Species of the Month, 02/14: American Mink

This is the second post in our "Species of the Month" series, written by Park Ecologist Peter VanLinn. It's one of several 2014 initiatives meant to share knowledge we have about the Park for those who love it. 

The American Mink was chosen for February because it begins the breeding season this month and because it may be more visible to visitors, as it searches for mates. Minks have been seen recently in Forest Park “playing” in the snow as they slide on their bellies down snow-covered, icy river banks.  


American Mink (Neovison vison)

 Photo courtesy of Danny Brown, Missouri Department of Conservation

Photo courtesy of Danny Brown, Missouri Department of Conservation

Park Locations: American Mink can be found throughout Forest Park along the waterways and forests, particularly Successional Forest, Kennedy Woods and along the waterway from Deer Lake to Steinberg Prairie.

Identification

  • Description: Almost entirely brown, medium-sized, slender, long-bodied mammal similar to a weasel but larger with small, flattened head, long neck, short legs and well-furred tail at a length of 1/3 the entire body
  • Total length: 16.5 – 27.5 in. (Minks are one of the few mammals in which males are larger than females)
  • Weight: 1.25 – 3.24 lbs.
  • Longevity: Usually live 1 to 2 years in the wild, occasionally up to 5 or 6 years.
  • Voice and sounds: Relatively quiet creatures but do have a variety of chuckles, growls, barks, hisses, squeals and screeches

Distribution and Abundance: Generally scarce, but more common in the Mississippi Lowlands of Missouri. Populations can vary from 8 to 22 minks per square mile.

Habitat: Require permanent water and prefer nearby timberlands. Minks dwell under the roots of trees in cavities and burrows along the banks of streams and rivers or the shorelines of lakes and marshes, usually within 600 feet of open water.

Behaviors: Minks travel widely, with males encompassing home ranges of up to 45 linear miles where they make use of many temporary homes. Females have smaller home ranges and usually occupy only one or two homes per year.

Minks are mostly nocturnal in habit, but often come out at dawn or dusk, and occasionally during the day. They are not social and live alone except during the season when young are being raised. When snow is present, minks have been known to slide down stream banks on their bellies similar to their relative, the river otter.

American Minks can run at speeds between 7 and 8 miles per hour and use their hind legs to rear up and gain a better view of their surroundings. They can also swim at a rate of 1 to 1.5 miles per hour.

Minks can be very aggressive and are known to attack animals larger than themselves. They are known as good fighters.

A Mink’s eyesight is not acute; they rely on their strong sense of smell to locate prey. 

 Photo courtesy of Sharon Deem, St. Louis Zoo’s Institute for Conservation Medicine

Photo courtesy of Sharon Deem, St. Louis Zoo’s Institute for Conservation Medicine

Reproduction

  • Breeding: Begins in late February
  • Mating: Occurs until early April
  • Gestation: 40 – 75 days, average of 51 days
  • Litter: 2 – 8 young per litter, with 4 t– 5 being the average
  • Young: Kits are born blind, toothless and may be naked or with a thin cover of fine silver hair
    • At birth kits are 3.5 inches long and weigh less than 0.25 ounces 
    • At 2 weeks fur begins to form and turn reddish
    • At 3 weeks teeth begin to cut through gums
    • At 5 weeks weaning begins and eyes open
    • At 7 weeks permanent teeth come in
    • Between 6 – 8 weeks, young will be taken on a foraging trip with adults for the first time
    • Young will stay with family until the end of August and reach maturity at 10 months of age.

Food: Minks prey upon mice, rabbits, and other small terrestrial animals as well as aquatic-dwelling species such as fish and crayfish. They have also been known to prey upon birds, foxes, squirrels, muskrats, cats, shrews, moles, bats, turtles, snakes, insects, spiders, snails and the eggs of many different animals.

Predators: Humans, dogs, owls, foxes, coyotes and bobcats.

Conservation and Management: The mink’s food habits do not seem to impact human interests largely, but they can provide a check for other species that might be a nuisance to humans, such as muskrats. Minks have been known to occasionally take chickens, but are generally not destructive.

Mink harvest regulations remain strongly enforced after longtime harvest of the species for its fur led to significant impacts to populations.

Constructing logjams and brush piles near water will attract minks to streambeds and lakeshores.

Note: Information for this post was gathered from the Missouri Department of Conservation website and the book The Wild Mammals of Missouri by Charles W. Schwartz and Elizabeth R. Schwartz.