Moves to save the tiny woodland mammal from extinction could herald the reintroduction of larger lost species such as the wolf and sea eagle

More than 100 years after they were last recorded by Victorian naturalists in Yorkshire’s Wensleydale valley, rare dormice have returned to a secret woodland location there.

Last Thursday, 20 breeding pairs of rare hazel dormice (Muscardinus avellanarius) were reintroduced in the Yorkshire Dales national park as part of a national scheme to reverse the decline of one of Britain’s most threatened mammals.

The tiny, golden-brown creatures, known for their sleepy disposition and winter hibernation, were once widespread throughout England and Wales. Exact numbers are unknown, but their distribution and population has declined significantly over the past 100 years, and the species is now classed as vulnerable to extinction.

We want to create a landscape for dormice and that will make the population more robust Ian White

Dormice depend on well-managed woodlands and healthy, connected hedgerows for their survival. But changes in land use since the second world war have been so drastic that the dormice that remain in southern Britain have limited living space and are increasingly isolated.

“Throughout most of our history we have used and managed woodlands, but since the end of the last war that stopped,” said Ian White, who as dormouse officer of the People’s Trust for Endangered Species (PTES) is in charge of the reintroduction programme. “Now woods are mostly used for people to walk their dogs. The dormouse is a species that really benefits from that management – it’s because we stopped that they struggled and became extinct in places.”

Facebook Twitter Pinterest The hazel dormouse enjoying its favourite pastime. Photograph: Alamy

Last week’s release, led by the PTES and supported by a coalition of conservation groups, is the 22nd in the last 23 years. More than 800 dormice have been released at 21 different sites across 12 English counties where they had become extinct.

“One of the exciting things about this release is that dormice were known to be at Wensleydale valley in 1885, so we really are putting them back within the counties where they have been lost,” said White.

Ahead of the release, he and his team found a site of dense, good quality woodland while the captive-bred dormice waited in quarantine. After checks by vets, the dormice were then paired up and placed in “soft release” cages – secure wooden nest boxes fitted to the trees and surrounded by a metre-square mesh cage that allows them to gradually acclimatise to their new habitat.

For 10 days, the dormice will be checked and fed daily, then a small opening will be made, allowing them the freedom to explore their new home while retaining the security of the cage. These will be removed in October, when the animals start to hibernate.

“The hope is that we have a free-living population in the wood, but we won’t know how they have fared until next year,” said White. Unsuitable habitat, captive-bred animals and incorrect management could all scupper the chances of success. A distinctive factor of this release is the aim of linking up with another released dormouse population three miles away by managing the land between. “We want to create a landscape for dormice and that will make the population more robust,” said White.

Woodlands were traditionally managed through coppicing, which provided varied food and plenty of light for dormice. But the practice has been lost, with remaining woodland sliced up by roads, railways and fields. England lost more than 50% of its hedgerows between 1946 and 1993, from an estimated 500,000 miles to 236,000. And as dormice spend all their time off the ground, the scheme aims to create links between populations in the form of improved hedgerows, woods and drystone walls.

Facebook Twitter Pinterest Dormice in nest boxes from ZSL. Photograph: ZSL

“It’s very important that we reintroduce the dormouse because they are a good species to get people involved with conservation,” said White. “They are a fascinating species that is rare but you can still see. They promote good woodland management and what’s good for dormice is good for a large range of species like birds, bats and butterflies.”

Helen Meech, the director of Rewilding Britain, an organisation campaigning to restore lost species and habitats to the British countryside, said that such reintroductions would increase people’s tolerance to living with more wild animals once again.

“People’s everyday wildlife experience is becoming grey squirrels and pigeons,” she said. “We are increasingly disconnected from nature. In 30 to 40 years’ time, we might get to the point where we can start to think about bringing back wolves, bison or moose, but let’s start with species that will have a lighter impact for now.”

Lost British species

Over centuries, Britain has lost many key species such as beaver, boar and wolf that are critical for healthy ecosystems. Here are some of the species conservationists are proposing to reintroduce…

Lynx

Facebook Twitter Pinterest An Eurasian lynx in Hundshaupten, southern Germany. Photograph: David Ebener/AFP/Getty Images

Believed to have disappeared from Britain about 1,000 years ago. Experts say the return of the lynx would help control the fast-growing population of red deer, allowing forests to regenerate and support greater biodiversity. The preference of the Lynx, a shy animal, to stay in its woodland habitat would make a threat to livestock or humans unlikely. The Lynx UK Trust is seeking a licence for trial releases in Scotland and the Kielder forest in Northumberland.

Beavers

Facebook Twitter Pinterest A beaver in Knapdale, Scotland. Photograph: Steve Gardner/Scottish Wildlife/PA

After an absence of 400 years, beavers are back in Britain. The Devon Beaver project cites improvements in biodiversity and water after the reintroduction of a pair near Okehampton in 2011. Scotland’s first reintroduction, in Knapdale forest in 2009, was hailed an “outstanding success”, but an unlicensed free-living population in the river Tay has caused problems. Wales also has reintroduction plans.

Wolves

Facebook Twitter Pinterest A wolf in the Bavarian forest national park. Photograph: Alamy Stock Photo

Lost to Britain in the 1700s, the wolf is the most controversial species proposed for reintroduction given its potential to kill livestock. But they are critical to the restoration of ecosystems that have been overgrazed by deer. Despite their fearsome reputation, they present a low risk to people. Because of the space a wolf population would need, the Scottish Highlands would be the obvious place for their reintroduction and could generate millions of pounds in tourism.

Sea eagle

Facebook Twitter Pinterest A white-tailed sea eagle. Photograph: Alamy

The sea eagle, also known as the white-tailed eagle, was driven to extinction in Britain earlier this century. A reintroduction programme by Scottish Natural Heritage and the RSPB has seen it return to the Inner Hebrides island of Mull. Proposals to bring it back to the east of England failed following concerns from landowners about the threat to livestock. Successful schemes in Europe have offered compensation.

Wild boar

Facebook Twitter Pinterest A wild boar sleeps in the forest mud, Germany. Photograph: Clement Philippe/Alamy

Boar disappeared in the 13th century because of hunting. They increase biodiversity and create space for trees and plants to grow, but can cause damage to crops and gardens. The species has been quietly re-establishing itself in the woodlands of Britain for several decades.