Hazel dormouse: Ten tiny dormice get the 'all clear' from vets - ahead of their release to the wild

Ten tiny hazel dormice have been given the all-clear by vets, ahead of their release into the wild next month.

Britain’s population of the once-common native rodents is thought to have decreased by more than 50% over the past few decades, but ongoing efforts to restore their numbers have seen more than 1,000 dormice reintroduced into 25 woodland habitats across 13 English counties since 1993. Unfortunately, the famously sleepy critters remain one of the our rarest mammals, according to the Woodland Trust, and they are a priority species under the UK’s Biodiversity Framework.

Hazel dormice face a number of threats. The biggest one is habitat fragmentation, caused by the loss of the woodlands and hedgerows they rely on to survive. Warming temperatures driven by climate change also have the potential to disrupt their long hibernations.

The ten young dormice are part of an annual reintroduction programme led by the People’s Trust for Endangered Species (PTES), with help from the Zoological Society of London (ZSL), Natural England, Paignton Zoo, the Common Dormouse Captive Breeders Group, Forestry England and The Greensand Trust - to rebuild populations of this native species.

Each 20-gram dormouse had a 10 minute appointment with wildlife vets from ZSL’s Institute of Zoology, during which their heart and lungs were checked with a stethoscope, and their eyes, ears, nose, teeth and fur were examined. They were also microchipped and x-rayed - to check their bones and overall health.

The health checks are part of the ZSL's disease risk analysis and health surveillance team’s efforts to ensure they are fit and healthy enough to be released to the wild this summer - in a secret woodland location - and that there is no risk of them passing diseases on to local wildlife.

Ahead of a previous release, PTES dormouse officer Ian White said relocating them to the wild involved keeping them in sealed cages for about 10 days in their new home, so they could get used to the smells and sounds. “And then after 10 days, a small opening will be made in the cages and then the dormice are free to come and go. Dormice are relatively sedentary, they don’t move very far, so an area equivalent to about half a football pitch will take one dormouse.”

He said they have been fed on a diet of corn, fruit and bird feed while in quarantine, but in the wild they will eat honeysuckle and bramble flowers, hazelnuts, and insects living on trees. Mr White told PA: “Two things dormice need, a fairly diverse range of food species, so old woodlands where you have got a range of trees, a range of different plants that they can feed on is important.

“And also because they are fully arboreal when they’re active they need connectivity, the kind of tree and shrub level to enable them to get around, which is why you need ongoing management,” he added.