Muskox

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Muskox
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Bovidae
Subfamily: Caprinae
Genus: Ovibos
Blainville, 1816
Species: O. moschatus
Binomial name
Ovibos moschatus
(Zimmermann, 1780)
Range map: blue indicates areas where the muskox has been introduced in the 20th century; red indicates the previous established range.

The muskox (Ovibos moschatus, musk ox) is an Arctic mammal of the family Bovidae, noted for its thick coat and for the strong odor emitted by males, from which its name derives. This musky odor is used to attract females during mating season. Muskoxen primarily live in the Canadian Arctic and Greenland,[2] with small introduced populations in Sweden, Siberia, Norway, and Alaska.

Contents

Evolution [edit]

As members of the subfamily Caprinae of the family Bovidae, muskoxen are more closely related to sheep and goats than to oxen; however, they are placed in their own genus, Ovibos (Latin: "sheep-ox"). The muskox is one of the two largest extant members of Caprinae; along with the similarly sized takin.[3]

Today's muskoxen are descended from ancestors believed to have migrated from Siberia to North America between 200,000[4] and 90,000 years ago,[5] during the Pleistocene period, when it was a contemporary of the woolly mammoth. Along with the bison and the pronghorn,[6] the muskox was one of a few species of Pleistocene megafauna in North America to survive the Pleistocene/Holocene extinction event and live to the present day.[7] The muskox is thought to have been able to survive the last ice age (the Wisconsin glaciation) by finding ice-free areas (refugia) away from prehistoric peoples.[5]

Fossil DNA evidence suggests muskoxen were not only more geographically widespread during the Pleistocene, but also more genetically diverse.[8] During that time, other populations of muskoxen lived across the Arctic, from the Ural Mountains to Greenland. By contrast, the current genetic makeup of the species is more homogenous. Climate fluctuation may have affected this shift in genetic diversity: research indicates colder periods in Earth's history are correlated with more diversity, and warmer periods with more homogeneity.[7]

Physical characteristics [edit]

This skull, in the collection of The Children's Museum of Indianapolis, displays the muskox's large horns.

Both sexes have long, curved horns. Muskoxen stand 1.1 to 1.5 m (4 to 5 ft) high at the shoulder, with females measuring 135 to 200 cm (4.4 to 6.6 ft) in length, and the larger males 200 to 250 cm (6.6 to 8.2 ft). The small tail, often concealed under a layer of fur, measures only 10 cm (3.9 in) long. Adults, on average, weigh 285 kg (630 lb) and range from 180 to 410 kg (400 to 900 lb).[9][3] Their life expectancy is 12–20 years. The thick coat and large head suggests a larger animal than the muskox truly is; the bison, to which the muskox is often compared, can weigh up to twice as much.[10] However, heavy zoo-kept specimens have weighed up to 650 kg (1,400 lb).[11] Their coat, a mix of black, gray, and brown, includes long guard hairs that almost reach the ground. Rare "white muskoxen" have been spotted in the Queen Maud Gulf Bird Sanctuary.[12] Muskoxen are occasionally domesticated for wool, meat, and milk.[13][14] The wool, qiviut, is highly prized for its softness, length, and insulation value. Prices for yarn range between $40 and $80 per ounce (28 g).[15][16][17]

Range [edit]

Prehistory [edit]

During the Pleistocene period, muskoxen were much more widespread. Fossil evidence shows they lived across the Siberian and North American Arctic, from the Urals to Greenland.[7] The ancestors of today's muskoxen came across the Bering Land Bridge to North America between 200,000[4] and 90,000 years ago.[5] During the Pleistocene/Holocene extinction event, however, the muskox's range was greatly reduced, and only the populations in North America survived. The last known muskox population outside North America, which lived on Siberia's Taymyr Peninsula, died out about 2,000 years ago.[8]

The muskox gradually moved across the Canadian Arctic Archipelago, arriving in Greenland from Ellesmere Island at about 350 AD, during the late Holocene. Their arrival in northwestern Greenland probably occurred within a few hundred years of the arrival of the Dorset and Thule cultures in the present-day Qaanaaq area. Human predation around Qaanaaq may have restricted muskoxen from moving down the west coast, and instead kept them confined to the northeastern fringes of the island.[18]

