Natural hunters and predators, mink are wary and wily animals. If you see one, you're liable to see it on the move as it lopes briskly along a shoreline, or crawls underneath some brush or into a hole in a stream bank, reappearing a minute later to continue on its way. You may also see one swim expertly across a stretch of open water, clamber up on a muskrat house, sniff the air and then disappear into vegetation behind it. The average adult female mink is 50cm long and weighs about a kilogram. About the size of a small house cat, the larger males average 53cm long and weigh around two kilograms.
Tails take up about a third of their total body length.
The fur is soft and glossy , a rich brown to almost black above and pale underneath. Buff to white-colored patches occur on the lower chin, throat and chest, but these vary in size and shape among different animals. Mostly nocturnal, mink remain active year-round. Except when breeding or raising young, males and females select individual home territories which they mark with their scent glands and defend actively. Once a territory is established, most activity is restricted to within in.