Muscardinus avellanarius

Дата канвертавання24.04.2016
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Muscardinus avellanarius

('Common’ or ‘Hazel dormouse')
Vital Statistics

  • Head and body length: 60 - 90 mm, Tail: 55-80mm

  • Weight: 15-30g (heaviest just before it starts hibernating)

Life span

  • Around 5 years


  • Nuts, fruit, seeds, flowers, pollen, insects (depending on availability)


  • Disappearance from many parts of North and West England

  • Decline in numbers and distribution by at least 50% during the past 100 years (extinct in at least seven counties where it was reported present a century ago).

  • Present in Essex, Kent, Surrey, Sussex, and a few places in Suffolk.

  • In 2005, total adult population estimated @ 45,000 (Dr J. Battersbyco-ordinator, Tracking Mammals Partnership): distributed among variety of widely fragmented sites.

Limiting Factors

  • Competition - from edible dormouse Glis glis: squirrel-sized, non-native - minor pest since introduction in 1902.

  • Weather - mild winters affect ability to hibernate – frequently wake, using precious autumn fat

store. Cold wet summers may induce torpor, which can badly disrupt breeding cycle.

  • Behaviour - reluctant to cross open ground

  • Habitat loss - agricultural land use and management. In many areas, deer/livestock are major problem, compromising regeneration, reducing shrub layer extent and diversity.

  • Specialised diet


  • Habitat Regulations 1994

  • European protected species in the Lower Risk category of the 2000 IUCN Red list. (International Union for Conservation of Nature)

  • The Wildlife and Countryside Act 1981

  • Listed under Appendix III of the Berne Convention and Annex IV of the European Habitats & Species Directive


  • In 1992 added to English Nature’s Species Recovery Programme. Essex Biodiversity Project in conjunction with Essex Wildlife Trust’s dormouse Recovery Program are working on protecting and consolidating the species at selected sites where it still occurs.

  • Intention to re-establish dormice in counties from which they have been lost under UK Biodiversity Action Plan (“UKBAP”).

Survey /Indicators

  • Check nest boxes at least twice a year (ideally May and October); record any animals present.

  • Optimum number for examining boxes =3: one to open box, one to take notes, and one to double-check.

  • All data from schemes using 50 or more nest boxes should be submitted to the National Dormouse Monitoring Programme.

  • Nest is a grapefruit-sized ball-like structure made from shredded materials, usually woven with shredded honeysuckle bark.

Further information

  • Muscardinus avellanarius is rare and nocturnal, normally occurs in mixed deciduous woodland and is frequently found in species-rich hedgerows and scrub.

  • May also occur in gardens and conifer plantations.

  • Considered important as ‘bioindicators’ as they are particularly sensitive to habitat and population fragmentation. Also termed a “flagship species’ as, where occur, habitat usually suitable for a wide range of other species.

  • Suffered from widespread loss of older woodlands; where conifers have replaced native broad-leaved and deciduous trees.

  • Reduction/removal of hedgerows destroyed many old corridors used for moving between woodlands

  • Badly timed mechanical flailing can destroy berries, blossom and nuts in hedges that would otherwise be attractive.

  • Woodland with continuous shrub layer best habitat, but, heavy shading at canopy level means lower layer of plants and shrubs do not fruit richly or are suppressed – reducing/removing key foods.

  • Require variety of hedgerow species to provide requirements - e.g., bramble, chestnut, dog-rose, hazel (the nuts of which are a major source of fattening food in preparation for hibernation), honeysuckle and oak.

  • Robust summer sleeping sites/resting places such as hollow tree branches/ old bird nests/squirrel dreys preferred - coppice stools /hollow tree stumps may be used as hibernation sites.

  • Hibernation on/under ground from about October until March/April - once in hibernation, dormice do not generally leave nests until the following spring.

  • Nest boxes a substitute for natural tree holes and, where provided, may be used by high proportion of dormouse population.

  • Boxes seldom successfully used for hibernation - internal temperature too variable.

A licence from English Nature or the Countryside Council for Wales (CCW) is required to carry out the inspection of nest boxes where dormice are known to be present.


Bright, P., Morris, P., and Mitchell-Jones, T. (2006) The dormouse conservation handbook (2nd ed), Natural England

Arkive: Images of life on earth
BBC Science & Nature – Wildfacts
Essex Biodiversity Project
Essex Wildlife Trust
The Mammal Society Fact Sheet
The Peoples Trust for Endangered Species
UK Biodiversity Action plan
The Conservation (Natural Habitats, &c.) Regulations 1994
Wildlife and Countryside Act 1981

Download available from

European Community Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora


Further reading

Peoples Trust for Endangered Species lead on the National Dormouse Monitoring Programme by collating and inputting the data from over 200 sites across the UK. The NDMP has been running for the past 20 years and has 350 monitors responsible for organising box checks throughout the year. In 2006 4881 hazel dormice records were entered into the database. Dormouse Monitor (a newsletter) is published twice a year and contains news and articles concerning dormouse conservation.

(View a sample publication at

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