Living Organisms / Animalia / Craniata / Mammalia / Rodentia / Myoxidae / Muscardinus / Species
Muscardinus avellanarius - Hazel dormouse (Click photographs/illustrations: full picture & further details)
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INFORMATION AVAILABLE

GENERAL & REFERENCES

APPEARANCE / MORPHOLOGY

LIFE STAGES / NATURAL DIET / PHYSIOLOGY

BEHAVIOUR

HABITAT & RANGE

CONSERVATION

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General and References

Alternative Names (Synonyms)

  • Common dormouse
  • Hazel mouse
  • Sleeper
  • Muscardin (French)
  • Haselmaus (German)

Alternative species names (the second part of the binomial species names): [Genus] abanticus; [Genus] angilicus; [Genus] corilium; [Genus] kroecki; [Genus] muscardinus; [Genus] niveus; [Genus] pulcher; [Genus] speciosus; [Genus] trapezius; [Genus] zeus (B141).

Names for new-borns / juveniles

 
Names for males  
Names for females  

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General Appearance

Orange-brown, mouse-sized rodent with a slightly bushy tail, prominent large black eyes, largish ears, short muzzle and long whiskers (B142, B144, B153, D30).

Similar Species

  • Distinguished from other mouse-sized rodents by bushy tail.
  • Much smaller (half size) than Myoxus glis - Fat dormouse, which has larger bushier tail and is grey-brown not orange-brown.

(B142, B153, D30)

Sexual Dimorphism
  • Males and females similar.
  • Longer ano-genital distance in male, and testes may be noticeable in breeding season.

(B153).

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References

Species Author

Debra Bourne

Major References

Husbandry references:
B151, D24

ORGANISATIONS
(UK Contacts)

ELECTRONIC LIBRARY
(Further Reading)
Click image for full contents list of ELECTRONIC LIBRARY

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TAXA Group (where information has been collated for an entire group on a modular basis)

Parent Group

  • Dormice (Rodents)

Specific Needs Group referenced in Management Techniques

  • Dormice (Rodents)

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Husbandry Information

Notes

--
Individual Techniques linked in Wildpro

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Appearance / Morphology

Measurement & Weight

Length Head-body length: 60-90mm, usually 80-85mm for adults in summer (B142). 68-85mm (D30); 60-90mm (B147); 2.6-3.4 ins./6.5-8.5cm (B144).
Height --
Adult weight General 15-20g (B142); 15-40g (B147); 0.5-1.1 oz. / 13-32g (B144); about 17g (15-22g), but 25-40g pre-hibernation, 15-20g post-hibernation (B153).
Male --
Female May be about 26g when pregnant (B142)
New-born weight --
Growth rate 10-13g for sub-adults at end of winter (B142); juveniles 40-50mm, 7-14g; may be 18-28g pre-hibernation and 12-16g post-hibernation (B153)

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Head

General --

Skull:

Nose: short blunt muzzle, long whiskers (B142, D30).

Ears: relatively small, rounded (B142, B147).

Dentition (Teeth) I 1/1, C 0/0, P 1/1, M3/3. Four cheek teeth in each row, numerous transverse ridges on each large cheek tooth (molars), which are multiple-rooted. Premolars small, single-rooted (B142, B153).
Eyes Large, prominent black eyes (B142, B147, D30).

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Legs and Tracks

Hind foot 15-18mm. Feet slender and very prehensile, pads large (B142, B143).

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Tail

Slightly bushy, similar length to head and body (B142, B144, D30)

Length: 57-68mm (B142); 55-75mm (B147); 2.4-3.4ins. / 6-8.5cm (B144).

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Coat / Pelage

Adult Female Soft dense coat.
  • Dorsal and tail: uniform orange-brown (also described as yellowish-brown, sandy-yellow or yellowish-red).
  • Ventral: pale buff/pinkish buff; throat white, may extend onto abdomen in thin line.
  • Tail: Dorsal brown, ventral paler (B147).

(B142, B144, B147, B153, D30)

Variations (If present)
  • Tail tip white (about 10% of population) (B142, B153).
  • Albino individuals rare (B142, B153).
Moult Winter pelage in October (B142).
New-born / Juvenile
  • First coat grey. Moulted about 18 days old. (B142).
  • Juveniles (second coat) grey-brown rather than orange-brown (B142, B153).

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Neonate (New-born) Characteristics

Blind, hairless, pink, helpless (B142, B153).

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Detailed Anatomy Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

  • Reproductive: Four pairs of nipples (B142, B147).
  • Scent Glands: near anus (B142).

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Life Stages / Natural Diet / Physiology

Reproductive Stages

Breeding Season --
Oestrus / Ovulation --
Gestation / Pregnancy
Parturition / Birth
  • Britain: May to September (exceptionally October).
  • Continental Europe: peaks late June/early July and late July/early August.
  • (B142).
Neonatal development
  • Birth: blind, pink, helpless.
  • 7 days: grey fur.
  • 13 days: coat well developed.
  • 18 days: eyes open, moult first grey coat.
  • 30 days: start to leave nest.
  • 40 days: independent; may remain with mother to 8 weeks.

(B142, B153)

Litter size
  • Average about 4, but 2-7 and even up to 9 recorded (B142); 1-7, mainly 3-5 (B144); usually 4-5, occasionally 7-8 (B153).
Time between Litters / Litters per year
  • Usually one, sometimes two litters per year (B142, B153)
Lactation / Milk Production --
Sexual Maturity
  • Year following birth (B142); one year (B144)
Longevity
  • 4 years recorded in wild, 6 years in captivity (B142); four years (B144); may reach 4-5 years in wild (B153).

