American mink

Mustela vison

Mink are small carnivores of the mustelid family.  They are predators, killing a wide variety of principally water-side animals - anything from small frogs and fish to water voles and moorhens. 

The species in Britain is an American import but is very similar to the European mink (Mustela lutreola), which is now extinct here and endangered in continental Europe.

The American mink is a very recent introduction.  It first became established in the late 1950s, when animals escaped from fur farms in several parts of Britain, but particularly in the south-west. 

Over the last 30 years the species has been spreading along watercourses into almost all lowland Britain.  It is also well established along rocky coastlines.

To some extent, it can be argued that the mink fits into an ecological niche which is vacant in Britain.  On the other hand, in its native North America, the mink is able to prey on the ubiquitous and highly prolific muskrat.  Thus, it can equally be argued that the addition of a non-native predator without its natural food base is likely to damage our native fauna severely. 

Indeed, there is good evidence for this on small offshore islands, where the appearance of mink has been associated with complete nesting failures of colonies of the black-headed gull, common gull, common tern and Arctic tern.  Mink are also thought to have been responsible for the disappearance of the moorhen on the Hebridean islands of Lewis and Harris.  However, on mainland Britain, populations of moorhen, coot and little grebe - species most likely to have been affected - seem to be holding their own.  The most serious effect here seems to be on the water vole and there is evidence that these mammals fast disappear from watersheds after mink have arrived.

Mink are extensively trapped by gamekeepers and riparian-owners, since there is no doubt that these animals do serious damage to penned gamebirds, waterfowl and fish.  Mass kills are frequent and we have evidence of kills of up to 180 in a single night in pens containing some 400 gamebirds.

Unlike some of our native carnivores, and in spite of their recent appearance, mink are now relatively common.  There are estimated to be 110,000 in Britain.

The Trust has carried out extensive research into the control of the American Mink using the Trust's Mink Raft which it invented about 10 years ago. The raft allows gamekeepers and riparian owners to detect their presence before trapping them.