Bos mutus

The yak (Bos mutus or Bos grunniens) is a medium-sized bovid mammal with woolly fur, native to the mountains of Central Asia and the Himalayas, it lives in the steppe plateaus and cold deserts of Nepal, Tibet, Pamir and Karakoram, between 4000 and 6000 meters of altitude, where it is found both in the wild and domestic.

La palabra n#39;yak' es del idioma tibetano གཡག་ - yag, o gyag, donde solamente el macho es llamado así, la hembra es una dri o nak.

Description

Wild specimens (subspecies mutus), now rare, are gregarious animals with invariably long hair (especially in the abdominal area, where it can reach the ground), dense and black (in the old animals adopts a brown tone) that hangs on both sides of the body and also from the extremities, with a hump on the shoulders and long horns a meter in length that emerge on both sides of the broad skull, almost horizontally, to then bend downwards. up and somewhat inward. The tail is hairy from its very base and has a large tuft at the end.

Males, which are larger than females (they only reach half the size of males), can reach 2 meters in height at the withers — which appears so high due to an elongation of the process spiny, that the head seems to start from a lower position—and weigh up to 1000 kilos. The hooves have a large support surface, while the secondary hooves scrape the ground while climbing. Females have two pairs of breasts. The body is elongated, which is due, in part, to the fact that it has a pair more ribs (14 in total) than the other bovids.

Taxonomy

Linnaeus classified domestic yaks as Bos grunniens (Latin: grunning ox) in 1766, later the wild variety was classified as Bos mutus ("mute ox") when it was shown that they belonged to the same species, it had to be assigned a single scientific name. Generally in cases like this the priority principle used in scientific nomenclature would be applied, which establishes that the one registered first must remain as the specific name, with grunniens being the oldest.

But the International Commission on Zoological Nomenclature determined in 2003 in opinion 2027 that yaks, like 17 other domestic species, should be named after their wild variety, Bos mutus, to avoid the paradox that the previous lineages, the wild ones, were named as subspecies of their descendants. Therefore, the specific name that prevails for yaks is Bos mutus, leaving the term Bos mutus grunniens as the trinomial name that designates the domestic subspecies.

Yaks belong to the genus Bos, so they are closely related to domestic cows (Bos primigenius taurus). Mitochondrial DNA analyzes to determine the evolutionary history of yaks have been somewhat confusing. The yak may have diverged from the bull at some point between one and five million years ago, and there is some indication that it may be more closely related to bison than to other members of its own genus. Fossils of what have been found have been found. which appear to be close relatives of the yak, such as Bos baikalensis, in eastern Russia, suggesting a possible route by which yak-like ancestors of American bison could have entered the American continent.

Behavior

They are the ungulates that ascend to the highest altitudes, as they can reach 6000 meters above sea level. They feed on low plants and lack predators, although they can be attacked (very rarely) by bears, wolves and snow leopards.

Wild yak herds consist of females, calves and young animals. Males live alone or in groups of up to 12 individuals. The yak stays in places that offer good pasture, frequents areas of grass and lichens; If these are scarce, they immediately migrate to another place. Their good sense of smell allows them to always find the most suitable places. It is an animal that distributes its activity at dawn and dusk, being a good climber on steep, snow-covered rocky terrain. To feel comfortable he needs water and he also likes to bathe. The yaks huddle together during snow storms, turning their rear ends toward the wind. Excited animals raise their tails upward, as if it were a flag. Packs of wolves attack yaks and capture mainly calves. For this reason, an attacked herd places, if possible, its calves in the center.

Yak growls can be heard during the mating season. The males then fight each other vigorously, so that on many occasions they are seriously injured. The mating period begins in September, lasting until the end of October. The females give birth to a calf after a gestation that has lasted about 270 days. Wild yak females only give birth once every 2 years. They reach sexual maturity when they are 6 to 8 years old.

Domestication

Yaks have been domesticated for 3000 years. The domestic yak has a height at the withers of 140 centimeters for a weight of 700 kilograms. They can be crossed with domestic cows and generate fertile individuals producing more milk and a higher fat content. In fact, much of the differences between wild and domestic yaks are due to this characteristic. The latter are much smaller than their wild ancestors, they have shorter horns and even many domestic yaks lack them and the color of the hair can be black, brown, chestnut, whitish and even spotted in various colors. The yak is bred as a domestic animal in cold areas in extensive regions of Asia, ranging from Afghanistan and Bukhara to Mongolia and northern China. Relatively recently, yaks were imported into southern Greenland, being the only domestic animal of its kind. size that has managed to acclimatize perfectly on the island.

In Central Asia they are used to carry loads (they can transport a load of 150 kilograms along steep mountain paths), they are also used to ride and pull the plow. They are also raised for their meat, which is suitable for human consumption. It produces very fatty milk (with which high-quality cheeses and butter are made), although in smaller quantities than other domestic bovine animals and skins (resistant and warm).. The yak tail is used as a fly repellent.

The yak is sheared once a year, the wool of the adult animals being somewhat rough and long, but it can be perfectly used to make blankets, ropes and other objects. The dried excrement is used as fuel, highly appreciated In areas poor in wood due to the high altitude, the yak is a highly appreciated animal in Tibet, where families decorate their animals with ribbons both to differentiate them from others and for simple aesthetic reasons.

Conservation

The wild yak is currently listed as Vulnerable on the IUCN Red List. It was previously classified as endangered, but was downgraded in 1996 based on the estimated rate of population decline and current population size. The last assessment in 2008 suggested a total population of no more than 10,000 mature individuals. The wild yak is experiencing threats from various sources. Poaching, including commercial poaching, remains the most serious threat; males are particularly affected by their more solitary habits. Disturbance and interbreeding with herds of cattle is also common. This may include the transmission of livestock-borne diseases, although direct evidence of this has not yet been found. Conflicts with the herders themselves also occur, such as in pre-emptive and retaliatory killings for the kidnapping of domestic yaks by wild herds, but appear to be relatively rare. Recent protection against poaching in particular appears to have stabilized or even increased population size in several areas, leading to IUCN delisting in 2008. In both China and India, the species is protected officially; In China it is present in several large nature reserves.

Gallery

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  Yak with wet coat in Altái.

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  Yaks grazing.

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  Yak with traditional ornaments in Sikkim, India.

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  Pastoralism of yaks in Tajikistan.

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  Yak caravan in Solukhumbu, Nepal.

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  Yak wool yarn yarn.

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  Yak milk butter in Lhasa market, Tibet.

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  Statue of yak in Lhasa.