A hierarchy of dominant and subordinate animals within the pack help it to function as a unit. Wolves communicate with fellow pack-mates and other wolf packs by scent marking, vocalizations, facial and body postures. Also use barks, whimpers, growls and howls to express themselves. They communicate through howling. This is an important and effective way to send long distant messages to other wolves.
Pups begin to howl at one month old.
Wolves mate in February or March. Females give birth two months later to a litter of pups. An average litter is four to seven pups. Litter size and pup mortality depend on food supply, weather and the health of the mother. Wolves need open land and an abundant supply of prey to survive.