Wolves live in family groups called packs. A pack is usually made up of a male parent, a female parent and their pups from the last few years.

Usually, four to six pups are born together in a litter. The pups in a litter are called littermates. Their first home is usually a den, which can be a small cave or a hole dug in the ground. It must be big enough to shelter the mother and pups from weather and protect the pups from other animals that may want to hurt them. Packs sometimes use the same den for several years, or they may find a new den each year.

More Info: wolf.org