Gray wolves have a gestation period of approximately 63 days. The pups are born in a den carefully selected by their mother. When they are born, wolf pups weigh about just one pound. Like all puppies, gray wolf pups are born deaf and blind, usually can't smell very well at all either, and get to places by crawling. They have dark fur and small ears. Pups feed from their mother at birth. For the first fourteen weeks, the period of maximal growth, pups gain about 3 pounds per week. At three weeks the pups leave the den. In approximately a little over 20 days, the pups blue eyes have opened, though they still can't see very well. At this time their walking and chewing skills develop. The pups are weaned at about 6 weeks and are able to eat regurgitated meat rather than milk. Pups' hearing improves starting at 27 days and their ears begin become erect. At four weeks, the pups bodies begin to grow into adult proportions, though they will have large feet. They also begin to grow adult hair. At between 8 and 10 weeks the mother will abandon the den, completing the weaning process. Shortly later, the pup's eye color will change from the bright blue of newborns the the brown color of adults. At 12 weeks, the pups begin their hunting ventures, and at 7-8 months, the pups travel with the rest of the pack. From between 4 and 6 months the pups will grow their adult teeth. Wolves reach sexual maturity at 22 months of age, and generally stay with the pack until they are 3 years old. At this age, some wolves will leave the pack to go start their own packs or, in a few cases, become loners.
