The gray wolf, also called the timber wolf, is the largest of about 41 wild species within the dog family. They range in size from 26" to 38" shoulder height, 39" to 80" in length (tip of nose to end of tail), and vary in weight from 57 to 130 pounds. Their coats may vary in color from gray to brown, from white to jet black.
They usually hunt at night and feed primarily on large hoofed mammals such as deer, caribou, elk, and moose, but sometimes eat berries, birds, beaver, fish, and insects. Animals that they kill are usually young, old, or otherwise weaker members of their populations because they are easiest to capture. Most pursuits of prey range in length from 110 yds to 3.1 miles. Healthy wolves rarely, if ever, attack humans. Their range once covered most of North America. However, today only a few upper states and Canada have a wolf population large enough to maintain itself.
The gray wolf mates for life and lives in packs which can vary in size from 2 to over 15, but are usually from 4 to 7 wolves. The leader of the pack is normally the strongest male, who often determines when and where the pack will hunt, as well as other activities of the pack.Wolf packs are formed primarily of family members and relatives. They may travel more often, and greater distances than any other terrestrial animal. Their territories may cover from 100 to 260 sq. mi, depending on the abundance of food and water. Territories may also overlap, although wolf packs very seldom confront one another. Some wolves leave their packs to become lone wolves. Loners may start their own packs if a mate and a vacant area can be found.
Breeding season can vary from January in low latitudes to April in high latitudes. A wolf pack will alternate between a stationary phase from spring through summer and a nomadic phase in autumn and winter. The stationary phase involves caring for pups at a den or home site. During summer, most movements are toward or away from the pups, and adults often travel and hunt alone. By autumn, pups are capable of traveling extensively with the adults, so until the next whelping season the pack usually roams as a unit throughout its territory in search of prey. Though often only the highest ranking male and female in a pack will breed, all members of the pack are involved in raising the young. Mortality factors affecting wolves include persecution by humans, killing by other wolves, diseases, parasites, starvation, and injuries by prey. Most wolves probably live less than 10 years in the wild.