The alpha female and male are the pack leaders, tracking and hunting prey, choosing den sites, and establishing the pack's territory. The alpha pair mate in January or February and give birth in spring, after a gestation period of about 65 days. Litters can contain from one to nine pups, but usually consist of around six. Pups have blue eyes at birth and weigh about one pound. Their eyes open when they are about two weeks old, and a week later begin to walk and explore the area around the den.
Pups romp and playfight with each other from a very young age.
Scientists think that even these early encounters establish hierarchies that will help determine which members of the litter will grow up to be pack leaders. Wolf pups grow rapidly, reaching 20 pounds at two months and full size in a year. All adults share parental responsibilities for the pups. They feed the pups by regurgitating food for them from the time the pups are about four weeks old until they learn to hunt with the pack. A wolf pup is the same size as an adult by the time he or she is about a year old, and is able to mate by about two years of age.