Dormice are well known for their habit of sleeping for much of the time. Their popular English name is thought to derive from the French word 'dormir' meaning 'to sleep'. Dormice are known to hibernate for as much as seven months of the year. At the onset of colder weather in October, the animals will select a suitable site close to the ground to build a nest. They then curl up and go to sleep until April. During hibernation, dormice slow down their bodily functions and enter a state of extreme torpor. In this state they feel cold to the touch and take some time to rouse themselves when handled. However, they do wake up periodically for a few hours at a time. They survive extended periods without food by living off stored reserves of fat laid down in the fruitful autumn months. Dormice feed high up in the trees on a variety of food. They eat flowers and pollen during the spring, fruit in summer and nuts, particularly hazel nuts, in autumn. It is thought that insects are taken too. This variety of food must be available within a small area, a requirement which limits the suitability of some sites for dormice. Dormice become sexually mature at one year old and their breeding season is from May to September. They produce between two and seven young and can raise two litters a year. The young dormice stay with their mother until they are about ten weeks old. As well as their grass-woven nests, dormice are known to use tree cavities and boxes for rearing young. They hibernate in nests built just below ground.

This attractive rodent can be easily distinguished from mice by its long, fluffy tail. One of the smaller members of the family of dormice, it has bright golden fur on its back and a pale, cream-coloured underside. The dormouse has large eyes which betray its strictly nocturnal existence.

The common dormouse occurs in Europe and northern Asia Minor (Turkey). In continental Europe, it is fairly widespread, although it is absent from Iberia, south-west France, and northern parts of Fennoscandia and Russia. It is also absent from eastern Ukraine and southern Russia. Island populations occur in southern Britain and on Corfu and Sicily (Morris 1999, Rossolimo et al. (2001). In the Alps it occurs up to 1,920 m (Spitzenberger 2002).

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 )

The dormouse is found across Europe as far east as the Ural mountains and south to the Mediterranean. In the UK its range is largely restricted to the south of England and Wales. Even here it is threatened by loss and fragmentation of its habitat.

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.

Habitat and Ecology

Systems

• Terrestrial

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

The dormouse lives in dense, deciduous woodland, coppice and thick shrubbery. Hazel coppice is a preferred habitat and the dormouse builds spherical nests of grass and honeysuckle bark situated a few feet from the ground. Here it spends the greater part of the day before emerging after dark to forage high in the canopy.

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.

Known Predators:

• barn owls (Tyto alba)
• lanner falcons (Falco biarmicus)
• red foxes (Vulpes vulpes)
• wild boars (Sus scrofa)

Muscardinus avellanarius is prey of:
Falco biarmicus
Tyto alba
Vulpes vulpes
Sus scrofa

This list may not be complete but is based on published studies.

Muscardinus avellanarius preys on:
Insecta
Aves

This list may not be complete but is based on published studies.

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 ; acoustic

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.

Range lifespan

Status: wild: 4 (high) years.

Average lifespan

Status: wild: 3 years.

Range lifespan

Status: captivity: 6 (high) years.

Average lifespan

Status: captivity: 4 years.

Average lifespan

Status: wild: 4.0 years.

Average lifespan

Status: captivity: 6.0 years.

Maximum longevity: 5.3 years (captivity) Observations: Maximum known lifespan in the wild is 4 years (Ronald Nowak 1999). It has been reported that these animals live up to 6 years in captivity (http://www.demogr.mpg.de/longevityrecords), which is possible but unverified. Record longevity in captivity is 5.3 years (Richard Weigl 2005).

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); 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)

Barcode of Life Data Systems (BOLDS) Stats
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

Classified as Lower Risk-near threatened by the IUCN Red List and Vulnerable in the UK. Listed under Appendix III of the Berne Convention and Annex IV of the European Habitats & Species Directive.

Population

Population Trend

Major Threats

In addition to the effects of habitat loss, dormice have declined as a result of the isolation of their woods and inappropriate woodland management. The animals are reluctant to cross open ground and consequently are vulnerable to local extinctions when woodland is lost. The grubbing out of hedgerows in recent decades has removed these wildlife 'corridors' between woods that might have allowed dormice to move more freely to alternative sites. Because of their specialised diet they are unlikely to be found in recently established woodland or isolated old woods of less than 20 ha in size.

Conservation Actions

The common dormouse is no longer 'common'. Because of its serious decline, it is listed as a UK Biodiversity Action Plan (UKBAP) species. English Nature has also included it in their Species Recovery Programme (SRP). The initial objectives for saving the dormouse included gaining more knowledge as to its range and numbers, securing the existing populations, promoting suitable woodland management and re-introducing animals to appropriate sites.Because of its popularity with the public and its potential as an excellent 'indicator species' the dormouse became the centre of a publicity campaign designed to draw attention to the threat to the animal and its habitat. This included producing information on the value of old, well managed woodland, establishing a National Nest-box Recording Scheme on computer database and involving the public and school children in 'The Great Nut Hunt'. Part of National Dormouse Week, the Great Nut Hunt encouraged people to search their local woods for signs of nibbled hazel nut shells. Unlike squirrels which open nuts by splitting them, dormice nibble a small hole and extract the kernel piecemeal. The discovery of these nuts, indicating the presence of dormice, showed that the wood was still in a favourable condition. The last Great Nut Hunt took place in 2001.

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.