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Wild Yak - Bos grunniens
Topic Started: Jan 7 2012, 02:25 PM (6,641 Views)
Taipan
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Wild Yak - Bos grunniens

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Facts
Also known as: Yak
Previously known as: Bos mutus and Bos mutus grunniens
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Artiodactyla
Family Bovidae
Genus Bos (1)

Size
Body Length: Up to 325 cm / 10.8 ft.
Shoulder Height: Up to 200 cm / 6.6 ft.
Tail Length: 60 cm / 24 in.
Weight: 305-820 kg / 670-1805 lb.

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Description
A huge and imposing hulk of an animal, the wild yak has stocky, high and humped shoulders and a broad, drooping head. Both males and females have horns, which grow out of the sides of the head and curve upwards halfway along their length. The horns of females are shorter than those of the males, reaching just 51 cm, compared to 95 cm in males; females are also just one third of the body size of males. For protection against the extreme cold of Tibet, the wild yak has a dense undercoat of soft, closely-matted fur, covered by dark brown, long and shaggy hair that almost reaches the ground. The legs are relatively short and have broad hooves that are slightly splayed to aid walking through thick snow.

Range
The wild yak was once numerous and widespread on the entire Tibetan plateau to the north of the Himalayas, but it is now found only in remote areas of this region, where there is little human disturbance. A few wild yaks have been seen in the Chang Chemmo Valley of Ladakh in eastern Kashmir, India. The wild yak is thought to number 10,000 to 15,000, and is distinct from the smaller domestic yak, whose population numbers 12,000,000 .

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Habitat
Found in alpine tundra and cold desert regions in uninhabited mountainous regions between 4,000 and 6,000 metres altitude. These regions are subject to temperatures dropping below -40ºC, much hail and snow, saline lakes and sparse vegetation. The wild yak spends the colder months of the year at lower elevations, but retreats into higher regions during the warmer period between August and September each year.

Biology
Well adapted for life in cold and harsh conditions, the wild yak is protected from the cold by its thick coat and low number of sweat glands, which help to conserve body heat. It has a large lung capacity and particularly small and numerous red blood cells, enabling it to get the most oxygen possible from the thin, mountain air. Considering its bulk, the wild yak is fairly nimble as it moves around on snowy rocks, grazing on grasses, herbs and lichens, and eating ice and snow as a source of water. It feeds mostly in the morning and evening, and will travel long distances due to the scarcity of the vegetation. With so much protection against cold weather, the wild yak is very sensitive to heat and moves seasonally to avoid higher temperatures. It can withstand strong winds and snowstorms for hours, but may bathe in lakes and streams when the temperature is exceptionally low.

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Wild yaks tend to gather together, especially the females and young, forming herds of usually 10 to 30 animals, but herds up to 200 are also found. Herds have no fixed members and may join together, or split into smaller herds. Females reach sexual maturity at three to four years, although full size is not reached until six to eight years. Mating takes place in September and single calves are born from April to June, after a gestation of 260 days. The young are weaned before they are one year old, but females will not give birth again for another year. Wild yaks can live for up to 23 years.

Threats
Wild yaks are hunted commercially for their meat. Also, habitat loss brought about by pastoralists has reduced their range by more than half in the last hundred years. Interbreeding between domestic yaks and wild yaks, as well as the transmission of diseases from domestic livestock to wild yaks has also contributed to a decline in population numbers.


Status
The wild yak is classified as Vulnerable (VU A1cd + 2cd, C1) on the IUCN Red List 2004 and is listed on Appendix I of the Convention on Migratory Species (CMS or Bonn Convention). It is also listed under Schedule I of the Indian Wildlife Protection Act 1972.

Conservation
The wild yak has been protected in China since 1962 as a Class I protected animal, but this is almost completely without enforcement in the remote areas inhabited by yaks, and commercial hunting continues. Only the very large Chang Tang Reserve in China provides real protection for the remaining wild yak. Whilst the population is less significant in India, the wild yak is also protected there under the Wildlife Protection Act of 1972.

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Taipan
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Yak Fight

Edited by Taipan, Jun 20 2014, 04:53 PM.
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Mother Yaks Are a Step Above the Rest
To find food and dodge predators, mother yaks reach higher ground than males or childless females.


