Ovibos moschatus ( Zimmermann, 1780)
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publication ID |
https://doi.org/ 10.5281/zenodo.6512484 |
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DOI |
https://doi.org/10.5281/zenodo.6773144 |
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persistent identifier |
https://treatment.plazi.org/id/03F50713-99CD-FF76-037F-FB9EF8E3F3E9 |
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treatment provided by |
Conny |
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scientific name |
Ovibos moschatus |
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Muskox
French: Boeuf-musqué / German: Moschusochse / Spanish: Buey almizclero
Taxonomy. Bos moschatus Zimmerman, 1780 ,
Canada (Manitoba, between Seal and Churchill rivers).
The Muskox originated in Asia and spread to North America ¢.90,000 years ago. Ouvibos and Budorcas were formerly considered closely related and classified in the tribe Ovibovini , but Ovibos , based on mtDNA analysis, has a closer genetic relationship to Nemorhaedus and Capricornis than to other genera of the tribe Caprini . Control-region sequences of mtDNA comparisons between Muskox populations reveal small differences and do not support recognition of subspecies. Monotypic.
Distribution. Arctic areas of Alaska, Canada, and NE & N Greenland. Successfully introduced into W & SW Greenland, Norway, Russia, and several areas of Alaska outside their natural range. View Figure
Descriptive notes Head-body 190-230 cm, tail 9-10 cm, shoulder height 120-151 cm; weight 200-410 kg. Adult males are 25% larger than females. Amber-colored horns emanate from a boss (knob-like protuberance) and grow down below the eye and outward, with sharp, upturned tips. General body color is dark brown, the legs and middle back are white, and the muzzle is pale. The blocky body, broad head, short and stout legs, short neck, humped shoulder, and voluminous, long shaggy hair that extends beyond the knees and in some individuals to the ground combine to distinguish Muskoxen from other caprines. So does their tendency to stand with the head held low, and the slight slope of the body from the shoulder to the hindquarters. The Muskox is the largest herbivore in the circumpolar Arctic. An exceptionally thick coat of underwool and large stores of body fat that provide energy and insulation in adults and calves are adaptations to extreme cold conditions. Muskoxen do not exhibit a latitudinal or climatic trend in body size. Diploid chromosome number is 52.
Habitat. Most populations occur on tundra in areas of shallow snow or in wind-swept foraging sites with lower snow accumulation, in subarctic maritime, continental arctic, and High Arctic habitats. Their habitats include seashore sand dunes, riparian areas, and coastal plains. On Banks Island, Canada, situated in the high Arctic, the four habitats are characterized as wet sedge meadow, upland barren, hummock tundra, and stony barren. Muskoxen are physiologically and anatomically adapted to long, harsh, cold winters at temperatures that can be as low as —80°C with wind chill. On the Taymyr Peninsula, they experience temperatures ranging from -52°C to 25°C. On Banks Island, mean minimum daily temperatures from December to March range from -30°C to —-40°C; mean maximum daily temperatures from June through August range from 5°C to 10°C. Mean annual precipitation is 9 cm and over 95% of the island is below 500 m. Muskoxen can scrape for forage at snow depths of 20-40 cm, depending on snow hardness and density. In a southernmost and Low Arctic area in Greenland, where winter forage availability was higher and vegetation growth more vigorous, the animals grew faster, matured earlier, reproduced earlier, reached larger adult sizes, and had a higher rate of reproduction than Muskoxen in more northern, high Arctic areas where climatic conditions were less favorable. Few Muskox populations occur along the tree line ecotone or below the tree line. Competitive exclusion has been proposed as a causal relationship where Muskoxen have increased and Reindeer/ Caribou have declined, but conclusive ecological evidence is lacking. Gray Wolves (Canis lupus) are the principal predators. Brown Bears ( Ursus arctos) can also be a threat; individual bears can become proficient predators. When approached by predators, Muskoxen face them as a group, with young animals behind the group or within a circle of adults.
Food and Feeding. Muskoxen are primarily grazers, principally feeding on sedges and grasses, but willows and forbs are an important diet component in North America and Russia, especially during the summer. Diet varies regionally depending on season and plant species availability and nutritional quality. On Banks Island, the Muskox diet is dominated by sedge and willow; willow is an important dietary component during September, October, and January. Willow has a high nitrogen concentration and may complement and supplement the consumption of graminoids, although Muskoxen probably have a low requirement of nitrogen for growth. Annual diet in Taymyr Peninsula, Russia, is 47-86% grasses, 10-52% shrub leaves and twigs, 2-7% lichens and 0-2-12% mosses, which are poorly digestible. Muskoxen have a slow metabolism and low forage requirements, are able to digest low-quality forage, and have the ability to accumulate large fat reserves.
