Thus, a pack generally produces only one litter each year, averaging five to six pups. The female delivers the pups two months later in the back chamber of a den that she digs. Sometimes the female selects a hollow log, cave or abandoned beaver lodge instead of making a den. At birth, wolf pups are deaf and blind, have dark fuzzy fur and weigh about one pound. They grow rapidly during the first three months, gaining about three pounds each week.
Pups begin to see when two weeks old and can hear after three weeks.
At this time, they become very active and playful. When about six weeks old, the pups are weaned and the adults begin to bring them meat. Adults eat the meat at a kill site often miles away from the pups, then return and regurgitate the food for the pups to eat. The hungry pups jump and nip at the adults' muzzles to stimulate regurgitation. The pack abandons the den when the pups are six to eight weeks old.