Hazel, or common, dormice, Muscardinus avellanarius, are found throughout Europe, but are found more often in the south western regions of Europe. Hazel dormice are also found in regions of Asia Minor.
Biogeographic Regions: palearctic (Native )
Muscardinus avellanarius is the smallest of the European dormice and has a head to tail length of 115 to 164 mm. The tail makes up about one half of overall length. Hazel dormice weigh from 15 to 30 g.
Looking similar to many other mouse-sized mammals, they have prominant black eyes and small, round ears, but can be distinguished by a thick, bushy tail. Coloration of hazel dormice is a brown to amber color on the dorsal side of the body, and white on the ventral side. Young hazel dormice lack the identifying color of the adults and are a duller and greyer in coloration.
The feet of hazel dormice are very flexible, and are adapted for climbing.
The dental formula of the hazel dormouse is (I 1/1, C0/0, P1/1, M 3/3 = 20). The cheek teeth of the hazel dormouse have a unique pattern of ridges.
Range mass: 15 to 30 g.
Average mass: 20 g.
Range length: 115 to 165 mm.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike
Average basal metabolic rate: 0.351 W.
Muscardinus avellanarius inhabits deciduous forests that maintain a thick layer of scrub plants and underbrush. Being agile climbers, hazel dormice spend much of thier time in the tree canopy searching for food. They also inhabit hedge rows in rural areas of Britain.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: forest
Habitat and Ecology
Muscardinus avellanarius consumes a diet consisting mainly of fruits and nuts, but will also eat bird eggs, fledglings, insects and pollen if they are readily available. Hazelnuts are a favorite nut of hazel dormice. Nuts which have been opened by these animals are easily distinguished by a smooth, round hole that is unlike that made by other rodents. Hazel dormice specialize on nuts in the weeks prior to hibernation, but do not store food for the winter.
Foods that are high in cellulose are avoided, as hazel dormice lack a cecum, and cannot digest the cellulose.
Animal Foods: birds; eggs; insects
Plant Foods: seeds, grains, and nuts; fruit
Primary Diet: herbivore (Granivore )
Muscardinus avellanarius will aid in pollination when eating the pollen of a flower. Hazel dormice are preyed upon by raptors in the summer, and are easy winter prey for red fox and wild boar.
Ecosystem Impact: pollinates
Muscardinus avellanarius is fast and agile in the trees, allowing hazel dormice to escape predators among the branches and underbrush of the forest. Nevertheless, predation by raptors occurs. During hibernation, wild pigs and red fox will dig hazel dormice out of winter burrows to eat them.
- barn owls (Tyto alba)
- lanner falcons (Falco biarmicus)
- red foxes (Vulpes vulpes)
- wild boars (Sus scrofa)
This list may not be complete but is based on published studies.
Known prey organisms
This list may not be complete but is based on published studies.
Life History and Behavior
Muscardinus avellanarius will produce chirping and whistling sounds, not unlike those sounds that are made by other species of dormice. It is also likely that these animals communicate with tactile signals, especially between rivals, between mates, and between mothers and their offspring. Visual signals and scent communication are important in other rodents, and probably play some role in communication in this species also.
Communication Channels: visual ; tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
Little is known about the longevity of M. avellanarius in the wild, but research suggests that individuals live an average of 3 years, at the end of which their teeth show heavy wear. The longest known lifespan of a wild individual was 4 years. In captivity they generally live for about 4 years, and up to 6 years.
Status: wild: 4 (high) years.
Status: wild: 3 years.
Status: captivity: 6 (high) years.
Status: captivity: 4 years.
Status: wild: 4.0 years.
Status: captivity: 6.0 years.
Lifespan, longevity, and ageing
The mating system of this species has not been reported. However, males are very territorial, and so these animals are probably polygynous.
Muscardinus avellanarius has 1 or 2 litters per year. Birth rates peak from June to early July and from late July to August. Litter size in hazel dormice is from 1 to 7 young, but most litters are of 3 or 4 young. The eyes of neonates are sealed shut, but will open at about 3 weeks of age. Young become independant at about 5 weeks of age. Reproductively maturity is not reached until the summer following an individual's first hibernation.
Breeding interval: Hazel dormice apparently can breed twice per year.
Breeding season: Breeding typically occurs from June to October.
Range number of offspring: 1 to 7.
Range gestation period: 22 to 28 days.
Average gestation period: 24 days.
Average time to independence: 35 days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 minutes.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
Average birth mass: 0.8 g.
Average number of offspring: 4.
Average age at sexual or reproductive maturity (male)
Sex: male: 335 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 335 days.
Hazel dormice are altricial, being born with eyes shut. They are cared for in a nest by their mother, who provides milk, protection, and grooming. M. avellanarius females care for the young for about 5 weeks, after which time the young become independent. The young hazel dormice are raised in a nest that is usally in a stump or hollow tree.
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 (Protecting: Female)
Molecular Biology and Genetics
Statistics of barcoding coverage: Muscardinus avellanarius
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
Muscardinus avellanarius populations are declining in the northern areas of its range, due to loss of forest habitat. Hazel dormice are currently listed as lower risk in the IUCN red list, and has no special status on the CITES lists.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
Relevance to Humans and Ecosystems
There are no known adverse affects of M. avellanarius on humans.
Muscardinus avellanarius is a really cute animals, and is a popular species for photographs that are used as postcards and as greeting cards.
The hazel dormouse or common dormouse (Muscardinus avellanarius) is a small mammal and the only living species in the genus Muscardinus. It is 6 to 9 cm (2.4 to 3.5 in) long with a tail of 5.7 to 7.5 cm (2.2 to 3.0 in). It weighs 17 to 20 g (0.60 to 0.71 oz), although this increases to 30 to 40 grams (1.1 to 1.4 oz) just before hibernation. The hazel dormouse hibernates from October to April–May.