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A newborn yak stands close to its mother in the high-altitude Tibetan grasslands.

Martha M. Hamilton
for National Geographic
PUBLISHED JUNE 19, 2014

Female wild yaks don't worry about a glass ceiling.

In fact, according to a new study led by the Wildlife Conservation Society, mother yaks leave males behind in the valley bottoms and forage above them on steep mountain slopes that average 15,994 feet.

That's a height at which humans would be likely to develop altitude sickness, but it suits the huge, grazing mothers and other females—which gather at similar heights but on less steep slopes, and tend to make up much larger groups than males—just fine.

Bigger than bison, wild adult yaks range in shoulder height from about 5 to 7 feet (1.5 to 2.1 meters) and in weight from about 670 to 2,200 pounds (304 to 998 kilograms).

The steep terrain probably helps protect calves from predators, and the more humid high meadows produce higher protein food, says Joel Berger, lead author of the study conducted by U.S. and Chinese researchers in the last two months of 2012.

Tough Terrain

Because yaks are even harder to track in temperate seasons, the team worked in rough conditions.

"It was late winter and pretty cold," says Berger, a member of the Wildlife Conservation Society, a professor of wildlife conservation at the University of Montana, and a National Geographic grantee. "And we were camping. I think the coldest was minus 24 degrees."

The researchers also crossed large stretches of what Berger called "polarlike desert," looking for the widely distributed animals.

The males, especially, are widely distributed. They tend to congregate no more than two at a time, while females tend to cluster in groups of 30 on average.

Past Is Prologue?

Yaks are the largest grazers north of the tropics—and larger than American bison, their close relatives. Like bison in the U.S., the yaks that inhabit the Tibetan-Qinghai Plateau were once threatened by hunting.

Today they're listed as endangered species by both the Chinese and American governments. About 20 years ago, before the strong intervention of the Chinese government, "one could see yak skulls spread across the high elevation steppes just as bison skulls were 150 years ago" in the U.S., says Berger.

Yaks and bison are similar to each other in many ways but also different. For instance, noting the types of habitats in which bison are found—ranging from Mexico's Chihuahuan Desert to the evergreen forests in the far north of Canada—and the yaks' restriction to the cold climes of Asia, the study notes that "it is unclear whether the ecological partitioning of space and time in yak males and females would parallel that for bison."

In contrast to bison, which have recovered to some extent, yaks—because of their remote habitat—afford conservationists an opportunity to study a species' adaptations to climate and biological challenges without having to factor in the impact of human activity and habitat fragmentation.

Knowing how yaks use high-elevation habitat could help strengthen conservation programs in the Tibetan-Himalayan region, where glacial melting is among the fastest on Earth. The study is centered in an area about the size of Montana and Nebraska together, which is covered by other large reserves.

Whether the threat is melting glaciers, poaching, or hybridization with domestic yaks, the study concludes, knowing whether—and how—these factors force change among yaks "will require knowing something about how the two genders use space."

Maybe the lesson from female yaks to females of other species is to keep on aiming high.

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In a new study, researchers show that wild yak mothers are found on higher ground than their male counterparts. The scientists expect this is an adaptive way to avoid predators and to access more nutritious food.

http://news.nationalgeographic.com/news/2014/06/140619-yaks-mothers-wild-climb-altitude-tibet-himalaya-bison/
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Roberta


There is hardly any pictorial material to be found on the web regarding wild yaks using English search terms. I put together the following collection to rectify that. These pictures give a much better impression of the exact morphology of the wild yak than pages of dry words can; and they show so much better than descriptions how awesome and at the same time beautiful these creatures truly are.

A note up front: Depending on current strain on the Chinese internet, not all pictures may show. In that case, click on the picture or on the source link (the files may open easier directly than via hotlinks), or try again at a later time. Most of the pages these pictures came from show more yak pictures, so it is worthwhile to visit them. Some of these pages show a wild jumble of wild and domestic yaks; the domestic yaks can mostly be discerned by their differing colouration, by their differing horns (more upright, slenderer, and often differently shaped), by their more opulent belly hair, and sometimes by their differing body shapes.

