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Bats

There are approximately 1100 species of bat worldwide, which accounts for almost one fifth of mammal species across the planet. Most of these (around 70%) are insectivorous. 17 species are known to breed in the UK, although this number decreases as you go north. Bat populations have suffered dramatically from loss of natural and man-made roost sites, habitat fragmentation and impoverishment of feeding areas.

Some bat species have evolved to exploit specific habitat or prey types. The noctule for example, captures and eats flying beetles, whilst brown long eared bats are specialist “gleaners” capable of capturing insects off leaves in the canopies of trees. The Daubenton’s bat has evolved to capture aquatic insects, by trailing its comparatively long and hairless legs in the water as it flies over river, streams and ponds. In contrast, the UK’s most common bat, the common pipistrelle is less specialist and occurs across most of the country.

Most bats have several roost sites that they use at different times of year. In winter, they generally require a location with constant temperature and high humidity for hibernation. Females congregate together in late May and June to give birth and suckle their young. Such maternity roosts can be used by as little as 2 or 3 females, but large roosts can include in excess of 1000 mothers. Males tend to roost singly or in small groups throughout the year.

Legislation

All bat species and their roost sites are fully protected under The Wildlife and Countryside Act 1981 (as amended).

The Act makes it an offence to:

  • intentionally kill, injure, take, possess or trade in any bat species (as listed in schedule 5);
  • interfere with places used for shelter or protection or intentionally disturb animals occupying such places.

All bat species are listed on Annex IVa of the European Habitats Directive 1992 (EC Directive 92/43/EEC on the Conservation of Natural Habitats and Wild Fauna and Flora). In the UK the Directive has been transposed into national laws over several years and are now known as “The Conservation of Habitats and Species Regulations 2010”. Under this legislation a person commits an offence if they:

  • deliberately capture, injure or kill any bat;
  • deliberately disturb any species in such a way as to be likely significantly to affect-
  • the ability of any significant group of animals of that species to survive, breed or rear or nurture their young
  • the local distribution or abundance of that species;
  • damage or destroy a breeding site or resting place.

All UK bat species are also listed on Appendix III of the Bern Convention (Convention on the Conservation of European Wildlife and Natural Habitats, 1982) and, except the pipistrelle, are listed in Appendix II. All UK bat species are protected under the Agreement on the Conservation of Bats in Europe (under the Bonn convention on the Conservation of Migratory Species of Wild Animals).

The UK Biodiversity Action Plan includes seven bat species on the priority species list and has plans for five, including soprano pipistrelle (UK BAP, 2007). 18 species of bat are native to the UK, with an estimated population of 1.28 million, the common pipistrelle is the most common, the only other species with the status "common" are soprano pipistrelle and brown long-eared bats. Four species, Daubenton's, Natterer's bat, Whiskered and Brandt’s bat, with populations between 150,000 - 30,000, are locally common. Five of the remaining species are vulnerable and four, including the grey long-eared bat, with an estimated population of only 1,000, are rare. Alcathoe’s bat has recently been discovered as resident although its status and distribution are not yet known.

Bats are listed as Priority Species in most Local Biodiversity Action Plans.

Survey

There are several types of bat survey that can be undertaken, but all follow prescribed methodologies. Buildings, trees and other structures can be physically searched for evidence of bat occupation. This can be time consuming, depending on the complexity of the structure, and require the use of specialist investigation equipment such as endoscopes. Dusk emergence and dawn return surveys use experienced bat surveyors equipped with bat detectors to observe the potential roost site and record the locations, species and numbers of bats emerging from or returning to the site. A minimum of two site visits is required. Remote detection and recording of bat activity can be achieved through the use of infra red video camera’s and/or remote bat recorders such as the Anabat © system. Foraging bats surveys to identify bat use across a wider area are often implemented to gain an understanding of how bats use features in the wider countryside.