Mink Biology

What Is A Mink?

The mink belongs to the order Carnivora, which means it is carniverous – a meat-eater. The order Carnivora also includes other meat-eaters such as lions, tigers, hyenas, coyotes, and wolves.

Within the order Carnivora, the mink belongs to the family Mustelidae, commonly known as the weasel family. This family also includes skunks, otters, fishers, martens and wolverines.

Within the family Mustelidae, however, the two living species of mink are now placed in different genuses. The smaller, extremely rare European mink continues to be called Mustela lutreola, but the American mink, formerly called Mustela vison, is now called Neovison vison. A third species, the sea mink, or Neovison macrodon, was hunted to extinction in the late 19th century.

The common name “mink” comes from the Swedish word “maenk”.


BEHAVIOR: What do mink do all day?

GROSS ANATOMY: What do mink look like?

REPRODUCTION: How and when do mink mate?

DIET: What do mink eat?

HABITAT / DISTRIBUTION: Where are mink found?

LIFESPAN: How long do mink live?

PREDATORS: What other animals eat mink?

OIL: Why is mink oil so good for your skin?

OTHER FURS: How does mink compare to skunk or weasel?

 
GENERAL BEHAVIOR

WILD MINK

Mostly nocturnal, mink remain active year-round. Except when breeding or raising young, males and females select individual home territories which they mark with their scent glands and defend actively. Once a territory is established, most activity is restricted to within in.

Denning sites are often close to water in well-maintained bank burrows abandoned by or stolen from muskrats or beavers. Other choices can include spaces under large exposed tree roots, beaver lodges, muskrat houses and hollowed-out stumps or fallen logs.

Males usually range over far larger areas than females, and often use two or more dens throughout their territory. A male mink may occupy as much as 2.5 miles of stream habitat or about 2,500 acres in wetland habitat. An adult female generally travels less and occupies about one mile of stream habitat or about 40 acres in wetland habitat.

A male increases its movement greatly during the breeding season and defends its territory against other males, although the males’ home ranges sometimes overlap. A male may use several dens within its range and different males may use the same den at different times.

A female defends her territory against other females and may even defend it against males at certain times of the year. She usually has one or two dens and is the only one to use them. Juveniles that have recently left the family group often use several dens until they establish their own home range, which are usually smaller than those of older mink.

While a mink may be active all day long, it is most active from dusk to dawn. It is active year-round although it may remain in its den for a day or two during severe winter weather. A mink usually lives alone except during the breeding season and when young mink live with the family group until they are old enough to claim their own territories. The mink marks its territory and advertises its presence by depositing droppings and leaving its scent in prominent locations such as on flat rocks and logs.

Mink are semi-aquatic and can dive to a depth of 16 feet using their partially webbed feet for propulsion. They are also good climbers.

Startled mink may squeal, hiss or snarl, and release a scent similar to, but far weaker than, skunk, that can be smelled up to 10 feet away. The scent dissipates much faster than skunk, and is far less penetrative. This scent is also used as a marker to advertise their presence to other mink.

MINK AS PETS

Note: In the US, mink cannot be taken from the wild without a permit from the state authorities.

Adult mink are bold, ferocious and virtually untameable, but if they are taken as kits they are playful and can become attached to the person who cares for them.

But they still don’t make good pets. While dogs and cats have been selectively bred for pet-quality traits over thousands of years, domesticated mink are livestock that have been bred for life on a farm.

While some farmers have selectively bred mink for tameness and can handle them without gloves, they still retain their aggressive traits. Mink have very sharp teeth and claws and can inflict nasty injuries on their handlers. They are also carnivorous and so need a high protein diet. Given the chance, mink will eat your pet guinea pigs, rabbits and goldfish.

If ferret-like pets are what interest you, consider a ferret (if ownership is legal in your state). Ferrets have been raised for pet quality for thousands of years. That said, they are still not for everyone. Dogs and cats are infinitely better choices for the average person. But always be cautious with any animal. A thousand Americans a day are treated in emergency rooms for dog bites, mostly children bitten in the face.


