The edible dormouse is the largest of all dormice, being around 14 to 19 centimetres (5.5 to 7.5 in) in head-body length, plus a 11 to 13 centimetres (4.3 to 5.1 in) tail. It normally weighs from 120 to 150 grams (4.2 to 5.3 oz), but may almost double in weight immediately prior to hibernation. It has a generally squirrel-like body, with small ears, short legs, and large feet. Its fur is grey to greyish-brown in colour over most of the body, with a clear line separating off the white to pale buff underparts. Unlike most other dormice, there are no dark markings on the face, aside from faint rings around the eyes. The tail is long and bushy, with fur slightly darker than that on the body. Females have from four to six pairs of teats.
The edible dormouse is capable of limited autotomy; if another animal grasps the tail, the skin breaks easily and slides off the underlying bone, allowing the dormouse to escape. The exposed vertebrae then break off and the wound heals over, forming a fresh brush of hair.
The edible dormouse is found throughout much of western Europe, although it is absent from Portugal, Scandinavia, and most of Spain and the British Isles, as well as from the North Sea coasts of France, Germany, and the Low Countries. It is rather more sparsely distributed through central Europe and the Balkans, but can be found as far north-east as the upper Volga River. It is also found on a number of Mediterranean and Baltic islands, including Sardinia, Corsica, Sicily, and Crete. Beyond Europe, it is found in scattered populations throughout northern Anatolia, the Caucasus region, and along the southern coast of the Caspian Sea.
It was accidentally introduced to the town of Tring in England through an escape from Lionel Walter Rothschild's private collection in 1902. As a result, the British edible dormouse population, now 10,000 strong, is concentrated in a 200-square-mile (520 km2) triangle between Beaconsfield, Aylesbury and Luton.
Though this animal is regarded as a pest by some, in the United Kingdom the Wildlife and Countryside Act 1981 prohibits certain methods of killing and taking it, and removing them may require a licence.
Ecology and habitat
Edible dormice inhabit deciduous forests dominated by oak and beech, from sea level to the upper limits of such forests at 1,500 to 2,000 metres (4,900 to 6,600 ft). They prefer dense forests with rocky cliffs and caves, but may be found in maquis vegetation, orchards, and urban margins. They have frequently been reported from caves as deep as 400 metres (1,300 ft), where they can shelter from predators.
Population densities range from 2 to 22 individuals per hectare. Females inhabit only very small home ranges, of 0.15 to 0.76 hectare (0.37 to 1.9 acres), but males occupy much larger ranges of 0.8 to 7 hectares (2.0 to 17 acres), with several burrows.
Edible dormice are primarily herbivorous, feeding mainly on berries, apples, and nuts. However, they are adaptable, and have also been reported to eat bark, leaves, flowers, invertebrates, and even eggs. When present in large numbers, they may cause damage to orchards and be considered a pest. Their primary predators include owls, foxes, pine martens, and wildcats.
Edible dormice are nocturnal, spending the day in nests taken from birds, or located in hollow trees or similar shelter. They are good climbers, and spend most of their time in the trees, although they are relatively poor jumpers. They are not generally social animals, although small groups of closely related adults have occasionally been reported.
Communication is partly by sound, with the animals making various squeaks or snuffling sounds, and partly by scent. Scent glands are present on the feet and at the base of the tail, and are used to mark the ground, especially during periods of sexual activity.
Edible dormice hibernate from roughly October to May, depending on local climatic conditions. They prepare a den in soft soil or hidden in a cave, and rely on fat reserves to survive through the winter. During hibernation, metabolic rate and body temperature fall dramatically, and the animal may cease breathing altogether for periods of up to an hour.
They have adapted well to the presence of man and will now frequently hibernate in insulated attics and even dark shelves in cupboards, particularly if there are soft materials on the shelf to make a nest. They can be regarded as a pest in this situation due to the fire risk from gnawed electrical cables and fouling from their faeces. In recent years they have become resistant to many rodicides.
The breeding season is from late June to mid August, and results in only one litter per year. Males are non-territorial, and may visit the territories of several nearby females to mate, becoming aggressive to any other males they encounter. The male attracts a female by squeaking, then conducts a circular courtship dance before mounting her.
Gestation lasts from 20–31 days, and results in the birth of anything up to eleven young, although four or five is more typical. The young are initially blind and helpless, and weigh around 2 to 3 grams (0.071 to 0.11 oz). They develop their fur by 16 days, and open their eyes after around 3 weeks. They begin to leave the nest after around 30 days, and are sexually mature by the time they complete their second hibernation. Compared with similarly sized mammals, they have an unusually long lifespan, and have been reported to live up to twelve years in the wild.
Although the edible dormouse is the only living member of its genus, a number of fossil species are also known. The genus Glis first originated in the middle Oligocene, although it did not become common until the Pliocene. By the Pleistocene, only one species, Glis sackdillingensis, is known to have survived, and this is likely the ancestor of the modern species, which first appeared in the early to mid Pleistocene.
It was farmed and eaten by the ancient Romans (usually as a snack), hence the word edible in its name. The dormice were kept and raised either in large pits or (in less spacious urban surroundings) in terra cotta containers, the gliraria, something like contemporary hamster cages.
To this day, wild edible dormice are consumed in Slovenia, where they are considered a rare delicacy and dormouse trapping an ethnic tradition. Use of dormice for food and fur and of dormouse fat as a medicament is documented there since the 13th century. Seasonal dormice feasts were welcome protein supplements for the impoverished peasantry.
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