Mink

Quick Take

• This small, unassuming animal can take down prey nearly its own size, and even large predators think twice before approaching it. See prey and predators →
• Captive minks can grow to a startling size compared to wild ones, and the reason why reveals something unexpected about selective breeding. Captive mink size facts →
• One species of mink is thriving across an entire continent, while its close relative is racing toward extinction, and the two are connected in a surprising way. American vs. European mink →
• The mink played an unexpected role in the Covid-19 pandemic that prompted an entire country to take drastic, controversial action. Minks and Covid-19 →

The mink is a proficient swimmer, a territorial neighbor, and a surprisingly tenacious predator. This animal may not look like much of a fighter, but the mink can take down prey that’s almost as large as itself. Even large predators must be careful about how to approach this rather tetchy animal. Because it spends a great deal of time in the water, the mink has a water-repellent coat laced with oil. Its fur is considered to be such high quality that the mink has remained a vital part of the fur trade for centuries. It is still raised in captivity all over the world.

4 Mink Facts

• In captivity, the American mink is bred in early spring and then killed at six to eight months of age, right as the fur reaches its maximum quality. Captive minks can reach up to twice the size of wild ones due to better nutrition and selective breeding. They also have a wider range of fur colors, including pearl, blue, and sapphire.
• Minks are known to be susceptible to SARS-CoV-2, the virus that causes Covid-19. Denmark ordered that its captive minks be culled after it was discovered that a new strain of the virus was infecting the species, and possibly spreading to a few people, but the effectiveness of this action was controversial.
• Much like the closely related ferret, some people keep the mink as a pet, but because of its wild instincts and very specific needs, it is an immense challenge to keep around the home.
• Since this creature appears to suffer psychologically from close captivity, animal rights activists have protested on the animal’s behalf for better living arrangements.

Evolution

Between about 28 and 30 million years ago, during the Oligocene era, the first mustelid roamed Oregon, North America. Known as Corumictis wolsani, it was similar in size to the smallest member of the Mustela genus, the least weasel.

During the Miocene era, about 16 million years ago, the family Mustelidae emerged. As members of this family, minks belong to the family Mustelidae, with the European mink in the Mustela genus alongside ferrets, polecats, and weasels, while the American mink is classified under the Neogale genus.

Classification and Scientific Name

There are currently two recognized species alive in the world today. Mustela lutreola, or the European mink, is actually part of the same genus as the weasel, while Neogale vison (formerly Neovison vison or Mustela vison), or the American mink, is the only living member of its genus. Both species were once classified within the genus Mustela, but taxonomists believed that the American mink exhibited enough differences to warrant a separate genus classification. There used to be two members of the genus Neogale, but the sea mink, or Neogale macrodon, was driven to extinction in the late 19th century.

Both species belong to the family Mustelidae along with the badgers, wolverines, and otters. In fact, this creature is often mistaken for an otter because they share a very similar semi-aquatic habitat and lifestyle.

Appearance

The mink looks very similar to the closely related weasel or marten. It has a long, lithe body, a pointed nose, rounded ears, short legs, and webbed feet. The thick, water-repellent oiled coat of fur is dark brown or black in color (though albino and tan mutations do occur in the wild). Most members of the European species have white markings on the chin and lips with additional white spots on the throat, stomach, and chest, whereas only some members of the American species exhibit the same markings. If the specimen lacks white markings entirely, it is almost certainly an American mink. The outer layer of the coat, which consists of guard hairs, is three times as dense as the fur of the closely related ferret. Each guard hair is surrounded by numerous smaller hairs as well.

The American mink is generally the larger of the two species. It weighs 1.25 to 4.5 pounds and reaches 12 to 21.5 inches long (with half of that just being the tail). The European mink, on the other hand, weighs 1 to 1.6 pounds and measures 12 to 15 inches long. Both species are significantly smaller than the otter but about the same size as a ferret. Females tend to be smaller than males on average.

Behavior

The mink’s entire lifestyle revolves around the ability to switch between terrestrial and aquatic motion at any time. With its incredible webbed feet, the mink is a fast and agile animal in the water. It can dive to depths of 16 feet and swim underwater for over 100 feet, but almost never ventures far from land. Unlike the closely related otter, the mink swims high on the surface and creates a V-shaped wave with its nose. When it isn’t in the water, the mink walks on the ground with a hopping or bounding motion. It can also climb trees to chase prey or escape danger.

