Common Names: mink
Species: Mustela vison
General Description: The North American Mink is characterized by a long, sleek body and short legs; a structure that is highly comparable to its close relative, the weasel. Its head is small (not much larger in diameter than its thin, long neck) with a pointed nose and muzzle and short whiskers that are only minutely visible. It has small beady eyes, as well as short ears that are barely longer than the fur that surrounds them. A mink’s fur, which is highly valuable and sought after, can have great colour variation depending on the area it is found in. For the most part, the wild strain has a chocolate to almost black pelage that is short, thick and, soft, with black areas around the feet and tail tip and a white patch on the underside of the chin. The fur also contains long, black, oily guard hairs that prutrude from the soft undercoat. Some members of the species may have more irregular white patches on the throat, chest, and stomach area or there are even cases of “cotton” pelts that consist of a light coloured underfur. As a courtship aid, and less often a mode of defense, the mink has anal glands just below the surface of the skin in the rectal area which can spray a noticeably unpleasent musk, similar to that of a skunk. Indications that a mink has been in the area are more prominent in the winter and may include such signs as holes in the snow from plunging after prey or even troughs like that of an otter slide.
The size of the mink is around that of a small house cat with males (body length of 491-620mm) being slightly larger than their female counterparts (body length between 420-597mm). The mink also has a long, bushy tail which constitutes about 1/3 of the total body length (158-210mm in males and 128-180mm in females). The weight range of this species is between 1.68 and 2.31kg in males and 0.79-1.20kg in females.
The dentition pattern found in mink is like that of many other carnivorous animals with 34 teeth, including 4 prominent canines ideal for catching and killing prey. Worn teeth are often used as a sign of old age and mink are usually considered old after the age of seven. The life span of this animal however, ranges up to as much as ten years of age.
Geographical Distribution and Habitat Requirements: The North Amercian mink has quite a large distribution, inhabiting almost any temporal region available. It is located throughout New Brunswick, as well as the majority of the North American continent. There are six subspecies of Mustela vison known in Canada including; M.v.energumenos, M.v.evagor, M.v.ingens, M.v.lacustris, M.v.lowii, and M.v.vison which is the common inhabitant of New Brunswick. Below is a map of the vast distribution of the mink throughout North America.
The mink is found in regions containing any water source (even lakes and large rivers) but prefers small streams, ponds, and marshes. The marshland inhabitants are ,for the most part, larger in size than mink found in other areas. All mink species tend to stick within a days distance of water. It is an excellent swimmer, utilizing all four of its partially webbed feet, and is also a quick land predator and tree climber. In general, it tends to move to areas that harbor the greatest concentration of prey for increased ease in hunting. They may hunt more on land or in water depending on the area and time of year. Males tend to have a larger home range than females do, often covering several miles in a single day while occupying multiple dens. Females usually stick to a range within 100 yards up or down river of their den (they do not often acquire more than one living place).
General Biology: Mustela vison feeds on quite a large variety of preys including fish, frogs, crayfish, snakes, birds, rabbits, mice, muskrats and other rodents. It will also eat insects and carrion if readily available but not in excess and may even invade a nearby poultry house. The quantity of each prey type eaten depends mainly on season and densities. Mink have fairly poor vision and rely more on their sense of smell when hunting. Males tend to prey upon larger animals than females do and may take on animals larger than themsleves. The mink does have the ability to stalk its prey by slinking along the ground but is most often found to be an opportunistic hunter, scaring its prey first and then chasing it down. This species often acquires more food from a single kill than it can eat in one sitting. As a result, it has been known to drag its prey back to its den for later feeding.
The mink is a mainly nocturnal animal, an adaption learned mainly in practicing avoidance from humans and other predators. Mustela vison’s main predators are larger carnivorous mammals including foxes, bobcats, great-horned owls, coyotes, dogs, wolves, hawks, lynx, and even river otters. It usually lives in a burrow about 3 meters deep and only about 10 cm in width. The den is usually located within 200 meters of water and may be found under the roots of trees or beneath dead logs. It doesn’t normally dig its own den but rather seeks out an abandoned muskrat or beaver hole, digging new entrances if necessary. Although the mink does not hibernate, the den becomes a frequent shelter from the cold during the harsh winter months when it may actually sleep for several days at a time.
Mink are polygamous animals. Males, who are sexually viable as early as 10-12 months of age, will mate with a number of females during the breeding season which lasts from February to March, and tend not to form any lasting bonds. Females may also take more than one partner in a single breeding season. The gestation period for this species is usually around 50 days but due to delayed implantation, can be as short as 40 days or as long as 70. Delayed implantation is a phenomenon common to the weasel family where the egg lays dormant for a variable period of time (7 to 30 days) after fertilization and before initiation of development, which itself only takes 27-33 days. The young (often referred to as kits) are born somewhere around the first of May with anywhere from 1-10 in a single litter (four being the average). Newborns are blind and covered with fine white hair. After a couple of weeks they develop a fine coat of red hair and are weened at 5-6 weeks of age. By late summer they are experienced hunters and ready to leave the den.
Conservation: The North American species of mink is not listed as endagered by the IUCN, despite consistent interest in its valuable fur. The mink is a native species to New Brunswick and to most of the country except for Newfoundland, where it has been introduced. Although the mink is not endangered, it is still protected from over hunting with a declared hunting season of only two months during a time when it is insured that no babies or mothers are taken. There are also some habitat protection programs being installed in some areas in North America to aid in maintaining mink populations including wetland protection and restoration, managed grazing, conservation tillage, and filter strips and grass waterways. For more information on these techniques visit the Illinois Department of Natural Resources and view the section on conservation of Mustela vison.
Mink are also raised in large numbers on farms in order to support the high demand for their fur. This practice is quite controversial and has stirred up angry animal rights activists from all over. This domestic mink tends to be larger in size and has a greater variety in coat colour than its wild counterpart. In fact, it has become so different in some ways from its wild relative that it is often given the species name Mustela vison f. dom.