Bats are amazing creatures that are often misunderstood and feared by humans (they suck blood, get caught in your hair, etc), yet are extremely important to ecosystems, especially within tropical regions. In May and June female bats in Britain form maternity roosts, sometimes numbering into the many hundreds. Each adult typically gives birth to a single offspring in June and raises it for 6 to 8 weeks until it is almost adult size.
During spring and summer evenings when the weather is reasonable, bats can often be seen flying in urban areas as well as in the countryside. Many species of bat have managed to successfully adapt to the changes that humans have caused to their natural environment. As we have cut down much of the native woodland, bats have become increasingly dependent on houses as a substitute for the mature trees that used to be their home.
All of the British bats belong to a suborder known as microbats. They all use a type of biological sonar called echolocation to locate their prey, typically feeding on insects such as midges and moths. Bats should be encouraged for this reason alone, since one pipistrelle, for example, can consume as many as 3,000 insects in a single night - imagine the midge problem without this pest control!
It is important to remember that bats and their roosts are legally protected. If a bat roost is discovered in a dwelling (in England) please contact Natural England. If a bat is found on the ground or where it might be harmed, it is sensible to contact an expert on the Bat Conservation Trust's Bat Helpline. It is not illegal to pick up a bat that is unable to fly away, but always wear gloves since bats can bite and carry a type of rabies virus that is very rarely passed on to humans.