A description of the wild yak from a Chinese website (www.xjtszx.com/cn/slziyuan/1208665242.html):

The Yak
Body
Large and heavy body, but slightly smaller than the India bison
[presumably the gaur (Bos gaurus; CV thread)], body length of 200 to 260 cm [6’7’’–8’6’’], tail length of 80 to 100 cm [2’7’’–3’3’’], 160 to 180 cm [5’3’’–5’11’’] tall at the shoulder and weighing 500 to 600 kg [1,100-1,320 lb]. The hair is dark brown, particularly long and thick, especially on neck, chest and abdomen, hanging almost to the ground, thus forming an efficient protection when climbing over ice or lying on snow. The hair on the tail is very long, like a broom in general, it appears fluffy and excessive in volume, and hangs down to the heel; it is unique among bovines. There are 14 pairs of ribs, one more than in the other bovine species. No dewlap [I hope I translated this correctly], a large shoulder hump, short limbs, a short, wide trunk. The horns are conical, with a smooth surface, they first extend sideways, then curve upwards, with tips slightly bent backwards; they are formed like a crescent in general. The horns are usually 40 to 50 cm long [16–20’’], their widest spread is nearly 1 meter [3’3’’].
Habits
Yak usually wander and forage in the grasslands in groups of only 20–30, though sometimes they form groups of 200–300. Wild yak generally do not take the initiative to attack people; despite their huge physique they have a calm demeanour, displaying a dignified, honest look.



Horns + Colour

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(Source: http://m.tayeo01.cn/nviv7tdun.html)

The colour of the wild yak as seen in the pictures ranges from dark reddish brown over dark brown to black. Wild yak are described as having silvery hair as a pale ring around the muzzle (“mealy mouth”, “muzzle ring”) and along their spine (“dorsal stripe”, “eel stripe”). The silvery mealy mouth is visible in a lot of pictures, the silvery eel stripe not so. Instead many brown yaks sport a blackish eel stripe, like the one discernible in the picture above.

The horns show the so-called “primigenius spiral”, named after the horn shape of the aurochs (Bos primigenius; CV thread). The horns extend sideways out of their bases and in a relatively smooth curve spiral forwards, upwards and inwards. Wild yak, aurochs and kouprey (Bos sauveli; CV thread) sported this horn shape. As the wild aurochs and (presumably) the kouprey are extinct, the wild yak is the only species left with this horn shape. Some domestic cattle species (aurochs and yak) may show it to a certain degree, best of all possibly Maronesa (outward link).

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Image by Miguel Omar Ruíz Hernández showing the 3-dimensional shape of the aurochs horn
(Source: http://breedingback.blogspot.co.at/2013/11/the-horns-of-aurochs.html)

A thorough description of the primigenius spiral can be found in the Breeding-back Blog, “The Horns of the Aurochs.” While the horns of the aurochs were oriented at an angle of 60° to the face on average, though, the wild yak’s horns are oriented higher according to the pictures, at approximately 90°.

Horns are probably the feature by which individual yaks can best be recognised. Within the basic horn shape there is a lot of variation. The tips of the horns can be close together or wide apart, pointing more upwards or more inwards, some yaks have very tightly curved horns, in some yaks the horn curve is mostly two-dimensional instead of three-dimensional, and so on. There is also some size variation. The two yaks in the picture above have relatively average-sized horns, the one below has the largest set of horns among these pictures.

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(Source: www.pai-hang-bang.com/meitu/最大野牦牛.html)

Sometimes pictures also show supposedly wild yak, but with a different horn shape more reminiscent of domestic yaks, as for example this picture (source; also posted above in post #1) and this picture (source). These pictures may either not show wild yak at all but domestic yaks with a wild-type colouration or crosses between domestic and wild yaks (note the fence in the background of the first picture), or they may show wild yak with an introgression of domestic yak genes. There is a minor flow of these genes into the wild yak population through escaped domestic yak cows (source).

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyaks
Edited by Roberta, May 8 2017, 08:09 AM.
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Roberta


Female wild yaks

The following four are the only pictures which with certainty show female yaks. Except for the mating season the sexes stay apart, with the female herds containing females, juveniles and calves migrating to higher elevations than the bull groups. This may also be a reason for the scarcity of pictures of female wild yak. Tourist groups and others simply are more prone to encounter the bull groups at the lower elevations.

