Often found in hedgerows, dormice are small rodents who spend as much as three-quarters of the year asleep – and are known to snore.
Dormice are one the few UK mammals that hibernate, other species include hedgehogs and bats.
Dormice facts
Scientific name: Muscardinus avellanarius
Family: Gliridae
Diet: Flowers, fruits, and nuts
Predators: Owls, domestic cats, badgers
Size: 6cm-9cm
Weight: 15-40g
Lifespan: Five years
Sleeping mice
There are 29 different dormouse species globally, but Britain's only native resident is the hazel dormouse – or common dormouse. Hibernating from October to April, dormice get their name from the Latin 'dormeus', meaning sleepy. They curl up in a ball with their tail wrapped around them at the base of a tree in a tightly woven nest to sleep.
If food is scarce, dormice can conserve energy by lowering their body temperature and go into a 'torpor' – like hibernation out of season.
Dormice and our canals
Lined by woodlands, hedgerows, and trees, our canals and rivers provide ideal nesting places for dormice.
These rodents are important indicators of the health and biodiversity of woodland and hedgerows as they require plenty of insects, flowers, berries, and space to travel. We're actively working to maintain and improve habitats alongside canals, like installing dormouse boxes to provide secure nesting places for these animals.
The hazel dormouse has golden-brown fur, large black eyes, and a long, fluffy tail. With a body of just 6-9cm and a similar-sized tail, dormice are much smaller than squirrels and many other rodents. As such, they're often well hidden among the undergrowth.
A light brown dormouse with small, round ears, black eyes, and whiskers sits on a tree branch.
What do dormice eat?
Dormice prefer a diet of hazelnuts, berries, and insects. That said, their food sources vary throughout the year. In autumn, a dormouse eats nuts, seeds, and berries to survive the winter. After emerging from hibernation, they'll eat blossoming flowers from hawthorn and oak trees. In summer, dormice might feast on insects like caterpillars.
How do dormice breed?
The hazel dormouse typically has a single litter each summer, giving birth to around four or five young. They build a nest out of grass and leaves at the base of a tree or in a hedge. When born, the young are pink, hairless, and blind. Pale grey fur grows within 12 days and can see after 18 days.
Young dormice forage with their mothers at three weeks old and will leave the nest between six to eight weeks. Dormice sexually mature at about a year old, and their fur changes to its recognisable gingery brown.
Where do dormice live?
Dormice are found in very few places in the UK. In England and Wales, they're largely in the southern regions, but there are a few small, scattered populations in the midlands, mid-Wales, and the Lake District.
The hazel dormouse likes woody vegetation, favouring old coppice woodland, but you'll also find them in scrubland and old hedgerows.
Dormice come alive at night, climbing high into trees in search of food. As such, they're not easy to spot. However, they come down from their trees in the autumn to look for their winter hibernation home. Dormice often sleep in logs or among leaves at the base of trees.
Remember that dormice are a protected species. They're vulnerable to exinction and it's important you don't disturb them.
You're more likely to spot signs of a dormouse. Look out for the distinctive smooth circular holes in hazelnut shells – likely the remnants of a hungry dormouse.
What's the best time of day to spot dormice?
Dormice are nocturnal creatures, only coming out at night to hunt for tasty snacks.
What's the best time of year to spot dormice?
Dormice come out of hibernation from April to October. However, these arboreal creatures (living in the trees) are difficult to spot when they're high up. If you want to see a dormouse, look at the base of trees and hedgerows in the autumn when building their winter nests.
Threats to dormice
Dormice are becoming increasingly rare as their natural territory of hedgerows and woodland shrinks, and dormouse-friendly habitats become isolated from each other. These animals are in serious danger, with populations estimated to have dropped 52% since 1992.
Habitat loss and fragmentation is a major threat to dormouse survival. The loss of ancient woodland and hedgerows means that dormice are increasingly isolated, losing genetic diversity. Climate change is also disrupting dormice hibernation schedules. Milder winters mean they wake up earlier, using precious energy and struggling for food sources.
