The hazel dormouse (Muscardinus avellanarius) is Britain's only native dormouse species and one of the country's most charming mammals. Having declined by approximately 51% since 2000, the dormouse is now a conservation priority, with protection and active management essential for its survival in the UK.
Dormice are nocturnal, arboreal rodents that spend approximately 6-7 months of the year in hibernation — more than any other British mammal. They emerge in late April/May to breed, producing typically one litter of 3-7 young per year, with occasionally a second litter in good years. Dormice require connected, diverse woodland and scrub with a succession of fruiting species — hazelnuts, blackberries, honeysuckle flowers and berries, and tree flowers provide sequential food sources through the active season. They rarely descend to the ground, spending most of their waking lives in the shrub layer.
Dormice are restricted to England and Wales, with the stronghold in southern England. The range has contracted northwards and populations have declined dramatically. Causes include: woodland management changes (loss of coppicing creates dark, unsuitable conditions), habitat fragmentation (dormice rarely cross open ground, making isolated woodland patches population sinks), road mortality, cold wet springs delaying breeding, and climate change affecting the timing of food plant flowering and fruiting. Dormice are fully protected under the Wildlife and Countryside Act 1981.
Active conservation measures include: restoring coppice management (creating diverse structural habitat), planting food plants (hazel, honeysuckle, bramble), creating wildlife corridors between isolated woodland patches, installing dormouse nest boxes (providing artificial nest sites where natural tree cavities are limited), and captive breeding for reintroduction into sites where the species has been lost. The PTES (People's Trust for Endangered Species) National Dormouse Monitoring Programme coordinates long-term population assessment.
Dormouse conservation activities require welfare-conscious handling. Survey techniques include nest box checks (finding sleeping dormice — requiring careful, quick observation and return to the box), tube trapping, and translocation for development mitigation. Welfare considerations: dormice woken from hibernation face metabolic stress (using stored fat reserves at high rates during an unexpected warm period); handling should be minimal and in cool conditions; recaptured and translocated animals should be released at appropriate temperatures and with secure hibernation sites. Licences are required for any intentional disturbance of dormice.
Reintroduction programmes use captive-bred dormice born at specialist facilities (ZSL, Chester Zoo). Animals are conditioned to wild foods before release, released in woodland with installed nest boxes, and monitored via radio-tagging. Welfare during reintroduction includes: appropriate acclimatisation to outdoor temperatures before release, release timing (late summer ensuring fat reserves for hibernation), and post-release monitoring for survival and behaviour. Successful reintroductions to sites across England have established new populations in habitat where the species had been lost.
Dormice are particularly vulnerable to climate change impacts: warming springs may advance phenology but increase the frequency of cold snaps that kill animals coming out of hibernation prematurely; drier summers reduce bramble fruiting; mild winters interrupt hibernation (dormice woken by mild weather face starvation if food is unavailable). Climate change adaptation planning for dormice requires landscape-scale habitat connectivity allowing range shifts and maintaining diverse food plant communities.