In large sections of the country dormice have died out because the British climate does not really suit them, and suitable woodland habitats are disappearing. Few people have ever seen these shy, nocturnal creatures which live in the thickest parts of woods, and until recently very little was known about them.
Dr Pat Morris, a biologist from Royal Holloway and Bedford New College at Egham, Surrey, said: 'Dormice are not at all like mice, and, although they live in trees, not much like squirrels. In some ways they are closer to bats.'
Dormice hibernate in winter, like bats, and live on nuts, fruits and insects which they find in trees and thickets. Their favourite foods are blackberries, hazelnuts and honeysuckle flowers which they nibble at the base to obtain the nectar. They also strip the bark of the honeysuckle branches into fine soft threads, which they use to weave their nests.
'They like to nest in holes in trees or in bramble thickets,' Dr Morris said. 'But they have taken very readily to the nesting boxes we have provided in 11 counties, mostly in southern England.'
Dr Morris pointed to the honeysuckle climbing high into the tree tops as he followed a trail which wound through the Kent coppice leading from one nest box to the next. Local naturalists Shirley Thompson and Dr Graham Miles removed the nest boxes in turn from the trees and put them in a large plastic bag while they gently searched the nest with their fingers for dormice.
At Box 58 Mrs Thompson gave a little shriek: 'Oops,' she said, 'there are bees in there. I can feel them.'
In Box 47, which hung on the slim trunk of a coppiced sweet chestnut, Mrs Thompson found two dormice - a young female and a young male. They were about 12cm (5in) long, including their tails, with deep brown fur and large black eyes. Dr Miles slipped the female into a plastic bag and attached it to a spring balance. 'Nearly 16 grammes,' he said. 'Probably one of last year's young. Full-grown adults are likely to weigh over 20 grammes (0.8oz). These two will quite probably mate later in the season.'
In Box 55, which was strung up on a hazel branch, there was another young couple nesting. Nearby, in Box 66, two males and a female were in residence.
'Quite often males can be found sharing the same nest box,' Dr Morris said. 'They only fight later in the summer when mating starts.'
Dr Morris and his team have found that by marking animals and tagging them with miniature radio beacons, the same males and females often live together for two or more seasons. Even in the most suitable woodland habitat there are comparatively few animals - about four per acre (10 per hectare) - so there is not a large choice of mates.
Dormice (Muscardinus avellanarius) feed at night and during the day they become torpid - their body temperature drops from 37C (98F) to about 15C (59F) and they are difficult to rouse. During cold wet spells in summer, when there is not enough food for them, they become sleepy and so economise on energy expenditure. In northern parts of Britain the cumulative effect of bad summers makes it difficult for them to survive.
These little animals, sometimes called hazel dormice, should not be confused with the larger edible dormouse, Glis glis, introduced into this country in 1902 and now found wild only in the Chilterns. The hazel dormouse used to be found in woods over most of England and much of Wales, but probably never occurred in Scotland. Dr Morris, together with Paul Bright of the Vincent Wildlife Trust, is now encouraging the dormice to expand their territory by putting up nest boxes at 23 sites in 10 counties.
And, under a contract with English Nature, he plans to reintroduce them to counties where they have become extinct, probably beginning with Cambridgeshire next year. The project is being officially launched today in Kent by David Maclean, Minister of State for the Environment and Countryside.
'We plan to release animals which have been bred in captivity but we don't know how well they will survive,' Dr Morris said. 'We will attach a small radio transmitter to them so we can track them. Then we will be able to find them and be able to tell from their weight if they are managing in the wild. If they can't we will take them back.'
The presence of dormice in a wood may be detected by the pattern of chew marks on hazelnut shells.
More information can be obtained from A Practical Guide to Dormouse Conservation; The Mammal Society, Zoology Department, University of Bristol, Woodland Road, Bristol BS8 1UG; pounds 2.50, including postage.
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