Mammals: Mink

Deep in Kootenai Country Montana, near the three forks of the river named for the male moose, a cool September morning was arriving. As it did, the mist rose off the rocks in the water and a dark form appeared slinking along a log. The mink was lithe and agile as its high energy movements brought it to the end of the log. Once there, the tubular bodied almost black mustelid dove into the water, stayed submerged for a minute, and emerged excitedly with a small fish...

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The mink (Mustela vison), is a medium sized semi-aquatic carnivore about 24-inches long and weighs approximately 1-2 pounds. Mink have pointed noses and a keen sense of smell. The ears are short and rounded, and the head is dorsoventrally flattened to aid in a sleek swimming torpedo design. The thickly furred tail is about 8-inches long, and the mink’s fur is chocolate brown to black, with a white chin patch and underbelly. The fur is soft and covered with waterproof, oily hair. Historically, mink were a prized fur, sometimes called sable, and were made into luxurious and comfortable stoles, wraps and hats. The fur retains a beautiful luster, and this species is an official Montana furbearer managed and protected by regular fur harvest seasons.

Mink are versatile predators with semi-webbed feet, sharp claws and long whiskers. The term mustelid refers to musk bearing creatures, and they often mark territories for defense and mating. Habitat preference is usually near rivers, streams, lakes, beaver ponds, and wetland areas. They nest in hollow logs or stumps near water, piles of driftwood, or under rocks. Occasionally, they will den in old beaver lodges, muskrat mounds, or in bank dens of beaver or muskrat. There is a close relationship between mink and muskrat. During winter, mink may enter a muskrat den and kill the resident, taking over the den. Mink are adept in the water, and at times go subnivean under the snow to harvest mice and voles in winter.

The mink can be tenacious, and kill prey larger than itself. They are primarily nocturnal, very territorial, and quietly secretive. Diet consists mainly of fish, small mammals, birds, crayfish, eggs, lizards, grubs, earthworms, insects, mice, muskrats, and in summer prey on ducks and other waterfowl. Otters sometimes kill mink, and some owls may take the young kits or an adult mink on occasion. Mink mate from January through March, have a 40-80 day gestation period with delayed implantation, and an average of four young are born in April or May. Mink tracks exhibit a one-three-one toe pattern, and at times may show a two by two bounding stride imprint.

So when exploring Kootenai Country Montana, step quietly, use the cover of the timber, and sneak a peek into the many water bodies that dot the landscape. You may be rewarded by the sight of this secretive weasel slickly exiting the water with a squirming fish!

(Author’s Note: Reference - I.D. of Montana’s Furbearers; Frisina and Alt.)