Bat – pipistrelle
Pipistrelle bats are the most common of the 17 species of British bats, and the smallest. They vary in colour from pale brown to almost black, but usually they have red-brown fur. They have small dog-like faces with a broad flat head and short, broad ears. They have fairly narrow wings and a short tail. Their ears and muzzles are darker than their fur.
The bats emerge from roosting around 20 minutes after sunset, generally earlier on warmer nights.
Their fast jerky flight as they pursue, catch and eat insects in mid-air, distinguishes pipistrelle bats from birds. Usually these bats fly 5-10m (17-34ft) above ground level; alternatively they may be seen flying low over water.
Head and body length 3.5-4.5cm (1 ¼-1 3/4in)
Wingspan 19-25cm (7 ½-10in)
Pipistrelle bats are found over the majority of the UK apart from a few offshore islands.
The population of pipistrelle bats has declined in the UK over the past 30 years, between 1978 and 1993 there was a national decrease of 70 percent. All the UK species of bats are protected under the Wildlife and Countryside Act 1981, and it is illegal to harm them or disturb their roost sites. If you find bats roosting in or near your house, let Natural England or your local bat group know, and also seek advice from them before using sprays in the garden, or treating your home with chemicals.
Pipistrelles and other bat species have declined for many potential reasons, including loss of roost sites, toxic treatments of roof timbers, and loss of suitable feeding sites such as hedgerows, ponds and old grassland. Their decline is also partially attributed to the use of chemicals in agriculture to control insect populations, thus depriving the bats of food.
In urban gardens, cats pose a threat to many pipistrelle populations because they catch the roosting bats. Other predators are less likely in urban gardens.
To help maintain pipistrelle bat populations, you could put up a bat box which will provide roosting and safety for the bats, and you could also encourage twilight and night insects by planting night-scented flowers such as honeysuckles or evening primrose.
Bats occupy a wide range of habitats, including grassland, mature woodlands, farms, parks and gardens - as long as there are suitable structures to roost in. They also need hedgerows and wood edges, or man-made linear features, for their protection and navigation. They often prefer open grassy areas surrounded by trees or bushes near waterways or ponds, which provide a water and food source and roosting areas.
The pipistrelle bat is one of the most urban of UK bat species and is becoming more reliant on urban habitats, roosting in buildings and foraging in nearby wooded parks and gardens.
Where to find them in the garden
The two most important aspects of a garden to pipistrelle bats are trees and ponds. Mature trees provide roosting, shelter and safety, and they also play a fundamental role in their life cycle. Pipistrelle bats use trees for roosting sites where they can give birth to their young in a protected and sheltered environment and in winter they can safely hibernate in deep crevices. Tree habitats with their associated shrubbery attract a wide variety of insects which bats prey on.
Waterways and ponds provide bats with the water they need to rehydrate, and also attract midges and other flying insects which congregate in their thousands and provide a ready feast for bats.
Garden features which are associated with pipistrelle bats are old trees and bat boxes, undisturbed roofs and hollow walls that have access points, gaps behind drain pipes and between roof felt and tiles.
Bats hibernate from late November to late March, and this is when they are most likely to be found in buildings and tree holes. In warmer months they may have several daytime and temporary roosts.
Role in the garden
Pipistrelle bats feed on a wide variety of small, flying insects such as mayflies, lacewings, small moths, midges, caddis flies and mosquitoes. A single pipistrelle may consume up to 3000 insects in a night, showing both how important garden insects are and how useful bats can be in controlling unwanted species, so an abundance of insects is essential. For this reason they are an important addition to the garden to help to keep flying insect populations under control.
In urban areas where much of the environment is man-made, bats rely on gardens and parks for roosting areas, food and water sources, so keeping trees and ponds in gardens is encouraged to prevent them from declining further.
In the UK there are no predators which feed specifically on pipistrelle bats. Pipistrelle bats natural predators are owls such as the tawny owl and barn owl. Other British birds, such as kestrels, peregrine falcons and sparrow hawks, may also take bats. Weasels and stoats have been known to take low roosting bats, and it is also possible that foxes can do this. In urban situations cats are the most frequent predators.