GROSS ANATOMY

SIZE

Wild

Wild American mink weigh about 6 gms when born, and are weaned at eight to 10 weeks old, weighing about 350 gms (see Reproduction).

By the time it reaches adulthood, a male is about the size of a small house cat, weighing 680 – 1,300 gm, and measuring about 56 cm in length.

The smaller female weighs 450 – 700 gm, and measures about 54 cm in length.

The tail accounts for about a third of a mink’s total body length.

Lake and marsh-dwelling mink are usually larger than those that live along streams.

Domesticated

Domesticated mink are bred in part for their size, and are normally much larger than their wild cousins. This is partly the result of management and diet, but the main reason for the size of domesticated mink is genetics. To have large mink, you must select for large mink.

At birth, kits weigh about 10 gms and are weaned onto solid food after 24-28 days, weighing about 200 gms. They can more than double their size in the first few days of life, attesting to the nutritious quality of mink milk, and underlining the importance of good nutrition and health for lactating females.

The average weight of a domesticated adult varies by color and sex. Females of all colors range from 1,000 to 2,000 gm, and average about 1,400 gm. Males range from 2,000 to 4,000 gm, and average 2,600 to 2,700 gm.

FUR

A mink’s fur is silky soft and glossy, with the American mink having fuller and thicker fur than its European cousin.

In the wild, mink vary in color from chocolate brown to almost black above, with pale fur underneath. As a general rule, the fur of northern subspecies tends to be darker than that of southern forms. Buff to white patches are common on the midline from the chin to the vent, but these vary in size and shape from one population to the next.

Domesticated mink are selectively bred especially for their fur, resulting in a range of colors from almost black to white, including many shades not found in the wild. For more information about the many colors available for domesticated mink, see True Colors!

A mink’s coat helps keep it dry and also provides insulation against low temperatures. This is achieved by means of two components: guard hairs and underfur hairs.

The guard hairs are long, lustrous outer hairs whose main function is to keep the mink dry. (Marsh animals such as beaver and nutria have especially long and shiny guard hairs.) The guard hairs in a mink are thicker and longer along the center of the back, accounting for a “stripe” effect.

Each guard hair is surrounded by between nine and 24 underfur hairs which range in length from one-third to half the length of the guard hair. The function of the underfur is to retain heat, and the colder the climate a mink inhabits, the denser and woolier its underfur will beOften the underfur is a different color from the guard hair, usually lighter.

Mink molt twice a year. The thick, dark winter coat is shed in April, to be replaced by a much flatter and browner summer coat. Come August or September, the mink molts again, and by late November its winter coat is in its prime.

MOUTH

Mink have 34 teeth, with 4 prominent canine teeth to help in the killing of prey species.

They have the same dental formula as the weasel: I 3/3, C 1/1, Pm 3/3, M 1/2 X 2 = 34.

Photo courtesy of Skulls Unlimited International.

TAIL

The tail of the mink is moderately bushy and accounts for about a third of its body length, or 5 to 9 inches.

Even though a mink is semi-aquatic, it does not have a specialized tail for swimming as do other semi-aquatic mammals such as beaver, muskrats and otters.

EARS

A mink’s ears are round and small, but not as small as they appear. They are actually about an inch long, but are close-set to the head.

NOSE

A mink has a short, pointed nose. It relies heavily upon sense of smell when foraging for terrestrial prey.

EYES

A mink has small eyes, and its eyesight is only fair, so it tends to rely primarily on its sense of smell when hunting.

Its eyes are also not particularly well adapted to underwater vision, and so when fishing it will often locate its prey from above before diving in pursuit.

PAWS

A mink’s legs are short. The soles of the paws are hairy, but the pads are naked. There are five toes on each paw.

