Most bat species in the UK evolved to live in trees and caves, but as habitat loss has reduced these natural roosting sites, many bats have now adapted to roost in man-made structures. Bats can be found roosting in buildings including houses, outbuildings, mine shafts, tunnels, bridges and churches.
Man-made roosts can provide the stable conditions that bats need. Most bat species are now known to use buildings, but they use them in different ways, for example crevice-dwelling bats include the pipistrelle species, whilst serotine and Daubenton's bat use the roof space to roost and may be visible on the timbers. Artificial roosts are now essential in the survival of many bat species.
Unfortunately with this dependence on man-made structures comes a vulnerability to the activities of humans. If bats are disturbed during hibernation or when they are rearing their young, the local population can be hugely impacted. Demolition, renovations, artificial lighting, and chemical treatment of building materials can all have a detrimental impact on bats. Many buildings are now very well insulated and don't have spaces for bats to roost anymore, and as bats are unable to create their own entrance holes, they cannot roost in these buildings.
At Parc Slip nature reserve we have a pipistrelle bat roost in our office roof. This month, we did an emergence survey and counted the bats as they came out to feed for the night. We were pleasantly surprised to discover that we had 260 bats using the roost! We are pleased to be roost owners and it is a comfort to know that this bat population will be protected.
All bats and their roosts are protected by law and any structures which bats use for shelter are protected from damage or destruction whether occupied or not. It is the law that you must seek advice from your Statutory Nature Conservation Organisation (SNCO) before doing any works on structures where you think bats may be.