The dormouse is protected by legislation

The dormouse, one of the UK's most endangered mammals, had not been found in the county for decades before being reintroduced in 2002.

Sixteen pairs were placed in a wooded area east of Lincoln by the Forestry Commission.

A spokesman said a spot check has shown that the population of the animals has at least doubled.

Wildlife ranger Jim Alexander said: "We check them regularly and we are very pleased with the results because we were not sure they would survive."

Nut diet

"The originals were microchipped, but none of the ones that we found were chipped - so they were all born in the wood."

The tiny mammals are nocturnal and have two litters a year.

Much of their woodland and hedgerow habitat has been lost and grey squirrels compete with them for food.

Their diet consists mainly of fruit, berries, flowers, insects and hazelnuts.

Dormice are found mainly in the south of England, particularly in Devon and Somerset, but also live in Kent and Sussex.