Judging from the pictures, horn size does not seem to be much different between the sexes; maybe the horns of the females are a bit smaller on average in relation to body size. The colour of their coat also is pretty much the same. The most obvious difference between the sexes is their body size – if one were to see them together. (Edit: For more on sex dimorphism see post #13 below.)

In this picture the 90° horn angle is nicely visible:

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(Source: www.szfstkj.cn/photo/野牦牛.html)


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(“adult females and calves in Yeniugou, central Qinghai, China” – photo: Milo Burcham – source: www.bioone.org/doi/full/10.1644/836.1)


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(Photo: Joel Berger – source: www.livescience.com/26324-yaks-are-back.html)


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(“In the Kunlun Mountains of Tibet, a mixed herd of yak—-females, young males, and six-month-old calves—rest near a precipice in the Kekexili nature reserve” – photo: Joel Berger – source: http://news.nationalgeographic.com/news/2014/06/140619-yaks-mothers-wild-climb-altitude-tibet-himalaya-bison/)

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyaks
Edited by Roberta, May 18 2017, 07:20 AM.
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Roberta


Single wild yaks, presumably bulls

The following pictures might also be titled “Wild yak and human intruders.” I grouped them into three categories, ‘Watchful’, ‘Threatening’, and ‘Charging’.

Watchful yaks

The humans have ben spotted, the yaks are facing and watching them, but are otherwise relaxed.

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(Source: http://dcbbs.zol.com.cn/60/15_592965.html)


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                               (Source: http://e.dili360.com/ezhoukan/048/576.shtml)


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(Source: http://2010.shareoneplanet.org/pop_animal.aspx?id=57)


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(Source: www.kkxl.org.cn/gallery/3578)


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(Source: www.d3skg.com/content/m5SgeCGADocjg9Hb.html)

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyaks
Edited by Roberta, May 15 2017, 01:33 AM.
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Roberta


Watchful yaks, II

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                              (Source: http://bbs.photofans.cn/thread-554861-1-1.html)


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(Source: www.dwbiji.com/baohudongwu/372.html)


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(Photo: Milo Burcham – source: www.milosphotos.com/)


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(Source: www.animalinfo.org/species/artiperi/bos_mutu.htm)


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(Source: www.iltaw.com/animal/682)

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyaks
Edited by Roberta, May 15 2017, 01:33 AM.
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Roberta


Threatening yaks

These yaks have become agitated. They show this in two ways. All of them have raised their tails, and some have lowered their heads and are presenting their horns in a threatening pose. A couple already show some movement.

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                    (Source: http://bbs.photofans.cn/thread-554861-1-1.html)


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(Source: http://xzly.gov.cn/shengtai/wuzhong/22/show)


The dark eel stripe is very well visible in this yak:

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(Source: www.pai-hang-bang.com/meitu/西藏野牦牛.html)


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(Source: http://blog1.poco.cn/myBlogDetail-htx-id-7218255-userid-56498121-pri--n-0.xhtml)


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(Source: http://blog.cntv.cn/9068280-4590729.html)

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyaks
Edited by Roberta, May 16 2017, 02:21 AM.
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Roberta


Threatening yaks, II

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(Source: http://m.tayeo01.cn/nvntiddnv.html)


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                              (Source: http://mt.sohu.com/20160708/n458416167.shtml)


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                         (Source: www.67gu.com/qitu/94InypErnSCJaEZv.html)


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(Source: http://news.kedo.gov.cn/hotnews/hdpics/vision/622147.shtml#0)


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(Source: http://cn.photoint.net/picture-264.html)

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyaks
Edited by Roberta, May 19 2017, 07:51 AM.
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Roberta


Threatening yaks, III

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(Source: www.shareoneplanet.org/pop_animal.aspx?id=57)


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                    (Source: www.innovations-report.com/html/reports/environment-sciences/wild-yaks-shaggy-barometers-of-climate-change.html)


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(Photo: 康巴人 – source: http://bbs.photofans.cn/blog-271974-54320.html)


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(Photo: Milo Burcham – source: www.milosphotos.com/)


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(Source: www.bjjyj2012.com/photo/野牦牛主要分布.html)

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyaks
Edited by Roberta, May 19 2017, 07:51 AM.
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Roberta


Charging yaks

Finally, the yak charges. The Chinese-speaking web is full of such pictures. This may seem to be at variance with the statement quoted above that “[w]ild yak generally do not take the initiative to attack people; despite their huge physique they have a calm demeanour,” but I assume that all these yaks were very simply goaded into attacking. The photographer is not on foot, or even on horseback, they are sitting in a car, sometimes part of a convoy, and “the attacking yak”presumably simply is part of a tourist package.

