Hazel dormouse

©Danny Green

Hazel dormouse

Scientific name: Muscardinus avellanarius
The shy hazel dormouse is very hard to spot - not only is it nocturnal, but it is mostly confined to southern England, living at low densities, high-up in the tree canopy. It also hibernates for much of the year.

Species information


Length: 6-9cm
Tail: 5.7-6.8cm
Weight: 15-40g
Average lifespan: 5 years

Conservation status

Protected in the UK under the Wildlife and Countryside Act, 1981. Priority Species under the UK Post-2010 Biodiversity Framework. Listed as a European Protected Species under Annex IV of the European Habitats Directive.

When to see

April to October


The hazel dormouse (or just 'dormouse') is an agile climber and mainly nocturnal, so is rarely seen. It lives in deciduous woodland, hedgerows and dense scrub, and spends most of the spring and summer up in the branches, rarely coming down to the ground. It eats buds, hazelnuts, berries and insects. Hazel dormice build nests out of grasses, stripped honeysuckle bark and fresh hazel leaves, in which the female will give birth to up to seven young. They hibernate during the winter months, either on the ground (under logs, leaves, in grass tussocks and at the base of trees) or just beneath the ground where the temperature is more constant.

How to identify

The hazel dormouse has gingery-brown fur, large black eyes and a long, fluffy tail; it is much smaller than a squirrel.


Mainly found in southern England and Wales.

Did you know?

Hazel dormice, like many of our other small animals, hibernate through the winter months in order to survive. If food is scarce outside of hibernation season, they can save energy by dropping their body temperature and going into a state of 'torpor'. In fact, dormice can spend nearly three-quarters of the year 'asleep' in some form!

How people can help

The Wildlife Trusts manage many woodland nature reserves for the benefit of the wildlife they support. You can help by supporting your local Trust and becoming a member; you'll find out about exciting wildlife news, events on your doorstep and volunteering opportunities, and will be helping local wildlife along the way.