THE national treasure of the rodent world - water voles - are making a comeback in parts of the region.

Made famous as Ratty in Wind in the Willows, the mammals are one of the country’s most famous and most endangered creatures.

But they were brought to the brink of being wiped out after predatory mink were released into the countryside. Coupled with fewer suitable habitats, it meant the animals disappeared from 94 per cent of their habitats and the species was placed on the critical list.

But now several environmental agencies have teamed up to improve habitats for water voles, after finding they were making a come-back to North Yorkshire.

Brian Walker, wildlife officer with the Forestry Commission, said water voles have been found to be making bolt-holes high up on the North York Moors, away from the lowland streams where they are traditionally found.

"Water voles are thought of as a creature of lowland river streams, not upland moors and forest like Langdale,” he said.

“One theory is that they sought refuge from highly predatory mink in rivers like the Esk and Derwent. But it could be that they've been here all along and no one thought to look until they were found in the 1980s.

“So far we have identified around half a dozen sites, with a couple more in nearby Sneaton Forest. It's a very important colony and over the years we have been tweaking the environment to its advantage."

The Forestry Commission has teamed up with the North York Moors National Park Authority and the National Trust to dam woodland watercourses and remove conifers from the species’ streamside haunts. The work will improve water quality and has been funded by £24,000 from the Environment Agency.

The creatures are attracted to clean pools of water and the latest work aims to improve water quality by reducing sediment, which will also help other wildlife.

Another positive development for water voles could be the return of the otter, as it appears they do not tolerate the presence of mink.

Brian Walker said: “Fewer mink may allow water voles to branch out again.

“That would be very good news to prevent the fragmentation of the species.”