Checking the numbers of a British native - Veterinary Practice
Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now



Checking the numbers of a British native

A Veterinary Practice correspondent is on the lookout for signs of dormice

ONE of our rarest British mammals is also one of the cutest. Immortalised by Lewis Carroll in Alice in Wonderland at the Mad Hatter’s tea party, the hazel dormouse is rarely, if ever, seen by the casual naturalist out for a country walk.

The reasons? They are strictly nocturnal, spend most of their time in trees and bushes, and hibernate for many months of the year. You really have to know where to look, and to look very hard, to have any chance of crossing paths with one of these little fellows. Hazel dormice are natives of Britain (unlike the much larger fat or edible dormouse which was introduced in the early 1900s) and are the only British rodent to hibernate. They are also unique in being the only small mammals in Britain to have a fully furred tail and are unusually long lived (up to five years) for animals of this size.

Dormice hibernate in woven nests just below the ground, often at the base of a tree or underneath a log pile. Hibernation lasts from the first frosts of October or November through to April or May when they once more become active. Now they build a nest of honeysuckle bark or leaves some way off the ground in a tree or shrub, and forage for a variety of food which includes pollen, flowers, insects, fruit and nuts.

If the summer weather is poor and food is scarce, then they can also enter a state of torpor during the day, lowering their body temperature and heart rate temporarily and thus conserving valuable energy. Hence their widely recognised reputation for being constantly asleep.

Natural habitat

The natural habitat of the dormouse is deciduous woodland and thick, overgrown hedgerows. The practice of coppicing, particularly of hazel woodland, helps provide an ideal habitat because of the varied food sources and varied shrub and tree height that this sort of management provides. Hedgerows are important as habitat in their own right and as corridors which link areas of woodland with each other.

Dormice do not live in large numbers at any one site and being arboreal are very reluctant to cross open ground. This explains why the loss of ancient woodland, the splitting of large woods into smaller ones, and the destruction of many miles of hedgerows over the last hundred years has led to a serious decline in their numbers.

They are now extinct across half their previous range in England and are likely to decline further unless steps are taken to actively manage the land for their benefit. They are an excellent indicator species for the overall health of a woodland and its adjoining hedgerows.

Because they are so rarely seen it is very difficult to survey their numbers or work out an accurate distribution map for the species. One useful method of attempting this is to make use of the more obvious signs of dormouse activity in an area rather than sight of the animals themselves.

Nationwide survey

With this in mind the People’s Trust for Endangered Species (PTES), a UKbased charity committed to helping secure the future of endangered species worldwide, is launching a nationwide survey of woodlands around the country billed as the Great Nut Hunt.

Hazelnuts are one of the dormouse’s favourite foods and they open them in a very distinctive way that can be distinguished from nuts eaten by the likes of woodmice and bank voles. The Great Nut Hunt runs from last month through to March 2010 and people are being asked to collect any hazelnuts they find when out for a walk that have a hole gnawed in them.

These can be sent in to the Trust which will then identify whether or not it is the work of a hazel dormouse. They are hoping this year to exceed the 250,000 nuts sent in to them during a similar survey in 1993.

As if any further encouragement to take part were needed, PTES has commissioned the manufacture of 20 silver nuts and a single gold one that have been hidden across counties in England and Wales.

So a real treasure hunt as well as a serious scientific survey, which might just be enough to get the kids interested in going out for a country walk some cold and frosty morning.

For more information check out the website,

Have you heard about our
IVP Membership?

A wide range of veterinary CPD and resources by leading veterinary professionals.

Stress-free CPD tracking and certification, you’ll wonder how you coped without it.

Discover more