What are bats up to now?  At the beginning of autumn, the life cycle of the bat is slowing down, and they have finished breeding for the year.

The female bats have given birth to their pups (usually just the one) in May or June, whilst in their maternal colonies. They will hunt during night-time for themselves and provide the young bats with milk. Once the bats are about 6 weeks of age, they become more independent, and can start to hunt for insects themselves.

One of our smallest species, the Common Pipistrelle can consume approximately 3000 insects in one night of foraging, and our largest British species, the Noctule, will fly up to 10 kilometres whilst hunting for food. Many bat species will follow linear features such as hedgerows and can glean insects from the leaves as they forage. Noctule bats may be seen hunting insects such as dung beetles, over fields in the evenings.

Bats use echolocation to locate an insect, and this sound wave will ‘bounce’ off the environment, helping them to get closer to their prey until they are upon it. If listening to bats with a heterodyne detector, as we have done this year during the bat walks for the Green Connections Project, there is a ‘buzz’ as the bat approaches an insect, just before devouring it!

In September and October, bats will still be around, and can be seen as dusk develops, feeding and travelling in our evening skies. Males are looking for a female to mate with, and this is a social time in the calendar of bats, when they get together to procreate.

Once the temperatures drop, bats will start their hibernation and it has recently been discovered that they can travel long distances throughout the country to their hibernacula sites and will re-use a site if it is suitable.

Bats are mammals, and as they are warm blooded, they will go into a torpid state in the colder months, finding refuge in a cave, disused mine systems, in buildings and other man-made structures.

As they depend upon suitable temperatures and humidity, bats can rouse and will move around in their chosen hibernacula, to ensure that the environment remains useful for them. If there is a warm period during the winter months, they may even emerge and forage for insects. This is often the reason why we may see a bat on a sunny day in late winter or early spring, flying around in daytime.

If the females have already mated the previous autumn, they will now implant the fertilised egg and their pregnancy begins in spring. The majority of our 18 UK species of bat, will form their maternal roosts in the form of a colony of female bats in May, giving birth to their pup in June.

Once the young are able to feed for themselves, the colony will leave the maternity roost environment and disperse, feeding up in the autumn, to put on weight before they hibernate.

Janice Vincett

Green Connections Community Wildlife Officer