Of course, their sense of smell also tells them when food or enemies are near. That is one of the ways wolves communicate with their voices. Wolves don't howl at the moon. They will howl any time of the day but are most often heard in the evening because that is when the pack is most active. Sometimes, it seems as if they howl just for fun.
Wolves also bark to warn other pack members of danger or to challenge an enemy.
They make a squeaking noise to call the pups, and the pups' mother will whimper to calm them down. A howl may range from half-second in duration to about eleven seconds. Communal howls often begin with a few sharp barks by a few pack members, followed by a low howl that builds to a louder group howl. Wolves seldom stay on the same note while howling, but rather shift pitch to achieve almost harmonic effect. Far across the tanana, a mile or two to the south of us, a group of wolves were singing.