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.
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.
Related downloads
Information for professionals, such as builders, surveyors, architects, plumbers, roofers, pest technicians, double glazing installators and insulators.
This leaflet outlines the legislation which must be taken into account when working on trees.
This is intended as a guide for all those who might come across bats underground.
A good practice guide published by the Forestry Commission for England and Wales in partnership with BCT, CCW and English Nature (Natural England)