The public are being asked to report sightings of dormice in a bid to boost numbers of the endangered species.
Hazel dormice populations in the UK have fallen by around a third since 2000 and are now extinct in 17 English counties, according to the National Trust.
The conservation charity said the public could do a few simple things to help encourage the elusive animals, particularly if they live near a wood, such as allowing bramble to grow and leaving ivy on trees and piling up logs.
Habitat loss is believed to be the main reason for the decline, but increasingly warm winters are also having a negative effect, with dormice awaking from hibernation too early and hazel trees, their main habitat, showing signs of stress.
Rangers on the National Trust-owned Cotehele Estate in Cornwall carry out monthly checks of the local dormouse population, conducted each year from April to October.
Lead ranger George Holmes said: “Finding a snoring dormouse inside a nesting box is an amazing feeling – they’re such gentle and charismatic creatures.”
“Sadly, they’re so rare now that most people will never see one in their lifetime,” he continued.
“We’re working hard to improve numbers on the estate.
“Dormice are a key indicator species of the health of a woodland, so if the dormice are thriving, chances are other wildlife is too.
“Everyone can do their bit to encourage dormice and other wildlife, whether it’s by letting the ivy grow on a tree in your garden or stacking up a pile of logs as shelter.”
A special licence is required to handle these rare animals, which can be found curled up in a semi-hibernating state inside one of 50 wooden nesting boxes installed by the trust on the Cornish estate.
As well as counting the mice, rangers check their age, sex, weight and breathing condition, before submitting the information into a national database.
Dormice are arboreal, preferring to live high in the tree canopy and spending as little time as possible on the ground.
On the Cotehele Estate, rangers manage the woodland by coppicing, ensuring the tops of the trees touch to allow dormice to move freely through the woodland without crossing fields and roads.
Sightings of dormice can be reported at the People’s Trust for Endangered Species website – surveydata.ptes.org/dormouse-database.