Devon has Britain's biggest population of the rare greater horseshoe bat - and the largest roost in western Europe.

A new survey by the government's conservation advisers, English Nature, shows the county has the ideal conditions for them to thrive.

A new survey has found there are only 5,500 bats nationwide and Devon is home to about 1,800.

More surveys are to be carried out to monitor the health of the population.

They don't do people any harm - they're not blind and they're not going to fly into your hair

John Diamond, English Nature

Devon is good for greater horseshoe bats for several reasons.

The landscape has many hedges, which they use for navigation and winters are relatively mild, giving them a better chance of surviving hibernation.

There are also many old buildings, which the bats like to roost in.

And there is plenty of cow manure, home to the favourite food of young bats, the dung beetle.

John Diamond, from English Nature, said: "A few people know they're here and very few people actually see them.

"But that's one of their attractions - they're very elusive and few people know they're around.

"And, of course, they don't do people any harm - they're not blind, they're not going to fly into your hair and they only eat insects.

Protected species

"They're not going to chomp on your ankles. They're completely safe and they're very friendly little animals."

The bats, which have a wingspan of about seven inches, are protected species, meaning it is illegal to disturb them, which makes checking numbers difficult.

However, at one quarry at Buckfastleigh, there are an estimated 1,200 animals in the area's limestone caves.

English Nature is now working with landowners to ensure good conditions for the greater horseshoes in Devon's major roosts.