The exception to this is the very first photo. The wild yak bull here had ‘taken over’ a herd of domestic yaks, and the owner with the help of a WCS volunteer was trying to chase off the intruder (again in a car, not on foot), without success. (The story in English and more pictures at WCS, “Chasing the Intruder.” For more wild yak info on the WCS site see WCS, search results for wild yak.)

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(Source: http://programs.wcs.org/china/News/LatestNews/tabid/6788/articleType/ArticleView/articleId/1239/Chasing_the_Intruder.aspx)


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(Source: www.klmy126.com/mayituku/yssy/2011/1221/8626.html)


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(Source: www.dianliwenmi.com/postimg_5044523_13.html)


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(Source: www.wtoutiao.com/a/2192278.html)


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(Source: http://www.paoshouji.com/tu-yeniu/野牦牛.html)


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(Source: www.chinascenic.com/magazine/from-winter-through-summer-the-great-migration-of-the-tibetan-antelope-221.html)


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                              (Source: www.tibetmagazine.net/xzwh/201404/t20140416_101920.htm)


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                    (Source: http://blog.cntv.cn/9068280-4590729.html)


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(Source: www.szfstkj.cn/photo/野牦牛.html)


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(Source: www.szfstkj.cn/photo/野牦牛.html)


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(Source: http://baike.haosou.com/doc/5645446.html)


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                                        (Source: http://bbs.photofans.cn/thread-554861-1-1.html)


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                         (Source: http://bbs.photofans.cn/thread-554861-1-1.html)


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(Source: www.97ysz.com/jijabaiukym.html)


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                                   (Source: http://yaklover.tumblr.com/)


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(Source: www.szfstkj.cn/photo/野牦牛.html)


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(Source: www.arkive.org/wild-yak/bos-mutus/)


Groups of wild yaks

After all those individuals now some groups of yaks. As I can discern no size difference within these groups (mature animals vs. juveniles or even calves) I assume that these all are bull groups. This would be at variance with the article quoted in post #3, which stated that bull yaks “tend to congregate no more than two at a time”, but seeing that in semi-feral domestic cattle (aurochs, not yak) young bulls form small groups (up to the age they are strong and dominant enough to gain access to cows in heat) and only the older ones, the breeding bulls, live singly or in pairs the same might well apply to the wild yak.

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(Source: www.97ysz.com/jijabaiukym.html)


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(Source: http://blog1.poco.cn/myBlogDetail-htx-id-7218255-userid-56498121-pri--n-0.xhtml)


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(Source: www.97ysz.com/jijabaiukym.html)


This group shows a very high variation in horn shape:

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(Source: www.pbase.com/cokesmith/image/146679858)

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(Source: www.97ysz.com/jijabaiukym.html]www.97ysz.com/jijabaiukym.html]www.97ysz.com/jijabaiukym.html)


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(Source: www.paoshouji.com/tu-yeniu/野牦牛.html)


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(Source: www.taoniu.com/maoniu/guonei/2013/0517/290.html)


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(Photo: 加贝先生 – source: http://abc1234566-78.blog.163.com/blog/static/602414200911613551937/)


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(Photo: 加贝先生 – source: http://abc1234566-78.blog.163.com/blog/static/602414200911613551937/)


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(Photo: 加贝先生 – source: http://abc1234566-78.blog.163.com/blog/static/602414200911613551937/)


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(Source: http://phone.ts.cn/content/content_10822035.htm)


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(Source: http://thewildernessalternative.com/2013/06/22/yeniugou-back-to-the-sillem-valley/yeniugou-2013-9/)


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(Source: http://thewildernessalternative.com/qinghai/qinghai-22-2/)

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyaks
Edited by Roberta, May 19 2017, 07:48 AM.
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Roberta


Wild yaks in movement

Now to some pictures of yaks in movement. I roughly divided these into two categories, walking yaks (slow to fast walk) and running yaks (slow canter to outright gallop).

