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Long-tailed Weasel

Scientific Name: Mustela frenata


Easily distinguished as a member of the weasel family by the long, thin, tube-like body, short legs and a long tail, the long-tailed weasel is the largest of our native weasels whose fur color is dictated by the season. Snow white with a black tipped tail by mid-November, the molt begins with a gradual replacement of summer coat beginning on the belly that progresses over the back, taking about a month to complete. Between mid-February and mid-march, depending on regional duration of winter conditions, their fur changes back to dark brown on their back with a lighter color on the belly. They maintain the black tail tip year-round, an important feature to pay attention to, as the least weasel can be identified by not having that black tail tip.

This species of weasel is similar in size to a young gray squirrel. Males are considerably larger than females, and may weigh over a half of a pound, while females are noticeably smaller, tipping the scales at just over a quarter of a pound. Total length for males and females ranges from about 13.5-17 and 11-17 inches, respectively. Tail length proportions are similar and range from about 4-6 inches for males and 3-5 for females.

The long-tailed weasel is of economic importance, as many are taken by trappers each year.


Long-tailed weasels can be considered a habitat generalist, using open woodlands, brushlands and hedgerows with a high prey density and ample cover. Such habitat characteristics can be found in lands that have been recently cut over where increased sunlight provides for seed-bearing grasses and herbaceous plants which would in turn attract a diversity of small mammals using the newly accumulated slash on the forest floor. It is also theorized that a high diversity in prey species contributes to overall habitat suitability for this species.

Food and Feeding

Notably voracious, long-tailed weasels are reported to consume up to 1/3 of their body weight every day. They will hunt night and day for a wide variety of small mammals, and being a generalist affords the opportunity to make shifts in prey consumption based on availability. Tracks in the snow may lead followers to assume that their movements and motive are erratic and without purpose, but they are highly observant and with their keen senses of hearing and smell, investigate every possible rodent hole, hollow tree or rock crevice in which a meal might be found. This species of weasel will forage above and below ground, and has been reported to pursue prey into the canopy.

In New York State, rodents such as white-footed and deer mice along with meadow voles may make up the majority of prey consumed, but they have been documented to consume cottontail rabbits, chipmunks and squirrels, bats and a variety of birds and bird eggs as well. Their efficiency in foraging often lands the long-tailed weasel in trouble, as they have been known to raid some farmer's hen houses, leading to the unfortunate reputation of being an agricultural pest; however, their ability to control rodent populations in barnyards and crop fields likely outweighs the occasional loss of a chicken.


Long-tailed weasels breed in July and August and following mating, females undergo a period of delayed implantation which will last between 200-250 days; however, the majority of fetal development occurs within the last 27 days or so of the cycle. Litters of 4-5 kits are born in the den the following April or May. They are helpless at birth and being blind and naked they rely upon their parents for warmth and nutrition. Most parental care is provided by the female, but the males have been known to retrieve some food for the developing kits. Weaning occurs at about 35 days, as they develop pelage, their eyes open and are they beginning to eat meat. Females are reproductively mature and may breed in their first summer, while males generally do not breed until their second year.


Active year-round, day or night, long-tailed weasels are seldom inhibited from leaving their den. They lead a solitary life outside of the breeding season. As they have considerably large home ranges of 75 to 100 acres, long-tailed weasels may have multiple den sites for daily activities such as seeking cover, foraging, or mating. Once foraging opportunities dwindle or the pursued female leaves the area, the den may be abandoned.

Predators, Parasites and Disease

There is a considerable variety of external parasites that make their homes in the fur of the long-tailed weasel. Multiple species of fleas, ticks and chiggers can be found and the species encountered will vary with geographic location. Predators of long-tailed weasels are primarily red and gray fox and raptors such as the great-horned and barred owls, along with goshawks. Other predators include the suite of New York State carnivores such as coyotes, bobcat and domestic cats and dogs.