Bats are just one of the many species which hunt fungi-eating insects to build up their fat reserves in winter…
One of the earliest signs of spring – but undoubtedly one of the least noticed – is the emergence of bats from their winter hibernation. These are probably our least known and most poorly understood mammals. Most people are barely aware of their existence, yet with 16 British species they are our commonest mammal family.
This lack of understanding even extends to science. It was barely a decade ago that experts discovered an entirely new species, the soprano pipisterelle, in Lancashire. Unknown to science until 1996, incredibly we now think there are as many as a million of these little bats living alongside us.
Small wonder therefore that the public is even more ignorant. Most people think they are blind. In reality they have reasonable sight, but generally navigate with a superb echo location system based on ultra-sonic squeaks. Our nursery rhymes tell us they are a vital spell ingredient and – thanks to Dracula – they will forever be associated with gothic horror. A more real – but still groundless – fear is that they can get tangled in long hair. In fact their superbly sensitive sonar system is more than capable of spotting this on even the darkest night.
Perhaps we should start with hard facts. Although tropical bats eat fruit and drink nectar (and even blood), ours are all insectivores and on the northern edge of their range. Being small, warm-blooded and with high metabolic rates, they have high energy requirements – a serious problem in a Welsh winter when flying insects are scarce. Thus all our bats hibernate (although they will still wake up to hunt dopey insects fooled into emerging on sunny days).
By early spring with their fat reserves seriously depleted, they emerge to spend a hectic eight months feasting on flying insects. It is now that the fertilised egg which has lain dormant inside the female since the previous September implants. One baby is usually born in June, born blind and hairless, but it grows rapidly on very rich milk. By about three weeks it is flying alongside its mother as the pair dash to build up sufficient stores of fat for the coming winter.
As a result of this lifestyle, most bats make small migrations between roosts during the year. Hibernation, for example, might be in a frost-free cave, while the summer nursery is likely to be a tree or building. The last is probably most common, for unlike many creatures, bats are well-adapted to life alongside man. They are clean creatures (even their droppings are dry and odour-free) and they are prodigious pest-controllers (one bat eats 2,000 midges a night).
As a result, human attitudes towards these little hunters have recently undergone a revolution. While once they were disliked and linked to witchcraft, now they are heavily protected. This is we encounter the only serious drawback of sharing our lives with bats. All are now heavily protected and anyone with a roost must inform the authorities before doing anything which might disturb them. Because of their fondness for dilapidated buildings, this frequently causes problems for routine roof maintenance, let alone barn conversions.
This article is reproduced by kind permission of Daniel Butler www.fungiforays.co.uk