WINTER ESCAPISTS WITH THE HIBERNATION HABIT

By Helen Slade - Friday, January 4, 2008

The dormouse, one of the Island’s rarer residents, curls up for the winter with a store of food.

NATURE NOTES
from the IW Natural History and Archaeological Society
I WAS delighted to hear recently that a friend who lives in Newport has a family of hedgehogs living beneath a clump of pampas grass in her garden.
It prompted me to recall that hedgehogs are one of our Wildlife Watch species, about which the society would like current information, and also to give some thought to hibernation.
Hedgehogs, dormice and the various members of the bat family are the only mammals which undergo true hibernation in this country. All of them are present on the Island.
Seasonal hibernators are usually small animals whose source of food is absent during part of the year and who consequently have to find some way of surviving the cold weather that coincides with the loss of their food. It is not the same as being asleep, as there are a number of physiological changes within the body which drastically reduce the rate of metabolism.
Hibernation may not be total. The animals may rouse for very short periods, either to eat some of their food store if they have collected one for their nest, or to mate.
You might have seen, as I did, the recent programme on BBC TV in which Alan Titchmarsh accompanied a bat expert armed with a heat-sensitive camera into a cave. A winter roost of North American bats was filmed and one opportunist male bat woke sufficiently to seek out an unsuspecting female with which to mate. Cheeky chap!
Different types of bat hibernate in different places. Some like to hibernate in houses, some in caves (although not many on the Island) and some in trees. But there is a mystery because the number of hibernating bats that are known about on the Island does not account for all the bats that are present at other times of the year. On the continent, it is thought that some may migrate to central Europe to hibernate in colder climes.
It is important for bats to find sites where the temperature and humidity are constant. Their thin skin dries out easily if the hibernaculum is not moist enough.
Hedgehogs have seriously declined in recent years, perhaps because of the rise in badgers who consider them a tasty treat. Every year we receive a timely warning not to light bonfires without checking to see if a hedgehog has taken residence beneath the waiting pile of branches.
They construct a nest, or hibernaculum, by shuffling around in the pile of dead leaves they have collected until they form a tightly-packed weatherproof shelter, which is normally hidden under brambles or a hedge. Sudden arousal of an animal during hibernation due to some stressful incident may often be enough to kill them, never mind toasting them alive inadvertently. If you think you might have hedgehogs in your garden, try to avoid disturbing them, or allowing your pets to disturb them, for this reason.
The dormouse, like most hibernators, gorges itself as winter approaches, rapidly gaining weight to sustain itself during its long winter state of torpidity. Its very name acknowledges this hibernation habit, being derived from the French word, dormir, to sleep. The winter nest in which it hibernates is made of grass, dead leaves and moss, and the dormouse puts by a store of food inside. It hides the nest under dead leaves or tree roots and usually hibernates alone. Young dormice, which are born in the spring, may sometimes spend their first hibernation together.
Don’t forget to let the society know about any hedgehogs you see by visiting the website, www.iwnhas.org, and following the links to the Wildlife Watch project.

WINTER ESCAPISTS WITH THE HIBERNATION HABIT

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