Least weasel

The least weasel (Mustela nivalis), or simply weasel in the UK, is the smallest member of the genus Mustela and of the family Mustelidae (as well as the smallest of the Carnivora), native to Eurasia, North America and North Africa, though it has been introduced to New Zealand, Australia, Malta, Crete, Bermuda, Madeira Island, the Azores, the Canary Islands, Sao Tome, the Falkland Islands, Argentina and Chile. It is classed as being of least concern by the IUCN, due to its wide distribution and presumed large population.

Least weasels from various parts of its range vary greatly in size. The body is slender and elongated and the legs and tail are relatively short. The colour varies geographically, as does the pelage type and length of tail. The dorsal surface, flanks, limbs and tail of the animal are usually some shade of brown while the underparts are white. The line delineating the boundary between the two colours is usually straight. At high altitudes and in the northern part of its range, the coat becomes pure white in winter. Eighteen subspecies are recognised.