The mink (Mustela vison) is a member of the weasel family, which also includes skunks, otters, and wolverines. They are perhaps best know for their dark brown fur, which turns white at the chin and runs to black at the tips of their tails. They have long, slender torsos atop short legs. Full-grown females are usually 17 to 21 inches long and weigh 1.25 to 1.75 pounds, while full-grown males are usually 21 to 24 inches in length and weigh 2 to 3.75 pounds.

Minks are found along rivers, streams, lakes, ponds, and marshes throughout North America, northern Europe, and the former Soviet Union. They particularly like habitats that provide good cover—such as grass, brush, trees, and aquatic vegetation—and abundant prey. Minks den in cavities in brush or rock piles, logjams, exposed roots of trees, and abandoned muskrat burrows.

Wild minks are less abundant than they were 50 years ago. The quality of their habitat has been degraded through development, stream channelization, and the drainage of wetlands. Trapping and the fur industry have also depleted wild mink populations. An average of 115,000 wild minks were killed in traps each year between 1995 and 1998, even though the mink industry has increasingly turned to raising its animals in cages (26 million caged minks were killed each year between 1995 and 1998).

The average lifespan of a mink is less than one year, a number greatly affected by high infant mortality; it is uncommon for a mink to live as long as four years. Their chief predators are owls, coyotes, and cats—and, of course, man. Mink prey upon frogs, mice, rats, rabbits, fish, crayfish, birds, squirrels, and muskrats. Fierce fighters, they are capable of attacking prey much larger than themselves. They rely heavily on smell to hunt on land. Usually a mink will take prey back to the den before eating it, sometimes storing food for later.

Minks are nocturnal animals, active from dusk to dawn. They do not hibernate during the winter, though they do sometimes stay in their dens for a day or so during snowy or cold periods. Minks travel well on both land and water, swimming as deep as 50 feet under water on one breath and reaching surface speeds of up to 1.5 miles an hour. On land, mink walk or take low bounds of 10-24 inches, which can reach speeds of up to 7.8 miles per hour.

Mink live alone except when raising young. Females start breeding at 10 to 12 months of age. February and March are the months in which mating occurs. At this time, males mate with many different females. After about 50 days of gestation, generally at the beginning of May, females give birth to a single litter of about four kits. Born blind, hairless, and about 3.5 inches long, these kits will learn to hunt by 6 or 8 weeks. They will be able to care for themselves by the end of the summer.