Recent native range in North America [edit]

Muskox family in east Greenland

In modern times, muskoxen were restricted to the Arctic areas of Canada, Greenland, and the United States. The Alaskan population was wiped out in the late 19th or early 20th century. Their depletion has been attributed to excessive hunting, but an adverse change in climate may have contributed.[13][19] However, muskoxen have since been reintroduced to Alaska. The United States Fish and Wildlife Service introduced muskox onto Nunivak Island in 1935 as a means for subsistence living.[20]

Introductions in Eurasia [edit]

The species has also been introduced from Banks Island to the Scandinavian Peninsula, in parts of Sweden, and the Dovre mountain range of Norway between 1947 and 1953. An introduction attempt in Svalbard, however, was unsuccessful.[21]

In Russia, animals from Banks and Nunivak alike were imported and released in the Taymyr Peninsula between 1974 and 1975, and from Nunivak to Wrangel Island in 1975. Both locations are north of the Arctic Circle. Once established, these populations have been, in turn, used as sources for further introductions in Siberia between 1996 and 2010.[22] One of the last of such actions was the release of six animals within the "Pleistocene Park" project area in the Kolyma River in 2010, where a team of Russian scientists lead by Sergey Zimov aims to prove that muskoxen, along with other Pleistocene megafauna that survived into the early Holocene in northern Siberia,[23] did not disappear from the region due to climate change, but because of human hunting.[24]

Introductions in eastern Canada [edit]

Ancient muskox remains have never been found in eastern Canada, despite the ecological conditions in the northern Labrador Peninsula being suitable for them. In 1967, 14 animals were captured near Eureka, Ellesmere Island, and placed in a wool farm in Kuujjuaq, northern Quebec. Although the animals acclimatized and reproduced with no problem, the farm failed to make a profit. Subsequently, 54 animals from the farm were released in three locations of northern Quebec between 1973 and 1983, while the remaining were ceded to local zoos. Between 1983 and 1986, the released animals increased from 148 to 290, at a rate of 1.25 per year, and by 2003, an estimated 1400 muskoxen were in Quebec. Additionally, 112 adults and 25 calves were counted in the nearby Diana Island in 2005, having arrived there by their own means from the continent. Vagrant adults are sometimes spotted in the continental part of Newfoundland and Labrador, though no herds have been observed in the region.[25]

Ecology [edit]

During the summer, muskoxen live in wet areas, such as river valleys, moving to higher elevations in the winter to avoid deep snow. Muskoxen will eat grasses, arctic willows, woody plants, lichens, and mosses. When food is abundant, they prefer succulent and nutritious grasses in an area. Willows are the most commonly eaten plants in the winter. Muskoxen require a high threshold of fat reserves in order to conceive, which reflects their conservative breeding strategy. Winter ranges typically have shallow snow to reduce the energy costs of digging through snow to reach forage.[1] The primarily predators of muskoxen are Arctic wolves, which may account for up to half of all mortality for the species. Other predators, likely primarily of calves or infirm adults, can include grizzly bears and polar bears.[11]

Social behavior and reproduction [edit]

Nunivak Island, Alaskan muskoxen in the 1930s, shown here in defensive formation

Muskoxen live in herds of 12–24 in the winter and 8–20 in the summer.[26] They do not hold territories, but they do mark their trails with preorbital glands.[27] Male and female muskoxen both have separate age-based hierarchies, with mature oxen being dominant over juveniles.[26] Dominant oxen tend to get access to the best resources[11] and will displace subordinates from patches of grass during the winter.[26] Muskoxen bulls assert their dominance in many different ways. One is a "rush and butt", in which a dominant bull rushes a subordinate from the side with its horns, and will warn the subordinate so it can have a chance to get away.[28] Bulls will also roar, swing their heads, and paw the ground.[11] Dominant bulls sometimes treat subordinate bulls like cows. A dominant bull will casually kick a subordinate with its foreleg, something they do to cows during mating.[29] Dominant bulls will also mock copulate subordinates and sniff their genitals.[29] A subordinate bull can change his status by charging a dominant bull.[30]

