One of the protagonists in Kenneth Grahame’s The Wind in the Willows, Ratty the water vole, was notable for his friendly demeanour, mischievous manner and downright stubbornness.

If only real water voles shared the latter trait with good old Ratty.

Since Wind in the Willows was first published in 1908 their numbers have dropped from approximately eight million to as few as 354,000 at the turn of the century, making it Britain’s fastest declining mammal.

“The two main reasons for this decline are habitat loss and predation by the American mink,” explained Nicky Hoar of the Dorset Wildlife Trust.

“When I was a child I used to see them every day and then one day you wake up and think ‘I haven’t seen a water vole for years.’ It’s really serious.”

Even in the darkest hour for the water vole, numbers in Dorset remained relatively resilient with the invading American mink failing to penetrate the county’s waterways.

“We haven’t suffered so badly with mink in Dorset,” says Nicky. “Which is why we think water voles have hung on in the county.”

Concerned about the decline, the government announced full legal protection for the rodent in 2008 and, although it is not necessarily a legacy of this legislation, latest figures suggest the water vole is bouncing back.

“I’ve actually seen two this year on Brownsea Island,” explains Nicky.

“They’re the first I’ve seen in 30 years.”

The Environment Agency suggests that numbers may have risen to 500,000, fuelling speculation of a reversal in the water vole’s fortunes.

So what’s prompted this resurgence?

Projects to control mink have helped, as have habitat restoration schemes, like the ones taking place on the River Allen in Dorset.

“There have been a lot of improvements in habitat and the quality of water,” said Nicky, who has been working closely with water companies to improve the health of Dorset’s rivers. “The funding we’re receiving from Bournemouth and West Hants Water and Wessex Water helps us improve the habitat by restoring vegetation and managing scrub. We don’t want banks with nothing growing on them because water voles need places to hide away.”

These humble herbivores are a good barometer for the health of our waterways, so there is wider significance in the revival of the water vole.

“Mammals are a high level in the ecosystem and if they’re doing well you know the whole system is doing well,” explained Nicky.

If you’d like to help the Dorset Wildlife Trust with their water vole conservation visit Dorsetwildlifetrust.org.uk/appeal2010.