• Dormouse facts

    Muscardinus avellanarius


The Brad Pitts of the small mammal world, Dormice are a popular UK species that attract a lot of attention, but are rarely seen. Fast asleep during the day, Dormouse are heavily nocturnal as well as arboreal (living in trees). Enjoying hazelnuts, berries and the odd insect, they leave there nests at night and using there acrobatic abilities they

They may have round ears and long tails like mice, but dormice are not members of the same family as regular mice. Instead, they belong to the family Gliridae and, like other mice, share a suborder with squirrels and beavers.

But their story isn't all positive. Due to loss of habitat and a warming climate, their population has declined by 52% in the last 30 years.


Length: 6-9cm
Tail: 5.7-6.8cm
Weight: 15-40g
Average lifespan: 5 years
Diet: Flowers, pollen, fruits, insects and nuts

When to see them: April to October

UK conservation status: Considered at risk of extinction due to woodland habitat loss and mismanagement.


Dormice build their nests using grass and leaves at the base of trees or just beneath the ground where they can avoid the winter cold. In autumn, dormice start looking for the perfect spot to hibernate for winter.

Breeding: Usually having one, sometimes two, litters a year, between May and September, dormice can produce around 4 young, born blind and naked. Initially the young are grey in colour, but by the time they are ready to leave the nest, around 4 weeks old, they are almost the golden colour, like their parents.

The number of litters per year is largely controlled by the weather. In a year when food is scarce or when bad weather has prolonged hibernation or restricted the dormouse's feeding time, most litters may not be produced until August, September or even October. In these cases, the young dormice will struggle to build up enough fat to survive winter.

Their Threats

Sensitive to environmental changes, like many species of wildlife, our dormice are vulnerable to the drastic changes in our weather patterns. Loss of habitat and a warming climate are the two primary threats pushing dormice to extinction.

Unwilling to cross large, open spaces, fragmentation of dormice habitat, including ancient woodlands and hedgerows, make it increasingly difficult for dormice to find food and additional nest sites.

How you can help

There are a number of simple ways you can help dormice:

> Help prevent habitat fragmentation, through campaigns and appropriate woodland management.

> Place nest boxes in woodland areas. Their nest boxes are similar to that of bird boxes, but the entrance is placed at the back of the box adjoining the tree trunk.

> Plant hedgerows instead of fences to help create dormice corridors.

> Take part in local surveys and monitoring programs, to help with research of the species.

Useful contacts

Surrey Dormouse Group: http://www.surreydormousegroup...

Peoples Trust for Endangered Species: https://ptes.org/campaigns/dor...

Frequently Asked Dormice Questions

Dormice are quite a placid species, and unlike other species of mice, they will often stay in-situ when disturbed. If the dormice has not moved and is within it's nest, it does not look injured or ill, then place the nest back where you found it. If the animal is injured or looks sick, then please call our emergency helpline.

Dormice are protected under several national and international legislations. To deliberately kill, capture, or disturb a dormouse is an offence, along with damaging or destroying an active breeding or resting site.

If you have accidentally stumbled across the young, you must be sure they are definitely orphaned before touching or removing them from their nest.

If you have found them away from their nest, check surrounding hedgerows and trees for possible nest sites, you can also contact the peoples trust for endangered species, where they will be able to help identify possible active nests with their records.

If the young look weak and are not moving very much, please call us on our emergency helpline, but be sure to make a note of the exact location you have found them.

If a development may effect a dormouse population or dispersal route, a mitigation licence is likely to be required. The licence is usually written and submitted by an ecological consultant with the aim of protecting the dormouse population whilst the work is underway and ensuring, in the longer term, that there is no nett loss of dormouse habitat.