Muskox in Dovrefjell National Park, Norway

The mating (or "rutting") season of the muskoxen begins in late June or early July. During this time, dominant bulls will fight others out of the herds and establish harems of usually six or seven cows and their offspring. Fighting bulls will first rub their preorbital glands against their legs while bellowing loudly, and then display their horns.[30] The bulls then back up 20 meters, lower their heads, and charge into each other, and will keep doing so until one bull gives up.[28] Subordinate and elderly bulls will leave the herds to form bachelor groups or become solitary.[11] However, when danger is present, the outside bulls can return to the herd for protection.[31] Dominant bulls will prevent cows from leaving their harems.[11] During mating, a bull will casually kick an estrous cow with his foreleg to calm her down and make her more receptive to his advances.[29] The herds reassemble when summer ends.[31]

While the bulls are more aggressive during the rutting season and make the decisions in the groups, the females take charge during gestation.[11] Pregnant females are aggressive and decide what distance the herd travels in a day and where they will bed for the night.[32] The herds move more frequently when cows are lactating, to allow them to get enough food to nurse their offspring.[32] Cows have an eight- to 9-month gestation period, with calving occurring from April to June. Cows do not calve every year. When winters are severe, cows will not go into estrus and thus not calve the next year. When calving, cows stay in the herd for protection. Calves are able to keep up with the herd within just a few hours after birth. The calves are welcomed into the herd and nurse for the first two months.[11] After that, a calf then begins eating vegetation and nurses only occasionally. Cows communicate with their calves through braying. The calf’s bond with its mother weakens after two years.

Muskoxen have a distinctive defensive behavior: when the herd is threatened, the bulls and cows will face outward to form a stationary ring or semicircle around the calves.[33] The bulls are usually the front line for defense against predators with the cows and juveniles gathering close to them.[11] Bulls determine the defensive formation during rutting, while the cows decide the rest of the year.[31]

Conservation status [edit]

Historically, this species declined because of overhunting, but population recovery has taken place following enforcement of hunting regulations.[1] Management in the late 1900s was mostly conservative hunting quotas to foster recovery and recolonization from the historic declines.[1] The current world population of muskoxen is estimated at between 80,000[34] and 125,000,[20] with an estimated 68,788 living on Banks Island.[35]

In Greenland there are no major threats, although populations are often small in size and scattered, which makes them vulnerable to local fluctuations in climate. Most populations are within national parks, where they are protected from hunting.[1] Muskoxen occur in four of Greenland's protected areas, with indigenous populations in Northeast Greenland National Park, and three introduced populations in Arnangarnup Qoorua Nature Reserve, and Kangerlussuaq and Maniitsoq Caribou Reserves. Within these areas, muskoxen receive full protection.[1]

References [edit]

