Pipistrelle BatPipistrelle Bat

Bats manage to live alongside humans throughout Britain – you may even find them sharing your house. Don’t worry though, these much-misunderstood animals are not the evil creatures we often imagine them to be, but are simply flying mammals with a taste for insects.

In Britain there are fourteen species of bat, all of which are found on the south coast of England, with only seven or eight in the middle of England and decreasing to two or three in the north of Scotland. This variation is due to the greater availability of insects to feed on in the south, with its warmer climate and different farming methods; and possibly a greater number of roost sites. All the bats in this country are relatively small; the Pipistrelle, being one of the smallest, is just 5cm long, with a wingspan of 20cm and weighing 4 grams (the same as a 10 pence piece). One of the largest and most widespread is the noctule, reaching 8cm long and often mistaken for a swift, as it flies so high after sunset.

Family Life

Bats generally mate in the autumn, but delay fertilisation until warmer weather in spring, giving birth in the summer. The young bat suckles immediately, literally hooking on to the mother’s nipple with curved milk teeth. During the night the mother leaves her young tucked into a crevice in the roost, while she hunts for insects, identifying her "baby" on return by its high pitched squeaks and smell. All European bats feed on insects, from tiny gnats to large beetles – it’s estimated that in one night a Pipistrelle can eat up to 3,500 insects.
Some bats have adapted to city dwellings, swapping traditional roosting sites in tree holes or caves for small crevices in buildings – behind weather boarding or between roofing felt and tiles. Should you find bats roosting in your roof there is no need to worry about damage to property, they do not make nests, nor do they chew wood or wire. Bat droppings are dry and they also make very good fertiliser (if you can collect enough!). They tend to frequently change roosts in summer so may only visit your house for two or three weeks. This is the time of year to see bats (they hibernate in winter) when they emerge mainly around dusk and before dawn to feed.

Hibernation – the big sleep

During winter there are few active insects so bats cope with this seasonal lack of food by hibernating. As summer turns to autumn the bats store energy by building up to 35% of their body weight in fat. To conserve these energy supplies during hibernation their heart rate, breathing and other body systems are reduced, although they do "wake up" occasionally and heat up as they do so. The hibernation sites are very different from the summer roosts – damp to keep them moist, and cooler to allow their body temperature to drop, but not too cold so that they freeze.

Threats to Bats

Numbers of bats have been declining over the years due to loss of roost sites, timber treatments of roofs using chemicals toxic to bats, pesticides killing their prey and a dramatic loss of appropriate feeding sites. For these reasons bats are protected by the law under the Wildlife & Countryside Act 1981. It is illegal to harm bats or disturb their roost sites. If you find a sick or injured bat, or think that you have a roost in your house, then contact English Nature (01733 340345) who will put you in touch with a licensed bat worker.

Bat Myths

The saying "as blind as a bat" is entirely wrong, bats can see perfectly well although not in colour. Bats do not get tangled in long hair flying, as they have excellent "night vision" using echo-location – emitting a high frequency sound which usually can’t be heard by people. The bat listens for the returning echo of the sound from nearby objects and can build up a clear picture of its surroundings. The classic image of a bat drinking blood is linked to the Dracula myth. However, out of almost 1,000 species of bat around the world only three lap up blood from large animals and the comforting news is that they all live in South or Central America.

Bat Friends

Bats are under threat – so consider making your house and garden more bat friendly:
Put up bat boxes or install a bat brick for easy access to your roof space.
Encourage bats’ food (night flying insects) by planting night scented flowers such as honeysuckle or evening primrose.
Tell English Nature if you think bats are roosting in your house.
Take advice from English Nature before treating your home with chemicals or using sprays in the garden.
If you want to see bats then go for a stroll at dusk around your local park or nature reserve. Also look out for them in your neighbourhood usually near trees (particularly brown long-eared bats) or water (particularly Daubenton’s) or maybe under a street light, picking off all the insects attracted to it.