The South West has become a haven for one of the UK's most endangered bats, it has been revealed.

It is hoped the creatures will eventually be able to re-colonise other parts of the country from where they have been in retreat.

The number of lesser horseshoe bats, named after the shape of a flap of skin over its nostrils, plunged during the 1950s and 1960s as agricultural pesticides killed their prey and affected their reproductive capacity.

The thumb-sized bats which weigh just 6g, used to be prevalent in Yorkshire and Lancashire but now can only be found in Wales and the West.

There has been a resurgence in their population over the past 15 years due mostly to climate change.

Females and juveniles are emerging from hibernation in better condition due to the milder winters.

The bats, a protected species in the UK in 1981 under the Wildlife and Countryside Act, are unique because they use their nose and not mouth for echo-location with the horseshoe skin around their nose acting as a megaphone helping them fly safely in the dark.

The hotbed for the animals is Gloucestershire while significant numbers can be found in Wiltshire, Somerset, Herefordshire Bath and Dorset.

Their favourite type of roost is in old stone buildings with slate roofs.

Henry Schofield, conservation co-ordinator for the Vincent Wildlife Trust in Herefordshire, is an expert on the bats.

He says their survival in the West means re-colonisation by the species can happen.

Mr Schofield became obsessed with the creatures, also found in some European countries, when he was a young man.

"I was living in North Wales and was in a cave and came across these really strange creatures hibernating," he said.

"They looked like dried prunes hanging from the roof and I was instantly fascinated by them.

" In 1990 I wrote my thesis on them for my PhD but there was next to no information at the time."

But this month the Vincent Wildlife Trust, which is based near Ledbury and specialises in the conservation of mammals, is publishing a handbook written by Mr Schofield dedicated to the conservation of lesser horseshoe bats. It is set to establish the UK as a "centre of excellence" for conservation of the bats in Europe.

The handbook marks the first time in the trust's 33-year history that it has shared its unique depth of knowledge.

Mr Schofield said: "What we do know is that the bats, which came over from Europe at the end of the Ice Age, used to be found in Lancashire, Yorkshire and Kent but are no longer there.

"Currently we estimate there is a population of 24,000 in the UK with around 12,000 in Wales and the rest in the South West, with Gloucestershire being a particular hotspot.

"They seem to love the West of the country because there are a lot of hedgerows and treelines which help with their echo-location.

"The South West was very important to the survival of these bats and now it' very important for their re-colonisation.

"We are hoping that over the next 50 or 60 years they will return to old haunts in Lancashire and Yorkshire – without the bats that survived in the South West and Wales that would not have been possible."

Natalie Buttriss, chief executive of The Vincent Wildlife Trust, said: "In producing the handbook our aim is to help conservation professionals do their jobs even better."

Copies of the book, at £19.95, can be ordered by contacting the trust by email, vwt@vwt.org.uk, or telephone, 01531 636441.