The dormouse is a tiny mammal, found across Europe, Asia, Africa, Scandinavia and Japan. They are the fairy of the mammal world, flitting from tree branch to tree branch, supping on nectar, sleeping in tangles of honeysuckle and undeniably one of the cutest of all animals in appearance.
- Phylum: Chordata (chordates)
- Subphylum: Vertebrata (vertebrates)
- Class: Mammalia (mammals)
- Order: Rodentia (rodents)
- Family: Gliridae (dormouse family)
There are 3 subfamilies of dormice; Graphiurinae, Myoxinae and Leithiinae which break into numerous subspecies. Dormice are not in the same family as rats and mice Muridae as they have four teeth in both their upper and lower jaw, unlike rats and mice who only have three. This write-up is primarily about the common dormouse Muscardinus avellanarius which is endangered in the UK and found across Europe as far as Iran.
The dormouse is well known for its habit of sleeping the year away. Very sensitive to temperature, the dormouse will only wake up and be active in the warm summer months, hibernating in the UK from late October to late May. The roots of its name come from the French 'dormir' - to sleep and the Anglo-Norman 'dormeous' - sleepy one. It is the only thing people remember about its most famous literary appearance...
There was a table set out under a tree in front of the house, and the March Hare and the Mad Hatter were having tea at it: a Dormouse was sitting between them, fast asleep, and the other two were using it as a cushion, resting their elbows on it, and talking over its head.
'Very uncomfortable for the Dormouse,' thought Alice; 'only, as it's asleep, I suppose it doesn't mind.'
Common Dormouse, Hazel Mouse, Dory Mouse, Dozy Mouse, Chestle Crumb, Sleeper
The common dormouse is a tiny thing, about 8cm in length with a fluffy tail about as long as its body, long whiskers and huge dark eyes. The fur is a golden honey colour, the underside of the dormouse being a whiter cream. Each foot has four toes for gripping onto and climbing upon vegetation in which the dormouse spends most of its active life. They weigh next to nothing, about the same as one or two large conkers, although they feed up in the autumn and then look extremely fat and comfortable.
Dormice have suffered over the past century from a change in landscape management and availability of habitat. It is thought they do best in areas of coppice and in hedgerows where there is a dense shrubby layer full of bramble, honeysuckle and wild clematis. They are also closely associated with hazel trees due to their fondness for the nuts in autumn. In the UK this has meant their range has contracted as traditional woodland management has ceased due to financial pressures and development. They are now only found in scattered locations across the south, west and middle of the UK with a handful in the Lake District, when 100 years ago they were found up in Northumberland, across the peaks and much more widely throughout the rest of the country. They much prefer dense, scrubby woodland edges to the sparse, gloomy interior of mature woodland, but are adaptable, a large colony recently found to be living in mature gorse bushes and heather in south Devon.
Dormice are unable to process green matter such as leaves and grasses and so spend their lives feeding up on fatty and sugary substances. They are an extremely active nocturnal mammal, leaping from bush to shrub in order to gain access to flowers for nectar, berries, seeds, nuts, soft bodied invertebrates (such as caterpillars and other larvae) and even eggs. They are thought to depend heavily on the fats in hazel and sweet chestnuts to get them through the cold winters when they hibernate. Certainly they are most commonly found in areas where these tree species occur and are making a comeback in areas where coppicing has been reintroduced, both sweet chestnut and hazel being favourite trees of this type of woodland management.
Nesting and Hibernation
Dormice make three types of nest, the breeding nest, the shelter nest and the hibernating nest. They are the artisans of nest building along with field mice, creating intricately woven balls which appear to have no conceivable entrance, out of grasses and stripped bark from honeysuckle and wild clematis. A wren's nest can easily be mistaken for a dormouse nest, but the wren will have a prominent 'front door' whereas the dormouse will merely have an impenetrable ball. Both creatures like placing their nests fairly close to the ground in thick shrubs and brambles.
The breeding nest is built in the late spring and early summer and is the largest nest where the female will have her young. The shelter nests are created by the adolescent dormice as they stretch their prehensile toes and leave their mother to feed up for the winter. These nests are often quite close to the original birth nest and are in clumps of bramble so the young mice can take full advantage of the blackberries that begin to appear at that time of year. The winter nest is built in an abandoned burrow, an old tree stump, a coppice stool or just a leafy hollow in the ground and here the dormouse will spend the winter months, dropping into a torpor and surviving on the fat stores it has built up during the active summer months.
Dormice become sexually active after one year and produce one or two litters of up to seven young per year. The young dormice are born blind and furless but are ready to leave the nest after about a month. Until they have first hibernated their coats are a greyer colour than a fully grown adult but revert to the honey colour at the beginning of the next active season. Dormice are thought to live for about 4 years, although one female kept in captivity stuck around till the ripe age of 6.
- Dormice open hazel nuts in a very distinctive way, creating a smooth sided hole in the top of the nut and then nibbling the kernel out in bits. Surveys of nuts have proved a very popular pastime for children and can be carried out in the autumn in areas of hazel woodland
- Dormouse surveys are very popular in the UK as the dormouse is a particularly charismatic species and easily taken to the heart of the public. Due to recent study dormice are being 'refound' across the country and greater support is being given to the preservation and conservation of their much needed habitat.
- Fragmented habitats due to road building or farming practises is the main reason for population decline as the tiny rodent is incapable of crossing large open areas, staying instead in areas of tree cover and being prone to islandisation and population collapse. However, they have been known to cross open spaces, one intrepid dormouse travelling 100m across a field to reach a barn on which was growing an extensive honeysuckle plant.
- In the UK there are lots of projects to help look for dormice. We don't really know how rare they are, because we don't really know where they are! Get in touch with The Mammal Society http://www.abdn.ac.uk/mammal/ or your local Wildlife Trust http://www.wildlifetrusts.org/ if you think you live near some possible dormouse habitat, and they can help you get materials to do a dormouse survey.
- In order to handle dormice you need to obtain a special license from English Nature. You can apply online, but you need to show that you have spent time with a qualified dormouse expert in order to prove you won't hurt the little critters by accident. (They are prone to their tails falling off if handled roughly)
The Dormouse Family