Gwent Bat Group

Bat  Conservation Trust

UK Bats

The information on this page has been kindly provided by the Bat Conservation Trust © Bat Conservation Trust 2008. It may be reproduced only with BCT`s permission

In the UK, we are lucky enough to have 17 resident species of bat - that`s almost a quarter of our mammal species.

Every summer, thousands of people venture out to experience the wonder of bats in their natural environment. Sadly, bat populations have suffered severe declines during the past century, but the Bat Conservation Trust and more than 100 local bat groups are working hard to help our bats hang on.

Explore this section to find out more about our 17 species, bat behaviour, how they navigate in the dark and where they live.

UK Bat Species

There are 17 species of bat in the UK.

They range from the tiny pipistrelle, weighing in at around 5g (less than a £1 coin!), to our biggest bat, the greater mouse-eared - which is still smaller than the palm of your hand!

The bat sounds available on this page are from a heterodyne bat detector. More bat sounds are available in our Bat Sound Library, which is available to BCT Members and National Bat Monitoring Programme (NBMP) volunteers.

Bat Behaviour

What do bats eat?

All native British bats eat insects. Each species has its favourite types, hunting them in its own special way. Most are caught and eaten in mid-air, though it is sometimes easier to hang up to eat larger prey. All bats have very big appetites, because flying uses up lots of energy. A common pipistrelle can eat over 3,000 tiny insects in a single night!
You can help to provide food for bats by planting a wildlife friendly garden.

How do bats catch their prey in the dark?

Bats are not blind, but at night their ears are more important than their eyes. As they fly they make shouting sounds. The returning echoes give information about anything that is ahead of them, including the size and shape of an insect and which way it is going. This system of finding their prey is called echolocation - locating things by their echoes.

Where do bats live?

Bats do not make nests, but choose various places throughout the year to roost. Some prefer hollow trees, others caves, some use both at different times. Many shelter in buildings, behind hanging tiles and boarding, or in roof spaces. For several weeks in summer, female bats choose somewhere warm to gather in a maternity roost. Here they have their babies, staying until the young are able to fly and feed themselves. Bats are often found roosting in houses, both new and old. You may realise that you have bats roosting in your house during the summer months, when they are most likely to be active. If you think you have bats in your house, call the Bat Helpline on 0845 1300 228 and ask for a copy of our ‘Living with Bats` booklet, which gives advice and information for roost owners, or your download it usnig the links below.

Mating / Breeding

Bats mate during the autumn and sometimes into the winter when they hibernate. The females then store the sperm and do not become pregnant until the spring when the weather gets warmer. Pregnant females gather together in maternity roosts to have their young and these may be the same group and the same site each time. Pregnancy lasts between 6 to 9 weeks depending on the species and can be influenced by availability of food and climate. Females usually give birth to a single baby each year which they keep close to them and nuture. Bats are very sensitive to disturbance during the maternity season and may abandon their young if this happens. For 4-5 weeks the young are suckled by their mothers until they are old enough to fly and they begin to venture out from the roost to forage for food.

Echolocation

Bats are not blind; in fact they can see almost as well as humans. But to fly around and hunt for insects in the dark, they use a remarkable high frequency system called echolocation.

Echolocation works similarly to sonar. Bats make calls as they fly, and listen to the returning echoes to build up a sonic map of their surroundings. The bat can tell how far something is by how long it takes the sounds to return to them.

These calls are usually pitched at too high a frequency for adult humans to hear naturally - but they can be heard by using a device called a bat detector

Individual bat species echolocate within specific frequency ranges that suit their environment and prey types. This means that we can identify many bats simply by listening to their calls with bat detectors.

Human hearing ranges from approximately 20Hz (cycles per second) to 15 to 20 kHz (1000Hz) depending on age. In comparison, some bats can hear sounds up to 110 kHz in frequency. By emitting a series of often quite loud ultrasounds that either sweep from a high to low frequency or vary around a frequency, bats can distinguish objects and their insect prey and therefore avoid the object or catch the insect.

