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Conserving the Nature of America

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people.

Gray Wolf Biology and Ecology


White wolf walking in snow with fir trees in background.

Photo courtesy of MacNeil Lyons; NPS


Wolves are highly social animals that live in groups, called packs, which typically include a breeding pair, their offspring, and other non-breeding adults. Wolves are capable of mating by age one or two and sometimes form a lifelong bond. On average, four to five pups are born in early spring and are cared for by the entire pack. For the first six weeks, pups are reared in dens. Dens are often used year after year, but wolves may also dig new ones or use some other type of shelter, such as a cave.


Pups depend on their mother’s milk for the first month, then are gradually weaned and fed regurgitated meat brought by pack members. By the time pups are five to six months old they are big enough to begin traveling with the adults. After a year or two, young wolves often leave their packs to try to find a mate and form a pack or join other existing packs. In the Northern Rocky Mountains, lone dispersing wolves travel on average 60-70 miles, but have traveled as far as 600 miles in search of a mate or territory. Wolf packs live within territories, which they defend from other wolves.


Their territories range in size from less than 50 square miles to more than 1,000 square miles, depending on habitat and seasonal movements of available prey. Wolves travel over large areas to hunt, as far as 30 miles in a day. Although they usually trot along at five miles per hour, wolves can run as fast as 40 miles per hour for short distances.


Wolves play an important role as top predators in the ecosystem they inhabit. Studies at Yellowstone National Park found that reintroducing wolves back into their historic ecosystem cascaded throughout the landscape. Ravens, foxes, wolverines, coyotes, bald eagles, and even bears benefit because they feed on carcasses of animals killed by wolves. Coyote density in some areas has declined because wolves view them as competitors and often kill them within their territories; which may be responsible, in part, for an increase in small rodents in some areas. Declines in the elk population have allowed willow, aspen, and cottonwood regrowth. This, in turn, provided food for beavers and habitat for songbirds.


Wolves use their distinctive howl to communicate. Biologists have identified a few of the reasons wolves howl: to reinforce social bonds within the pack, to announce the beginning or end of a hunt, sound an alarm, locate members of the pack, or warn other wolves to stay out of their territory. Wolves howl more frequently during winter breeding season and at rendezvous sites used in pup-rearing.





  • Was that a Wolf? (PDF) a fact sheet on how to identify wolves and differentiate from coyotes and wild dogs




Gray Wolves in the Western Great Lakes States