The social order of pack members will change throughout time as wolves sexually mature, reach old age, become ill or wounded, and become weakened. In a pack, only the alpha male and female are allowed to breed. Any attempt at breeding by other members of the pack is met with aggression by the alpha pair. Although the largest documented pack was one of 36 animals in Alaska, the average wolf pack consists of four to seven individuals. Most Yellowstone visitors are eager to hear the howl of a wild wolf.
Wolves do utilize several vocalizations for the purpose of communication.
Howls, yips, squeals, growls, chirps, and barks may be used by wolves to express themselves. In general, howling is used as a means of long distance communication. For short range communication, wolves use scent marking. Scent marks are used by a wolf pack to advertise its presence in an area. Gray wolves were recently reintroduced into Yellowstone National Park with a goal of ten breeding pairs or about 100 wolves in the park.