Dormice in danger

Dormice sleep for eight months of the year

By environment correspondent Alex Kirby

One of the United Kingdom's smallest and shyest mammals, the dormouse, is facing a new threat to its survival.

Researchers say the animals have vanished from two-thirds of the hedgerows where they were living just 20 years ago.

We think they are unable to find enough food in the autumn, and start hibernating without having eaten

PTES spokesman

They say new ways of cutting back hedgerows are to blame, and believe the destruction of the vegetation leaves the hibernating dormice to die in their winter sleep.

Dormice, which are now legally protected, survive in the southern part of the UK, below a line stretching roughly from East Anglia, through the English Midlands, and ending in west Wales.

Ecologists from Royal Holloway, University of London, supported by the People's Trust for Endangered Species (PTES) and the UK Government's official wildlife adviser, English Nature, surveyed 100km of hedgerows in Kent, Sussex, Somerset and Wales, and 57 other sites around the country where dormice had also been recorded between 1979 and 1984.

They found that the species had disappeared from 68% of the hedgerows where it had been found in the early 1980s.

Underground hibernation

The leader of the research team, Dr Paul Bright, said: "Clearly this is a huge loss over a very short period of time, with major implications for hedgerow biodiversity. Dormouse loss is undoubtedly related to intensification of hedgerow management."

The dormouse has completely disappeared in some places

Many hedgerows nowadays are cut back annually by mechanical flails. But the PTES says at least two to three years of growth is required for the hedgerows to produce enough berries to support dormice in viable numbers.

The dormice eat hazel nuts, blackberries, guelder rose hips, elderberries and the fruit of the wayfaring tree, and depend on a variety of other trees and bushes as well, including hawthorn and blackthorn.

At the beginning of autumn they normally weigh somewhere between 15 and 22g, but increase this to 25-40g before they start their underground hibernation.

They live off this accumulation of food while they are asleep, emerging in the spring at about their normal early-autumn weight.

Key indicator

But a PTES spokesman told BBC News Online: "We think they are unable to find enough food in the autumn, and start hibernating without having eaten.

"Then they simply starve to death in their sleep. We have looked at other possible causes of their disappearance, but it is the loss of the berries in the hedgerows that seems to correlate most closely to what is happening."

Conservationists regard the dormouse as a key indicator of biodiversity.

In other words, it is like a canary in a coal mine: a healthy environment can support a viable dormouse population, but where they cannot survive in reasonable numbers, other species are likely also to be at risk.

The PTES says what is happening to the dormice is a warning about the fate of the hedgerows themselves, which it describes as "green corridors" between increasingly isolated patches of woodland.

Even within southern Britain, the dormouse has become extinct in certain localities, and it is one of many species to rely on the network of hedgerows to travel from one beleaguered colony to another, in order to maintain a healthy breeding population.

English Nature has re-introduced dormice to a number of sites under its species recovery programme. In 2001, more dormice are to be re-introduced into woodland in Cambridgeshire and Norfolk.