A hare's tail is classified as a scut, a kind of short, erect tail found on other herbivorous woodland animals, such as deer and rabbits. It comes from a Middle English word meaning hare, which originally derives from the Old Norse word "skutr," meaning stern.
A hare's scut is between 2 and 4 inches long. Although short, the scut is used for interspecies communication. Rabbits, deer and hares all utilize a particular kind of motion called tail flagging. Flagging consists of moving the scut very rapidly from side to side. In deer, flagging of the scut indicates agitation; in rabbits and hares, it is a sign that the animal is ready to breed.