  1. ^ a b c d e f Gunn, A. & Forchhammer, M. (2008). Ovibos moschatus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 31 March 2009. Database entry includes a brief justification of why this species is of least concern.
  2. ^ Animal Life in Greenland – an introduction by the tourist board. Greenland-guide.gl. Retrieved on 2011-09-15.
  3. ^ a b Burnie D and Wilson DE (Eds.), Animal: The Definitive Visual Guide to the World's Wildlife. DK Adult (2005), ISBN 0789477645
  4. ^ a b Wildlife Management Advisory Council (North Slope) fact sheet. taiga.net.
  5. ^ a b c Hinterland Who's Who ISBN 0-660-13637-6
  6. ^ Smithsonian Institution. North American Mammals: Pronghorn Antilocapra americana
  7. ^ a b c Switek, Brian. "Prehistoric DNA Reveals the Story of a Pleistocene Survivor, the Muskox." Laelaps blog on Science Blogs, posted 10 Mar. 2010. Accessed 18 Jan. 2013.
  8. ^ a b "Muskox Suffered Loss Of Genetic Diversity At Pleistocene/Holocene Transition". Science Daily. 2005-10-06. Retrieved 2011-03-03. 
  9. ^ "Ellis, E. ''Ovibos moschatus''". Animaldiversity.ummz.umich.edu. Retrieved 2011-03-03. 
  10. ^ Muskox videos, photos and facts – Ovibos moschatus. ARKive. Retrieved on 2012-08-23.
  11. ^ a b c d e f g h i Lent, Peter C (1988). "Ovibos moschatus". Mammalian Species 302 (1–9). 
  12. ^ "Search for the Legendary White Musk-ox". Thelon.com. 2010-08-06. Retrieved 2011-03-03. 
  13. ^ a b Muskox. Alaska Department of Fish and Game
  14. ^ Paul F. Wilkinson (1974). The history of musk-ox domestication. Polar Record, 17, pp 13-22. doi:10.1017/S0032247400031302.
  15. ^ "The Qiviut Fiber and Yarn". Qiviut.com. Retrieved 2011-03-03. 
  16. ^ Large Animal Research Station.uaf.edu. Retrieved on 2012-08-23.
  17. ^ Muskox Wool – Qiviut (Kiv-ee-oot). alaskabeadstore.com. Retrieved on 2012-08-23.
  18. ^ Bennike, Ole; Andreasen, Claus (2005). "New dates of musk-ox (Ovibos moschatus) remains from northwest Greenland". Polar Record 41 (2): 125. doi:10.1017/S0032247404004127. 
  19. ^ "The Incredible Journey". Nps.gov. 2010-12-28. Retrieved 2011-03-03. 
  20. ^ a b "Muskox, (Ovibos moschatus) US Fish & Wildlife Service". Fws.gov. Retrieved 2011-03-03. 
  21. ^ Aulagnier, S. et al. (2008) Guide des mammifères d'Europe, d'Afrique du Nord et de Moyen-Orient. Delachaux et Niestlé, Paris
  22. ^ http://www.lhnet.org/reintroduction-of-musk-ox-in-the-northern-russia/
  23. ^ http://www.rhinoresourcecenter.com/pdf_files/131/1312936307.pdf
  24. ^ http://news.nationalgeographic.com/news/2005/05/0517_050517_pleistocene.html
  25. ^ http://www.canadianfieldnaturalist.ca/index.php/cfn/article/view/398/398
  26. ^ a b c Tener, J. S. (1965). Muskoxen in Canada a biological and taxonomic review. Ottawa: Queen's Printer.
  27. ^ Owen-Smith, N. (1977). "On Territoriality in Ungulates and an Evolutionary Model". The Quarterly Review of Biology 52 (1): 1–38. doi:10.1086/409720. 
  28. ^ a b Wilkinson, P. F., Shank, C. C. (1976). "Rutting-fight Mortality among Musk Oxen on Banks Island, Northwest Territories, Canada". Animal Behavior 24 (4): 756–758. doi:10.1016/S0003-3472(76)80004-8. 
  29. ^ a b c Reinhardt, V. (2005). "Courtship behavior among musk-ox males kept in confinement". Zoo Biology 4 (3): 295–300. doi:10.1002/zoo.1430040311. 
  30. ^ a b Gray, D. R. (1986). "Standing his ground: How the muskox survives the rigours of an Arctic winter". Nature Canada 15: 19–26. 
  31. ^ a b c Freeman, M. (1971). "Population Characteristics of Musk-Oxen in the Jones Sound Region of the Northwest Territories". Journal of Wildlife Management 35 (1): 103–108. doi:10.2307/3799877. 
  32. ^ a b Jingfors, K. (1982). "Seasonal Activity Budgets and Movements of a Reintroduced Alaskan Muskox Herd". Journal of Wildlife Management 46 (1): 344–359. doi:10.2307/3808645. 
  33. ^ Miller, F. G., Anne. (1980). "Behavioral Reesponses of Musk Ox to Simulation of Cargo Slinging by Helicopter, Northwest Territories". The Canadian field naturalist 94 (1). 
  34. ^ "Robert G. White Large Animal Research Station, University of Alaska". Alaska.edu. 1963-10-12. Retrieved 2011-03-03. 
  35. ^ "Annual Report of Research and Monitoring in National Parks of the Western Arctic 2003, Parks Canada". Pc.gc.ca. 2009-04-15. Retrieved 2011-03-03. 

External links [edit]

Wikispecies has information related to: Muskox
Wikimedia Commons has media related to: Muskox

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