrelle. You can usually tell the two species apart by their echolocation calls, with the peak echolocation frequency of the soprano pipistrelle at 55 kHz, the highest of the three UK pipistrelles. However, due to the variability of the calls made by each species depending on where they are (they often call lower when in the open and higher when in a cluttered environment like a wood), then sometimes the calls can overlap.

Status and distribution

The soprano pipistrelle is a common and widespread bat species, and is found across all of Great Britain and Ireland and in Scotland is more numerous than common pipistrelle. In Europe it is found in Norway – further north than the common pipistrelle. Although historically as with all of our bat species, there are signs that the population is starting to increase again. The latest report from the Bat Conservation Trust shows that there has been a 58.9% increase in numbers on field surveys since recording began in 1999, the baseline year for monitoring.

The soprano pipistrelle is widely distributed and has been recorded in 33 of Nottinghamshire’s total of 36 hectads since 2010.

Roosts

Soprano pipistrelles are often encountered in buildings where they roost in crevices, such as under roof coverings, in soffits and fascias, or under hanging tiles. Females will gather in large groups (often larger than any other UK bat species) to give birth their single pup. Soprano pipistrelle colonies will often have two or more roosts and will often return to the same roosts year after year, which means they can be monitored. There are several maternity roosts exceeding 400 breeding females in the county, and a small number exceeding 700. There are also several bat box schemes which support good numbers of this species. Bat boxes often also support single bats, although these can be found in a variety of places; in buildings and other structures, and in trees.

Hibernating soprano pipistrelle have been found in the county in cavity walls and cracks and crevices in buildings. They have also been found in holes in trees and are regularly recorded in bat boxes.

Food and foraging

The soprano pipistrelle eats a variety of small insects, including aquatic midges and mayflies. It is a species strongly associated with water and woodland, and can sometimes be seen hunting in woodlands up to an hour before sunset. They are also often observed feeding under tree branches and overhanging vegetation.

Click below to play a video with time exspansion and heterodyne bat echo location calls.

Nathusius’ Pipistrelle (Bat of the year 2015 by BatLife Europe)

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.