Weasels hunt largely underground or under snow, and are active day and night. Some larger species are more often nocturnal. Home ranges are smaller in habitats rich with prey, in the nonbreeding season, and in the smallest species. However, four grisons observed together in captivity showed no evidence of the mutual grooming characteristic of social animals. Most mustelids, sociable or not, may be seen in parties of females and young just before the dispersal of the litters.
Some people persecute small mustelids as pests of game and poultry.
The extinction of the European polecat in England was probably due to intensive gamekeeping. Others hail weasels and polecats as useful exterminators of rodents. Both opinions are exaggerated. All weasels and polecats eat large numbers of voles, mice, rats and rabbits - in one year a single family may consume thousands of such prey. This was the attitude in Europe before the introduction of the domestic cat in the 9th century.