They are found worldwide, except for Antarctica and most oceanic islands. Other Pennsylvania mustelids are the fisher, striped skunk, mink and otter. Ferrets, badgers and wolverines also belong to the family. Ranges of the three species overlap in Pennsylvania, the Great Lakes states and parts of Canada. In Pennsylvania, the ermine is found mostly in the northern and eastern parts, the long-tailed is common throughout the state, and the least is found in greatest numbers in the southcentral and northwest.
Weasels have long, slim bodies.
Their short legs have five small-clawed toes on each foot. Weasels travel with a loping gait, stopping occasionally to sit on their haunches or stand on their back legs to look around. Weasels are consummate predators. Their senses of sight, smell and hearing are acute, their hunting instinct is keen, and they are active, aggressive and quick. They kill and consume a wide variety of prey, including animals larger than themselves.