THE WATER VOLE, the once- familiar riverbank creature immortalised as Ratty in The Wind In The Willows, has disappeared from 89 per cent of its former habitats and is now Britain's most threatened animal, the Wildlife Trusts revealed yesterday.
A new survey of water vole sites shows that the 67 per cent decline recorded 10 years ago, already a cause of great concern to naturalists, has continued. On vast stretches of Britain's rivers and streams, the hero of Kenneth Grahame's animal adventure saga (with Mole and Mr Toad) has disappeared. "If we leave things as they are now and don't intervene, we will almost certainly see the species go extinct," said Rob Strachan, the scientist behind both surveys.
Habitat loss and pollution have played a part, but the principal cause has been predation by wild mink, which have become established in Britain over the past 50 years after escapes from fur farms. As mink are not only fierce hunters but powerful swimmers they can pursue water voles in water as well as down their burrows and have taken a terrible toll in any areas where they are present.
Mr Strachan, a researcher at Oxford University's wildlife conservation research unit, first alerted the public to the animal's decline a decade ago with a survey of 2,970 sites where water voles had been recorded over the previous 60 years: he found them absent from more than two-thirds. The new, unpublished survey, done between 1996 and 1998, has now found more losses. "The decline is catastrophic," Mr Strachan said. "It is happening right under our noses, with such rapidity."
One of the main dangers, he said, was that the remaining populations were fragmented and vulnerable to dying out naturally. They could be rescued by habitat restoration and control of mink.
The parlous state of the animal was revealed by the Wildlife Trusts yesterday in a situation report, Rescuing Ratty, which gives a detailed picture of the present status and of the work being done to help it. "It seems almost unbelievable to describe the water vole as a threatened species," said Simon Lyster, the Wildlife Trusts' director general. "We are determined to do all we can to save it."
The trusts launched their report at a prime water vole site on Crane Park Island nature reserve in Whitton, near Twickenham. Run by the London Wildlife Trust, a water vole colony is flourishing on the banks of the Little River Crane. Habitat restoration, such as planting a reed bed and creating earth banks for burrows, is securing the colony, said the warden, Alex Robb. "I think we're an excellent model for the type of work that can be done to encourage the population to increase," she said.
Water voles are often known as water rats, but are not rats at all. Unlike rats, which have protruding ears, pointed noses and nearly hairless tails, water voles have small ears, a blunt nose and tails covered in fur.
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