Northwestern Gray Wolf

Canis lupus occidentalis


This subspecies of gray wolf has a coat of black, white, gray, tan and even blue-ish. Gray or black wolves are the most common color phase found to occur. They typically stand about 76 cm (30 inches) at the shoulder and weigh 38-52 kg (85-115 pounds, although they can weigh as much as 66 kg (145 lbs).

Range and Habitat

The Northwestern wolf, more commonly known as the Rocky Mountain wolf, inhabits parts of the western United States, western Canada, and Alaska, including Unimak Island of the Aleutians, and is the sub-species that was reintroduced into Yellowstone National Park (YNP) and central Idaho in 1995-6.

Territory size in Alaska averages 966 square kilometers (600 square miles). The average pack size for the Northwestern wolf is generally 6-12 wolves, with some packs as large as 20-30 with one in Yellowstone documented at 37. Wolf packs in Yellowstone National Park average 9.2 wolves with an average territory of 560 square kilometers (348 square miles).


The prey base of the Northwestern wolf includes a variety of hoofed mammals and other rodents, such as moose, bison, elk, caribou, Dall sheep, Sitka Black-tailed deer, mountain goats, beaver, salmon, vole, lemmings, ground squirrels and snowshoe hare.

Breeding and Maturation

The pack's social structure generally determines which wolves breed, usually only the dominant wolves or breeding pair mate and produce a single litter of pups. However when prey in winter is abundant, a wolf pack may occasionally have multiple litters born that spring. The mating season is usually early January through late February, with a litter of 4 to 6 pups born 63 days later in a den. A den may be located in a rock crevice or a hole dug by the parents or even a tree stump. The pups are born deaf and blind, but can hear within a 12 to 14 days. After 3 to 6 weeks, the pups usually leave the den and begin to investigate their surroundings, staying close to the safety of the den. As the pups mature, the pack moves to a more open area or "rendezvous site" within their territory. By fall the pups are large enough to travel and hunt with the pack. Wolves generally reach adult size by six to eight months of age and are usually sexually mature by 22 months.


Legal shooting and trapping of wolves occurs throughout Alaska. Over the past decade 11 to 20 percent of Alaska's wolf population has been harvested each year. Studies indicate that wolves could sustain an annual harvest of 30 to 40 percent without decreasing the population. The wolf population in Alaska is estimated at 7,500-11,000 wolves. The population in the northern Rocky Mountains (Greater Yellowstone Area, northwestern Montana, and Idaho) is estimated to be around 1200 and increasing (2006 USFWS pop. estimate).

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