The hazel dormouse has golden-brown fur and large, black eyes. It is a nocturnal creature and spends most of its waking hours among the branches of trees looking for food. It will make long detours rather than come down to the ground and expose itself to danger.
Distribution and habitat
The hazel dormouse is native to northern Europe and Asia Minor. It is the only dormouse native to the British Isles, and is therefore often referred to simply as the "dormouse" in British sources, although the edible dormouse, Glis glis, has been accidentally introduced and now has an established population. Though Ireland has no native dormouse, the hazel dormouse has recently been found in County Kildare, and appears to be spreading rapidly, helped by the prevalence of hedgerows in the Irish countryside. The first record of the Dormouse in Ireland is noted in Co. Kildare in 2010.
The United Kingdom distribution of the hazel dormouse can be found on the National Biodivestity Network website.
- Hedgerows – These are species-rich and connected to woodland. Ideally, they are three to four metres high, and left at least seven years before cutting, because many shrubs do not begin to fruit until that time period has passed.
- They usually only travel less than 70 m from their nest.
In winter (October to November), the hazel dormouse will hibernate in nests on the ground, in the base of old coppiced trees or hazel stools, under piles of leaves or under log piles as these situations are not subject to extreme variations in either temperature or humidity. Dormice are almost completely arboreal in habit but much less reluctant to cross open ground than was thought even recently. When it wakes up in spring (late April or early May), it builds woven nests of shredded honeysuckle bark, fresh leaves and grasses in the undergrowth. If the weather is cold and wet, and food scarce, it saves energy by going into torpor; it curls up into a ball and goes to sleep. The hazel dormouse, therefore, spends a large proportion of its life sleeping − either hibernating in winter or in torpor in summer.
Examination of hazelnuts may show a neat, round hole in the shell. This indicates it has been opened by a small rodent, e.g., the dormouse, wood mouse, or bank vole. Other animals, such as squirrels or jays, will either split the shell completely in half or make a jagged hole in it.
Further examination reveals the cut surface of the hole has toothmarks which follow the direction of the shell. In addition, there will be toothmarks on the outer surface of the nut, at an angle of about 45 degrees to the cut surface. Woodmice and voles bite across the nutshell leaving clear parallel toothmarks from inside to outside. Woodmice also leave toothmarks on the outer surface of the nut but voles do not.
The hazel dormouse requires a variety of arboreal foods to survive. It eats berries and nuts and other fruit with Hazelnuts being the main food for fattening up before hibernation. The dormouse also eats Hornbeam and blackthorn fruit where hazel is scarce. Other food sources are the buds of young leaves, and flowers which provide nectar and pollen. The dormouse also eats insects found on food-source trees, particularly aphids and caterpillars.
Plants of value to dormice
- Hazel is the principal food source, supports insects, forms an understory of poles, especially when coppiced, which makes it useful for its arboreal activity. The hazel dormouse's Latin name avellanarius means 'hazel'.
- Oaks supply insect and flower food; the acorns are of little value.
- Honeysuckle bark is their primary nesting material, and flowers and fruit are used for food.
- Bramble flowers and fruits provide food over a long period. The thorns give protection for nests. Dormice thrive on blackberries.
- Sycamore supplies insects and pollen, and a habitat. However, they cast a dense shade which decreases the understory.
- Ash – seed keys whilst they are still on the tree
- Viburnum lantana – fruits and flowers
- Yew – fruits are a favoured food
- Hornbeam – seeds
- Broom – flowers (in early summer)
- Sallow – unripe seeds, supports many insects
- Birch – seeds
- Sweet chestnut provides an excellent foodsource, and the flowers are eaten, as well.
- Blackthorn – fruits (Balckthorn fruit called "Sloe")
- Hawthorn flowers are an important food in the spring. The fruit is eaten occasionally.
- Predation from Eurasian badger, fox, stoat, weasel
- Trampling, e.g., deer, human
- Lack of food source, e.g., from too frequent hedge-trimming, or competition from other species, e.g., squirrels
- Destruction of forest and hedgerow habitats, or their diverse range of species, as a broad spectrum of food is required across the calendar year.
- Amori, G., Hutterer, R., Kryštufek, B., Yigit, N., Mitsain, G., Meinig, H. & Juškaitis, R. (2008). Muscardinus avellanarius. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 29 October 2009.
- Mitchell-Jones, A. J., Amori, G., Bogdanowicz, W., Kryštufek, B., Reijnders, P.J.H., Spitzenberger, F., Stubbe, M., Thissen, J.B.M., Vohralik, V. & Zima, J. (1999). The atlas of European Mammals. London: Academic Press. p. 484.
- Ahlstrom, Dick. (2013-07-16). "The dormouse makes first appearance in Ireland". Irish Times.
- Mooney, John. (2013-09-08). "Rare UK dormouse moved to Ireland". Sunday Times.
- Marnell, F. and Donoher, D. (2013). First confirmed record of Hazel Dormouse (Muscardinus avellanarius) in the wild in Ireland. Ir Nat J. 33: 77-78
- The Dormouse Conservation Handbook published by Natural England
- Dormouse: European protected species. Natural England Species Information Note SIN005 (19 October 2007)
- Hedgerows for Dormice. Ptes.org. Retrieved on 2012-12-28.
|Wikimedia Commons has media related to Muscardinus avellanarius.|
- The Mammal Society site with a Hazel dormouse fact sheet. There is also a book entitled The Dormouse available, by Pat Morris.
- Peoples Trust for Endangered Species site describing the hazel dormouse and its conservation
- Information and images from the BBC
- Extensive information and pictures
- Pet care
- A lot of facts, links and book reviews about the dormouse
- Dormouse nest-box construction