Wild yak

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Wild yak
Temporal range: 5–0  Ma
Early Pliocene – Recent
Wild Yak Stuffed.jpg
Stuffed specimen
CITES Appendix I (CITES) [1]
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Bovidae
Subfamily: Bovinae
Genus: Bos
B. mutus
Binomial name
Bos mutus
Przewalski, 1883
Bos mutus map.png
Distribution of wild yak
  • Species Level:
    • Poephagus mutus
  • Subspecies Level:
    • Bos grunniens mutus
    • Bos primigenius mutus
    • Poephagus grunniens mutus

The wild yak (Bos mutus) is a large, wild bovine native to the Himalayas. It is the ancestor of the domestic yak (Bos grunniens).



The ancestor of the wild and domestic yak is thought to have diverged from Bos primigenius at a point between one and five million years ago. [2] The wild yak is now normally treated as a separate species from the domestic yak (Bos grunniens). [3]


The wild yak is among the largest extant bovid species. Adults stand about 1.6 to 2.05 m (5.2 to 6.7 ft) tall at the shoulder, and weigh 500–1,200 kg (1,100–2,600 lb). The head and body length is 2.4 to 3.8 m (7.9 to 12 ft), not counting the tail of 60 to 100 cm (24 to 39 in). [4] The females are about one-third the weight and are about 30% smaller in their linear dimensions when compared to bull wild yaks. Domesticated yaks are somewhat smaller. [5] [6] [7] [8]

They are heavily built animals with a bulky frame, sturdy legs, and rounded cloven hooves. To protect against the cold, the udder in females and the scrotum in males are small, and covered in a layer of hair. Females have four teats. Both sexes have long shaggy hair, with a dense woolly undercoat over the chest, flanks, and thighs for insulation against the cold. In males especially, this undercoat may form a long "skirt" that can reach the ground. The tail is long and horse-like, rather than tufted like the tails of cattle or bison. The coat is typically black or dark brown, covering most of the body, with a grey muzzle (although some wild golden-brown individuals have been reported). Wild yaks with gold coloured hair are known as the wild golden yak (Chinese :金色野牦牛; pinyin :jīnsèyě máoniú). They are considered an endangered subspecies in China, with an estimated population of 170 left in the wild. [9]

Two morphological types have been identified, so-called Qilian and Kunlun. [4]

Distribution and habitat

Wild yaks once ranged up to southern Siberia to the east of Lake Baikal, [10] but became extinct in Russia around the 17th century. [11] Today, wild yaks are found primarily in northern Tibet and western Qinghai, with some populations extending into the southernmost parts of Xinjiang, and into Ladakh in India. Small, isolated populations of wild yak are also found farther afield, primarily in western Tibet and eastern Qinghai. In historic times, wild yaks were also found in Bhutan, but they are now considered extinct there. [1]

The primary habitat of wild yaks consists of treeless uplands between 3,000 and 5,500 m (9,800 and 18,000 ft), dominated by mountains and plateaus. They are most commonly found in alpine tundra with a relatively thick carpet of grasses and sedges rather than the more barren steppe country. [12]

The wild yak was thought to be regionally extinct in Nepal in the 1970s, but was rediscovered in Humla in 2014. [13] [14] This discovery later made the species to be painted on Nepal's currency. [15]

Behaviour and ecology

A painting of a wild yak, published by Rowland Ward LTD in 1898. Wild oxen, sheep and goats of all lands, living and extinct (Plate IV) BHL9370000.jpg
A painting of a wild yak, published by Rowland Ward LTD in 1898.

The diet of wild yaks consists largely of grasses and sedges, such as Carex , Stipa , and Kobresia . They also eat a smaller amount of herbs, winterfat shrubs, and mosses, and have even been reported to eat lichen. Historically, the main natural predator of the wild yak has been the Himalayan wolf, but Himalayan black bears, Himalayan brown bears and snow leopards have also been reported as predators in some areas, likely of young or infirm wild yaks. [9]

Thubten Jigme Norbu, the elder brother of the 14th Dalai Lama, reported on his journey from Kumbum in Amdo to Lhasa in 1950:

Before long I was to see the vast herds of drongs with my own eyes. The sight of those beautiful and powerful beasts who from time immemorial have made their home on Tibet's high and barren plateaux never ceased to fascinate me. Somehow these shy creatures manage to sustain themselves on the stunted grass roots which is all that nature provides in those parts. And what a wonderful sight it is to see a great herd of them plunging head down in a wild gallop across the steppes. The earth shakes under their heels and a vast cloud of dust marks their passage. At nights they will protect themselves from the cold by huddling up together, with the calves in the centre. They will stand like this in a snow-storm, pressed so close together that the condensation from their breath rises into the air like a column of steam. The nomads have occasionally tried to bring up young drongs as domestic animals, but they have never entirely succeeded. Somehow once they live together with human beings they seem to lose their astonishing strength and powers of endurance; and they are no use at all as pack animals, because their backs immediately get sore. Their immemorial relationship with humans has therefore remained that of game and hunter, for their flesh is very tasty.

