Another American alien species is the American mink. Thoughtlessly introduced into the wild it now appears over most of the UK except for the very north of Scotland. It’s a lively, bold predator; much more likely to be spotted than the shyer otter. It’s not even that perturbed by humans. It ravages the banks of the rivers where water voles live and the females, particularly, are small enough to slither into the voles’ nesting holes. Like foxes taking poultry, they kill prolifically and continue until the entire group of birds or animals are dead; they will raid a hen house too, given the opportunity. They carry away some of the kill but leave a great deal behind.
Obviously American mink are great swimmers, having partially webbed feet, but they also climb trees and raid nests for eggs and chicks. It’s frustrating that the American Mink don’t have a much greater impact on American signal crayfish. They do take crayfish as a regular part of their diets; however, the native crayfish is far more vulnerable. They also take advantage of ground nesting birds and moorhens are particularly suffering a decline from the predation by American mink.
American mink are smaller and slighter than otters; they are brown with a white chin/throat and under parts. Breeding light coloured specimens selectively for the fur trade rendered the British feral mink a lighter brown than the true American Mink. They have somewhat fluffier tails than otters and more pointed faces. Although there are reports that the species is diminishing more needs to be done by way of trapping and removing mink from sensitive areas where water voles are established and breeding.
The reintroduction of the otter in many areas will hopefully help stop the catastrophic crash in water vole numbers that has happened over the last 6 decades – up to 95% loss. Otters prey on mink and, by reducing numbers, allow water vole numbers to improve. Although otters eat water voles the otter is too large to enter the water vole burrow so the whole family is at less risk of obliteration.
The above photo shows the difference between a mink and an otter. If nothing else the foot print of an otter has the webbing visible and is an appreciable size, the footprint of an American mink is as dainty as a kitten’s and the webbing is not visible, in size no bigger than a 2 pence piece.
It is essential to remember that if you catch an American mink in the UK you may not then release it back into the wild, nor may you keep it. It must be humanely dispatched with a suitable firearm. If you are unable to do this you should contact a game keeper, a ranger or the RSPCA.