All About the Hazel Dormouse - Hazel Dormouse Facts and Information

The Hazel Dormouse is a tiny, endangered species that inhabits ancient woodlands and hedgerows.

Hazel Dormouse (Muscardinus avellanarius) Appearance & Behaviour

The Hazel Dormouse is a tiny creature, with a body length of 6 cm to 9 cm and a tail that's a similar length. They have soft, golden brown fur, large black eyes, and a long furry tail. They weigh no more than 40 grams.

They are a nocturnal species, and also arboreal (which means they spend most of their time living in trees). This lifestyle makes them hard to spot, as during the day they spend their time sleeping in nests, usually in a hollow tree branch.

Hazel Dormice are a species that do seasonal dormancy, which means they sleep and hibernate for the winter months. To conserve energy, they sometimes enter a state of torpor during the colder periods.

Conservation Status

In the UK, the Hazel Dormouse is a threatened species. Numbers of this species are estimated to have fallen by 52% between 2008 and 2018. The loss of woodland habitat and hedgerows has a majorly impact on this population, as they won't leave the safety of the trees.

They are protected by the Wildlife and Countryside Act in the UK, as well as being a priority species under the UK post-2010 biodiversity framework. They are also listed as a European Protected Species under Annex IV of the European Habitats Directive.

Threats to Hazel Dormice, a Priority Species

Climate Change

The change of climate is a big threat to this species. Winter months are becoming milder, and this disrupts hibernation, waking them early. This is a problem as they wake when food isn't available and struggle to survive.

Habitat Loss

Hazel Dormice will not leave the safety of trees to cross open spaces, so as the UK is losing more woodlands and hedgerows, the species is becoming more isolated and vulnerable. This is thought to be the major reason for their decline.

No Woodland Management

Traditional woodland management, like coppicing, was incredibly helpful for dormice, but in recent years, these have been used less, so there are fewer coppice woodlands, and Hazel Dormice are feeling the impact.

What Do Hazel Dormice Eat?

Across the year, the Hazel Dormouse diet varies. During the Autumn, this creature fattens themself up by eating berries, nuts (like Hazel Nuts), and seeds. They need this extra fat reserve to help them during the winter months.

To eat nuts, Dormice make a small round hole on one side, and leave tooth marks on the nut surface, so if you spot characteristically chewed nuts on the woodland floor, you know Dormice are around.

When they wake up from their long sleep, they head towards foods like blossoming flowers off of tree branches, especially Hawthorn and Oak. As it creeps into summer, they will also feed on insects, like Caterpillars.

Hazel Dormouse Habitat

As a species, the Hazel Dormice's ideal habitat is in areas with new growth of woody vegetation, which is usually areas that have some form of woodland management, like coppicing. However, they will also reside in old coppice woodlands, shrublands, deciduous woodlands, old hedgerows, and conifer plantations.

Since the population has shrunk, they're spread across the UK has too. In southern England, they are found in southern counties such as Devon, Somerset, and Kent. There are also some scattered populations across the Midlands, Wales, and the Lake District.

Hazel Dormouse Breeding Season

Breeding season spans from May to September, with many litters being born from July to August. For female Dormice, pregnancy lasts three and a half weeks, and the average size of a litter is four.

For the summer, the females build nests that are well insulated so that they can conserve energy and maintain their body temperature. They also use specially designed nest boxes.

Once born, the young are fed by the mother for four weeks until they are weaned. After this, the young Dormice might stay with their mother for a further four weeks, until they become independent and go on to live their own life.

Early breeding females may have a second litter, as well as some of the young, because they become sexually mature after eight to ten weeks.

Five Facts about Hazel Dormice

  1. Hazel dormice hibernate for about six months of the year.

  2. They live mostly in trees and rarely go down to the ground.

  3. Their long, fluffy tails help them balance while climbing.

  4. They are nocturnal and very quiet, making them hard to spot.

  5. They are a protected species in many countries due to habitat loss.