Dryomys nitedulaforest dormouse

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Geographic Range

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)

Habitat

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)

  • Range elevation
    3,500 (high) m
    ft

Physical Description

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)

  • Range mass
    18 to 34 g
    0.63 to 1.20 oz
  • Range length
    80 to 130 mm
    3.15 to 5.12 in

Reproduction

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)

  • Breeding interval
    In Israel the species will breed 2 to 3 times per year. In Europe the species breeds only once per year.
  • Breeding season
    In Israel, the mating season extends from March to December. In Europe the mating season occurs from May to August.
  • Range number of offspring
    2 to 7
  • Average number of offspring
    3
    AnAge
  • Range gestation period
    21 to 30 days
  • Range time to independence
    4 to 5 weeks
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

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)

  • Parental Investment
  • no parental involvement
  • altricial
  • pre-fertilization
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

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

Behavior

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)

  • Range territory size
    204.1 to 314 m^2

Home Range

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

Communication and Perception

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.

Food Habits

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)

  • Animal Foods
  • birds
  • eggs
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit

Predation

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)

Ecosystem Roles

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)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

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

Economic Importance for Humans: Negative

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)

  • Negative Impacts
  • crop pest

Conservation Status

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)

Other Comments

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)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Kimberly Skahan (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

ultrasound

uses sound above the range of human hearing for either navigation or communication or both

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Boratynski, P., A. Rachwald, W. Nowakowski. 1999. Ultrasound communication calls in Forest Dormouse (*Dryomys nitedula*). IVth International Conference on Dormice (Rodentia, Gliridae). Accessed 11/01/02 at http://www.trakya.edu.tr/conference/d13.htm.

Haberl, W. 1999. "The Dormouse Hollow: Dryomys" (On-line ). The Dormouse Hollow. Accessed 10/20/2002 at http://www.gliratium.org/dormouse.

Hecht, J. 2002. Family Treat. New Scientist, 174/2340: 14.

Kashtalian, A. 1999. Dormice of Belarus: ecology, distribution and history of study. IVth International Conference on Dormice (Rodentia, Gliridae). Accessed November 01, 2002 at http://www.trakya.edu.tr/conference/df6.htm.

Mack, T. 2001. The Rise of the Dormouse. International Wildlife, 31: 38.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.

Nowakowski, W. 1999. The system of spatial distribution of *Dryomys nitedula* in the Bialowieza Forest (Eastern Poland). IVth International Conference on Dormice (Rodentia, Gliridae). Accessed 11/01/02 at http://www.trakya.edu.tr/conference/d14.htm.

Obuch, J. 1999. Dormice in the diet of owls in the Middle East. IVth International Conference on Dormice (Rodentia, Gliridae). Accessed 11/01/02 at http://www.trakya.edu.tr/conference/d21.htm.