Bats

There are 17 species of bat in the UK, all of which are protected by law because their numbers have decreased so dramatically.

BRITISH BAT SPECIES

Noctule Greater horseshoe bat
Common Pipistrell Leisler’s bat
Pygmy Pipistrelle Brandt’s bat
Brown long-eared bat Barbastelle
Serotine Grey long-eared bat
Lesser horseshoe bat Bechstein’s bat
Natterer’s bat Nathusius’ Pipistrelle
Whiskered bat Greater mouse-eared bat
Daubenton’s bat  

The Pipistrelle bat is the commonest British bat and also the smallest. Its brown fur is variable in tone. Common in woodland and farmland but also often seen in towns where it roosts in lofts and buildings. Emerges just after sunset and has jerky flight pattern and fluttering wings. Found throughout most of Britain and Ireland.

Bats are heterothermic, which means that their body temperature is not constant but depends on the temperature of the air around them and on what they have eaten. Roosts are chosen carefully for their warmth and nearness to a good food supply.

Bats usually choose to roost in trees. Summer roost sites are usually in south-facing roofs of modern housing.

In winter when there is less food to be found the bats hibernate. Pipistrelles hibernate from late November until late March. Hibernation sites have been found in North facing small spaces in buildings, including high up in multi-storey flats.

The felling of dead, old and hollow trees has reduced the availability of natural roost sites for bats. Bat boxes provide artificial roosts and are important for conservation and research, but they cannot entirely replace natural tree holes.

Bat Boxes

NO WOOD PRESERVATIVES should be used because these may be harmful to bats. Untreated boxes will last roughly ten years.

Location

Site in areas where bats are known to feed, but with few potential roosts. Place boxes as high as possible in sheltered and wind-free areas exposed to the sun for part of the day, up to three boxes per tree. An area around the box needs to be cleared to allow bats direct and easy access to the box entrance. Woodland rides and glades are ideal, particularly if close to a marsh, pond or river.

Box inspection

Bats and their roosts are protected under the Wildlife and Countryside Act 1981, making it an offence to disturb, handle or kill bats. If a few boxes are installed on your property it is reasonable to delay obtaining a licence until bats are found. The occupancy of boxes can be checked by watching at dusk.

Boxes should not be inspected between June and mid-August when bats are giving birth and lactating. It may be some months or years before boxes are regularly used.

Checking boxes

If you are checking a box that you suspect has bats in it, by law you should be in possession of a bat box checking license from an SNCO. Open carefully because bats may be hanging on the top. When a box has been inspected bats must be removed before the top is replaced to prevent trapping the bats’ feet. The bats should be placed at the entrance and allowed to crawl into the box.

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