A mink’s paw is partially webbed, but not as webbed as those of some other semi-aquatic mammals such as beaver, muskrats and otters. This makes mink both good climbers and swimmers, though not outstanding at either.

SCENT

Mink have highly developed anal scent glands, typical of members of the weasel family.

Mink are generally solitary animals, with males being particularly intolerant of one another. They mark the boundaries of their terriritory using musky secretions from these anal glands.

Mink can also spray with these glands as an act of aggression or self-defense, in the same way as skunks, although the spraying range is far less, and the scent is less repulsive, dissipates faster, and does not penetrate clothing to anything like the same degree.

Because mink on fur farms are bred for docility and are used to being handled by humans, spraying is rare. When it does occur, it is usually during vaccination or some other medical procedure.


REPRODUCTION

WILD MINK

Mating takes place once a year, in February and March, with females remaining in heat for about three weeks.

As the mating season approaches, males leave their territories and travel long distances in search of females. One male may mate with several females and each female may be mated by several males.

How does this promiscuous mating behavior favor the strongest males? Experiments on mink farms indicate that when a female is mated by several males, it is the last mating which produces most of the kits. This suggests that in the wild, the males which father the most kits are the stronger ones which are still mating at the end of the season. Further supporting this notion is the fact that when the mating season comes to an end, the male mink stays with the last female mink it mated with.

Fighting, which is common among rutting males, also favors the stronger animals.

Seven to 30 days may elapse between fertilization and implantation of the egg, with gestation proper lasting 27-33 days. The average total gestation period is about 51 days, but young can be born as early as 40 days.

The offspring, known as “kits”, are born in April or May. Litters range in size from two to 10, but five or six is typical. Newborn kits weigh about 6 gms and wear a short coat of fine, silvery-white hair. When they are about 2 weeks old, this coat is replaced by a dull, fluffy, reddish-brown coat. Kits are also born deaf and blind, gaining their hearing and sight when they are five weeks old.

At eight to 10 weeks old and weighing about 350 gms, kits are weaned and begin to accompany the mother on hunting trips. Even though they are capable of fending for themselves at two months, kits stay with their mother until autumn when they leave to establish their own territories. At five months old, kits are as large as adults, but sexual maturity is not reached until 10 months.

Despite the fact that mink have a fairly short life span in the wild, they are extremely prolific and capable of completely replacing their populations over a three-year span.


DIET

WILD

Mink are carnivorous and take a variety of prey from aquatic and bank-side habitats, hunting mainly at night but also by day.

The European mink is comparatively selective, eating mainly frogs. But American mink are aggressive predators and take a wider range of prey, often attacking animals larger than themselves.

Mostly they eat small mammals such as meadow voles and shrews and they swim and dive underwater to catch fish and crayfish. They are also known to eat birds, eggs, frogs, clams, freshwater mussels, snakes, rats, ground squirrels, salamanders, and a variety of insects. Occasionally, larger males will attack and eat small rabbits or young muskrats, especially during fall when the muskrats are dispersing from their nests and are the most vulnerable to attack. They can catch trout with ease, and have been known to catch a trout up to 1 foot in length. Occasionally, they have been known to catch ducks. They are also known to raid poultry houses.

Their eyesight is not particularly well adapted to underwater vision, and fish are often located from above before the mink dives in pursuit. Mink rely heavily upon sense of smell when foraging for terrestrial prey.

Usually, mink will capture and kill their own food, killing most of the small animals, birds and fish it feeds on by biting them at the base of the skull or the nape of the neck. But the fact that they are attracted to traps by carcasses of birds and other animals suggests that they also feed on carrion.

DOMESTICATED

Mink raised on fur farms are an important means of recycling the waste products from the production of human food. In one year, each animal consumes over a hundred pounds of feed, or more than 20 times its body weight.

Each year Americans alone consume 37 million beef cattle, almost 9 billion chickens, turkeys and other poultry, and over 4 billion pounds of fish and shellfish. Rather than going to waste, these by-products are put to good use, recycled by such businesses as pet food companies, aquariums, zoos, and fur farmers.

