Hazel Dormouse

• It spends most of its life asleep: it hibernates from October to April or May and, if the summer is cold and food is scarce, it also goes into torpor.
• Its specific epithet, avellanarius, comes from the hazel, its main source of fat before hibernating.
• You can tell it has eaten a hazelnut by the clean round hole it leaves in the shell: a squirrel would smash it and a vole would leave a ragged gap.

Skeleton type

Vertebrate - internal bony skeleton (mammal)

Habitat and environment

Deciduous woodland, hedgerows and gardens of Europe and Asia Minor, from France to the Urals and from Sweden to Greece and northern Turkey. It depends on tall hedgerows well connected to woodland

Size at birth

The young are born naked and blind

Sexual maturity

In the year after the one they were born in

Gestation / incubation

22-25 days

Litter / clutch size

3-7 young as a rule, with a maximum of 9, and one or two litters a year

Sources consulted: IUCN Red List (e.T13992) · Wachtendorf 1951 (tipología de nidos) · Armitage et al. 2025, Oecologia · People's Trust for Endangered Species · Antropocene.it

Best time: From late April to October, outside the hibernation period