Fat dormouse  (Glis glis)

The fat dormouse is classified as Least Concern (LC) by the IUCN Red List (3).

The fat, or edible dormouse (Glis glis) was introduced to Britain in 1902 (3). This is a fairly large dormouse, with a very bushy tail and short, thick silvery grey fur which is white or yellowish-white underneath (3); overall it has a somewhat squirrel-like appearance (2). The hands and feet have hard pads, which are adaptations for climbing (3). The name 'edible' dormouse arose as the Romans used to eat them as a delicacy (2); the alternative name of 'fat' dormouse refers to the appearance of this species before it goes into hibernation (4). Furthermore, the Romans used to fatten these rodents on chestnuts and acorns inside clay pots called 'glisaries' or enclosures prior to eating them (6).

In Great Britain, the fat dormouse has a small distribution that is restricted to the Chiltern Hills, but its range is expanding. It occurs throughout central Europe (4), but has declined in many areas and is uncommon (3).

You can view distribution information for this species at the National Biodiversity Network Gateway.

The fat dormouse inhabits mature broadleaved woodland, gardens, houses and orchards (4).

The fat dormouse is nocturnal, and lives in groups with related individuals (4). Adapted for climbing and leaping through the tree canopy (3), this species feeds on nuts, fruit, bark and fungi as well as animal matter including insects, bird eggs and even small birds (4). The breeding season occurs between June and August, during this time, fighting between males may occur over access to females (3). Females attract males to mate with them by rubbing their anal area along the ground. This produces an odour trail, which the male sniffs and scent-marks (5). Whistling sounds also indicate readiness to mate. The male will pursue the female for a while; she may rebuff him aggressively, but when he gives up she often follows him, and mating occurs (5). Males usually leave the female after mating takes place in order to find more potential mates (5). Females produce one litter a year, consisting of two to nine young (4), typically in a nest inside a hollow tree (3), lined with grass, feathers and hairs (5). The young are born blind, naked and helpless, and are weaned by about four weeks of age (3). Mother and offspring seem to learn to recognise each other by exchanging saliva (7). The fat dormouse hibernates underground or in grass-lined hollows in trees from October to April (4). Towards the end of summer they begin to construct tunnels in the ground; they enter these tunnels to hibernate as soon as the weather begins to get cold, and groups of fat dormice have been found hibernating together (5).

This introduced species is considered to be a pest of orchards and forestry, as it can damage fruit crops and its habit of bark stripping is very destructive (4). In houses they can cause serious problems by chewing through wires and wood. They are therefore controlled in some areas (4). They have declined in many parts of the European range as a result of deforestation (3).

In Great Britain there is no conservation action in place for the non-native fat dormouse (4).

View information on this species at the UNEP World Conservation Monitoring Centre.

There may be further information about this species available via the National Biodiversity Network Gateway.

For more on the fat dormouse:

• Macdonnald, D. W. & Tattersall, F. T. (2001) Britain's mammals- the challenge for conservation. The Wildlife Conservation research Unit, Oxford University. Available from
  www.wildcru.org