Diet will vary depending on the type of livestock agriculture prevalent in a particular region. In Wisconsin, one of America’s leading dairy producers, farmed mink receive a diet based around spent cattle and expired produce such as cheeses. Old chickens and expired eggs are other local food sources ideally suited to mink bearers. A farm located near the ocean, by contrast, will tend to include a lot of fish remains in its diet.

Most fur farmers collect these leftovers themselves, personally visiting chicken farms, packing plants and slaughterhouses around their county. They then mix these ingredients on the farm, carefully measuring the protein, fat and ash content to ensure their animals receive the proper nutrition all year long.

Mink are tricky to raise, with varying nutritional requirements during the growing and reproductive phases of their lives.

Further reading:

Super Duper Recyclers – How Fur Farmers Turn Waste into Beauty. FCUSA commentary, October 1999.


HABITAT AND RANGE

HABITAT

Mink are semi-aquatic animals and the best places to see them are in wetland environments such as large marshlands or along lakeshores, rivers and streams. They rely on the presence of waterways as travelpaths and major sources of food and shelter. They are excellent swimmers and divers and can stay under water for some time.

One way to find mink is to look for muskrat huts and burrows. If they are abandoned, mink will simply move in, but they may also take over occupied huts, killing and eating the occupants. Mink will also make dens in natural cavities in stream banks, under trees and in drift piles, lining them with grass, leaves, fur or feathers.

Mink are wanderers, especially the male. He sometimes will be gone for two weeks at a time. The female usually stays close by its den, and as a rule, will stay by for years unless food drives it to a new location.

The number of mink in an area usually depends on the amount and quality of available habitat, but there is usually about one mink for each 50 acres of wetland habitat and three or four mink for each mile of good stream habitat.

RANGE

Mink originally evolved in North America. The European species is a late migrant to Eurasia across the Bering Land Bridge during the last glacial phase of the Pleistocene. The two species have only been geographically isolated for some 10,000 years and are, in consequence, very similar in appearance, although there are skeletal differences, and American mink grow to a greater size (as do males of each species).

AMERICAN MINK

The American mink, Neovison vison, is native to North America, where they are found right across Canada south of the tree line, through all of the United States except for the southwestern deserts.

Though inconspicuous, they are far from rare, with healthy habitats often supporting eight or more per square kilometer.

For the purpose of fur farming, they have been introduced to many parts of Europe, including Iceland, north-central Europe, the British Isles, Norway, Belarussia, the Baltic States, Spain and Siberia. As a result of escapes from fur farms and their intentional release in Russia in the 1930s and ’40s in order to establish a superior source of “free range” fur, the American mink is now naturalized in many parts of Europe and has in places supplanted the native species.

(Reference: The Smithsonian Book of North American Mammals, by Don Wilson and Sue Ruff, 1999.)

EUROPEAN MINK

The European mink is the most endangered carnivore in Europe. It once inhabited a vast territory from the Ural mountains to eastern Spain and from central Finland to the Black Sea. Since the beginning of this century its range has decreased drastically. At present, isolated populations can be found in only one-fifth of its former range.

The European mink is included in Appendix II of the Convention on the Conservation of European Wildlife and Habitat as a species which needs strict protection. In the IUCN Action Plan For Conservation of Mustelids and Viverrids, it is considered a high priority for species conservation. The European mink is also in the Red Data Book.

Experts are not sure of the reason for the decline of the European mink, but the most likely factors are competition from the introduction of American mink, a reduction in suitable habitat due to human activity, and over-hunting.

