A RARE species of bats has put a proposed 550 home development on hold.

An application by Persimmon Homes to build the homes on land south of Paxcroft Mead, in Green Lane, Trowbridge, was deferred by West Wiltshire District Council on Thursday for more information to be gathered about roosting Bechstein's bats.

Rachel Hughes, assistant conservation officer with English Nature, said: "They are pretty much the rarest mammal in Britain.

"There are only five roosts in Wiltshire and we are the stronghold for the whole of Britain, which is why they are not to be disturbed. Because of their rarity and their lifestyle, in that they roost in trees rather than houses, locating them is often difficult and we don't know a lot about them."

The multi-million pound scheme for the 50.5-hectare site includes a distributor road, primary school, local shop, open space and sports pitches. The bats live in the nearby Biss Woods and the fear is the light pollution from the development would disturb them.

The district council's cabinet was advised by the planning officer to defer the application on Thursday for more information to be gathered on the possible impact on the bats.

Cllr Ernie Clark said: "It is important that we protect our wildlife, especially something as rare as these bats appear to be. I would find it very hard to approve something that would cause devastation to a protected species such as this.

"At the end of the day there are plenty of places in Trowbridge where you could put houses but there are very few places where these bats can live."

As well as the Bechstein's bats there are also Greater and Lesser Horseshoe bats at the site, which are also protected species. The county ecologist has asked for further survey work, including radio tracking, to be carried out to establish how all three species of bats are using the area.

A spokesman for Persimmon Homes said: "We have undertaken numerous bat surveys in the area which have satisfied key agencies that our research and approach is sound and mitigation proposals are acceptable.

"For committee last week the county ecologist requested further survey work be carried out to enhance our current findings and we are investigating the details in order to satisfy all parties concerned."

A number of objections to the proposal have been raised by people living in the area and Hilperton Parish Council has also objected.

Bechstein's bat factfile

It is extremely rare in the UK, found mainly in Dorset, Wiltshire and Hampshire.

It has a wingspan of 300mm.

It lives on a diet of moths, mosquitoes and beetles.

It emerges only after nightfall.

Its life span can stretch to 21 years.