Northern Ireland's Priority Species

Pipistrellus nathusii – nathusius’ pipistrelle

Pipistrellus nathusii

Pipistrellus nathusii Keyserling & Blasius 1839
Family: Vespertilionidae

Bats are the only true flying mammals and in Northern Ireland there are eight species. All our bats are insectivorous; they only eat insects and they use echolocation to build up a ‘sound picture’ of their environment and prey.

The presence of Nathusius’ pipistrelles in Northern Ireland was first recorded by J. Russ in August 1996, using a time expansion bat detector. A month later a live but not flying, bat was found in South Belfast, It was subsequently identified as Nathusius’ pipistrelles. Not only were these the first records of the Nathusius’ pipistrelle but it was the first new mammal to be identified in Ireland for some years. Since then a number of nursery colonies have been identified in a number of counties throughout Northern Ireland.

In brief

  • Found predominantly in Counties Antrim and Down
  • Roosts are always within 2km of water, such as Lough Neagh
  • Emerge very soon after dusk to feed on flies, midges, mosquitoes etc.
  • Considered to be a vulnerable species in the European context
  • Most recently discovered mammal in Ireland
  • Largest of the three pipistrelle species, weighing in the region of 8-15g
  • A distinctive feature is its tendency to ‘play dead’ rather more so than the other pipistrelles when handled.

Species description
Weighing in at between 8 and 15g, the Nathusius’ pipistrelle is a small bat but larger than the common pipistrelle. It also tends to share the roost with the soprano pipistrelle. The fur colour ranges from reddish-brown to dark brown and the hairs can be pale at the tips. The fur on the underside is somewhat shorter and paler.

Flight is similar to that of the other pipistrelles — erraticbut quite fast, having relatively long, narrow wings. They prefer to hunt for flies, midges, small moths, mosquitoes etc. along woodland or parkland edges generally in close proximity to water. Todate, there are only a few records of nursery roosts in Northern Ireland and they are in the cavity walls of older buildings. There is one Northern Ireland record of a Nathusius’ pipistrelle roost in a domestic dwelling — an old stone farmhouse where they are sharing the roost with another species of bat.

Life cycle
Little is known about the reproduction and life cycle of the Nathusius’ pipistrelle in Northern Ireland because there are so few records. Their life cycle is likely to be similar to that of all our other bats in that they probably hibernate from November to March or early April with the young being born into the nursery roost from June to July and independent about six weeks later. It is not known where the Nathusius’ pipistrelle hibernates in Northern Ireland.

Similar species
Common pipistrelle and soprano pipistrelle.

How to see this species
So far these pipistrelles have been located predominantly in Counties Antrim and Down and a few in Counties Fermanagh and Armagh. The best method of finding them is probably using a bat detector set at about 40kHz frequency.

Current status
So far there are only nine records of Nathusius’ pipistrelle and most of those are of single bats or have been located using bat detectors. Given the lack of information regarding the presence of roosts, it is hard to gauge how many individuals may exist but they still face the same problems as our other bat species, especially those that favour wet environments.

Like our other bats, Nathusius’ pipistrelles and their roosts are fully protected against deliberate damage or destruction by The Wildlife (NI) Order in 1985. They are also protected under the Conservation (Natural Habitats etc) Regulations (NI) 1995.

Why is this species a priority in Northern Ireland?

  • Bats as a group are considered to have declined.

It is listed as a species requiring strict protection in Annex IV of the Habitats Directive (1992) and Appendix II of the Bern Convention (1979). It is thought to be at the extreme north-western limit of its range and is considered to be a vulnerable species in the European context.

Threats/Causes of decline
The removal of hedgerows, flight ‘corridors’ for bats, causes the fragmentation of feeding habitat. This makes it difficult for bats to reach their feeding areas as they do not like flying over open ground. The increased use of pesticides has resulted in severe declines in the abundance of insect prey. It can also contaminate what insect prey is available.

Deterioration in water quality by, for example, pollution, may severely affect the range of prey species available. The removal of waterside trees and vegetation can all contribute to a drop in bat numbers. Removing hollow or damaged trees may contribute to actual or potential roost damage or destruction.

Conservation of this species

Current action

  • The Northern Ireland Bat Group collates records for this species
  • Implementation of the Northern Ireland Habitat Action Plan for Species Rich Hedgerows and the Woodland Habitat Action Plans.

Proposed objectives/actions

  • Maintain the current range.

What you can do
Plant insect-friendly plants. Leave trees that have holes but are otherwise safe. Monitor sites and population sizes and send in records to the Northern Ireland Bat Group, c/o National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU. Tel: 028 9039 5264, [at]

Further information

Northern Ireland Habitat Action Plans

The Wildlife (Northern Ireland) Order 1985

Northern Ireland Bat Group

Bat Conservation Trust

Stebbings, RS and Jeffries, DJ. Focus on Bats. (2004). (Adapted for N Ireland and published by Environment & Heritage Service).

Hayden, T and Harrington, R. (2000). Exploring Irish Mammals. Town House and Country House Ltd, Dublin, Eire.

Allen, P, Forsyth, I, Hale, P, and Rogers, S. Irish Naturalists’ Journal (2000). Special Zoological Supplement.

Text written by:
Lynne Rendle, CEDaR Vertebrate Officer, Ulster Museum

iNaturalist: Species account : iNaturalist World Species Observations database