Wolves howl for a variety of reasons. Pack members will chorus howl to defend their territory and rally the pack together. Most howls heard in the pack are chorus howls. These group "sing-a-longs" may be started by any pack member, or they may be a response to the howling of a neighboring pack of wolves or a coyote. Wolves will even howl to something that even sounds similar like a train whistle, fire or police car siren or even a human. Such howls, though social in nature, also serve to defend the pack's territory against other wolves.

Wolves can recognize the voices of others. The response of a packmate, of a known neighboring pack or a complete stranger are all solicit different responses.

Contrary to popular belief, wolves do not howl at the full moon any more often than at any other time of month. They also do not howl just at night. They do howl more frequently during the hours around sunrise and sunset, for they are more active then. Wolves also howl more often in the winter months than in the summer. However they can be heard howling any time of day any time of the year.