Species: Myotis nattereri
IUCN Red List Status: Least concern, although becoming scarce in UK
All bat species in the UK are legally protected, both by domestic and international legislation.
Distribution: found throughout Britain & Ireland except Northern Scotland. Also occurs throughout Europe, Asia & Japan.
Habitat: woodland, parkland & farmland.
Size: head & body about 4 to 5cm; up to 30cm wingspan.
Life-span: can live for 25 years.
Description: light brown above, pure white underneath. Quite large, drooping, pale ears with upturned tips. Long, reddish face with bare, narrow muzzle.
Food: small insects.
The Natterer's bat is named after the early 19th century Austrian naturalist who discovered it. If you are bat-watching just after sunset you may be able to identify it from its white underside as it flies slowly at about roof-top level. Whilst it is flying, this bat often points its tail downwards, whereas other bats trail their tail behind them. Also, if you get the chance to examine one closely, Natterer's bat is the only bat with a fringe of tiny hairs along the edge of each tail membrane.
Hunting and Feeding
The Natterer's bat is a nocturnal insect-eater, hunting only after sunset and throughout the night. It tracks down small, flying insects ,such as moths, by its echo-location system, similar to the radar-scanning equipment used by aircraft and ships. A special fleshy spike, known as a tragus, in each ear is part of its sound-reception system. This special 'radar' also keeps them from bumping into objects in the dark!
Insects are usually captured in mid-flight, but sometimes the bats will pick insects off leaves.
Like all British bats, Natterer's bat hibernates during the winter, when there is a shortage of insects. In December the bats look for a cool spot around the entrances to caves, but if they cannot find a suitable cave, a hollow tree or similar site is used. They may wake up from time to time during hibernation but do not emerge until early March.
During the summer, female Natterer's bats gather together to form nursery colonies in hollow trees or the roofs of houses. After a pregnancy of fifty to sixty days, the female has only one baby (or very rarely twins), born in June or July. The young bat pup can fly by the time it is four weeks old. Young Natterer's bats do not have the white underparts of the adult - they are greyish-brown all over during their first year.
Natterer's Bat and Humans
Like all species of bat in Britain, the Natterer's bat is less common than it used to be. The reason for its decline is that its food and shelter has been seriously threatened by modern farming practices and destruction of natural habitats.
Many insects have been killed by insecticides used to destroy crop pests. Bats which eat surviving contaminated insects may accumalate poisons which kill them or stop them from having young. Herbicides (weedkillers) used by farmers and gardeners to destroy weeds takes away the food plants of insect larvae such as caterpillars - and this leads to even fewer insects for bats to eat.
Many countryside ponds have been drained or filled in; these are breeding habitats for several species of insects which would provide food for the bats. Hedgerows provide shelter for insects and miles of these important wildlife habitats have been removed to allow more room for crops and more working space for farm machinery. Old grassland is a good habitat for insects and provides bats with open areas to fly and hunt. Over the years, more and more old grassland has been ploughed up. The loss of mature deciduous woodland (the type made up of trees that lose their leaves in autumn) is a serious threat to bats. Conifer plantations support fewer insects and the trees do not have holes where bats can roost or hibernate. Caves are another important hibernation place and many of these have been blocked up.
Bats are harmless but scarey folk-tales have caused them to be feared by people over the years. Even today, some people drive bats out of house lofts and churches because they think they are doing harm. All species of bat are protected by law and it is an offence to interfere with bat roosts.
If the Natterer's bat is to survive into the 22nd century, it is important for everyone to realise that bats are useful because they eat many insects that damage crops and trees. Allowing bats to help control insect numbers is much less destructive than using chemical sprays, which can kill useful insects, such as pollinating bees, and other wildlife.
If you would like to find out more about bats and how to help them, visit the The Bat Conservation Trust.
Image: Bat (Natterer's) by Ján Svetlík