Animal Field Guide

Mink

Mustela vison
(Mustelidae)

Global Rank: G5
State Rank: S5

Agency Status
USFWS:
USFS: none
BLM: none

This medium-sized, semi-aquatic carnivore has a long, thin body; short, sturdy legs; short, pointed nose; short, rounded ears, and a dorsoventrally flattened head. Thickly furred tail. Usually rich dark brown in color with a white chin patch. Sometimes white spots on belly. Fur is soft and lustrous with long, glossy guard hairs. Dense pelage is its only obvious aquatic adaptation. Total length: 19 to 28 inches. Weight: 1.5 to two pounds (FWP). A medium-sized mammal with an elongate body, a long tail, small rounded ears, and relatively short legs; pelage is soft, luxurious, and generally rich brown to almost black dorsally; the underparts are paler, sometimes with a whitish chin patch and whitish spotting elsewhere; 5 digits on each foot; head-body 330-430 mm in males, 300-400 mm in females; tail 158-230 mm in males, 128-200 mm in females; mass 681-2310 g in males, 790-1089 g in females; basilar length of skull 58-69 mm (Nowak 1991, Hall 1981, Burt and Grossenheider 1964).

Weasel - has white or yellow under-parts. martin - has buffy patch on throat and breast. river otter - much larger (fwp). differs from weasels in having brown rather than white or yellowish underparts. differs from marten in having a white chin patch (marten has pale buff patch on throat and breast), generally darker pelage (marten's pelage generally is yellowish brown except on the feet and end of the tail), and 4 rather than 5 upper postcanine teeth. differs from the fisher in having 4 rather than 5 upper postcanine teeth, a white chin patch, and smaller size. river otter is much larger (up to 130 cm total length and 11 kg).

Raised and trapped for pelt, which yielded about $17 per pelt in the early 1980s in Oklahoma (Caire et al. 1989).

Non-migratory. Males make extensive movements and juveniles disperse.

Usually found along streams and lakes. Commonly occurs in marshes and beaver ponds. Permanence of water and dependable source of food are most important habitat components. Often uses den sites of other animals and is commonly found in association with muskrats. Semi-aquatic forager. Can kill prey larger than itself. Chiefly nocturnal, territorial, and secretive. Dens underneath piles of brush or driftwood, under rocks, in hollow logs, and in houses or dens abandoned by beavers or muskrats. Very aggressive mating behavior (FWP). Wetland habitats--riverine, palustrine, lacustrine.

Preys primarily on small mammals, birds, eggs, frogs, and fish. Its diet is almost entirely animal. During summer preys on waterfowl (FWP). Aquatic and terrestrial prey. Order of importance varies. Lacustrine: fish, mammals, invertebrates, birds, herp's. Palustrine: birds, invert's, mammals, herp's. Oppor- tunistic.

Almost complete population turnover within 3 years. Diameter of movements for males usually not greater than 3 miles. Two adjacent females had home ranges of 19.3 and 50.4 acres.

Mates from January through March; 40- to 79-day gestation; delayed implantation; young born during April or May; averages four or five per litter (FWP). Apparently breed in March, perhaps earlier. Average 4 young/ litter. Born in April or May. By 8 weeks of age, the young may accompany female on hunting trips.