The European Mink Conservation & Breeding Committee (EMCC), based at the Tallinn Zoo in Estonia, provides the following country-by-country breakdown of the European mink’s current status:

Austria: Last record is from the 19th century.
Bulgaria: Last record is from 1951.
Byelorus: Common until the 1940s. At present there is a small population of 150-200 in the northeast of the country.
Czechoslovakia: Last records are from the early 1950s.
Estonia: A small population inhabits the northern part of the country.
France: Present in an area of western France extending from Normandy to the Spanish border. Status is unclear.
Georgia: Formerly the species inhabited the riverbanks by the Black Sea. Now most likely extinct.
Germany: Vanished in the mid-19th century.
Great Britain: Fossil records from 500,000 – 400,000 B. C.
Hungary: Last record is from 1952.
Latvia: No precise information. Most likely extinct.
Lithuania: Started to decrease in the 1940s. Last record is from 1979.
Moldova: In the 1930s, population began declining very rapidly. Now extremely rare.
Netherlands: Fossil records from 2300 – 2100 B. C.
Poland: Started to decline at the beginning of the 20th century. Last specimens were recorded in 1925-26.
Romania: Unconfirmed reports suggest that a population still survives in the Danube delta.
Russia: There are populations in the Volga, Dnepr and West-Dvina river basins. The population with the highest density lives in the Tver Region.
Spain: Population is concentrated in a small area in the north of the country.
Switzerland: Only known record is from the mid-19th century.
Ukraine: By the 1980s, only small isolated populations survived in the upper courses of rivers. May now be extinct.
Yugoslavia: Only known record is from 1914.

For more information about the conservation status of the European mink, visit the Tallinn Zoo, or contact the EMCC, Tallinn Zoo, Paldiski Road 145, Tallinn EE-0035, Estonia; Tel: 372-2-599855; Fax: 372-6-393049.


LIFESPAN

WILD

Estimates of the average lifespan of a wild mink vary, from less than a year to less than three years, but these figures reflect the large number that fall prey to disease, starvation and predators while they are young and poorly equipped to fend for themselves. The vast majority of wild mink do not live through their first six months.

Those that reach adulthood and find abundant sources of food may live to the age of four, and a small percentage of these successfully reproduce. Dental evidence suggests that occasionally they may live as long as seven years.

DOMESTICATED

Due to the farmer’s care of the mink raised on his farm, almost 100% of the mink born annually will survive their early months of life. Out of these, the finest are retained for breeding stock for the following year while the rest of the mink will be harvested for pelts for use in cold weather clothing, fine oil and other products at about 7 to 8 months.


PREDATORS

The principal predators of wild mink are foxes, wolves, coyotes, bobcats and great horned owls.

Many also die from fighting with other mink.


OIL

Mink have a thick fatty layer just below the skin. This fatty layer is recovered after the pelt is removed from the carcass and is then rendered down to make mink oil.

An industrial grade is used for waterproofing and conditioning leathers.

Fine, triple-refined cosmetic grade mink oil is prized for use on the face and body. Studies suggest it is the closest known oil to human skin oil, and contains approximately 17% palmitoleic acid, an essential Omega 7 fatty acid also produced in the human body.

Palmitoleic acid is used by the body to moisturize and lubricate the skin. In individuals with dry skin, an external source of palmitoleic acid can be beneficial. Mink oil is rapidly absorbed through the pores (not the epidermis) but does not clog pores as it lubricates. It enables the skin to re-moisturize itself by trapping moisture from the lower cell layers.

The supreme softness, smoothness and moisture-retaining properties imparted to skin are believed to be due to the special ratio of glycerides contained in mink oil. Many users rave that it helps prevent fine lines and wrinkles, works wonders in hair products, and that it also works as a soothing treatment for sunburn.

We’d like to hear from you on your experiences with mink oil. Please contact Fur Commission USA.

Further information.


FURTHER READING

Missouri Conservation Commission Missouri mammals; Mink; Mustela vison
National Trappers Association
 The Mink, Mustela vison
Mink Mating & Young by Nina K. and Joanne M. created for the Museums in the Classroom program sponsored by Illinois State Board of Education, Brookfield Zoo, Illinois State Museum, and Kildeer Countryside CCSD 96.


For further information contact Fur Commission USA.

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