Mink fur is usually dark brown with white patches on the chin, chest, and throat areas. The fur is soft and thick, with oily outer hairs that waterproof the animal's coat. The body is long and slender with short legs and a pointy, flat face. The toes are partially webbed, showing the mink's semi-aquatic nature. Body length is usually around 2 feet or 610 mm with up to half of this length being the tail. Females, on average, are smaller than males. Adult females weigh between 0.7 to 1.1 kg, while males range from 0.9 to 1.6 kilograms. Body length varies as well, with males measuring from 580 to 700 mm and females from 460 to 575 mm.
Mink are found throughout the United States, appearing in parts of every state except Arizona. They are also present in most of Canada, including an introduced population on Newfoundland. Only along the Arctic coast and some offshore islands are they absent.
American mink have also been accidentally introduced to the British Isles, where they escaped from fur farms in the 1960's. As a non-native predator their effects on native wildlife there are serious.
Although mink are found throughout North America, they tend to prefer forested areas that are close to water. Streams, ponds, and lakes, with some sort of brushy or rocky cover nearby are considered good mink habitat.
During the winter, female mink become fertile and mate with one or more males (who also have more than one mate).
Both males and females begin mating at ten months. A female's pregnancy period varies from 40 to 75 days. The young are born in late spring (April or May), with litter sizes usually ranging between 1 to 8 individuals. Each newborn weighs 8 to 10 grams and appears pink and wrinkled, with a thin coat of white fur covering the body.
The young open their eyes at three and a half weeks and are weaned at a month and a half. They remain with the mother through the summer until fall, when they leave to establish their own territories.
The maximum lifespan for a mink is usually around 10 years.
Mink are mostly solitary animals, with males being particularly intolerant of one another. They mark the boundaries of their home range using strong-smelling substances from scent glands. They are mostly active at night, especially near dawn and dusk. Mink are also skilled swimmers and climbers. In searching for food, they can swim up to 30 meters (100 feet) underwater and dive to depths of 5 meters. Mink dig their burrows in the banks of rivers, lakes and streams, or they may use the old dens of other mammals, such as muskrats. Mink may line the interior of their home with dried grass and leaves, as well as with the fur from past prey.
Mink communicate using odors, visual signals, and sounds. They are fairly quiet, but rely heavily on odors for communicating territorial boundaries and for finding mates.
Mink have excellent senses of vision, smell, and hearing.
The diet of mink varies with the season. During the summer they eat crayfish and small frogs, along with small mammals such as shrews, rabbits, mice, and muskrats. Fish, ducks and other water fowl provide additional food choices. In the winter, they mostly prey on mammals.
Mink have few natural enemies. They are occasionally killed by coyotes, bobcats and other carnivores, but their main threat remains humans. Mink, like most members of the weasel family, are aggressive and fearless predators. They do not hesitate to defend themselves against animals larger than themselves. Mink may be occasionally taken by birds of prey, or young in a nest may be taken by snakes, but they are agile, secretive in nature, and they blend in with their background, so they can avoid most predators.
Mink are important predators of small mammals throughout their range.
The only negative affects that mink might have is the possible competition between mink and humans for water fowl or other game species.
Mink pelts have for years been considered one of the most luxurious furs on the market. Originally all fur came from wild mink, causing a severe strain on the species. However, starting in the mid 1900s, mink ranches were set up to help bring a more constant pelt supply to the market. Ranching was very successful, with the number of mink ranches in the United States reaching a high of 7200 during the mid-1960s. While the number of ranches has declined nationally to 439 (1998), a total of 2.94 million pelts were still produced (both wild and domestic mink), that were valued at $72.9 million dollars. The quality of a pelt, which affects the price, is determined by its size, color, texture and density.
The biggest threat towards mink survival is the continued existence of the fur market. Forty-seven states and all Canadian provinces now have limited trapping seasons on mink, with the length of the season varying from area to area. Limits on the number of mink that can be caught have also been set in many places. Both of these strategies allow the limited removal of mink in order that wild populations will remain constant.
Another threat includes the destruction of mink habitat. Mink depend heavily on wetlands. Creating, enhancing, and maintaining such habitat allows for the continued existence of healthy populations throughout the range of the species.
The presence of pollution such as mercury and hydrocarbon compounds (e.g., DDT and PCBs) also threatens mink. These chemicals build up within the mink's tissues and can cause problems in reproduction or even threaten the animal's life. Closer regulation over the use and disposal of these chemicals is necessary.
Tanya Dewey (editor), Animal Diversity Web.
Allison Poor (editor), University of Michigan-Ann Arbor.
Kurt Schlimme (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.
July 22, 1999. "National Agricultural Statistics Service: Mink" (On-line). Accessed Oct. 14, 1999 at http://usda.mannlib.cornell.edu/reports/nassr/other/zmi-bb/mink0799.txt.
Chapman, J., G. Feldhamer. 1982. Wild Mammals of North America. Baltimore and London: The Johns Hopkins University Press.
Kurta, A. 1995. Mammals of the Great Lakes Region. Ann Arbor, MI: The University of Michigan Press.
Van Gelder, R. 1982. Mammals of the National Parks. Baltimore, MD: The Johns Hopkins University Press.