A training event is to be held for volunteers helping to record the number of dormice in South Gloucestershire.
Nationally dormice numbers have fallen to around 40,000
As the authority's dormouse records are old, the Dormouse Project aims to find out more about where the remaining dormice live.
Project coordinator Sally Pattison said: "Training is needed as they sleep for most of their lives, so it is nearly impossible to spot one."
The project also wants to determine how best to preserve their landscape.
"Surveying for the rare and elusive dormouse is easy and fun but requires some knowledge as dormice are a protected species which live in the tree canopies and seldom travel on the ground," said Ms Pattison.
"They feed on nuts, berries, nectar and insects and therefore rely on very rich wildlife habitats so you might find them in woods, old hedgerows, scrub, bramble patches and even overgrown gardens,"she said.
Volunteers will be asked to put up dormouse nesting tubes in their locality and check them every four weeks throughout the summer and autumn.
Dormice numbers have declined to such an extent only around 40,000 are left in the UK and they are now considered a rare species.