Weasels are long-bodied, small predators belonging to the genus Mustela. This Genus includes species called weasels, stoats, mink, and ferrets. Weasels can be found in North and South America, Europe, and Asia. Weasels are active predators, primarily eating mammals smaller than themselves such as mice and voles. They may also eat birds and their eggs, frogs, and occasionally attack creatures larger than themselves such as rabbits and hares. Mink have a more aquatic lifestyle and feed primarily on fish and other aquatic creatures.
The Least Weasel (Mustela nivalis) and the Stoat (Mustela erminea) are both common in Scandinavia and surrounding areas and would have been known to historical Vikings. Least Weasels are simply called 'weasels' in Britain, while Stoats are referred to as 'weasels' in Ireland.
In reality, many weasel species are hunted and farmed for their soft pelts. Occasionally weasels can be both a help and a hindrance to farming, as they eat pest species such as mice, but are also known to kill and eat chickens and their eggs. The Ferret is a domesticated weasel species, used for at least a thousand years for hunting rabbits in their warrens. Though hunting still occurs in some parts of the world, ferrets are more commonly kept as pets in modern times.