Bat Habitats

Bats rely on shelter away from predators and a constant source of water and insects to survive. To enable UK bat populations to flourish, we need a diverse range of sites available where bats can forage and roost.

Bats can be found in grassland, farm land and near waterways and ponds - so long as there are sufficient structures to roost in and peripheral wood, hedgerow or manmade linear features for their protection and navigation.

Bats are also becoming more reliant on urban habitats, where they roost in buildings and forage in nearby wooded parks and gardens. Habitat choice can be species-specific and some bats will journey further out to seek the habitat they prefer.

Tree habitats are an important type of natural habitat which support nearly all species of bat and play a fundamental role in their life cycle. They 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 and they also utilise trees and hedgerows as navigational landmarks for their nocturnal flight path. The edges of woodland and hedgerows are linear features which create a corridor for bats to commute from one area of countryside to another such as from their roost site to new foraging grounds.

Waterways and ponds not only provide bats with the water they need to rehydrate but also attract midges and other flying insects which congregate in their thousands and provide a ready feast for bats. The Daubenton’s bat, in particular, is often seen to skim over the top of the water to feed on a variety of water insects and pipistrelles, although being the most commonly found bat in buildings, will often feed over the water of a nearby river or pond.

Bat Roosts

The place a bat lives is called its roost. Bats need different roosting condition at different times of the year, and will often move around on a regular basis to find the condition that meets their needs.

In summer, for example, female bats need warm safe places to have their babies. These are called maternity roosts. In winter, when bats go into hibernation, they need a cooler, constant temperature and so often move into underground sites, such as caves. Find out more about the yearly cycle of a bat.

All UK bats eat insects, and so roosts should be near good foraging habitats, such as pasture, woodlands or water.

Bats also need to be able to travel safely between their roost and foraging habitat. Bats navigate in the dark using a sonar system called echolocation, which requires objects for their calls to bounce off, so roosts tend to be near things such as hedgerows, treelines, or rivers, which allow them to travel more safely. Open spaces are more dangerous for bats, as it leaves them open to predation.

Bats have been discovered roosting in all sorts of places, but there are three broad roost types that are the most common.

Built structures

All our British bat species will make use of buildings on occasion, but for some species, buildings are essential as roost sites. This situation has arisen over a long period of time as tree cover and availability of caves which would have provided natural roost sites have become scarce and long ago bat species adapted to share our built structures, whether it be older properties, modern houses, bridges, barns or churches.

• How and when do bats use buildings?
• Bats and churches

Trees

Around three quarters of British bat species are known to roost in trees. The remaining species could also use trees but because of a lack of suitable and available habitat many bats choose to favour man-made structures.

Trees provide bats with adequate shelter and attract a diverse range of insect species for them to feed on. Since bats are not able to bore holes or make nests they will use whatever gaps are made available to them by other animals or by the natural decay of the wood or from arboricultural methods.

Bats may use different parts of the tree depending on time of the year and temperature and for different reasons. For example in the summer they may use the higher canopy sites to have their young in warmer temperatures but in winter may go deeper and lower into the tree.

Species of tree such as oak, beech and ash are particularly suitable but any tree has potential for a bat roost if there are hollows in the trunk or in branches, woodpecker holes, loose bark, cracks, splits, thick ivy and root cavities. It is hard to locate a tree roost especially when looking from the ground so when planning to fell or prune a tree expert advice is required.   

Underground Sites

Bats hibernate where they are less likely to be disturbed by light, noise and predators in underground sites including caves, mines, cellars, and service tunnels. Such sites are often referred to as hibernacula and provide the optimum humidity and stable low temperature which the bats require during the winter. Some bats also use underground roosts during the night in summer for feeding or for mating. Of all UK species, greater and lesser horsehoe bats rely most heavily on caves for roost sites.