Oxfordshire's water voles under threat of extinction
Water voles are being preyed on by non-native American mink
Water voles in Oxfordshire are on the verge of extinction because of the non-native American Mink.
The invasive mammal was brought to the UK in the 1920s when its fur was fashionable.
But after several escapes from mink fur farms they quickly became established in the English countryside.
The American Mink is one of several species named in The State of Britain's Mammals report by researchers based in Oxford.
It was written for the People's Trust for Endangered Species by the Wildlife Conservation Research Unit, part of the Department of Zoology at the university.
The unit's mission is to solve practical problems related to wildlife conservation and management.
"This is very much an Oxfordshire problem," said Professor David Macdonald, one of the report authors.
"We're now involved in trying to captive-breed water voles and return them to the habitats from which they have been wiped out.
"The only way forward is for the mink to be removed and that means killing them.
"There's a lot of people in the British countryside who believe that that is the appropriate thing to do, for example people with fishing rights, with gamekeepers on their land, will routinely kill mink to stop their depredation on game.
"There are also people concerned with nature conservation like the county wildlife trust and in their attempts to restore the water voles they will trap and kill mink - with a heavy heart no doubt - but because this is the only possible solution for saving the water vole."
Voles monitors track the recovery
The water vole, which evolved with natural predators such as stoats, weasels and otters, is easy prey to the opportunistic mink, which follow them into both the water and into their burrows.
"It's an example of a fairly recent arrival which has had a devastating affect on local biodiversity and we face a very stark choice," said Professor Macdonald.
"I'm really sad to have to put it in these terms because these American Mink are both beautiful and wonderfully adaptive and one might actually rejoice in them in their native habitat, but if we want water voles to recover there's a simple choice: the mink have to go."
Water voles were once abundant in Oxfordshire but the last two decades have seen their numbers hit hard, due to both the impact of mink as well as agricultural intensification.
Professor Macdonald explained: "The habitat along the waterways which is home to the water voles has turned from a soggy sponge of marshland into just a narrow ribbon of habitat along which the water voles can live, but along which the mink can also hunt.
"There's really no chance of escape."
Red squirrel populations are being obliterated by the grey squirrel
The water vole's plight mirrors that of the red squirrel, widely annihilated by its grey counterpart, also imported from America.
The native British red squirrel survives in vastly reduced numbers in places such as Scotland and the Kielder Forest in Northumberland, but its only hope of survival depends on stricter controls.
"The public and the conservation community faces an ugly choice thrust upon it, not by the introduced animals but rather by the people who introduced them," concluded Professor Macdonald.
The list of great mammal invaders includes species not generally thought of as non-native to the UK, such as rabbits, ferrets, and some breeds of hares, deer, rats and mice introduced by Normans, Saxons and as far back as the Romans.
It also includes more recent introductions, such as the Red-necked Wallaby, native to South Australia and Tasmania but now threatening the Capercaillie, a large grouse found on Loch Lomond.
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