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Natural Diet

  • Hazelnuts, seeds, buds, berries, delicate leaves, insects, possibly bird eggs and nestlings.

(B144, B147)

Varies with season.

  • Early summer: flowers, pollen
  • Later: fruits, including ash keys, berries, nuts.
  • Also insects: may be particularly important in summer (mid-June to mid-August) (B153)
  • Before hibernation: chestnuts, acorns, hazelnuts (eaten while still green, on tree) important.

(B142, B153)

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Detailed Physiology Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

Temperature 34-36C; down to 0.25-0.5C during hibernation (B147)
Pulse --
Respiration --
Faeces --
Haematology / Biochemistry --
Chromosomes 2n = 46 (B142).
Other --

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Behaviour

Feeding Behaviour

  • Sequential specialist feeder - change diet according to seasonal food availability (B143, B153).

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Parental Behaviour

  • Prolonged maternal investment - juveniles remain with mother for 6-8 weeks (B153).

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Social Behaviour / Territoriality

Intra-specific
  • Little known. Multiple occupancy of nests frequently recorded. B142
  • Range probably about 0.5 hectares, but may use larger area over whole season (B142)
  • May reach 8-10 individuals per hectare in favourable habitats (B143, B153)
  • Males strongly territorial in breeding season (B143).
Inter-specific --

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Sexual Behaviour

Some evidence pair bonds are persistent: same male and female may be found sharing nestbox in consecutive years (B142, B153).

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Predation in Wild

  • Foxes, badgers, weasels, corvids (crow, raven, magpie). 
  • Rarely owls or cats.
  • (B142). 
  • Owls (B144).
  • Rarely owls, sometimes weasels (B153).

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Activity Patterns

  • Mainly arboreal. In tree canopy and scrub.
  • Agile climber; run and jump.
  • Rarely on ground.
  • May travel about 250m per night.
  • Territory may be 0.7 square miles (2 square kilometres) (B147).
  • Home range typically only about 3,000square metres (B153).
  • Usually stay within 50m and certainly 70m of nest.
  • Males range more widely than females and home range of male may overlap those of two or more females.
  • May be two or more in same nestbox. Males will not share nestbox with one another during breeding season but will share with females.
  • Hibernate in nest, at or below ground level, from October to April in Britain; may arouse periodically, rarely leave nest.
  • In Russia may be August to May (B147).
  • Triggered when temperatures fall below 16C (B147); body temperature may be reduced to 0.25-0.5C (B147).
  • Summer torpor may be used in early summer when poor food supply and/or wet or windy nights (B153).

(B142, B147)

Circadian
  • Nocturnal and crepuscular.
  • Active all night in summer, but only few hours per night in autumn.
  • Leave nest about one hour after sunset.
  • May reduce activity in bad weather.
  • Juveniles and pre-hibernation sometimes active in daytime.

(B142, B144, B147, B153)

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Habitat and Range

General Habitat Type

  • Mixed broadleaf woodland with ample secondary growth and scrub such as bramble.
  • Woodland edge and overgrown clearings preferred.
  • Trees with edible seed preferred (hazel, sweet chestnut, beech).
  • Coppice (particularly hazel coppice) commonly used, also hedgerows rich in tree species, damp woodlands, marshy areas and reed beds with alders and bramble present.
  • Coppice of 15-20 year rotation preferable (B153)
  • N.B. Physical structure of vegetation important, particularly requiring arboreal pathways as may be provided by climbing plants such as honeysuckle, and by sprawling coppice.

(B142, B143, B144, B147, B153, D30)

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Nests / Burrows / Shelters

  • Above ground in summer, usually 1-2m from ground, sometimes up to 10m high. In treeholes, bush or in lower branches of tree. Also behind loose bark. use old bird nests and squirrel dreys.
  • Availability of tree holes may limit dormouse numbers (B153).
  • Use nestboxes if provided (B153).
  • Globular nest constructed from shredded bark (occasionally grass), with outer layers of leaves.
  • 15cm diameter breeding nest (B142); 120mm (B147).
  • 10cm nests made by newly-independent juveniles, often in group only few metres apart. Individual nests 60-80mm (B147)
  • May use several nests in succession.
  • Hibernation nest also woven,: in burrow, in stump or tree hollow or beneath debris on ground. Vegetation bound with sticky salivary secretion. (B147, B153).

(B142, B144, B147, B153)

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Distribution and Movement (Migration etc.)

Normal Western Palearctic: Europe and northern Asia Minor. Widespread Mediterranean to southern Sweden and from Britain (not Ireland) eastwards to Russia, reaching about 50E. Not found Iberia. Present Corfu, Sicily. (B51, B143, B147).
  • In Britain: range decreased. Found locally in suitable habitats in mid-Wales, also western and southern England: Leicestershire, Suffolk and further south (B142, B143, B147, D30) (mainly south of line from River Thames to River Severn (B153).
Occasional and Accidental --
Introduced

--.

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Conservation

Intraspecific variation

Five subspecies recognised; appearance of all rather similar (B143).

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Conservation Status

Wild Population -
(Importance)
  • In Britain: native, localised and declining population. Pre-breeding population estimate of about 500,000, with 465,000 in England, 0 in Scotland, 35,000 in Wales. Population estimate of this widely-distributed species was based on a limited amount of data and considered likely to be inaccurate by up to 50% in either direction (B221).
General Legislation
CITES listing --
Red-data book listing Lower Risk - near-threatened (B143, B147).
Threats In Britain: loss of habitat, particularly of ancient woodland, and management changes to woodland resulting in heavy shading, loss of shrub layer, loss of aerial pathways connecting feeding sites (B221).
Captive Populations --
Trade --

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