Wolves are highly social animals, and the family structure is focused around the pack. Packs typically consist of a breeding pair—the “alpha male and alpha female”—and their young from previous years. Pack size doesn’t vary much between years because the wolves that either leave or die each year are replaced by newborn pups.

Wolves breed in late winter, and give birth to an average of four to five pups in April. The pups are born in a den dug by the breeding female, around which the pack congregates. Wolf pups spend their first six to eight weeks at the den, and are weaned at around six weeks of age. Once they begin eating meat, the pups are fed by adult members of the pack.

As the pups become older the pack typically moves them from the den to “rendezvous sites”, which are usually wet meadow areas within a pack’s territory where the adults can leave the pups while they go off to hunt. Wolves may use several rendezvous sites during the summer months until the pups are big and strong enough to travel full-time with the pack, generally by late September or October.

An adult male wolf stands about 30 inches at the shoulder and can be over six feet long from the tip of nose to point of tail. It will weigh 70 to 110 pounds. Females are slightly smaller, usually 60 to 80 pounds.