Forest dormouse
Dryomys nitedula
Ralph Martin · Aksyi
Key facts in one look
- Size
- Body 79–103 mm, 30–40 g
- Diet
- Fruit, seeds, insects
- Status in Georgia
- Native, stable population
- Habitat
- Forests, scrub, orchards
- Family
- Gliridae
- Conservation
- LC / LC
A black stripe runs across the forest dormouse's face, around the eyes to the ears, and looks like a mask. Its bushy tail makes it look like a small squirrel, though it weighs only 30–40 grams. It lives in forests, scrub and orchards, is a skilled climber and is active at night. It spends the winter hibernating underground, often among tree roots. Caucasian populations differ genetically from those of central Russia so much that they may be a separate species. It is not threatened in Georgia, but if you find one, never pick it up by the tail: the tail is easily damaged.
Identification
Forest dormouse: how to identify it
A small, squirrel-like rodent with a bushy tail. Its most striking feature is a black stripe that rings the eyes and reaches the short, rounded ears. It is most easily confused with the fat dormouse.
Head and body 79–103 mm, tail 66–96 mm, weight 30–40 g. It gets heavier before hibernation: in Lithuania it weighs about 30 g in summer and about 43 g before hibernation. It is larger in the east of its range.
The back ranges from pale ash-grey to grey-brown and even rust; in Transcaucasia it is mostly grey. The belly is yellowish white to greyish. The tail is one colour, greyer than the back. When the animal is alarmed, the tail fur stands on end.
The fat dormouse is much larger, with a body over 13 cm, and has only a narrow dusky ring around the eyes, not a mask. In the forest dormouse the black stripe reaches the ear. At night, in a torch beam, this stripe is how you recognise it.
Colour
Swatches are illustrative. Do not identify a species by colour alone.
It is an animal of shrubs and dense undergrowth: it lives in broadleaf, mixed and coniferous forests, orchards and scrub. Its main need is a shrub layer and dense young trees, so “bush dormouse” would suit it better. In the mountains it occurs in many forest types, in places even on treeless rocky ground. It nests in tree hollows or nest boxes, or builds a nest among thick, preferably thorny twigs. In Georgia its range exceeds 20,000 km².
The forest dormouse map combines public iNaturalist observations. Regions are taken from the records-by-region table, and the status column separates regions with enough records from regions with too few records. Record counts reflect observation effort rather than population density. Records are still too few to mark any region.
Data: Reptiles.ge + iNaturalist · Methodology
- Field observation
- Several records in one spot
- Region with records
In the Caucasus, where orchards or wild fruit trees are plentiful, it eats mostly plant food: apricots, apples, pears, plums, acorns and beechnuts. It adds insects to this. In the north and west of its range it eats more animal food: in hollows and nest boxes it takes birds, nestlings and eggs, as well as insects, their larvae and millipedes. It also eats raspberries, bilberries, hazelnuts and tree flowers.
It is active at night and at dusk. It is a skilled climber but also comes down to the ground. It is mostly solitary, though males and females are seen together in the breeding season. It makes many high-pitched calls, including ultrasound. It hibernates in an underground nest, often among tree roots. In the north it is awake for only 4–5 months, in the south for longer. In the Caucasus a female may have two litters a season. Gestation lasts 27–28 days. In Azerbaijan litters average 5.1 young. The young become independent at about 1.5 months, and females breed after their first hibernation. The longest recorded life in the wild is 6 years.
Globally the forest dormouse is Least Concern (LC, 2016). In Georgia the 2021 national assessment also lists it as Least Concern (LC), with a stable population. It has the widest range of all Palearctic dormice and lives in many protected areas. In Europe it is protected by the Bern Convention and the EU Habitats Directive, and in some countries at the edge of its range it is on the Red List. Densities are low elsewhere, but up to 20 animals per hectare have been counted in Armenia.
Related guides
Continue with related pages
By the black stripe across its face, which rings the eyes and reaches the ears. This mask sets it apart from the fat dormouse at once. The body is up to 10 cm long, the tail bushy and grey. The fat dormouse is much larger and has no mask.
In the Caucasus mostly fruit and seeds: apricots, apples, pears, plums, acorns and beechnuts. It also eats insects. Further north it is more of a predator and also eats bird eggs and nestlings. So its diet depends on where it lives.
That depends on where it lives. In the north of its range it is awake for only 4–5 months, from late April to early September. In Bulgaria it is active for up to 8 months, and in Israel almost all year. The winter nest is underground, often among tree roots.
Globally it is Least Concern (LC, 2016), and in Georgia the 2021 assessment also lists it as Least Concern (LC), with a stable population. In Europe it is protected by international conventions, and in some countries at the edge of its range it is rare. With its wide range and many protected areas, it is not threatened as a species.
References
What this profile is based on
Species profiles are compiled from peer-reviewed literature and established biodiversity databases, and are reviewed as new taxonomic and conservation data become available.
Prepared by the Reptiles.ge editorial team from the sources listed here.
