American mink are members of the mustelid family; related to species such as badgers, otters, polecats and stoats.  In size, they are much smaller than an otter but larger than a stoat and similar in size to a polecat or domestic ferret. They are mostly a very dark brown, appearing almost black and may have a few white patches on their chin, throat, or underside. They may occasionally be other colours, such as a silvery grey. This variation relates to the breeding of American mink in various colour forms in fur farms, from which the ancestors of our feral American mink escaped or were released.

Fully grown males might be around 1.5 kg with adult females half the size, weighing around 750 gm. They are semi aquatic so are usually seen in or near water, although they occasionally hunt some distance away, perhaps along hedgerows or to visit a game release pen. Out of the water American mink are most likely to be confused with polecats, which are making a comeback, and may also visit the waterside.  However, American mink are a more uniform colour and may go into the water when disturbed, whereas polecats are truly terrestrial.

American Mink

© Ken Mattison


© Kentish Plumber

When swimming American mink are only likely to be confused with otters, the other semi aquatic mustelid.  However, otters are much larger and when they swim most of their body is submerged, although some of the tail may be visible. When American mink swim their back is clearly visible above the water.

American Mink

© Ian Preston


© Stephen Gibley