Walking yaks

The first one again very nicely shows the 90° horn angle:

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(Source: http://m.tayeo01.cn/nviv7tdun.html)


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(Source: www.nzmc.org/ztg/564)


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(Source: www.97ysz.com/jijabaiukym.html)


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(Source: http://travel.163.com/15/0406/14/AMHA6RSV00063KE8.html)


This picture seems a bit hazy, despite the yak throwing a shadow. Maybe a dust storm coming? That might also explain the raised tail, which means the animal is not in a relaxed mood.

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(Source: http://niaolei.org.cn/posts/49383)


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(Source: www.wd147.com/wangluomeinv/phgnppd.html)


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(Source: http://finance.gansudaily.com.cn/system/2006/07/03/010066851.shtml)


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(Source: www.97ysz.com/jijabaiukym.html)


Running wild yaks

Wild yak and even domestic yak “can gallop like a horse – an attribute that is enjoyed by herdsmen who organize annual races.” (Wiener at al, The Yak, FAO )

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(Source: www.greenchina.tv/news-9867.xhtml)


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(Source: www.wildchina.cn/index.php/news-article-id-78)


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(Source: www.paoshouji.com/tu-yeniu/野牦牛.html)


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(Source: www.paoshouji.com/tu-yeniu/野牦牛.html)


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(Source: http://124.xingshuo.net/siwameinv/kgkkiol.html)


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(Source: www.allposters.com/-sp/Herd-of-Wild-Yaks-Running-across-the-Chang-Tang-Nature-Reserve-of-Central-Tibet-December-2006-Posters_i5263737_.htm)


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(Source: www.cntuke.com/picture2950601)


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(Source: www.qhhtly.com/DocumentShow_SelfPlay_41763.html)


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(Source: http://news.sohu.com/20060809/n244707676.shtml)


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(Source: www.iucnredlist.org/details/full/2892/0)


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(Source: http://blog1.poco.cn/myBlogDetail-htx-id-7218255-userid-56498121-pri--n-0.xhtml)


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(Source: www.arkive.org/wild-yak/bos-mutus/)


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(Source: www.szfstkj.cn/photo/野牦牛.html)

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyak
Edited by Roberta, May 19 2017, 07:48 AM.
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Roberta


The photogenic rest

A few more pictures, not really fitting into any of the other categories.

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(Photo: Yann M. – source: http://thewildernessalternative.com/2012/10/20/sillems-mountain-finch-rediscovered/smf-16/)


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(Source: www.chine-informations.com/actualite/photos-tibet-protection-des-animaux-sauvages_30290.html)


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(Photo: 加贝先生 – source: http://abc1234566-78.blog.163.com/blog/static/602414200911613551937/)


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(Photo: 梁旭昶 / Liang XuChang – source: http://programs.wcs.org/china/News/LatestNews/tabid/6788/articleType/ArticleView/articleId/904/A_place_called_Home_-_Wild_Yak_conservation.aspx)


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(Photo: Wan Zhikang – source: http://china.wcs.org/News/LatestNews/tabid/6788/articleType/ArticleView/articleId/1139/New_hope_for_the_Tibetan_wild_yak.aspx#.VEvOcYeVrgo)


The next two pictures, part of a larger series, are similar but differ in a multitude of details. Maybe the same yak taken in different seasons?

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(Photo: Coke & Som Smith – source: www.pbase.com/cokesmith/image/146679876)


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(Photo: Coke & Som Smith – source: www.pbase.com/cokesmith/image/146679870)


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(Source: www.97ysz.com/jijabaiukym.html]www.97ysz.com/jijabaiukym.html]www.97ysz.com/jijabaiukym.html)


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(Source: http://shidi.eco.gov.cn/ly/2009/0902/110159.html)


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(Source: www.97ysz.com/jijabaiukym.html)



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(Source: www.mala.cn/thread-6719706-1-1.html)

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(Photo: Milo Burcham – source: www.milosphotos.com/)


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(Source: www.szfstkj.cn/photo/野牦牛.html)


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(Source: www.arkive.org/wild-yak/bos-mutus/)


This yak sports the strongest deviation from the standard horn shape that I encountered – longer, thinner, very long upwards-pointing tips. But still very much the wild yak horn shape, and not the domestic horn shape.

