Dryomys nitedula
forest dormouse

Forest dormice (Dryomys nitedula) occur in the Palearctic region. They are present throughout Europe and range as far south as northern Africa and as far east as Japan. (Haberl, 1999)

Forest dormice are found in dense forests, usually deciduous and mixed forests, as well as thickets at elevations of up to 3500 m. Forest dormice utilize cultivated areas such as gardens and also rocky meadows. They choose dense shrubbery or lower branches of trees in which to make a nest. (Haberl, 1999; Kashtalian, 1999)

Head and body length of forest dormice ranges from 80 to 130 mm. Tail length ranges from 60 to 113 mm. Body weights range from 18 to 34 g. Dryomys is considered to be very similar to Eliomys, but is smaller. The braincase of forest dormice is more rounded and the auditory bullae are smaller when compared with Eliomys. (Haberl, 1999)

Forest dormice are squirrel-like in appearance, with a grayish brown to yellowish-brown dorsum and buff white underside. They have a flat and bushy tail that is more uniform in color than Eliomys. (Haberl, 1999)

Not much information is available on the mating system of this species.

The breeding season for forest dormice varies throughout the species' range. In Israel, the breeding season extends from March to December. On average, each female gives birth 2 to 3 times a year. In Europe, the breeding season lasts from May to August, and usually just one litter occurs each year. The gestation period is between 21 and 30 days. Usually 2 to 5 individuals are born per litter, although occassionally up to 7 may be possible. (Haberl, 1999)

Each offspring weighs approximately 2 g at birth. Eyes do not open until around day 16 of life, and independence from the mother is not achieved until the young are 4 to 5 weeks of age. In Europe the young will wait until after their first winter to mate. (Haberl, 1999; Nowak, 1999)

There is little information available on the parental care of this speices. Neonates are altricial, and do not open their eyes until they are about 16 days old. Young are dependent upon their mother until they are 4 to 5 weeks of age. Until they are independent, it is likely that the mother provides them with food (milk), grooming, and protection. Male parental care has not been reported, but cannot be ruled out, either. (Haberl, 1999; Nowak, 1999)

Dryomys nitedula can be expected to live up to 5.5 years in the wild. (Haberl, 1999)

Forest dormice are highly arboreal. They have the ability to climb with great agility, and can also leap from branch to branch up to 2 m. (Haberl, 1999)

This species constructs in trees. These nests tend to be clustered in groups. Forest dormice typically assemble temporary nests, which are often poorly constructed and flimsy. Much more energy is put into the construction of natal nests, which are very solid. These usually exist 1 to 7 m above ground level and have diameters of 150 to 250 mm. These nests are spherical in shape with one entrance usually facing the tree trunk. The nests are constructed from leaves and twigs and lined with bark or moss fragments. (Haberl, 1999; Kashtalian, 1999)

Dryomys nitedula is nocturnal and exhibits hibernation as well as daily torper. In Israel, these animals remain active year round even at higher elevations. They do undergo torpor during the winter for a certain period of time each day. In northern parts of their distribution, such as in Europe, forest dormice hibernate from October through April. While hibernating, a dormouse will sit on its hind legs, curl up into a ball, wrap its tail around its body, and press its hands to its cheeks. They have been observed to occasionally emerge to eat from stores of food. In Russia they are thought to be active throughout the entire winter. (Haberl, 1999)

Forest dormice are very territorial, with territory sizes range from 65 to 100 m in diameter. Individuals claim relatively large plots of land and live at very low densities, usually only 2 to 3 adults per acre. (Mack, 2001; Nowakowski, 1999)

These animals typically maintain territories with a diameter of 65 to 100 m. (Mack, 2001; Nowakowski, 1999)

Dryomys has been observed to emit a variety of vocalizations. Most notable of those is a delicate, melodious squeak that appears to function as an alarm call. Research on captive individuals has demonstrated that D. nitedula has the ability to emit repeated series of ultrasounds. The signals were given off by both sexes in situations suggesting a social character of the communication. These communications were entirely inaudible to the human ear. (Boratynski, et al., 1999; Haberl, 1999)

Although not specifically reported for this species, it is likely that tactile, chemical, and visual signals are part of the repetoir of communication. Mammals typically use tactile communication during mating, conflict, and rearing of young. Chemical communication can be important in individual identification, as well as in reproductive contexts. Visual signals are often given, by means of body posturing, to indicate hostile or friendly intent.

Forest dormice are omnivores. They eat leaves as well as choice flowers, fruits, and nuts. They also eat arthropods, eggs, and young birds. Animal matter is observed to be preferred dietary item during the summer. (Haberl, 1999; Mack, 2001)

Dryomys nitedula is nocturnal, occurs at low densities, and individuals are very careful to not travel away from brushy cover. These behaviors make these animals difficult prey to find. Remains of forest dormice have been found in the pellets of owl such as Strix aluco and Bubo bubo in eastern Europe. (Mack, 2001; Obuch, 1999)

Forest dormice may play a role in controlling poulations of arthropods that make up a significant part of their diet. They also eat seeds and fruits, and therefore may aid in the dispersal of seeds. Because this species provides food for predators such as owls, forest dormice may have some positive impact on populations of these predators. (Haberl, 1999; Mack, 2001)

There was no specific data on the positive economic significance for humans of D. nitedula.

Populations of D. nitedula have been known to cause economic damage by raiding fruit orchards and gnawing at the bark of coniferous trees. (Haberl, 1999)

Dryomys nitedula is regarded as endangered in the Czech Republic and as rare in most other European countries. IUCN designated forest dormice as lower risk, but the species is not listed by CITES. The threat to the population stems mainly from the destruction of forest habitat throughout their range. (Haberl, 1999)

The UK has developed a National Dormouse Monitoring Programme, which exists primarily to monitor hazel dormice. Hazel dormice are a cherished child storybook star in England and Wales, but the program elements are a standard for all species of dormice. Researchers have placed dormouse nest boxes on trees in woodland areas where dormice have been known to occur, and return to those boxes to count, sex, and weigh the dormice. Research is done in order to form a database for the species and monitor the health of the population. (Haberl, 1999)

English Nature has been running a reintroduction program that has been reintroducing captive-bred dormice since 1994 to areas where populations were at one time plentiful. Also the English government has begun to award farmers incentives to replant hedgerows which are very important to the habitat of forest dormice. Such conservation efforts would also be helpful in maintaining populations of other species of dormice, such as D. nitedula. (Mack, 2001)

A fossil of a dormouse- like mammal was found recently, which is beleived to be the earliest eutherian ancestor. The fossil was found in its entirety, very well preserved in a lake bed in China. Eomaia, the name given to the fossil meaning "ancient mother", possesses skeletal features closer to modern placentals than to marsupials. This signifies that the split between the two groups occured more than 125 million years ago before Eomaia came into existence. Before Eomaia was found the oldest recorded fossil of a placental mammal was 110 milllion year old teeth and the oldest skull and skeleton was only 75 million years old. (Hecht, 2002)