All you need to know about the Muskoxen
The muskox (Ovibos moschatus, in Latin "musky sheep-ox"), also spelled musk ox and musk-ox (in Inuktitut: ᐅᒥᖕᒪᒃ, umingmak; in Woods Cree: ᒫᖨᒨᐢ, mâthi-môs, ᒫᖨᒧᐢᑐᐢ, mâthi-mostos), is an Arctic hoofed mammal of the family Bovidae, noted for its thick coat and for the strong odor emitted during the seasonal rut by males, from which its name derives. This musky odor is used to attract females during mating season. Its Inuktitut name "umingmak" translates to "the bearded one".
Its Woods Cree names "mâthi-môs" and "mâthi-mostos" translate to "ugly moose" and "ugly bison", respectively. Muskoxen primarily live in Greenland and the Canadian Arctic of the Northwest Territories and Nunavut, with introduced populations in the American state of Alaska, the Canadian territory of Yukon, the Scandinavian Peninsula, and Siberia.
Evolution
Extant relatives
As a member of the subfamily Caprinae of the family Bovidae, the muskox is more closely related to sheep and goats than to oxen; however, it is placed in its own genus, Ovibos (Latin: "sheep-ox").
It is one of the two largest extant members of Caprinae, along with the similarly sized takin. While the takin and muskox were once considered possibly closely related, the takin lacks common ovibovine features, such as the muskox's specialized horn morphology, and genetic analysis shows that their lineages actually separated early in caprine evolution.
Instead, the muskox's closest living relatives appear to be the gorals of the genus Naemorhedus, nowadays common in many countries of central and east Asia. The vague similarity between takin and muskox must therefore be considered an example of convergent evolution.
Fossil history and extinct relatives
The modern muskox is the last member of a line of ovibovines that first evolved in temperate regions of Asia and adapted to a cold tundra environment late in its evolutionary history.
Muskox ancestors with sheep-like high-positioned horns (horn cores being mostly over the plane of the frontal bones, rather than below them as in modern muskoxen) first left the temperate forests for the developing grasslands of Central Asia during the Pliocene, expanding into Siberia and the rest of northern Eurasia.
Later migration waves of Asian ungulates that included high-horned muskoxen reached Europe and North America during the first half of the Pleistocene. The first well known muskox, the "shrub-ox" Euceratherium, crossed to North America over an early version of the Bering Land Bridge two million years ago and prospered in the American southwest and Mexico.
Euceratherium was larger yet more lightly built than modern muskoxen, resembling a giant sheep with massive horns, and preferred hilly grasslands.
A genus with intermediate horns, Soergelia, inhabited Eurasia in the early Pleistocene, from Spain to Siberia, and crossed to North America during the Irvingtonian (1.8 million years to 240,000 years ago), soon after Euceratherium. Unlike Euceratherium, which survived in America until the Pleistocene-Holocene extinction event, Soergelia was a lowland dweller that disappeared fairly early, displaced by more advanced ungulates, such as the "giant muskox" Praeovibos (literally "before Ovibos").
The low-horned Praeovibos was present in Europe and the Mediterranean 1.5 million years ago, colonized Alaska and the Yukon one million years ago and disappeared half a million years ago.
Praeovibos was a highly adaptable animal that appears associated with cold tundra (reindeer) and temperate woodland (red deer) faunas alike. During the Mindel glaciation 500,000 years ago, Praeovibos was present in the Kolyma river area in eastern Siberia in association with many Ice Age megafauna that would later coexist with Ovibos, in the Kolyma itself and elsewhere, including wild horses, reindeer, woolly mammoth and stag-moose.
It is debated, however, if Praeovibos was directly ancestral to Ovibos, or both genera descended from a common ancestor, since the two occurred together during the middle Pleistocene. Defenders of ancestry from Praeovibos have proposed that Praeovibos evolved into Ovibos in one region during a period of isolation and expanded later, replacing the remaining populations of Praeovibos.
Two more Praeovibos-like genera were named in America in the 19th century, Bootherium and Symbos, which are now identified as the male and female forms of a single, sexually dimorphic species, the "woodland muskox", Bootherium bombifrons.
Bootherium inhabited open woodland areas of North America during the late Pleistocene, from Alaska to Texas and maybe even Mexico, but was most common in the Southern United States, while Ovibos replaced it in the tundra-steppe to the north, immediately south of the Laurentian ice sheet.
Modern Ovibos appeared in Germany almost one million years ago and was common in the region through the Pleistocene. By the Mindel, muskoxen had also reached the British Isles. Both Germany and Britain were just south of the Scandinavian ice sheet and covered in tundra during cold periods, but Pleistocene muskoxen are also rarely recorded in more benign and wooded areas to the south like France and Green Spain, where they coexisted with temperate ungulates like red deer and aurochs. Likewise, the muskox is known to have survived in Britain during warm interglacial periods.
Today's muskoxen are descended from others believed to have migrated from Siberia to North America between 200,000 and 90,000 years ago, having previously occupied Alaska (at the time united to Siberia and isolated periodically from the rest of North America by the union of the Laurentide and Cordilleran Ice Sheets during colder periods) between 250,000 and 150,000 years ago.
After migrating south during one of the warmer periods of the Illinoian glaciation, non-Alaskan American muskoxen would be isolated from the rest in the colder periods. The muskox was already present in its current stronghold of Banks Island 34,000 years ago, but the existence of other ice-free areas in the Canadian Arctic Archipelago at the time is disputed.