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(Source: www.wildtibet.org/wild-shop.htm)


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(Photo: Xi Zhinong – source: www.arkive.org/wild-yak/bos-mutus/)


Twice the same yak, out of a series of seven photos:

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(Source: www.flickr.com/photos/128857250@N05/15891874975/)


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(Source: www.flickr.com/photos/128857250@N05/15891876145/)


Great news: The following picture shows a wild yak in Nepal, where it has recently been rediscovered after having been thought to be extinct for 50 years:

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(Photo: Geraldine Werhahn – source: www.ekantipur.com/2015/04/21/editors-pick/extinct-wild-yak-found-in-humla-study/404342.html)


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(Source: www.cornel1801.com/bbc/PLANET_EARTH_online_documentary_film.html)


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(Source: http://news.ts.cn/content/2014-12/15/content_10818690_all.htm)


Yak skulls

Some yak skulls for lovers of anatomy. Sadly I found no pictures of complete wild yak skeletons.

The first two pictures obviously show the same skull, incomplete as the whole muzzle is missing and only partially defleshed. These pictures give a feeling for the size of the animal, and especially for the diameter of the horns.

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                                   (Source: http://news.enorth.com.cn/system/2002/11/03/000445724.shtml)


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(Source: http://laolv168.blog.sohu.com/152329211.html)


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(Source: http://news.enorth.com.cn/system/2002/11/03/000445724.shtml)


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(Source: www.ly234.com/post/201307/5071.html)


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               (Source: www.smalltao.com/product/7769703728/taobao-agent)


I am not sure if the skull above and the skull below are really wild yak skulls. The horn shape is perfect, but the horns seem a bit thin.

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               (Source: www.smalltao.com/)


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          (Source: www.scientificlib.com/en/Biology/Animalia/Chordata/Mammalia/BosGrunniens01.html)


Again twice the same skull. This one with thinner horns.

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(Source: www.panoramio.com/user/4861077)


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(Source: www.panoramio.com/user/4861077)


The perfect primigenius spiral (if this looks familiar, it was already posted in the Breeding-back Blog post mentioned above):

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(Source: www.tennants.co.uk/catalogue/Lots/35313.aspx)


Said to be a skull from a six month old wild yak; that must have been some major misunderstanding:

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(Photo: Sky Dancer – source: http://redskydancer.blogspot.de/2013/07/sey-rinpoche-s-monasteries.html)


Very short horns, but thick in relation to their length. Also, they leave the base at very strong upwards and forwards angles, instead of simply laterally.

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               (Source: www.yoybuy.com/es/monbacharacteristics_50022003/15992213447.html)


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(Source: http://tupain58.com/vso-头骨结构画法.html)

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyaks
Edited by Roberta, May 19 2017, 07:48 AM.
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Roberta


Sexual size dimorphism in wild yaks

Relative to mass, a small female wild yak may be only one-third the size of a large male; in contrast, female domestic yaks are 25–50% smaller.

Horns of male and female wild yaks vary in size and shape and are far more massive in males (Fig. 3). Generally, they have a “wide lateral sweep, turning then forward and finally upward and slightly bent inward,” are smooth except for a “few low transverse ridges at the base,” and vary among individuals (Allen 1940:1260). Early descriptions provide fragmentary summaries of various horn measurements. A recent sample of 53 adult male and 12 adult female wild yaks from the Chang Tang provides a contemporary reference (cm): length of outside curve, male 47.5–99.0, female 37.0–64.5; basal circumference, male 26.0–42.0, female 17.5–23.0; and tip-to-tip, male 26–83, female 18–67. In Yeniugou (“Wild Yak Valley”), Qinghai, a particularly large male had a basal circumference of 45 cm.