Thubten Norbu, Tibet is My Country [16]

Wild yaks are herd animals. Herds can contain several hundred individuals, although many are much smaller. Herds consist primarily of females and their young, with a smaller number of adult males. On average female yaks graze 100m higher than males. Females with young tend to choose grazing ground on high, steep slopes. [17] The remaining males are either solitary, or found in much smaller groups, averaging around six individuals. Groups move into lower altitude ranges during the winter. [1] Although wild yaks can become aggressive when defending young, or during the rut, they generally avoid humans, and may flee for great distances if approached. [9]


Wild yaks mate in summer and give birth to a single calf the following spring. [18] Females typically only give birth every other year. [9]


The wild yak is currently listed as Vulnerable on the IUCN Red List. It was previously classified as Endangered, but was downlisted in 1996 based on the estimated rate of population decline and current population sizes. The latest assessment in 2008 suggested a total population of no more than 10,000 mature individuals. [1]

The wild yak is experiencing threats applied by several sources. Poaching, including commercial poaching, has remained the most serious threat; males are particularly impacted because of their more solitary habits. Disturbance by and interbreeding with livestock herds is also common. This may include the transmission of cattle-borne diseases, although no direct evidence of this has yet been found. Conflicts with herders themselves, as in preventive and retaliatory killings for abduction of domestic yaks by wild herds, also occur but appear to be relatively rare. Recent protection from poaching particularly appears to have stabilized or even increased population sizes in several areas, leading to the IUCN downlisting in 2008. In both China and India, the species is officially protected; in China it is present in a number of large nature reserves. [1]

Impact on humans

The wild yak is a reservoir for zoonotic diseases of both bacterial and viral origins. Such bacterial diseases include anthrax, botulism, tetanus, and tuberculosis. [19]

Related Research Articles

<span class="mw-page-title-main">Bison</span> Genus of mammals

Bison are large bovines in the genus Bison within the tribe Bovini. Two extant and numerous extinct species are recognised.

<span class="mw-page-title-main">Bovinae</span> Subfamily of mammals

Bovines comprise a diverse group of 10 genera of medium to large-sized ungulates, including cattle, bison, African buffalo, water buffalos, and the four-horned and spiral-horned antelopes. The evolutionary relationship between the members of the group is still debated, and their classification into loose tribes rather than formal subgroups reflects this uncertainty. General characteristics include cloven hooves and usually at least one of the sexes of a species having true horns. The largest extant bovine is the gaur.

<i>Bos</i> Genus of wild and domestic cattle

Bos is the genus of wild and domestic cattle. Bos is often divided into four subgenera: Bos, Bibos, Novibos, and Poephagus, but including these last three divisions within the genus Bos without including Bison in the genus is believed to be polyphyletic by many workers on the classification of the genus since the 1980s. The genus as traditionally defined has five extant species but this rises to eight when the domesticated varieties are counted as separate species, and ten when the closely related genus Bison is also included. Most but not all modern breeds of domesticated cattle are believed to have originated from the extinct aurochs. Many ancient breeds are thought to have originated from other species. Zebus and taurine cattle are thought to descend from ancient Indian and Middle Eastern aurochs, respectively.

<span class="mw-page-title-main">Gaur</span> Largest species of the bovid family

The gaur, also known as the Indian bison, is a bovine native to South Asia and Southeast Asia, and has been listed as Vulnerable on the IUCN Red List since 1986. The global population was estimated at a maximum of 21,000 mature individuals in 2016, with the majority of those existing in India. It has declined by more than 70% during the last three generations, and is extirpated from Sri Lanka and most likely Bangladesh. Populations in well-protected areas are stable and increasing.

<span class="mw-page-title-main">Yak</span> Long-haired domesticated bovid

The domestic yak, also known as the Tartary ox, grunting ox or hairy cattle, is a species of long-haired domesticated cattle found throughout the Himalayan region of the Indian subcontinent, the Tibetan Plateau, Kachin State, Yunnan, Sichuan, Gilgit-Baltistan (Kashmir), and as far north as Mongolia and Siberia. It is descended from the wild yak.

<span class="mw-page-title-main">Gayal</span> Species of domestic cattle

The gayal, also known as the Drung ox or mithun, is a large domestic cattle distributed in Northeast India, Bangladesh, Myanmar and in Yunnan, China.

<span class="mw-page-title-main">Banteng</span> Species of wild cattle discovered in Southeast Asia

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<span class="mw-page-title-main">Markhor</span> Species of mammal

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<span class="mw-page-title-main">Tibetan antelope</span> Species of mammal

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<span class="mw-page-title-main">Wild water buffalo</span> Species of mammal

The wild water buffalo, also called Asian buffalo, Asiatic buffalo and wild buffalo, is a large bovine native to the Indian subcontinent and Southeast Asia. It has been listed as Endangered in the IUCN Red List since 1986, as the remaining population totals less than 4,000. A population decline of at least 50% over the last three generations is projected to continue. The global population has been estimated at 3,400 individuals, of which 3,100 (91%) live in India, mostly in Assam. The wild water buffalo is the most likely ancestor of the domestic water buffalo.

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  13. Extinct Wild Yak found in Nepal
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  15. Josua Learn, 2019, Snapping the Yak: How an Iconic Photo Ended Up on Nepal's Currency
  16. Tibet is My Country: Autobiography of Thubten Jigme Norbu, Brother of the Dalai Lama as told to Heinrich Harrer, p. 151. First published in German in 1960. English translation by Edward Fitzgerald, published 1960. Reprint, with updated new chapter, (1986). Wisdom Publications, London. ISBN   0-86171-045-2.
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  19. Dubal, Z (2013). "Bacterial and Viral Zoonotic Diseases of Yak" (PDF). S2CID   51834203. Archived from the original (PDF) on 19 September 2018. Retrieved 18 September 2018.{{cite journal}}: Cite journal requires |journal= (help)