10 Things You Didn't Know About Dormice

These exceedingly tiny and notoriously sleepy rodents are not technically mice.

Hazel dormouse
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Dormice—perhaps best known for the dormouse cameo in "Alice's Adventures in Wonderland" and the subsequent film adaptation—are nocturnal, mouse-like rodents native to the woodlands of Africa, Asia, and Europe. Their characteristically small stature and perpetual drowsiness makes these pocket-sized mammals decidedly adorable, but the continued loss of their habitat and warming of the climate means they're also in trouble. From their strong familial bonds to their innate climbing abilities, discover the most fascinating facts about these tiny yet complex creatures.

1. Dormice Are Not Technically Mice

A dormouse peeks through yellow flowers
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They may have round ears and long tails, but dormice are not members of the same family as regular mice, Muridae. Instead, they belong to the family Gliridae and, like other mice, share a suborder with squirrels and beavers. The primary difference between dormice and the rodents that creep into homes in the winter? The former has a fluffy tail while the latter's is scaly.

2. They're Known for Their Sleeping Habits

dormouse asleep in a nest on a bed of leaves
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Dormice that live in temperate climates go through long periods of hibernation lasting six months or more. They make their nests along the forest floor, hidden by logs and piles of leaves. Sometimes they'll use an abandoned bird's nest or build their own nest with bark and leaves. They like to hibernate at the base of well-established hedgerows. Although they may wake up during a particularly lengthy sleep to get a snack, the animals usually try to eat enough food to fatten up before hibernation begins.

3. Even Their Name Is a Nod to Their Sleep Behaviors

This dormouse found a cozy sleeping spot.
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The name dormouse is thought to stem from the French word "dormir," which means to sleep. The second element, "mouse," although commonly mistaken for another rodent of this same aesthetic, likely derives from the feminine version of "dormir" ("sleeper"), which is "dormeuse," Online Etymology Dictionary says. Even when they aren't hibernating, they're always dozing. One dormouse, according a 2015 report published in the Journal of Comparative Physiology B, slept for a whopping 11 months.

In all fairness, though, nocturnality is primarily to blame for their tendency to sleep through the day. It's also believed to be a survival tactic, preserving energy when food is scarce or when the weather is colder. Sleeping cools their body temperature, preserves body fat, and slows their metabolic rate. As one scientist told the BBC, "This shows how the wild mice cope with the unpredictability of food."

4. Like Us, Dormice Live With Their Families

These little guys play follow the leader on a log.
Miroslav Hlavko / Shutterstock

Female dormice breed once or twice a year. They usually give birth to litters of four between May and August, and they continue to live in close-knit family groups as the young mature. The infant dormice—hairless and generally weighing no more than a sheet of paper—open their eyes at three weeks and don't leave their mother's side until they're about six weeks old. Some dormice can live up to five years, which is a long time for a small rodent.

5. They Can Be Smaller Than Your Thumb

baby dormouse on a green branch
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Dormice vary greatly in size. For instance, an edible dormouse (found in Western Europe) can be more than twice as long as a Japanese dormouse. At their largest, they can reach 8 inches in length, but the smallest ones are as little as 2 inches long. They can weigh between .5 ounces (that's less than a slice of bread, for reference) and 6.5 ounces.

6. They're Expert Climbers

Climbing dormouse
Miroslav Hlavko / Shutterstock

With their long, grasping toes and sharp claws, dormice are said to be some of the most acrobatic arboreal animals. They may be tiny, but their ability to scurry up trees and twigs comes in handy when they're trying to avoid predators, such as foxes and weasels, or reach a dangling berry. These claws give the creatures an advantage when it comes to digging, too.

7. There Are 29 Different Species of Dormice

A dormouse pauses while climbing a twig
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Various species of dormice can be found all around the world, from the African savannah to the British Isles. Although most are golden-brown in color and have distinctive fluffy tails and brown eyes, their physical characteristics can vary based on which part of the world they inhabit. Some are large, some small, some appear to have dark masks around their eyes. One of the rarest of the 29 species is the elusive and little-known mouse-tailed dormouse, hailing from Bulgaria and Turkey.

8. They Eat Flowers

Sometimes even a dormouse has to stop and smell the flowers.
Miroslav Hlavko / Shutterstock

This dormouse might look as though it's taking in the aroma of a big bunch of flowers when really it's enjoying an afternoon snack. These creatures are omnivores, primarily fueled by hazelnuts (which they eat in especially high quantities right before hibernation). They also dine on small insects, fruits (in particular, berries), nuts, and flowers that provide nectar and pollen. They have to weigh at least 15-18 grams in order to survive hibernation, so eating as much as possible before winter comes is a top priority.

9. They Have Been Around for More Than 30 Million Years

Glis glis – edible dormouse
Jasius / Getty Images

The tiny dormice of today hail from giant dormice, an extinct ancestor (as big as a rat) from the Pleistocene. Fossils date back to the early Eocene epoch, a period of 33 to 56 million years ago, when they are thought to have lived alongside ancient horses, primates, and bats. They were discovered in Europe and Asia at least 30 million years before being discovered in Africa.

10. Dormice Are in Danger

Close-up image of a dormouse
Saguari / Shutterstock

The dormouse population is in decline both in number and range. The People’s Trust for Endangered Species (PTES) reported in 2019 that they are vulnerable to extinction in the U.K. Loss of habitat is their biggest threat, when the hedgerows and old coppiced forests that they love are removed. In light of that, the organization has been releasing breeding pairs into woodland areas since 1993, and the U.K. has installed a number of wildlife bridges with complex tunnels, ropes, and poles to help these creatures and others cross dangerous open spaces safely.

Save the Dormouse

  • Report all dormouse sightings to the PTES via its National Dormouse Database. The organization encourages the public to look for these creatures by tracking half-eaten hazelnuts.
  • Contact a rescue group like the Wildwood Trust immediately if you see an injured dormouse — they are common targets for cats.
  • Adopt a dormouse through the PTES's House a Dormouse program.
  • Register for a license to monitor dormice in the U.K. with Natural England.
View Article Sources
  1. "dormouse (n.)." Online Etymology Dictionary.

  2. Hoelzl, Franz, et al. "How to Spend the Summer? Free-Living Dormice (Glis glis) Can Hibernate for 11 Months in Non-Reproductive Years." Journal of Comparative Physiology B, vol. 185, no. 8, 2015, pp. 931-939., doi:10.1007/s00360-015-0929-1

  3. "The State of Britain's Dormice 2019." Peoples Trust for Endangered Species.