Hazel Dormouse (Muscardinus avellanus)

c_Amy_LewisHazel Dormouse © Amy Lewis


The hazel dormouse is an agile small mammal, typically around 7-8cm long and a 5-6cm long tail. Hazel Dormice are almost entirely nocturnal and they live in deciduous woodlands, thick scrub and hedgerows where there is plentiful low-level growth. It lives arboreally through the warmer months, sleeping in a nest of finely stripped bark- particularly honeysuckle and leaves. The dormouse will pass the time from late October to mid-April in hibernation at ground level or just below, preparing a nest amongst tree roots, thick bed of leaves or grass tussocks. In June or July, sometimes a litter earlier, the female gives birth to a litter of four young. Very occasionally there are 2 litters in a year.


The Hazel Dormouse will feed on flowers and insects, later on in the year, it will fatten on berries and nuts- especially hazelnuts-to reach a hibernating weight of up to 35 grams.

How to track/identify?

It is very unusual to see a Dormouse as they live in cover and are only active at night. However, the mammal once was seen, it very distinctive. They have rich golden-brown fur all the way to the top of its tail as well as round shiny black eyes like elderberries. Dormice do leave signs of their presence. Their summer nests in shrubs or woodland understorey are grapefruit-sized balls and hazelnuts are eaten by them display around entry hole.

Did you know?

  • Hazel Dormice populations have undergone a serious decline as forestry practices have changed and suitable areas of habitat have become fragmented.
  • Appropriate nest boxes help to maintain populations where habitat is less than ideal.
  • Dormice prefer not to cross open ground and will choose aerial routes if possible, either going from branch-to-branch or using trailing plants.
  • Dormice often snooze away indifferent spells of weather curled up in a snug nest.

Reserves where they are present

Dormice are present in Oysters Coppice and Blackmoor Copse.

Others in the Mammal Family

American MinkBank VoleBadger, Brown Hare, Grey SquirrelHedgehogHouse MouseOtterRabbitRed FoxWeaselWild Boar

Print out a copy of the Hazel Dormouse fact sheet

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