MAMMALS
Status: Common, Native Resident

AMERICAN MINK
(Mustela vison)

Description 

The American mink is a dark brown, semi-aquatic weasel prized for its luxurious fur. The mink has short legs, webbed toes, and a long skinny body that enable it to be an excellent swimmer. There is distinct sexual variation in the size of mink. Adult males weigh 2 to 3.5 pounds (0.9-1.6 kg) and measure 23 to 27 inches (58-68.6 cm) in length. Adult female mink are smaller than males and weigh 2 to 2.5 pounds (0.9-1.1 kg) and measure 18 to 22 inches (46-56 cm) in length. The fur of the mink is very thick and water repellent, with long, glossy hairs that are light to dark brown. There are usually some white markings on the chin and throat. Mink in South Dakota are darker in color than those in the southern part of North America where mink have lighter red fur. 

Distribution

The American mink can be found in almost any part of the United States and Canada except Arizona, dry areas of the west, and southern California. In South Dakota, mink are found statewide near fresh water habitats. Mink live near streams, rivers, ponds, and wetlands, and are especially common in the glacial lakes region in the northeast.

Natural History

Mink live along lakes, rivers, and streams, and densely vegetated areas in swamps and marshes. Their den may be an abandoned beaver den, a hollow log, or a burrow dug by the mink. In South Dakota, muskrat bank dens or houses built from vegetation are often used by mink. All dens are temporary because mink move frequently. Males and females den separately except when breeding.

Mink are very territorial with both sexes hostile to intruders. Males fight routinely in or out of breeding season, their attitude changing only during courtship when they become very mild-mannered. However, the male may bite the female repeatedly on the neck while mating. The mating season occurs from February to April, and sometime extends into May. Gestation is variable, from 37 to 78 days, the fluctuation probably due to delayed implantation of the embryo. The litter consists of 3 to 10 young, with one litter born a year. Mink are weaned in 6 weeks, hunt with their mother at 8 weeks, and become sexually mature in less than a year.

Mink maintain hunting territories by marking an area with a strong odor from their scent glands. This odor is as irritating to some people as that of a skunk. Muskrats are the preferred prey, but many frogs, fish, rabbits, mice, snakes, and marsh-dwelling birds are taken. Mink often raid poultry houses that are located on nearby farms. The mink will either eat on the spot or carry their prey back to their dens. They routinely kill more than they can eat and store the extra for later. Very few predators are known to prey on the mink, though they occasionally are attacked by red fox, coyotes, or great horned owls. Probably more mink are killed by other mink than by any predator. Automobiles kill a few, as well as humans who trap mink for their pelts.

Significance

Ecologically, mink are very important animals in the fresh water food chain, but they also have an important commercial value. The fur of the mink is one of the most desired in the world because of its glossy appearance and density, making it ideal for coat making. Most of the animals used for clothing are raised on commercial mink farms. These farms produce many different colors of mink pelts to satisfy the fashion industry.

Management Considerations

Mink populations are managed through controlled trapping that is open to South Dakota residents only. Residents who purchase a license and furbearer stamp may trap mink throughout the state from early November through January. Overtrapping can occur when fur prices are high, so careful regulation of the harvest is important. Clean water and conservation of wetlands, streams, and rivers are important management considerations. Also, over development of lake and river shorelines will result in loss of mink habitat.

Glossary

Aquatic - referring to fresh water.

References

Jones, J. Knox, et al, 1983. Mammals of the Northern Great Plains. University of Nebraska Press. Lincoln, NE.
Nowak, Ronald, and John Paradiso, 1983. Mammals of the World. 4th edition. John's Hopkins University Press, Baltimore,
Maryland.
Grzimek, Bernhard, 1975. Grzimek's Animal Life Encyclopedia . Van Nostrand Reinhold Company, New York, NY.

Written by:
Corey Schuh, biology student, Northern State University, Aberdeen, SD. 1997.

Illustrated by:
Kathy Colavitti, independent artist, Green Bay, WI.

Reviewed by:
Doug Backlund, Resource Biologist, S.D. Dept. of Game, Fish, and Parks, Pierre, SD.

Publication of the American Mink fact sheet was funded by the South Dakota Department of Game, Fish and Parks, Division of Wildlife, Pierre, SD.