Breeding. Muskoxen have a polygynous mating system. Mating occurs in August-September and most calving is from mid-April to early June, after a gestation period of 235-245 days. The female reproductive threshold is when body weightis ¢. 160 kg. In captive animals, the onset of estrus and mating occur most often during the night. Most cows first calve as three-year-olds and have been recorded to calve up to 18 years of age. Twinning is rare. Calving takes place within the herd and young are born at temperatures as low as —30°C. At birth, calves weigh about 10 kg. Young males do not participate in mating until they are physically mature enough to challenge older males, probably at 5-8 years of age. In the Arctic National Wildlife Refuge in Alaska, calf-female ratios in June 2000 and 2001 declined to fewer than 5 calves:100 females greater than two years of age, compared to an average of 48 calves:100 females in 1990-1994 and 29 calves:100 females in 1995-1999. Increased Brown Bear predation was implicated as a major cause of the calf decline. A female in the wild lived for more than thirty years, but most probably do not live beyond twenty years of age.
Activity patterns. Muskoxen alternate resting and feeding. Feeding is the dominant activity during winter. Calves tend to spend more time lying and standing and less time feeding than other age classes. Males in bachelor herds spend a greater proportion of time foraging and less time resting than they do when in mixed herds.
Movements, Home range and Social organization. Muskoxen can move over large areas; tagged animals have been recorded to move 120-130 km. However, most populations have regular patterns of local movements and seasonal migrations. Herd size is usually 5-12 animals in summer and 12-30 in winter. Groups may exhibit loose cohesion; shifting of individuals between groups is characteristic. Adult males occur as harem bulls in mixed herds, in bachelor groups, or alone. Large populations can have densities of 1-5-2 ind/km?. In the Taymyr Peninsula, Russia, herd size consisted of 17-23 animals at high population densities. Young males tend to remain in herds with their mothers until the age of two. Some remain with female herds until they are subadults, depending on the aggressiveness of dominant males.
Status and Conservation. Classified as Least Concern on The IUCN Red List. Muskoxen were historically present from Point Barrow in Alaska, and extended across the circumpolar Arctic through Canada into north-eastern Greenland, and south as far as north-east Manitoba. In the 19" century the species became extinct in Alaska, but was reestablished from Greenland stock, initially on Nunivak Island, in 1936. Nunivak Island Muskoxen were introduced on Nelson Island and into north-eastern and north-western Alaska and the Seward Peninsula between 1967 and 1981. The introduced populations in north-eastern and north-western Alaska are the only ones living within the historical distribution of the species. From north-eastern Alaska, Muskoxen spread to north-western Yukon, in Canada. They were never extirpated in Canada or Greenland, although their distribution became reduced in the former. Now Muskoxen naturally occur on the tundra west of Hudson Bay in Nunavat, Canada, and extend westward through the Northwest Territories, reaching almost to the Mackenzie River. They are also present on most of the larger islands of the Arctic Archipelago, with the exception of Baffin Island, and have been introduced into northern Quebec. Extinct in Russia for 2000-3000 years, they were successfully reintroduced on the Taymyr Peninsula and also on Wrangel Island and Yakutia (Anabar River, Ust-Lensky Nature Reserve, Indigirka River) in Siberia. An estimated 121,000 Muskoxen occur in Canada, of which 75,400 are in the Northwest Territories and 45,300 in Nunavat. The total population in Alaska is ¢.3700. There are 9500-12,500 in Greenland and ¢. 2000 in Russia. Unregulated commercial hunting was the cause for the extirpation and decline of populations. Muskox numbers have increased; they have reoccupied historical ranges, and have been introduced in areas outside their historical distribution. Strictly controlled sport and subsistence hunting is permitted in Alaska, Canada, and Greenland, as is the commercial harvest for meat and hides, including the extremely fine underwool “qiviut.” Many ecological aspects of Muskox habitat and interspecific relationships remain unknown. Climate warming is likely to have a negative impact.
Bibliography. Barboza et al. (2004), Baskin & Danell (2003), Coté et al. (1997), Crater & Barboza (2007), Groves (1997), Groves & Grubb (2011), Grubb (2005), Gunn & Adamczewski (2003), Gunn & Forchhammer (2008), Hassanin et al. (2009), Ihl & Barboza (2005), Klein (2000), Larter & Nagy (2004), Lent (1978, 1988, 1999), Long (2003), Lyberth et al. (2007), Munn et al. (2009), Nowak (1999), Peltier & Barboza (2003), Reynolds et al. (2002), Rowell et al. (2003), Smith et al. (2002).
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