We may be about to see many bats as decorations and dressing up costumes over the next ten days, but in nature bats are now hard to spot as they are about to enter their long hibernation period. Amazingly, bats represent almost a quarter of all UK mammals! Here in the UK, we have some 18 species of bat, 17 of which breed on the British mainland. The largest UK bat is the noctule, which weighs the same as four £1 coins, whilst the smallest, the pipistrelle, weighs as little as a 2p coin.
Pipistrelle bat Chris Shields (rspb-images.com)
Bats will enter hibernation during the next few weeks and may not be fully active again until mid-May. While in this state of torpor, bats lower their body temperature and their metabolic rate slows. During hibernation, a bat's heart rate can drop to as slow as 4 beats a minute, which is quite a contrast to the 1,000 beats a minute they can reach while flying on a summer's evening! At such low levels of metabolism, they use less energy and can survive on the fat they have stored up, rather than expending vast amounts of energy in the cold weather searching for sparse food.
We may imagine bats hibernating in caves, but in fact almost three quarters of UK bats have evolved to roost and hibernate in trees. They are not able to bore holes or build nests themselves, so at this time of year they are on the lookout for whatever gaps, nooks and crannies they can find. They often like to roost in mature trees that are hollow from natural decay or have had cavities bored into them by other species, like woodpeckers. Because of an increasing lack of suitable and available tree habitat, many bats turn to man made structures, such as old barns and abandoned buildings. You might even find them wedged into holes in an old brick wall or in the roof of your house.
There are many great ways to attract bats to your garden. You may even find time over the winter months to build a bat box to put up in your garden ready for next year's hibernation.
The Bat Conservation Trust has lots more information about UK bats, and even some Halloween bat activities.
Just as essential to Halloween is the pumpkin. Pumpkin carving is of course great fun, but leads to an estimated 18000 tonnes of food waste every year in the UK. There are of course many recipes for the pumpkin flesh. And the RSPB has some useful advice for separating your pumpkin seeds from the rest of the pumpkin. The seeds can then be dried to be eaten (by ourselves or left out for the garden wildlife), or stored and sown next spring ready for next year's Halloween crop!
Happy Halloween!