Least Weasel

Least Weasel.
Credit: Kevin Law


  • Common name: Least Weasel
  • Scientific name: Mustela nivalis
  • Order: Carnivora
  • Family: Mustelidae
  • Indigenous names for this species may be available through the Yukon Native Language Centre

Also known as


Viewing opportunities

  • Similar to its larger cousin, Ermine, the Least Weasel is rarely seen because it primarily hunts at night. Occasionally they are seen hunting near houses and bird feeders, where they can effectively control mouse and vole populations.
  • Least Weasel is distinguished from Ermine by its smaller size and tail without a black tip.


  • Long, thin weasel-like body.
  • Short legs and fur, small ears, and long, sensitive whiskers.
  • Short, stubby tail without a black tip.
  • Completely white fur in winter, and brown fur with white underside in summer.

Fast facts

  • Length: 25 cm
  • Weight: 30 to 100 g
  • Lifespan: 2 years
  • Predators: Hawks, kestrels, owls, coyotes, foxes and larger members of weasel family
  • Habitat: Boreal Forest

Conservation status

What is conservation status?

  • Yukon: S4S5 (Apparently secure/secure)
  • Global: G5 (Secure)

Yukon population estimate

Not determined.


Least Weasels are solitary carnivores with long slender bodies that are well adapted to moving through dense vegetation, debris and underground burrows. They can also effectively hunt small prey living under snow in winter, such as mice and voles, because they are able to access snow. Weasels are always on the hunt; their very high metabolic rate means that they must eat often to survive.


Small rodents, particularly mice and voles; shrews, birds, eggs, frogs and insects.


Least Weasel distribution map.

Sights and sounds

Weasel track, front.
Weasel track, front: 1.3 x 1.5 cm.
Weasel track, hind.
Weasel track, hind: 1.5 x 1.8 cm.

Weasels and people

  • Because its tiny size and lack of a black-tipped tail, there is little commercial value in Least Weasel fur.
  • Since weasels are considered the best mousers in the boreal forest, Yukon First Nation trappers like to have them around their cabins to keep the rodents down.