How do bats use churches?

Why are bats in churches?

Many medieval churches have bat roosts, and sometimes these roosts have been used for generations by bats. Cavities in old trees and caves offer suitable roosting spaces for bats, but as these natural roosting sites have been lost many bat species have adapted to using buildings for roosting.

Bats have very specific requirements for their roosts - maternity colonies select warmer sites, and in churches they are often found in the south aisle. Some species choose cracks and crevices for roosting, while others are free hanging and need space for when they take off. Many modern buildings offer little roosting opportunity for bats, or lack features in the surrounding landscape that bats use for commuting (these are often linear features such as hedgerows and tree lines).

Medieval churches are lasting features in a changing landscape and churchyards can offer rich habitat for wildlife, including the insects that bats eat.

How do bats use churches?

At least eight of the 17 species of bats breeding in Britain use churches to some extent. Old churches are often complex in structure, and over the centuries many gaps have formed that allow bats to enter the building. Inside, cracks and crevices in the supporting timber frame are used by roosting bats. During summer months, roof and eaves voids can house maternity colonies containing several hundred bats.

In most churches however, the number of bats is small and often the congregation may not even be aware of their presence.

Bats can be found in churches all year round. Colder parts of the church, for example the tower or crypt and underground boiler rooms, can be used by hibernating bats.