Wolves are noted for their distinctive howl, which they use as a form of communication. Biologists do not know all of the reasons why wolves howl, but they may do so before and after a hunt, to sound an alarm, and to locate other members of the pack when separated. Wolves howl more frequently in the evening and early morning, especially during winter breeding and pup rearing. Howling is also one way that packs warn other wolves to stay out of their territory.