weasel

Weasel is a common name for several small carnivorous mammals in the genus Mustela, within the family Mustelidae. Prominent species include the least weasel (Mustela nivalis), the stoat or ermine (Mustela erminea), and the long-tailed weasel (Mustela frenata). Weasels are native to most continents, with domesticated ferrets (Mustela putorius furo) descended from the European polecat (Mustela putorius).

They are slender, with elongated bodies and short legs, and they vary in size and fur color by species. Most have brown fur with lighter undersides, though seasonal changes occur in some species: the stoat, for example, may turn white in winter in northern regions. Fur density and length help insulation in variable climates.

Weasels are generally solitary and highly mobile hunters. They use scent marking to delineate territory and rely on agility to pursue prey through burrows, under vegetation, or along crevices. Habitats span forests, grasslands, farmlands, and even urban areas, reflecting their opportunistic feeding and broad ecological tolerance. Diet is primarily small mammals such as mice and voles, but they may also consume birds, eggs, and insects, depending on availability.

Reproduction varies by species but often includes a period of delayed implantation followed by a relatively small litter, with altricial young cared for by the mother. Lifespan in the wild is limited by predation and disease, but some individuals can live several years in favorable conditions. Weasels play a role in controlling rodent populations, and some species are valued in agricultural settings for pest suppression.