Mink

Geographic Range

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.

Mink have also been inadvertently 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.

Habitat

Although mink are found throughout North America, they tend to frequent forested areas that are in close proximity to water. Streams, ponds, and lakes, with some sort of brushy or rocky cover nearby are considered optimal territory.

These animals are found in the following types of habitat:  savanna or grassland, forest, lakes and ponds; rivers and streams, coastal, marsh.

Physical Description
Mass
700 to 1600 g
(24.64 to 56.32 oz)

Length
460 to 700 mm
(18.11 to 27.56 in)

Mink fur is usually dark brown with white patches on the chin, chest, and throat areas. The fur is soft and thick, with oily guard 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 substantially 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 580-700 mm and females from 460-575 mm.
 

Reproduction

Breeding interval: Breeding occurs once yearly.

Breeding season: Mating occurs during the winter months.

Number of offspring: 1 to 8

Gestation period: 40 to 75 days

Time to weaning: 6 weeks (average)

Time to independence: 6 to 10 months

Age at sexual or reproductive maturity: 10 months (average)

During the winter, female mink become fertile and mate with one or more males (who are also promiscuous).

Once a female is impregnated, her gestation 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 8-10 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. Both males and females begin mating at ten months.

Females nurse and care for their young until they reach independence.

The maximum lifespan for a mink is usually around 10 years.

Behavior

Mink are primarily solitary animals, with males being particularly intolerant of one another. They mark the boundaries of their home range using musky secretions from enlarged anal 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 utilize 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. 
Communication and Perception

Mink communicate using a variety of cues, including chemical, visual, and auditory signals. They are fairly quiet, but rely heavily on chemical signaling for communicating territorial boundaries and reproductive status.

Mink have excellent senses of vision, smell, and hearing.

Food Habits

The diet of mink varies with the season. During the summer it consists of crayfish and small frogs, along with small mammals such as shrews, rabbits, mice, and muskrats. Fish, duck and other water fowl provide additional food choices. In the winter, they primarily prey on mammals.

Primary Diet: carnivore (eats terrestrial vertebrates).

Animal Foods: birds; mammals; amphibians; reptiles; fish; aquatic crustaceans.
Predation

Mink have few natural enemies. They are occasionally killed by coyotes, bobcats and other carnivores, but their main threat remains humans. Mink, like most mustelids, 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, cryptic in coloration, and secretive in nature, thereby avoiding most predation.