With few pups to take the place of wolves that may die at any given time, it is understandable how harsh winters that limit food supply, or other threats outside of the pack, can negatively affect wolf populations.  Sometimes, however, more wolf pups are born than usual.  For instance, the natural social order of a pack may break down, especially if it is disrupted by the death of one of the alpha wolves.  In these cases, more females are likely to produce litters for the pack.

          Under normal conditions, however, as winter comes to a close, the dominant  male and female wolves in the pack begin a courtship process that leads to breeding.  The early stages of courtship can be described as "flirting."  The wolf pairs will approach each other while making quiet whining sounds.  They will mouth each other's muzzles, touch noses, and bump their bodies together.  Other courting behaviors include grooming each other's coats and nibbling on each other.

          The courting wolves will mate anytime between January and April.  Wolves are thought to pair and mate for life, and both parents look after their pups.  Before the pups are born, however, the female wolf finds an underground den to use as her birthing chamber.  The den consists of a long, narrow tunnel with a small hollow room at the end, large enough for the female wolf and her expected litter.  If a ready-made den, such as the one vacated by a fox or other animal, is not available, the female wolf may dig her own in the hillside, reside in the space between rocks, or find some other suitable natural enclosure in her surroundings.

          In the spring, after a 59- to 63-day gestation period, generally 4 to 7 wolf pups are born to the dominant pair.  Wolf pups weigh about 1 pound (0.5 kilograms) at birth and are blind, deaf, and helpless.  At first, they live on only the mother's milk.  When they are about 3 weeks old, they begin to eat meat and to leave the den for short periods.  Adult wolves provide the pups with meat.  An adult eats much meat after killing an animal.  To get some of this meat, the pups lick the mouth of the adult wolf.  The adult coughs up the meat, and the pups eat it.

          Wolf pups leave the den permanently when they are about 2 months old.  The pups move to an unsheltered area that is called a rendezvous site, and they remain there during the summer while the adults hunt and bring back food.  In the fall, the quickly growing pups and the adults begin to hunt together as a pack.