Howling

Howling is a vocal form of animal communication seen in most canines, particularly wolves, coyotes, foxes, and dogs, as well as cats and some species of monkeys. Howls are lengthy sustained sounds, loud and audible over long distances, often with some variation in pitch over the length of the sound. Howling is generally used by animals that engage in this behavior to signal their positions to one another, to call the pack to assemble, or to note their territory. The behavior is occasionally copied by humans, and has been noted to have varying degrees of significance in human culture. The long-distance howling of wolves and coyotes is one way in which canines communicate. Long-distance contact calls are common in Canidae, typically in the form of either barks (termed "pulse trains") or howls (termed "long acoustic streams"). Wolves howl to assemble the pack usually before and after hunts, to pass on an alarm particularly at a den site, to locate each other during a storm, while crossing unfamiliar territory, and to communicate across great distances. Under certain conditions, wolf howls can be heard over areas of up to . The phases of the moon have no effect on wolf vocalization, and despite popular belief, wolves do not howl at the Moon. Wolf howls are generally indistinguishable from those of large dogs. Male wolves give voice through an octave, passing to a deep bass with a stress on "O", while females produce a modulated nasal baritone with stress on "U". Pups almost never howl, while yearling wolves produce howls ending in a series of dog-like yelps. Howling consists of a fundamental frequency that may lie between 150 and 780 Hz, and consists of up to 12 harmonically related overtones. The pitch usually remains constant or varies smoothly, and may change direction as many as four or five times. Howls used for calling pack mates to a kill are long, smooth sounds similar to the beginning of the cry of a great horned owl. When pursuing prey, they emit a higher pitched howl, vibrating on two notes.