[7] According to English Nature's Dormouse Conservation Handbook, hazel dormice are "particularly associated with deciduous woodland" but also inhabit hedgerows and scrub.

This small mammal has reddish brown fur that can vary up to golden-brown or yellow-orange-brown becoming lighter in the lower part.

Starting from the onset of colder weather (October or November), the hazel dormouse will hibernate in nests on the ground, at the base of old coppiced trees or hazel stools, under piles of leaves, or under log piles, as these situations are not subject to extreme variations in either temperature or humidity.

When it wakes up in spring (late April or early May), it builds woven nests of shredded honeysuckle bark, fresh leaves, and grasses in the undergrowth.

If the weather is cold and wet and food is scarce, it saves energy by going into torpor; it curls up into a ball and goes to sleep.

The hazel dormouse, therefore, spends a large proportion of its life sleeping, either hibernating in winter or in torpor in summer.

[17] The oldest fossils of the genus Muscardinus date to the Serravallian stage of the Middle Miocene approximately 13.8 to 11.6 million years ago in what is now Spain.