Edible Dormouse

The non-governmental organization for the conservation of nature, the Lithuanian Fund for Nature, has chosen the edible dormouse as its symbol. In Lithuania, this very cute mammal belongs to rare and protected species; due to its special lifestyle it has not been seen by many people.

The edible dormouse has not been chosen accidentally. This species is deemed an indicator of a valuable deciduous or a mixed forest and a symbol of intact ecological balance, abundant biodiversity, and balanced use of natural resources—all major spheres, in which the LNF works on the topical issues of environmental protection.

Appearance and Other Characteristics
The edible dormouse is the largest of all the 28 species of dormice living in the world. Their bodies can grow 12-18 centimeters long, and their tail, 12-15 centimeters long. They can weigh 70-120 grams. Juveniles are grey while mature dormice are grey with a shade of brown. Their underparts have a white color, and their eyes are encircled by darker hair. Due to its bushy long tail, the dormouse resembles the little squirrel. It is a nocturnal mammal, living in trees for 7-8 years, able to see at twilight and climb branches nimbly, and falling asleep for winter hibernation that lasts over half a year.

Geographic Range
The edible dormouse is found in most of Europe and some southwestern Asian countries.
Lithuania is located on the northern edge of the edible dormouse’s natural habitat. In Lithuania and its neighboring countries, this mammal is rare and protected. To the south, the edible dormouse is a more common and frequent species which in some cases inflicts damage on fruit-tree orchards and forestry.
At present there are ten known places were the edible dormouse in Lithuania is found. Most of them are close to the Nemunas River and the Neris River, in addition rivers flowing into them. These living areas of the edible dormouse have been located only fairly recently, in the period between 1990 and 2008. Before that, from 1936 onwards, we knew only two natural habitats but the edible dormouse was gone from them.

In Lithuania, the edible dormouse lives in mature mixed-tree and deciduous forests rich with oaks, limes, and nut-trees. The remaining part of this species’ habitat has beech or mixed beech-oak forests.

The diet of edible dormice changes with every season. In the spring, when it is difficult to find nutritious food, they feed on buds, leaves, bark, beetles, and bird eggs or their fledglings. In summer and autumn, their staple food is the fruit of trees and bushes.
In Lithuania, the most important components of edible dormice’s nutrition are oak acorns and hazelnuts, and in a large part of their living area those are beechnuts. These calorie-rich fruit are ripe in late summer and the fall, a time period that is extremely important for dormice because at that time they raise their young and store up on fat reserves before hibernation in winter.

Nuts cracked by edible dormice. The arrows indicate their teeth marks (Photo: V. Šiožinytė)

Behavior, Reproduction, and Hibernation
Because edible dormice are nocturnal mammals, they are active at night. During the day they usually stay in tree hollows, bird houses, and other hiding places where they weave semi-open nests out of fresh green leaves or bird-nesting materials. Dormice produce 4 to 8 young, but not every year. Their reproduction depends on the availability of important nutritious plants: beeches, oaks, and hazel-trees. In springtime dormice taste the buds of these trees to find out if they will bear fruit. If the harvest is to be poor, dormice do not reproduce that year at all or a much smaller number of their population reproduces.
In Lithuania, edible dormice go into hibernation at the end of the autumn, in October. In wintertime they hibernate in the ground, under tree roots. During hibernation edible dormice slow down their breathing, and their body temperature changes according to the temperature in its nesting site. By the time they wake up in late May, they lose about a third of their weight.

Curled up in a ball, edible dormice sleep in their hibernation nests (Photo: R. Juškaitis)

Who is taking a picture of me? (Photo: V. Balkūnas)

Protection Status
The edible dormouse is included in the Lithuanian Red Book of Threatened Species. As belonging to Category 2(V), it is considered a threatened species, the population of which is growing smaller rapidly. In Lithuania, it belongs to a list of highly protected species and Appendix III (Protected Fauna Species) of the Bern Convention on the Conservation of European Wildlife and Natural Habitats.
As a highly protected species, the edible dormouse in Lithuania should fall under a plan designated to protect its species, yet such a plan has not been prepared yet.
It is difficult to evaluate the state of their natural habitats. Nearly all of them are included into various protected sites’ lists; in three of these natural habitats, we have established reserves for the protection of edible dormice. Those are the Strošiūnai Teriological, the Gastilioniai Botanical-Zoological, and the Semeniukai Zoological Reserves. However, the collected data shows that sites are being felled and some of them are already clearcut.

