The representation of the weasel family (Mustelidae) in Scotland is typical of Britain as a whole save that the polecat is absent and that Scotland is the UK's stronghold of the pine marten, although the purity of the latter breed is threatened by a release of American martens in northern England. Scotland hosts the only populations of the Scottish wildcat (Felis silvestris) in the British Isles with numbers estimated at between 400 and 2,000 animals, and of the red fox subspecies Vulpes vulpes vulpes, a larger race than the more common V. v. crucigera and which has two distinct forms. The wild cat is at risk due to the inadequacy of protective legislation and is now considered at serious risk of extinction. In 2013 it was announced that the island of Càrna is to provide a sanctuary and breeding station in order to protect the species. Exterminations of the population of feral American mink, which were brought to Britain for fur farms in the 1950s, have been undertaken under the auspices of the Hebridean Mink Project and the Scottish Mink Initiative, which hopes to create a mink-free zone in a large area stretching from Wester Ross to Tayside.