Along with the bison and the pronghorn, 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. The muskox is thought to have been able to survive the last glacial period by finding ice-free areas (refugia) away from prehistoric peoples.
Fossil DNA evidence suggests that muskoxen were not only more geographically widespread during the Pleistocene, but also more genetically diverse.
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.
Physical characteristics
Both male and female muskoxen 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).
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. However, heavy zoo-kept specimens have weighed up to 650 kg (1,400 lb).
Their coat, a mix of black, grey, and brown, includes long guard hairs that almost reach the ground. Rare "white muskoxen" have been spotted in the Queen Maud Gulf Bird Sanctuary. Muskoxen are occasionally domesticated for wool, meat, and milk. 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).
A muskox can reach speeds of up to 60 km/h (37 mph). Their life expectancy is 12–20 years.
Range
Prehistory
During the Pleistocene period, muskoxen were much more widespread. Fossil evidence shows that they lived across the Siberian and North American Arctic, from the Urals to Greenland. The ancestors of today's muskoxen came across the Bering Land Bridge to North America between 200,000 and 90,000 years ago.
During the Wisconsinan, modern muskox thrived in the tundra south of the Laurentide Ice Sheet, in what is now the Midwest, the Appalachians and Virginia, while distant relatives Bootherium and Euceratherium lived in the forests of the Southern United States and the western shrubland, respectively.
Though they were always less common than other Ice Age megafauna, muskox abundance peaked during the Würm II glaciation 20,000 years ago and declined afterwards, especially during the Pleistocene/Holocene extinction event, where its range was greatly reduced and only the populations in North America survived. The last known muskox population in Europe died out in Sweden 9,000 years ago, and the last one in Asia, which lived on Siberia's Taymyr Peninsula, about 2,000 years ago.
After the disappearance of the Laurentide Ice Sheet, the muskox gradually moved north 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.
Recent native range in North America
In modern times, muskoxen were restricted to the Arctic areas of Northern Canada, Greenland, and Alaska. 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. However, muskoxen have since been reintroduced to Alaska.
The United States Fish and Wildlife Service introduced the muskox onto Nunivak Island in 1935 as a means for subsistence living. Other reintroduced populations are in Arctic National Wildlife Refuge, Bering Land Bridge National Preserve, Yukon's Ivvavik National Park, a wildlife conservation center in Anchorage, Aulavik National Park in Northwest Territories, Kanuti National Wildlife Refuge, Gates of the Arctic National Park, and Whitehorse, Yukon's wildlife preserve.
There have been at least two domestication endeavours. In the 1950s an American researcher and adventurer was able to capture muskox calves in Northern Canada for relocation to a property he prepared in Vermont. One condition imposed by the Canadian government was he was not allowed to kill adults defending their young.
When nets and ropes proved useless, he and his crew herded family groups into open water where calves were successfully separated from the adults. Once airfreighted to Montreal and trucked to Vermont, the young animals habituated to the temperate conditions.
Although the calves thrived and grew to adulthood, parasite and disease resistance problems impaired the overall success of the effort. The surviving herd was eventually moved to a farm in Palmer, Alaska, which has been successful since the mid-1950s.
Social behavior and reproduction
Muskoxen live in herds of 12–24 in the winter and 8–20 in the summer. They do not hold territories, but they do mark their trails with preorbital glands. Male and female muskoxen both have separate age-based hierarchies, with mature oxen being dominant over juveniles.
Dominant oxen tend to get access to the best resources and will displace subordinates from patches of grass during the winter. Muskox 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.
Bulls will also roar, swing their heads, and paw the ground. 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. Dominant bulls will also mock copulate subordinates and sniff their genitals. A subordinate bull can change his status by charging a dominant bull.
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.
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. Subordinate and elderly bulls will leave the herds to form bachelor groups or become solitary.
However, when danger is present, the outside bulls can return to the herd for protection. Dominant bulls will prevent cows from leaving their harems. 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. The herds reassemble when summer ends.
While the bulls are more aggressive during the rutting season and make the decisions in the groups, the females take charge during gestation. Pregnant females are aggressive and decide what distance the herd travels in a day and where they will bed for the night.
The herds move more frequently when cows are lactating, to allow them to get enough food to nurse their offspring. Cows have an eight- to nine-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. Muskox are precocial, and calves are able to keep up with the herd within just a few hours after birth. The calves are welcomed into the herd and nursed for the first two months. 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.
The bulls are usually the front line for defense against predators with the cows and juveniles gathering close to them. Bulls determine the defensive formation during rutting, while the cows decide the rest of the year.
Components of glandular secretions
The preorbital gland secretion of muskoxen has a "light, sweetish, ethereal" odor. Analysis of preorbital gland secretion extract showed the presence of cholesterol (which is nonvolatile), benzaldehyde, a series of straight-chain saturated gamma-lactones ranging from C8H14O2 to C12H22O2 (with C10H18O2 being most abundant), and probably the monounsaturated gamma lactone C12H20O2. The saturated gamma-lactone series has an odor similar to that of the secretion.
The odor of dominant rutting males is "strong" and "rank". It derives from the preputial gland and is distributed over the fur of the abdomen via urine.
Analysis of extract of washes of the prepuce revealed the presence of benzoic acid and p-cresol, along with a series of straight-chain saturated hydrocarbons from C22H46 to C32H66 (with C24H50 being most abundant).
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