Northwestern wolf

Not to be confused with Yukon wolf.

Northwestern wolf Canis lupus occidentalis Temporal range: Late Pleistocene - recent
C. l. occidentalis at the Grizzly and Wolf Discovery Center at West Yellowstone, Montana.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Canidae
Genus:	Canis
Species:	C. lupus
Subspecies:	C. l. occidentalis
Trinomial name
Canis lupus occidentalis Richardson, 1829
C. l. occidentalis range (green)
Synonyms
alces (Goldman, 1941) ater (Richardson, 1829) mackenzii (Anderson, 1943 (1908)) pambasileus (Elliot, 1905) sticte (Richardson, 1829) tundrarum (Miller, 1912)

The northwestern wolf, Canis lupus occidentalis, also known as the Mackenzie Valley wolf or northern timber wolf is a subspecies of gray wolf in western North America. It ranges from the upper Mackenzie River Valley, southward into central Alberta.

Along with C. l. nubilus, C. l. occidentalis is the most widespread member of the five gray wolf subspecies in North America, with at least six different synonyms.

The subspecies was first written of by Scottish naturalist Sir John Richardson in 1829. He chose to give it the name occidentalis in reference to its geographic location rather than label it by its color, as it was too variable to warrant such. Phylogenetic analyses of North American gray wolves show that there are three clades corresponding to C. l. occidentalis, C. l. nubilus and C. l. baileyi, each one representing a separate invasion into North America from distinct Eurasian ancestors. C. l. occidentalis, the most northwestern subspecies, is descended from the last gray wolves to colonize North America. It likely crossed into North America through the Bering land bridge after the last ice age, displacing C. l. nubilus populations as it advanced, a process which has continued till present times.

Northwestern wolves have been responsible for a few notable attacks on humans, with at least two fatal attacks in the 21st century in which both victims were partially eaten: in 2005, a man was killed in Saskatchewan, Canada, while in 2010, a woman was killed while jogging near Chignik Lake in Alaska.

Description

Northwestern wolves are one of the largest subspecies of wolves with grown males weighing between 100 and 135 pounds (45–61 kg) in British Columbia. The adult males of this subspecies average 48 kilograms (106 lb) in Alberta. and 40 kilograms (88 lb) in Yukon. The heaviest recorded specimen was killed on 70 Mile River in east-central Alaska on July 12, 1939 and weighed 79.4 kilograms (175 lb). Sir John Richardson described the northwestern wolf as having a more robust build than the European wolf, with a larger, rounder head and a thicker, more obtuse muzzle. Its ears are also shorter, and its fur bushier.

Reintroduction

In Yellowstone National Park, artificially relocated northwestern wolves have been well-documented feeding on elk. They usually stampede the herd using pack teamwork to separate the younger elk from the adults. They also will charge young calves separated from their parents. Winter-weakened or sick elk also play an important part of Yellowstone wolf diets and it is estimated that over 50 percent of winter-weakened or sick elk in Yellowstone are killed by wolves. Of these, about 12 percent of carcasses were scavenged by other predators including; ravens, bald eagles, coyotes and grizzly bears. In the same national park, wolves also prey on bison, though such attacks usually involve sick animals or calves, as bison can easily kill wolves with their hooves.