Long-tailed Weasel

A weasel leaps across a road
Long-tailed weasels are mammals in Yellowstone National Park.

Courtesy Mike Warner

Black track of a long-tailed weasel
Long-tailed weasel track

Scientific Name

Mustela frenata


  • Typical weasel shape: a very long body, short legs, pointed face, long tail.
  • 13–18 inches long, 4.8–11 ounces.
  • Fur is light brown above and buff to rusty orange below in summer; all white in winter, except for tail, which is black-tipped all year.
  • Males 40% larger than females.
  • Compare to marten and short-tailed weasel.


  • Found in forests, open grassy meadows and marshes, and near water.
  • Eat voles, pocket gophers, mice, ground and tree squirrels, rabbits; to a lesser degree birds, eggs, snakes, frogs, and insects.


  • Breed in early July and August; one litter of 6–9 young per year.
  • Solitary animals except during breeding and rearing of young.
A wolf standing on a snowy bank near brown grass howls


Home to the largest concentration of mammals in the lower 48 states.

Last updated: October 21, 2020

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Contact Info

Mailing Address:

PO Box 168
Yellowstone National Park, WY 82190-0168



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