The race is on for major works on Ireland Bridge to be completed before a colony of about 300 bats return from hibernating in the Yorkshire Dales.

Work on the 17th century bridge in Bingley had to be put back last year following the discovery of the large colony of Daubenton’s bats.

The work was re-scheduled for the winter, to coincide with the bats leaving the area to hibernate in caves in the Yorkshire Dales.

Now as spring arrives, the bats are expected to return within the next couple of weeks, meaning many of the major works will have to have been completed by then.

Independent ecologist Peter Brooks, of Brooks Ecological Limited, Bradford Council’s appointed consultant, said he was happy the work was on schedule to be completed before the bats come home to roost.

He said: “Everything is going extremely well and they are on course to be ready for the bats to get back in shortly. The bats go away in the winter and they hibernate in caves in the Dales and they come back in the springtime and we expect them to start trickling back to the bridge now.

“The bulk of the areas where bats could get in to roost are unaffected by the works, but we needed to be present.

“We didn’t know inside the bridge how extensive the roosting chambers were.

“On the main arch, where they were digging, we found, as they dug away, that it didn’t dig into their homes.

“It was done over the winter for that reason because otherwise there was no way they could carry out the works without it committing an offence under the conservation regulations and the Wildlife and Countryside Act.”

Mr Brooks said the colony was of a regional importance due to its size.

He said: “It’s 300 Daubenton’s bats – that puts it as a regionally important roosting site – more than just locally, it’s regionally important.

“They have probably been in there for hundreds of years.”

The bridge is due to re-open in July.