Hibernation

Have you ever wished you didn't have to get up on cold, dark, winter mornings?

Well, some animals like the dormouse and hedgehog hardly get up, if at all, through the winter months. They stay asleep until the spring. This is called hibernation, a term which has its origins in the Latin word 'hibernare' which means 'to winter'.

The Dormouse

When the temperature starts to drop in the autumn, the dormouse will build a snug nest in a bramble thicket or hollow tree, curl up tight in a neat furry ball and settle down for several months' sleep. He will only wake in extreme cold to prevent himself from freezing to death. To warm himself up he will shiver violently and run around for a while before going back to sleep. The dormouse is one of three mammals in Britain that are considered to be true hibernators; the other two are hedgehogs and bats.

The Hedgehog

Bushy Park has a healthy population of hedgehogs so the chances are you will unknowingly pass by quite a few sleeping hedgehogs if you go for a walk in the Woodland Gardens during the winter months. Hedgehogs will start to hibernate from November, although they may delay settling down for their long sleep until as late as January.

Bats

Bushy Park is also home to at least seven species of bats which all like to find a cool, quiet place to sleep the winter away when the insects they love to eat are scarce. Amongst these are Pipistrelles, Daubenton's and Noctule. In the park they will choose a hollow tree trunk or hide in the crevices of tree bark. Elsewhere they like to bed down in caves or abandoned tunnels. They will occasionally wake up to look for a new place to sleep or to find food and water. Like dormice, bats are a protected species which means that you should not handle them yourself but contact an official body like the RSPCA if you are concerned about them.

Cold blooded animals in Winter

Cold blooded animals like frogs, toads and snakes also hibernate when the cold weather causes their body temperature to drop. The frog will find a sheltered place on land, for instance under a log, or on the muddy bottom of a pond, whilst the toad will only choose a dry place like the underside of a log or a stone. Snakes spend the winter in burrows or under logs protected from the cold and predators.

Like migration, hibernation is a survival strategy and is the way animals adapt to the changing climate which might otherwise kill them. When temperatures drop and food becomes scarce, hibernation provides a clever way for animals to conserve energy which would normally be required to keep them warm. It also means that they can avoid the need to eat until food becomes more plentiful again in the spring. In the autumn, animals that hibernate will build up fat stores in their bodies which they can live off whilst they are asleep.

How is hibernation different to sleep?

During hibernation, the rate at which an animals uses up their fat store slows down dramatically as their body temperature drops to match the temperature outside, and their heartbeat and breathing slow down. As a result of these metabolic (body chemistry) changes, the animal's life signs may be so slight that they appear to be dead, and so in this respect, hibernation differs from what we humans usually think of as sleep.

Hibernating animals will also take a long time to wake up. They will wake up thin and hungry in Spring when the temperature starts to rise � dormice may lose up to half their body weight during hibernation!

DID YOU KNOW that scientists are studying hibernation to see if it will provide a way of helping astronauts cope with the long journey to Mars, a distance of 50 million miles away?