The taxonomic classification of the American mink is: phylum (Chordata), class (Mammalia), order (Carnivora), family (Mustelidae), genus (Mustela), and species (vison). Other members of the Mustela genus include the weasel (Mustela nivalis), ferret (Mustela putorius), and European mink (Mustela lutreola).
Mink have been raised in captivity since 1866, and the accumulation of pertinent biological information has been encouraged by the economic importance of mink to the global fur industry, which is valued at greater than $11 billion USD. A vast body of information exists on the natural and life history of mink, including an extensive encyclopedia compiled by Sundqvist (1989) that contains almost 7,000 references. The monograph by Lariviere (1999) is also very thorough.
The mink is one of the most widespread carnivores in North America and is generally found throughout forested regions across the continent (except for the high Arctic and arid regions of the southern United States), especially those containing wetlands. Mink have also been introduced throughout Europe to support local fur industries because they can readily adapt to new habitats. Mink exist in South America, but their distribution there is unknown. Their occurrence across wide geographical areas ensures their presence in both polluted and non-polluted regions, thus permitting eco-epidemiological studies. A 2007 review paper by Basu and colleagues highlighted the importance of mink as a sentinel organism in environmental health. There are no reliable estimates of mink population numbers and most predictions are based on the analysis of fur harvest records. It has been estimated that approximately 10,000,000 mink inhabit North America, and given that 400,000 to 700,000 mink are trapped annually.
Mink are solitary, yet active mammals. Their linear home range is between one and five kilometers, and population densities range between 0.1 and 0.7 animals per square kilometer. Adults and males tend to have larger home ranges than juveniles and females, respectively. Their home ranges are variable and can be influenced by multiple factors, such as habitat quality, food supply, and season.
Growth and Reproduction
Mink are monoestrous and usually mate between February and April. The gestation period varies from 40 to 75 days because mink, similar to rabbits and cats, are induced ovulators and the developing blastocytes remain in the uterus for many days before implantation. Offspring are produced in late April or early May, and the average litter size is four kits. Kits are weaned at six to eight weeks of age, and both males and females reach sexual maturity during their first year. Males are generally larger than females in size (10%) and mass (50%). Life span is approximately three years in the wild, but in captivity mink can live up to eight years. This longevity ensures they can bioaccumulate pollutants to appreciable levels.
Feed and Ingestion
Mink are monogastric animals with a digestive tract more similar to that of humans than that of rodents as there is no cecum at the junction of the small and large intestine. Daily requirements are 140 to 200 grams per kilogram of body weight per day (g/kg b.w./d) of feed and 75 to 100 milliliters (mL) of water per day, and their nutritional requirements have been reviewed by the U.S. National Research Council’s Subcommittee on Furbearer Nutrition and others. Optimal diets consist of 18 - 30% fat, 25 - 40% protein, 20 - 50% carbohydrates, and 6 – 12% ash. Females need slightly more energy than males during the growth period (i.e., weaning to maturity), but this dimorphic difference does not exist in mature animals as both genders require approximately 140 kilocalories of metabolic energy per kilogram of body weight per day (kcal metabolic energy/kg b.w./d). It should be noted that mink require more energy, on a daily per kg basis, than humans.
Studies on the feeding habits of mink are based on the analyses of gastrointestinal tracts from trapped animals. In the wild, mink are opportunistic predators that consume a range of prey items available in their local habitat, including small mammals, frogs, snakes, and birds. As mink typically forage in close proximity to aquatic habitats, fish account for approximately 50% of their diet and represent the primary route by which persistent chemicals, such as mercury (Hg) and PCBs, are accumulated.
- Basu, N., Scheuhammer, A.M., Bursian, S.J., Elliott, J., Rouvinen-Watt, K., Chan, H.M. 2007. Mink as a sentinel species in environmental health. Environmental Research. 103: 130-144.
- Lariviere, S. 1999. Mustela vison. Mammalian Species. 608: 1-9.
- Sundqvist, C. 1989. Mink Encyclopedia. Release 1.0. Department of Biology, Abo Akademi, Porthansgatam 3, Turk, Finland