Dormouse

Dormice are small, nocturnal rodents belonging to the family Gliridae—sometimes called Myoxidae or Muscardinidae by different taxonomists. They live in Africa, Asia, and Europe. Their name comes from their habit of hibernating for six months or more. There are nine genera and 28 living species, and about half of those species are in the African genus *Graphiurus*.

The word "dormouse" likely comes from Middle English *dormous*, possibly from an Old Norse word meaning "benumbed" combined with "mouse." Some think it comes from a French word for "to sleep," but no such term is known to have existed. The scientific name *Glis* traces back to a Proto-Indo-European word for "weasel" or "mouse," related to Sanskrit and Ancient Greek words for the same animals.

These rodents are small, with bodies 6 to 19 cm long and weights from 15 to 180 g. They look mouse-like but have furry tails. Most are arboreal, agile climbers, and active at night. They have excellent hearing and communicate with various sounds. Dormice eat berries, flowers, fruits, insects, and nuts. Unlike other rodents, they lack a cecum—the part of the gut used to ferment plants. Their teeth are similar to squirrels', but they often lack premolars.

They usually breed once a year, sometimes twice, with litters averaging four young after a gestation of 22–24 days. Babies are born hairless and blind, opening their eyes around 18 days old. They become sexually mature after their first hibernation. Dormice can live up to five years and live in small family groups, with home ranges that vary by species and food availability.

In temperate areas, dormice are famous for hibernating up to six months—or longer if it stays cold—waking briefly to eat stored food. They build up fat in summer to survive this period.

Humans have a long history with dormice. The European edible dormouse (*Glis glis*) was a Roman delicacy, served as a savory appetizer or dessert dipped in honey and poppy seeds. Romans used special enclosures called *gliraria* to fatten them. Today, it is still eaten in Slovenia and parts of Croatia. Elizabethans believed dormouse fat induced sleep because the animals fatten before hibernating. Recently, dormice have entered the pet trade as exotic pets, with the woodland dormouse (*Graphiurus murinus*) being most common, and Asian garden dormice (*Eliomys melanurus*) also kept occasionally.

Dormice likely evolved in Europe. The earliest known genus, *Eogliravus*, lived in France during the Early Eocene, about 48–41 million years ago. They were not diverse then but spread out in the Oligocene, when hibernation may have evolved. Their peak diversity came in the late Early Miocene, around 17 million years ago, when Europe had 18 genera and 36 species, making dormice the dominant rodents there. The first Asian dormice appeared in the early Miocene, and several modern genera emerged then. Diversity declined until the middle Pliocene, when a new burst of speciation occurred, mainly from the African *Graphiurus* genus, which first appeared in the Pliocene. European dormice stayed less diverse than in their Miocene heyday. Some dormouse lineages grew to giant sizes on Mediterranean islands during the Pliocene and Pleistocene, with the rabbit-sized *Leithia* of Sicily and Malta being the largest.

Today, the family has 29 living species in three subfamilies and nine genera. These include the Japanese dormouse (*Glirulus japonicus*), the European and Iranian edible dormice (*Glis glis* and *Glis persicus*), the many African dormice of *Graphiurus*, the Chinese dormouse (*Chaetocauda sichuanensis*), and others in the subfamily Leithiinae.