Pipistrelle bats (Pipistrellus pipistrellus and Pipistrellus pygmaeus)

KingdomAnimalia
PhylumChordata
ClassMammalia
OrderChiroptera
FamilyVespertilionidae
GenusPipistrellus (1)
SizeWingspan: 180-240 mm (2)
Head-body length: 35-45 mm (2)
Weight3-8 g (1)

Listed under Appendix II of The Bonn Convention, Appendix III of the Bern Convention and Annex IV of the EC Habitats Directive. In the UK this species is protected under Schedules 5 and 6 of the Wildlife and Countryside Act 1981, and Schedule 2 of the Conservation Regulations 1994 (3).

It was recently discovered that there are actually two species of pipistrelle bat formerly grouped together as Pipistrellus pipistrellus. Both species are very similar but differences in the frequency of the echolocation calls and genetic differences distinguish the two (2), P. Pipistrellus echolocates at 45 kHz, and P. pygmaeus at 55 kHz (2). Research into behavioural and ecological differences between the two species is currently underway. The pipistrelles are Britain's smallest bats (4), are generally brown in colour, and have fast 'jerky' flight. An individual can eat up to 3000 insects a night (2).

Found throughout most of Europe (2), the pipistrelle is the most widespread and abundant bat species in the UK. However it has undergone a 70% decline in numbers between 1978 and 1993 (3).

Pipistrelles roost in trees and under external features of buildings, such as hanging tiles and soffits. They feed along woodland edges, in open woodland, suburban gardens, marshes and over water (2). Hibernation occurs in crevices in buildings and trees as well as in bat boxes (5).

Pipistrelles are active between March and November (4). They hunt and eat insects on the wing in open spaces between vegetation (6). A variety of insects are taken, including small moths, midges and lacewings (2). Mating generally takes place in autumn at mating roosts, females then congregate in maternity roosts between May and August. One young is usually produced between June and mid-July, which will start to fly around three weeks later (2).

The decline is probably due in part to changes in agricultural practices that have reduced the availability of insect prey (3). Pipistelles are also vulnerable to disturbance and loss of roost sites; toxic timber treatment chemicals in buildings are a particular threat.

The National Bat Colony Survey has monitored many pipistrelle colonies since 1978, and Scottish Natural Heritage has devised measures by which pipistrelle roosts can be conserved in houses. Ongoing research is underway to investigate aspects the ecology, physiology and activity of the two species. The pipistrelles are priority species under the UK Biodiversity Action Plan (UK BAP), the Species Action Plan aims to restore the population back up to pre-1970s numbers (3).

For more on British bats see the Bat Conservation Trust:
http://www.bats.org.uk/

The Vincent Wildlife Trust:
http://www.vwt.org.uk/index.php

Information authenticated by the Bat Conservation Trust:
http://www.bats.org.uk/

  1. National Biodiversity Network Species Dictionary http://www.nhm.ac.uk/nbn/
  2. Bat Conservation Trust (January 2002) http://www.bats.org.uk/
  3. UKBAP Species Action Plan (January 2002), available at: http://www.ukbap.org.uk
  4. Wardhaugh, A.A. (1995) Bats of the British Isles. Shire Natural History, Aylesbury.
  5. Bat Conservation Trust (2002) Pers Comm
  6. Altringham, J. (1999) Bats: Biology and Behaviour. Oxford University Press, Oxford.