Weasel, any of various small carnivores with very elongated slender bodies. Most live in the Northern Hemisphere and belong to the genus Mustela, which in addition to weasels proper includes 17 species of ferrets and polecats as well as the mink and the ermine.

Weasels are usually brown, grey or black with white or yellowish markings. All weasels become all white in the winter, though. The winter fur of the least weasel glows a bright lavender color when exposed to ultraviolet light, according to the Nature Conservancy.

Weasels come in many sizes, but the most notable is the least weasel. It is the smallest carnivore in the world, according to Animal Diversity Web (ADW). They weigh about 1 ounce (25 grams) and grow to just 4 to 10 inches (11 to 26 centimeters) long.

Weasels are bold and aggressive predators. They generally hunt alone. Because of their narrow bodies, weasels are able to pursue and capture rodents in their burrows and to chase them through holes and crevices, under dense herbage, up trees, or into water. Although proficient at catching mice, weasels are also notorious for raiding chicken coops. Because they cannot accumulate fat and thus must eat frequently, weasels often kill more prey than they can immediately consume and will store excess food for later use.

Weasels feed on small mammals and in former times were considered vermin since some species took poultry from farms, or rabbits from commercial warrens. Certain species of weasel and ferrets, have been reported to perform the mesmerizing weasel ‘war dance’, after fighting other animals, or acquiring food from competing creatures. In folklore at least, this dance is particularly associated with the stoat. Mice and voles make up 60% – 80% of their diet, however, they also eat rats, frogs and birds. Their prey is killed with a sharp bite to the back of the neck. Prey is usually taken on the ground.

Weasels are adaptable and live all over the world. For example, the long-tailed weasel lives in North America, while the tropical weasel lives in South America. Japanese weasels are found in habitats grasslands, forests, villages and suburbs across Japan. Mountain weasels are found in in central and east Asia and the African striped weasel is found, predictably, in Africa.

The most common weasel is the short-tailed weasel. It can be found in North America, Europe and Asia, in regions as far north as the Arctic. Their homes include marshes, scrubs, hedgerows, alpine meadows, riparian woodlands and riverbank habitats, according to the International Union for Conservation of Nature and Natural Resources (IUCN).

Neither the stoat or weasel is in any real danger of extinction in the UK, they are however threatened by hunting, habitat loss, poisoning and both often get run over on the country lanes. They do tend to live around farms as the hedgerow habitat and plentiful food supply suits them. This often leads them into conflict with farmers, especially problematic are stoats who are very able at snatching chickens, eggs as well as game birds.