Weasels are mammals forming the genus Mustela of the Mustelidae family. They are small, active predators, long and slender with short legs.
Weasels vary in length from 12 to 45 centimetres (5 to 18 in), and usually have a red or brown upper coat and a white belly; some populations of some species moult to a wholly white coat in winter.
They have long slender bodies, which enable them to follow their prey into burrows. Their tails may be from 22 to 33 centimetres (9 to 13 in) long. Weasels have a reputation for cleverness and guile.
Weasels feed on small mammals, and have from time to time been considered vermin since some species took poultry from farms, or rabbits from commercial warrens. Weasels occur all across the world except for Antarctica, Australia, and neighbouring islands.
The English word “weasel” was originally applied to one species of the genus, the European form of the Least Weasel (Mustela nivalis). This usage is retained in British English, where the name is also extended to cover several other small species of the genus.
It is thought that the name “weasel” comes from the Anglo-Saxon root “weatsop” meaning “a vicious bloodthirsty animal”. However, in technical discourse and in American usage the term “weasel” can refer to any member of the genus, or to the genus as a whole.
Of the 17 extant species currently classified in the genus Mustela, ten have “weasel” in their common name. Among those that do not are the stoat or ermine, the polecats, the ferret, and the European Mink (the superficially similar American Mink is now regarded as belonging in another genus, Neovison).
Collective nouns for a group of weasels include boogle, gang, pack, sneak and confusion.
Weasels are often the subject of the children’s song and nursery rhyme, “Pop Goes the Weasel.” Also, a weasel named Dunglap (voiced by John Kassir) is one of the title characters’ best friends in CatDog.
Weasels, ferrets and stoats were the enemies of Toad of Toad Hall in the popular children’s classic The Wind in the Willows.
The weasel is said to be the patronus charm of book and movie character Arthur Weasley in JK Rowling’s series “Harry Potter.”