The long-tailed weasel is found from sea level to timberline from Maine across the United States and southern Canada, south to Florida, Mexico, and South America, excluding the U.S. Southwest. Pennsylvania’s largest weasel, it is fairly common statewide; during years when Pennsylvania paid a bounty on weasels, eight of every 10 turned in were long-tails. The long-tailed weasel is similar to the ermine in proportion, color, and markings, although the long-tailed species is slightly larger and its tail is longer.
Adult males are larger and heavier than females. Length varies from 15 to 23.5 inches, including a 3.2- to 6.3-inch tail; weights are 2.5 to 9.3 ounces. Sexes are colored alike. In summer, upper parts are a uniform dark brown, extending onto the feet and toes (feet and toes of an ermine are white). The dark brown tail is tipped black. The long-tailed weasel normally becomes white only in northern sections of its range; in Pennsylvania, five of every six stay brown in winter, and farther south all individuals probably remain brown.
Long-tailed weasels are good swimmers and adept climbers that will chase a squirrel up a tree. Although generally solitary, two individuals may play together. A long-tailed weasel is a persistent, efficient predator, chasing prey, pouncing on it, hugging it with the forelegs, and biting the victim at the base of the skull. Prey: small terrestrial mammals, bats, hares, rabbits, birds and their eggs, frogs, snakes, earthworms, insects and carrion; smaller victims are eaten whole. A weasel can drag prey much heavier than itself.