Mackenzie Valley wolf
|Mackenzie Valley wolf|
|Subspecies:||C. l. occidentalis|
|Canis lupus occidentalis
|Mackenzie Valley wolf range (green)|
The Mackenzie Valley wolf (Canis lupus occidentalis) also known as the Canadian timber wolf is perhaps the largest subspecies of gray wolf in North America. Its range includes parts of the western United States, much of western Canada, and Alaska, including Unimak Island in the Aleutians, and was introduced into Yellowstone National Park and central Idaho. The subspecies has since spread into Washington, Oregon, Utah, and possibly other states.
Mackenzie Valley wolves typically stand about 32–34 inches (80–85 cm) at the shoulder and males weigh between 100 and 170 pounds (45–70 kg). The record is held by a wild wolf caught in Alaska in 1939 which weighed 175 pounds.
The Mackenzie Valley wolf's thick, long limbs are proportionally built for traversing through rough terrain such as deep snow or the cliffy edges of the Rocky Mountains. Its deep chest hosts large lungs, letting the wolf breathe more efficiently at higher altitudes, and allowing it to exert huge amounts of stamina traveling up to 115 km (~70 miles) in one day. Its powerful neck is a very important adaptation; it has to be strong to support the wolf's large head and is crucial for bringing down prey. The Mackenzie Valley wolf maximizes heat retention through such methods as using its bushy tail to cover its exposed nose during the winter. It sheds its undercoat during the summer months due to the hotter conditions.
The skull is 31 cm (12 inches) long and is armed with an impressive array of large canines and carnassial teeth which, when coupled with huge jaw muscles that are evident from the large sagittal crest and wide zygomatic arches, give it an incredible biteforce that is strong enough to break the bones of prey and even crack the femur of moose.
In Alaska, pack sizes are generally 6–12 wolves, with some packs as large as 20–30. Territory size averages 600 square miles (1,600 km2). Wolf packs in Yellowstone average 9.2 wolves with an average territory of 348-square-mile (900 km2), while wolf packs in Idaho average 11.1 and 364-square-mile (940 km2) territories.
The majority of the Mackenzie Valley wolf's prey includes wild boar, wood bison, muskox, moose, caribou, deer, elk, and small cats. Mackenzie Valley wolves introduced into Yellowstone have taken down adult Plains Bison, proving their success and adaptability in a whole new environment.
Mackenzie Valley wolves are not the most successful when it comes to killing moose, with a success rate as low as 10%. When preying on medium to large-sized animals such as caribou and elk, pack members will in turn chase an ill or disadvantaged prey and wait till they tire. They will then slowly start to tear away at the prey, attacking the flanks, the muzzle, neck, and hindquarters. Prey usually die from disembowelment, shock, and exhaustion caused by lack of air through suffocation and blood loss. For small prey, wolves will bite down and sever the jugular veins and windpipe, sometimes even shaking to break the animals vertebrae.
Current status and history
The Mackenzie Valley wolf was the subspecies used in the Yellowstone introduction effort, where it has become a successful apex predator much as it is in its vast northern range. In Yellowstone, it has been crucial in restoring environmental balance in that it has clamped down on the less fit members of the herds on which it feeds, thereby keeping large ungulate numbers in check and allowing certain floral and faunal species to recover, promoting biodiversity. Wolves were also introduced in central Idaho and entered northwest Montana from Canada. The wolf population in the Northern Rockies has since grown to an estimated 1,300 animals. The wolf population in Alaska is estimated at 7,500–11,000.
The protection given to the Mackenzie Valley wolf has allowed its population to rise dramatically, causing several young animals to leave the boundraries of Yellowstone and establish territories in areas where they may enter conflict with humans. In Wyoming and Idaho, 90 wolves have been killed to date because of livestock run-ins. In Montana, 32 wolves were killed in 2007 by federal agents. The Montana figure does not include an unknown number of wolves killed by ranchers defending their livestock. The death toll hit a record figure of 142 wolves in 2006. Federal officials plan to remove gray wolves in the Northern Rocky Mountains from the endangered species list in February 2008, although court challenges are considered inevitable and could delay a final delisting. In the Rocky mountains, non-lethal responses to livestock kills, such as hazing wolves away from a ranch, are used when they can be pushed into an area without livestock.
Since its reintroduction to Yellowstone, the Mackenzie Valley wolf's possible involvement in the decline of elk populations has been a subject of controversy. On one hand, Yellowstone officials have stated that computer analysis indicates that there is greater justification for believing that the human hunting rate and severe climate account for the majority of the decline, with wolf predation amounting to very little. Others state that the decline is an inevitable result of an exploded wolf population.
- Wozencraft, W. C. (2005). "Order Carnivora". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494.
- "Rocky Mountain Wolf". International Wolf Centre. Retrieved 2007-10-06.
- "A History of Wild Wolves in the United States". Annie B. White.
- Table listing the 1996 Idaho wolves. Forwolves.org (2002-11-01). Retrieved on 2012-12-29.
- Wolves[dead link]
- Mader, T.R. "WOLF PREDATION ON SHEEP IN ALASKA". Abundant Wildlife Society of North America. Retrieved August 17, 2013.
- "Wolf kills on the rise as livestock deaths continue". High Plains/Midwest AG Journal. Retrieved 2007-10-06.
- Yellowstone elk populations decline, but are wolves to blame?. Yellowstonepark.com (2007-01-21). Retrieved on 2012-12-29.
|Wikispecies has information related to: Canis lupus occidentalis|
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