Mustela frenata
Lichtenstein, 1831

mus-tel-e fri-not-e

Photo by Kevin Klag
An adult Long-tailed Weasel.

Like other weasels, the Long-tailed Weasel has a long, slender body, short legs, a long neck, and a flattened, triangular head. The fur is short and soft. During summer, the pelage is a rich brown color above and pale yellow or whitish below. The tail is brown tipped with black. To the north of Kansas, Long-tailed Weasels molt into white pelage for winter. In Kansas, winter pelage in most specimens resembles summer pelage except the fur is longer and more dense. However, an occasional weasel in northern Kansas has a winter pelage that is pure white or mottled white and brown.

Measurements of adult males, followed by measurements of adult females are as follows: total length 347-463 mm, 329-390 mm; length of tail 114-172 mm, 98-147 mm; length of hind foot 36-51 mm, 32-39 mm; length of ear 13-25 mm, 16-24 mm; weight 226-401 g, 130-178 g. 

The dental formula is incisors 3/3, canines 1/1, premolars 3/3, molars 1/2. 

Other weasel species in Kansas are the Least Weasel and the Black-footed Ferret. These species are similar in that males are much larger than females. Thus, male Least Weasels are nearly the size of female Long-tailed Weasels, and male Long-tailed Weasels are nearly the size of female Black-footed Ferrets. The Long-tailed Weasel can be distinguished from the Least Weasel by its larger body, longer tail, and black tip on the tail. The Long-tailed Weasel lacks the black feet and paler ventral coloration of the Black-footed Ferret. Additionally, the Long-tailed Weasel usually lacks the black mask that is characteristic of the Black-footed Ferret. However, populations of Long-tailed Weasel in southwestern Kansas and adjacent Oklahoma frequently have dark facial masks highlighted by patches of white. These sometimes are referred to as "bridled weasels."

The Long-tailed Weasel has the largest distribution of any weasel in the western hemisphere, ranging from southern Canada southward into South America. Although seldom seen, the species evidently occurs throughout Kansas. They occur in all life zones except desert, and they theoretically can be found in almost all natural habitats in Kansas, especially near water. 

The fossil record suggests that Mustela frenata evolved in the late Pliocene. It has been reported from more than 30 Pleistocene and Recent fossil sites all across the United States and adjacent Mexico. 

(, Museum Voucher) (, Observation) (, Literature Record)
Open icons are questionable records; Click on a marker to view details.
  • Occurrence Summary:  
  • 177 Total Records 
  • 173 Museum Vouchers 
  • 4 Other Observations 
Some county occurrences indicated below may be too imprecise to map above.
County Breakdown: County Name (# occurrences):
Anderson (1); Atchison (2); Barton (1); Brown (1); Cheyenne (3); Decatur (2); Doniphan (1); Douglas (96); Edwards (1); Ellis (4); Finney (2); Franklin (2); Geary (1); Graham (1); Greenwood (6); Hamilton (1); Jefferson (3); Kearney (1); Logan (1); Ness (1); Norton (1); Osage (3); Phillips (2); Pratt (1); Rawlins (7); Reno (1); Riley (2); Seward (4); Sheridan (1); Sherman (2); Stanton (1); Stevens (1); Thomas (5); Trego (5); Unknown (9); Wallace (1);

Natural History:
Long-tailed Weasels are active both day and night. Their dens often are refurbished from the dens of prey. They tend to be solitary except during the breeding season and when rearing young. The fact that they are strongly territorial limits their population size in any one area. Even so, they are regarded as rare or uncommon throughout much of their range, but this might be an artifact of being secretive and seldom seen, as opposed to actual rarity.

The Long-tailed Weasel is a generalist predator, feeding on a wide variety of prey and capable of switching to alternate prey when normal prey numbers are low. The larger males typically prey on larger animals than the smaller females. Prey include rabbits, rodents of all kinds, moles, shrews, Big Brown Bats, birds of all kinds, bird eggs, and occasional insects and snakes. They also consume carrion. They have a reputation for killing chickens and have been known to feed on newborn pigs. They may attack prey on the ground, in trees, in burrows, or in or from beneath snow. They can consume up to one-third their weight in one setting, and they cache leftovers for later use. They consume a lot of water (up to 25 cubic centimeters of water per day), which may be one reason why they are most common near permanent sources of water. Long-tailed Weasels kill small prey by seizing the victim in their teeth, then, wrapping their elongated body around the prey and holding with all 4 feet, biting the base of the skull to sever the spinal cord or crush the brainstem. Large prey, such as rabbits, are killed by repeatedly attacking the base of the skull and severing the muscles that support the head. Once the prey is incapacitated, the weasel strangles the prey or severs its carotid arteries. 

Weasels are fearless, even when attacked by other predators. Foxes and raptors are the principal predators on Long-tailed Weasels. Other predators include Coyotes, Bobcats, domestic dogs and cats, and large snakes. Humans and their automobiles also result in deaths. Finally, Long-tailed Weasels may contract Powassan virus.

The Long-tailed Weasel breeds in July and August. Fertilized ova develop for approximately eight days, then cease development for about seven and one half months. After this time the embryos resume development, and four to nine (usually six to eight) young are born 27 days later. The gestation period may cover 205 to 337 (average 279) days. The newborn young are blind, hairless, about 65 mm long, and weigh three grams. They soon develop a soft, white fur which is replaced in three weeks by adult fur. By the fourth week their teeth have erupted. Their eyes open by five weeks of age at which point weaning begins. During weaning the male may help provide the young with food. By 50 to 60 days the difference in size of the sexes is evident. Later the young accompany the female while she hunts, and disperse when they are 70 to 83 days old. Female Long-tailed Weasels may breed at three to four months of age while males are not sexually mature until the year following their birth. Maximum longevity of this mammal is three to four years in the wild, and up to five years in captivity.

Occurrence Activity:

Three subspecies of Mustela longicauda have been recognized in Kansas: Mustela longicauda primulina in the eastern two-thirds of the state; Mustela longicauda neomexicana in the southwestern corner of the state; and Mustela longicauda longicauda in the remainder of western Kansas. 

1896 Merriam, C. H. Synopsis of the weasels of North America. North American Fauna, 11:1-44. ():
1951 Hall, E. R. American weasels. Univ. Kansas Publ. Mus. Nat. Hist., 4:1-466. ():
1952 Cockrum, E. L. Mammals of Kansas. Univ. Kansas Publ. Mus. Nat. Hist. 7:1-303. ():
1984 Anderson, E. Review of the small carnivores of North America during the last 3.5 million years. Pages 2570266 in Contributions in Quaternary vertebrate paleontology: a volume in memorial to John E. Guilday. Carnegie Museum of Natural History, Pittsburgh, Pennsylvania. pp.
1994 Fitzgerald, J. F., C. A. Meaney, and D. M. Armstrong University Press of Colorado, Niwot, CO. 1-467pp.
1997 Sheffield, S. R., and H. H. Thomas Mustela frenata Mammalian Species 570():1-9
2008 Timm, R. M., G. R. Pisani, J. R. Choate, N. A. Slade, G. A. Kaufman, and D. W. Kaufman http://www.ku.edu/~mammals, . pp.
Account Last Updated:
11/19/2019 3:19:32 PM

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