Mammals
Hazel Dormouse
Muscardinus avellanarius · also called common dormouse
Curled into a tight ball beneath a blanket of fallen leaves, a hazel dormouse begins a hibernation that will last more than half the year, leaving only a brief window each summer to feed, breed, and build the fat reserves needed to do it all again.
Overview
The hazel dormouse, Muscardinus avellanarius, is a small, golden-coated rodent native to forest habitat across parts of Europe, including hedgerows and diverse native woodland. Its extraordinarily long hibernation period, near-total reliance on tree canopy rather than the ground, and sensitivity to woodland fragmentation make it one of the more conservation-sensitive small mammals found anywhere in European forests.
A life mostly spent asleep
With more of the year spent hibernating than active, the hazel dormouse compresses an entire year’s worth of feeding, breeding, and fat storage into a remarkably short summer window, leaving little room for error before winter sets in again.
Status
Near Threatened, having declined across parts of Europe due to the loss and fragmentation of the connected woodland habitat it depends on.
Hazel Dormouse: common questions
How long does the hazel dormouse hibernate?
This species spends more than half the year in hibernation, typically from autumn through spring, curling into a tight ball beneath leaf litter or within a nest, one of the longest hibernation periods relative to active time of any small European mammal.
Why does the hazel dormouse rarely touch the ground?
This species spends the vast majority of its active time in trees and shrubs, rarely coming down to the forest floor except to hibernate, a habit that makes it highly dependent on continuous, connected tree cover to move safely between feeding areas.
Why has the hazel dormouse declined in parts of Europe?
This species is sensitive to the loss and fragmentation of connected woodland habitat, and changes in traditional woodland management practices have reduced the continuous tree cover it depends on, contributing to its classification as Near Threatened in significant portions of its range.
What does the hazel dormouse do during its short active season?
This species must feed intensively on flowers, pollen, fruit, and nuts, breed, and build up sufficient fat reserves during a short active season, since the success of this brief period determines whether it can survive its long upcoming hibernation.