IUCN status
Scientific name
Muscardinus avellanarius
Deciduous woodland, shrubland and hedgerows

Dormouse UK

Dormouse conservation 

Once common across the UK, the hazel dormouse is now considered at risk of extinction due to woodland habitat loss and mismanagement. But by working together with our conservation partners, we've managed to successfully reintroduce over 1,000 dormice into 13 UK counties. We provide health checks which are crucial to the project, helping give dormice the best start possible as they return to the wild, whilst protecting local wildlife. 

our work protecting wild animals from disease 

Currently, the reintroduction programme is striving to improve post-release monitoring methods, as well as ensuring the dormice involved in the captive breeding continue to produce heathy, viable offspring to supplement the wild population.  

Follow the journey of 30 hazel dormice that we reintroduced to British woodland, from quarantine at ZSL to their new forever home. 

Hazel dormice threats  

The loss of woodland and hedgerows, and changes to traditional countryside management practices has caused UK populations to be in decline. Climate change also has the potential to disrupt their long hibernations. Predators like the domestic cat, owls and weasels can catch them as they forage, whilst badgers can eat them in their nests during hibernation, but predators do not have a major impact on their populations.  

Sleeping hazel dormouse
Sleeping dormouse 

Dormice in the UK

There are three dormouse species living in the UK, the native hazel dormouse and two invasive species, the garden dormouse and edible dormouse. Each of these species are from mainland Europe, and are much bigger than our native hazel dormouse. Edible dormice in particular can cause real problems, predating on bird nests, tree damage and even building damage. 

Edible dormouse, an invasive species living in the UK
A non native garden dormouse living in the UK

What do hazel dormice eat?  

Hazel dormice eat berries, seeds, flowers, pollen and nuts as well as any insects they find like . They change their diet in preparation for hibernation, focusing on fattier foods like hazelnuts. The hazel dormice we reintroduce to wild are supplemented with food after release to help give them the best start possible back in the wild.  

What do hazel dormice look like? 

Hazel dormice have golden-brown fur, and they are the only small British mammal with a furry tail. 

Hazel dormouse climbing on foilage
Hazel dormouse close-up, dark circular eyes with rosy orange fur

Hazel dormouse habitat and distribution 

In the UK, hazel dormice are most common in the woodland within the south of England at places like Sussex, Devon, and Kent. They are nocturnal and hibernate for five months of the year, from late October through to April, making them very difficult to find. But you might be able to spot the woven straw nest of a hazel dormouse amongst thick bushes. They are also found in most of mainland Europe. 


Dormouse habitat, British woodland
Dormouse in a nestbox
Dormouse habitat

Hazel dormice UK reintroductions  

Hazel dormice populations have decreased by 55% over the last twenty-five years, and they are now extinct in 17 counties in the UK. We’re working towards creating healthier, better connected, and bigger populations of hazel dormice, so hopefully one day they will be commonly found across the UK again.  

Sleeping hazel dormice get health checks

Hazel dormouse sleeping in nest
HAzel dormouse sleeping in British woodland
Sleeping dormouse

Thanks to the National Dormouse Monitoring Programme, dormouse nest boxes at each reintroduction site are checked every month. This post-release health surveillance can make a difference between success and failure because we can tackle disease threats before they become a problem. If a dormouse dies, we carry out a full post-mortem examination to understand those threats. We have built a database of pathological diagnoses from free-living dormice and continue to carry out scientific research to safeguard wildlife health.   

The results from the post release monitoring and any subsequent post-mortem examinations not only inform the dormouse reintroduction programme but also provides an insight into how small populations of highly threatened species function in the face of changing conditions (including habitat destruction and disease). 

Hazel dormice protection  

Hazel dormice are a priority species in the UK Biodiversity Action Plan and are protected under the Wildlife and Countryside Act 1981. 

Our hazel dormice impact 

  • Ensuring healthy dormice are released 

  • Detection of potential disease threats to translocated dormice 

  • Developing an understanding of health and disease in reintroduced dormouse populations 

Partners & Sponsors 

People’s Trust for Endangered Species, Natural England, Paignton Zoo, Common Dormouse Captive Breeders Group 

Fighting for wildlife

We go wherever nature needs us, join us on our journey across the globe restoring life everywhere. From our work deep in the rainforests of Africa through to the River Thames in London's city centre, subscribe for email updates about our progress recovering species.

British wildlife conservation

  • Atlantic sturgeon, UK native species
    Five metre British giants

    UK sturgeon

    The UK is home to 2 native species of sturgeon, the Atlantic (Acipenser oxyrinchus) and European sturgeon (Acipenser sturio). These species can reach up to 5m long and can live for over 60 years! 

  • scanning a pool frog
    One of only two native frogs in Britain

    Bringing back the pool frog to Britain

    Historically, the pool frog was present in Britain, but following loss and damage to their habitats the species went extinct and the last native population of pool frogs, in Norfolk, was lost.

  • sand lizard examination in gloves
    A closer look at sand lizard translocations

    Analysing disease risks during sand lizard translocations

    The sand lizard has disappeared over much of its former range in the UK. Habitat loss and fragmentation are cited as the main factors in the species decline.

  • Sperm whale in the Wash
    Understanding strandings

    Cetacean Strandings Investigation Programme (CSIP)

    Our 'CSI of the Sea' team coordinate the investigation of all cetaceans, marine turtles and basking sharks that strand around the English and Welsh coastline

  • Chequered Skipper butterfly on a leaf
    A previously extinct species in England

    Bringing back the Chequered skipper butterfly to English woodlands

    Post-release monitoring of the conservation work has provided evidence that the newly established populations are thriving once again in English woodlands.

  • Badger between two trees
    Badger vaccination

    Badger vaccination

    We’ve established the Badger Vaccination Project to research the impact of TB vaccination among badgers on rates of infection within wild populations.

  • Red kite flying - identifying fork tail clearly visible
    Driving a resurgence

    Red kite conservation

    We are protecting red kites to ensure their numbers never crash again, by providing expert health surveillance and supporting reintroductions.

  • Conservation in UK and Europe