1. Tree felling. Tree felling is the most serious threat facing edible dormice’s natural habitats. During the final felling a selected forest area is clearcut or severely thinned by cutting the most mature trees that are in fact most often used as dormice’s hiding places. Thinnings makes it very difficult for dormice to climb from one tree to another. Also, the hazel-tree tracks (and hazelnuts are a very important ingredient of dormice’s diet) are destroyed during thinnings.
Felling operations can disturb dormice when they are raising their young and be a direct cause of the young’s death. In wintertime dormice can die as a result of heavyweight tree felling equipment because dormice sleep in nests that are only about 30 centimeters below the ground.

2. Isolation. Forest-cutting and road-building fragment and oppress suitable habitats, sometimes even arresting the proliferation of edible dormice because animals, once isolated, become more vulnerable and their genetic diversity reduced.

3. Predators. During their active season dormice face their main predators, night birds of prey and martens, while during their hibernation in winter they have to beware of foxes and wild boars.

4. Unfavorable weather. At present we are witnesses to frequent and extreme weather phenomena, such as droughts, heavy rainfalls, storms, and more. Unfavorable weather has damaging effects on the main nutritious plants on which edible dormice feed, which leads to a less successful reproduction of dormice.

Other Species of Dormice in Lithuania
In addition to the edible dormouse, three other species of dormice are indigenous to Lithuania.

Hazel Dormouse (Photo: R. Juškaitis)

Hazel Dormouse (Muscardinus avellanarius). In some European countries, this species might be facing extinction. Therefore, it is included in Appendix IV (Animal and Plant Species of Community Interest in Need of Strict Protection) of the EU Directive on the Conservation of Natural Habitats and Wild Fauna and Flora, more widely known as the Habitats Directive, and Appendix III of the Bern Convention. In Lithuania, and particularly in the northern part of its territory, the hazel dormouse is fairly widespread, although its populations are not large. Hazel dormice live in mixed or deciduous forests. From leaves and grasses, they weave round nests in the densely entwined branches of bushes and trees or in bird houses. The fur of hazel dormice is yellow-brown or orange-brown; his underparts are of a lighter color.

Forest Dormouse (Photo: R. Juškaitis)

Forest Dormouse (Dryomys nitedula). Lithuania and Latvia are located on the farthest northwestern end of these dormice’s range of habitats, and in our country it falls under Category 3(R) of the Red Book of Threatened Species, Appendix IV of the Habitats Directive, and Appendix III of the Bern Convention. Forest dormice are known to live in their habitats in the districts of Šakiai and Kaišiadoriai. The fur of forest dormice is of a brown color with dark underhair, and its underparts have a lighter color. It differs from other dormice by a distinct dark stripe surrounding its eyes, whiskers, and ears.

Garden Dormouse (Photo: S. Büchner)

Garden Dormouse (Eliomys quercinus). In Northern and Central Europe, this species is quickly disappearing and thus it is included in Appendix III of the Bern Convention. In Lithuania, it is considered extinct and falls under Category 0(Ex) of the Red Book of Threatened Species. This species of dormice was last observed in its habitat in the Varėna District in 1957-1959. If compared to other dormice, the garden dormouse more often climbs out of trees and runs on the ground. It likes rocky surfaces. The upper part of its body is light brown, the underparts are white. A stripe of black hair goes from its whiskers, surrounds the eyes, passes its cheeks, goes around the lower part of its ears, and ends behind the ears. The tip of its tail is black and white.



Edible dormouse (Photo: R. Juškaitis)

The Dūkštai Valley is a natural habitat of the edible dormouse.(Photo: S.Pupininkas)

Edible dormice also live in bird houses. (Photo: V. Šiožinytė)