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(Photo: Daniel J. Miller – source: www.bioone.org/doi/full/10.1644/836.1)
Figure 3 – Skulls of male (left) and female (right) wild yaks (Bos mutus) from Yeniugou, central Qinghai, China, highlighting relative mass and sexual dimorphism in skull size and horn shape.


Excerpts from:
David M. Leslie Jr., George B. Schaller: “Bos grunniens and Bos mutus (Artiodactyla: Bovidae).” Mammalian Species, number 836, pages 1–17, 2009. doi: http://dx.doi.org/10.1644/836.1
Edited by Roberta, May 19 2017, 07:47 AM.
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Roberta


Excerpt from Z. L. Lu, “Reproduction and Conservation of Wild Yaks,” 27 November 2000. In: X. X. Zhao, R. C. Zhang (eds.), Recent Advances in Yak Reproduction, International Veterinary Information Service (www.ivis.org), Ithaca, New York, USA. — http://www.ivis.org/advances/Zhao/lu/IVIS.pdf

Types of Wild Yak

Wild yaks are classified as Qilian mountain type or Kunlun mountain type, according to their body conformation, horn shapes and the natural characteristics of the regions in which they live.

Qilian Mountain Type - The Qilian mountain type wild yak (called “Gaxi” by the nomads of Tibet) is found mainly on the alpine meadow in the west Qilian Mountain and the east part of the Aerjin Mountains. These yaks are not fierce and tough and generally do not attack people or other animals. Bulls are 160 - 170 cm at the withers, chest girth 210 cm, live weight 500 - 600 Kg with a prominent hump, long legs, long face, small muzzle, short ears, and no dewlap. Females are smaller than males; both have horns, but the male’s are bigger. The distance at the base of the horns is more than 70 cm with an ellipsoid and round scur. The horn grows outward and curves backward. The brisket, belly, rib, sides, legs, and hump are all covered by long hair. The hair is brown-black, and the nose ring, eye ring and back line are gray-white. The tail is long, fluffy and broom-like.

Kunlun Mountain Type - The Kunlun mountain type wild yak, called “Hengde” (snow hill wild cattle) by Tibetan nomads, is found mainly on the alpine meadows of upper reaches of the Yaluzangbu river, the Kunlun Mountain and the northern part of Tibet. These yaks are very aggressive and may attack people or other animals. They are bigger than the Qilian type. Adult males are 205 cm at the withers with a 270 cm chest girth, trunk length of 240 cm and live weight of about 1200 Kg. The shoulder has a prominent, tuberous projection and the legs are stocky. The face is short but the forehead is wide and prominent. On adult males, the scur is thick with a circumference > 50 cm (the nomads use these horns for storing milk). The distance at the horn base is up to 100 cm and the horn grows openly. Hair color is black or black brown and the back line is rather clear. The nose and eye rings are gray-white. Although the face does not have hair, the hair on the top of the head is long. Furthermore, there is long hair on the shoulder, rib, and legs (in bulls the hair may touch the ground).



Wild yak bull of the Kunlun mountain type

Four photos from a blog post of 5 February 2015 on 加贝先生’s blog (Mr. Gabe’s (?) blog), telling of a trip into the Kunlun mountains to watch wildlife, see http://561227-hdm.lofter.com/post/2d0775_617e807
  • When we see a male wild yak drinking water on an ice lake, we cautiously approach. It immediately is alert and hostile. We also are highly vigilant, ready to retreat. After an outburst of threatening display, the wild yak turns and runs to the grass. It does not run far and turns around, confronting us again. But as these animals, after all, are still afraid of people, after a while it runs off.

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(“P4, the wild yak in the ice lake” – Photo: 加贝先生 – source: http://561227-hdm.lofter.com/post/2d0775_617e807)


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(“P5, the wild yak turns away” – Photo: 加贝先生 – source: http://561227-hdm.lofter.com/post/2d0775_617e807)


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(“P6, the wild yak confronts us” – Photo: 加贝先生 – source: http://561227-hdm.lofter.com/post/2d0775_617e807)


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(“P7, to the depths of the wilderness the wild yak runs” – Photo: 加贝先生 – source: http://561227-hdm.lofter.com/post/2d0775_617e807)

wild yak photos / images
imágenes / fotos de yaks salvajes
images / photos de yak sauvage
Bilder / Fotos des Wildyaks
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