Minks blamed as water vole 'extinct' in the south-west

Water voles, Britain's most rapidly declining mammals, are believed to have become extinct in Devon and Cornwall, provoking proposals for a countrywide campaign to shoot American mink, the predators responsible.

Water voles, Britain's most rapidly declining mammals, are believed to have become extinct in Devon and Cornwall, provoking proposals for a countrywide campaign to shoot American mink, the predators responsible.

A national strategic plan to control mink numbers will be discussed tomorrow at a meeting in London of all of the organisations concerned with conservation of the water vole. The animal has disappeared from more than 90 per cent of its former territory, and has vanished completely from the South-west peninsula.

If the plan goes ahead, it would represent the most ambitious wild animal culling project Britain has seen, costing an estimated £3.4m and lasting in its initial phase for a decade. Even then, the aim would be to remove mink only from large discrete areas, not from the country as a whole, which would be almost impossible without unlimited resources and time.

The anti-mink campaign would dwarf the last such project to eradicate a non-native species, the elimination 20 years ago of the coypu, a big South American rodent that caused damage to dykes in East Anglia, and it would have to be agreed to by Government ministers. It would also have to be acceptable to the public. But scientists studying the water vole's decline are now convinced that there is an unavoidable trade-off between the presence of the mink and the absence of the water vole – if you have the one on your river, you simply don't have the other – and unless action is taken on a national scale, it will soon disappear completely.

The water vole is a popular animal, the chunky aquatic vegetarian immortalised as Ratty in Kenneth Grahame's The Wind in The Willows, but it has been all but wiped out by a small but deadly carnivore brought into Britain 70 years ago for the fur trade. American mink established themselves in the wild in Britain after escaping from fur farms, which have now been banned. They began to breed in the late 1950s, spreading out from Devon across the country.

Mink are related to stoats and weasels, but unlike them, they tend to live near water and are excellent swimmers, and water voles are their perfect prey. As their numbers built up, vole numbers started to tumble, a situation suddenly unearthed by a nationwide survey of the animal in 1989-90, which found that the voles had disappeared from 67 per cent of sites where they had been known before 1939.

When the survey was repeated between 1996 and 1998, the figure had gone up to 89 per cent. Nearly all riverbanks that once housed water voles house them no more, and Environ-ment Agency scientists looking for the animals in Devon and Cornwall have drawn a complete blank.

"I couldn't take you to a single site in Devon where we could say there are water voles," Mike Williams, a spokesman for the agency, said. "There are none left. It's very sad." Sonia Thurles, representing the agency in Cornwall, tells a similar story. "We've done a carefully designed field survey, but I reluctantly have to say that the evidence is piling up that they have become extinct," she said.

Although other factors, such as loss of riverside habitat, have played a part in the decline, in the past few years predation by mink has become accepted as the overwhelming reason.

Alastair Driver, chairman of the UK Water Vole Steering Group, the umbrella body that brings together all of conservationists trying to help the animal, said: "Some scientists doubted it originally, but now they realise all the evidence points to the simple fact that if you have mink, you won't have water voles." If the plan is to proceed, it must be backed by the chief executives of all the national wildlife agencies, including the Environment Agency, the Scottish Environment Protection Agency, English Nature, Scottish Natural Heritage and the Countryside Council for Wales.

The plan envisages mink being caught in live-capture cage traps on the riverbank, and then shot. Detailed guidelines intended to minimise suffering have already been drawn up. The trapping and shooting would have to be done voluntarily by landowners as well as the wildlife agencies and conservation bodies.

An initial outline put the cost of covering nine big areas, based on river catchments from the Essex and Suffolk coast to the central and southern Cairngorms, at slightly more than £3.4m over 10 years. More detailed costings are being prepared.

A CASE OF MISTAKEN IDENTITY

MINK MAY be the main cause of the water vole's demise but they are not the only one. It is also under threat because of mistaken identity.

According to the Wildlife Trusts, many people, including pest controllers, builders and developers, mistake water voles (above left) for brown rats (above right) and poison them or disturb their homes. The trusts have recorded many cases of accidental poisoning and in one instance the extermination of an entire group.

Now the trusts are launching an initiative to do away with the confusion, called Know Your Vole, with leaflets pointing out the differences for developers, pest controllers and members of the public.

For example, the water vole has small hidden ears, silky mid-brown fur, a blunt nose and a shorter furry tail, while the rat has big ears, grey-brown fur, a pointed nose and a scaly tail. Water voles eat vegetation, whereas rats are opportunists and will eat a variety of foods.

The confusion partly stems from the vole's old name of "water rat", as used in The Wind in The Willows, but in reality voles and rats belong to two separate sub-families of rodents.

"To small and vulnerable water vole populations the death of any water vole is a significant setback," Simon Lyster, the trusts' director general, said. "We are working to restore water vole homes along riverbanks and to combat the serious issue of indiscriminate poisoning, and the key to overcoming this problem is to build awareness of a water vole's characteristics."