The mink is a nocturnal species. It is highly active during the nighttime hours as it searches for prey. It also tends to spend the rest of the night awake in some capacity. Except for the relationship between the mother and her kits, the mink is an animal with no social organization to speak of. Instead, it lives and hunts almost entirely on its own and only tolerates the presence of other minks in the breeding season.

The mink is very aggressive toward other members of the species who trespass on its territory. Males are especially vicious toward other males who have nothing to offer them except for additional competition. Males are usually much more tolerant toward females. In fact, male and female territories sometimes overlap with each other.

The mink’s sense of vision and hearing are both highly developed, but the main means of communication is scent. The enlarged anal gland produces a rather pungent scent used to mark territory and warn off potential interlopers. Minks rarely make sounds except to express their agitation or displeasure.

Habitat

The mink is split geographically between North America and Europe. The American mink has an extensive range across almost all of Canada and the United States except for the extreme Arctic regions and the hot Southwest. The European mink once occupied a massive range across almost all of Europe, but due to decades of population loss, it is now only found in small pockets across its former territory. It is almost completely gone from Western and Central Europe.

Minks are well-adapted to lakes, ponds, rivers, and streams with extensive tree cover. Their homes consist of hollow logs or underground dens lined with grass, leaves, or the fur of their prey. The mink often keeps multiple dens around its large territory.

Diet and Predators

This creature is a very agile hunter, sometimes capable of killing animals larger than itself, but it is not an apex predator. Several other carnivores reside above it on the food chain.

What does the mink eat?

These animals will hunt almost any small- to medium-sized prey that lurks around freshwater shores: mice, rabbits, muskrats, fish, frogs, snakes, crayfish, and even waterfowl. Sometimes they supplement their diet with little bits of plant matter as well. Their main hunting strategy is to get behind their prey and deliver a swift bite to the neck. If the animal is simply too large to consume in one meal, then the mink will store the leftover meat in its den for safekeeping.

What eats the mink?

Minks make a tempting meal for all kinds of large predators such as coyotes, bobcats, wolves, foxes, and horned owls. Despite their ferocity, many will eventually fall victim to predators before they can die of natural causes.

Reproduction and Life Cycle

This is a promiscuous animal that likes to hook up with multiple mating partners throughout the breeding season (which typically occurs in February and March). The scent of the anal gland is believed to play an integral role in the process of attracting and securing a mate. After the pair copulates, the female has the ability to delay implantation for up to two weeks, resulting in longer birth cycles than would otherwise be expected. Both the American mink and European mink have similar gestation periods (40 to 75 days and an average of approximately 43.8 days, respectively).

At the end of the gestation period, the female produces a small litter of one to eight kits. Since the kits are completely dependent and vulnerable (it takes several weeks before they will open their eyes), the mother must provide for their care without any assistance from the father. The kits are weaned off their mother’s milk at six to 10 weeks of age and begin consuming meat. Both species reach sexual maturity at 10 to 12 months, but it takes the American mink slightly longer than its European counterpart to achieve full independence. Both species live for around 10 years in the wild.

Population

The American mink is classified as a species of least concern: the healthiest possible classification. The European mink, on the other hand, is now critically endangered. Several explanations have been offered to explain the sudden population decline, including habitat loss, overhunting, decline of prey animals, and competition with the similar American mink, which escapes from farms and invades local habitats. the American mink is more aggressive and adaptable than its European counterpart, and so it often ends up displacing it from the ecosystem.

All efforts to save the European mink from extinction may require conservationists to reduce the number of American minks that occupy the same territory. Unfortunately, the American mink is quite intelligent and resourceful and has so far resisted many efforts to trap it. Another problem is that, without an understanding of how to survive in the wild, many of the European minks raised in breeding programs and later released have often ended up dead.

As conservationists learn from these experiences and develop better strategies, they hope to reintroduce the European mink into its former territory by establishing small founding populations throughout Europe. Frozen semen is sometimes used to improve genetic diversity.