Dormice numbers have dropped by 50% in Britain over the past 100 years
A number of dozy dormice have been discovered hibernating in nest boxes at the Goblin Combe nature reserve in North Somerset.
The 128 acres (52 hectares) site is managed by Avon Wildlife Trust and is a biological Site of Special Scientific Interest (SSSI).
It stretches from Redhill, near Bristol International Airport, through to Cleeve.
The trust installed 50 dormouse nest boxes on nature reserves across the region a few years ago, in a bid to halt the decline in the species.
Dormice numbers have dropped by around 50% in Britain over the past 100 years and their conservation is now a national priority.
Hibernation usually takes place from November to April
Animals hibernate to avoid the cold weather
They also go into the deep sleep when food becomes scarce, as it's easier to conserve energy sleeping than foraging
Warm periods during winter are bad news, as they can lead to animals waking up
Long cold winters mean that the creatures stay asleep and conserve their energy for the arrival of spring
As recently as 2000, only one solitary dormouse was recorded on an Avon Wildlife Trust nature reserve.
But the numbers are starting to improve, with staff spotting 31 dormice during just one survey at Goblin Combe last year.
This year dormice have been found on a further three nature reserves, which means knowledge about local dormice can start to "increase hugely".
Avon Wildlife Trust will use the latest statistics to manage their woodlands and hedgerows to make them more attractive to dormice.
The trust, a registered charity, is the largest membership-based wildlife organisation in the area.
It has nearly 17,000 local members and manages 35 sites as nature reserves.