Wolves usually live in packs which consist of the adult parents, referred to as the alpha pair, and their offspring of perhaps the last 2 or 3 years. The adult parents are usually unrelated and other unrelated wolves may sometimes join the pack
A pack normally has only one litter of pups each spring, but in areas of high prey abundance more than one female will give birth in each pack. An average litter size for grey and red wolves are 4 to 6, but several may die if natural prey is not readily available.
Grey wolves prey primarily on large, hoofed mammals such as white-tailed deer, mule deer, moose, elk, caribou, bison, Dall sheep, musk oxen, and mountain goat. Medium sized mammals, such as beaver and snowshoe hare, can be an important secondary food source. Occasional wolves will prey on birds or small mammals.
Grey wolves in the wild have an average life span of 6 to 8 years, but have been known to live up to 13 years in the wild and 16 years in captivity. The natural causes of wolf mortality are primarily starvation, which kills mostly pups, and death from other wolves because of territory fights. While not usually a big problem, disease such as mange and canine provirus can be a concern in small and recovering populations. Injuries caused by prey results in some deaths. Human-caused mortality including legal, illegal, and accidental causes can be high in some populations. Pup mortality rates are highly variable, but approximately 40 to 60% of wolf pups die each year.
