It's not a
buffalo. It's not a
bison. It's not a
cow—it can't even
moo.
It's a yak.
On the other hand it is related to those creatures. They are all part of the Order Artiodactyla (even-toed ungulates) and the Family Bovidae. Even the same Subfamily Bovinae, but there they part company (though it does share the Genus with the cow...it still can't moo).
What can they do? Grunt. No, really. They grunt. The domesticated version is sometimes called the "grunting ox." Even the scientific name reflects that characteristic: Bos grunniens—from Latin for "ox" and Grunnio, meaning "I grunt." The wild version is thought to be sufficiently separate after centuries of domesticated selection to be given a different name: Bos grunniens mutus (or sometimes just Bos mutus). The original appellation was the same as the domesticated version when it was described by Carolus Linnaeus in 1766.
This grunting ox lives in the cold, mountain regions and dry plateaus of Tibet, mostly, with a few found in adjacent areas of China and India. There may be some in Bhutan. It once ranged in all those countries as well as Nepal, covering much of the Tibetan plateau of the Himalayas. They herd in areas with few people—though the greatest number is made up of the domesticated variety—at elevations between 4000-6000 m (12,000-19,200 feet). A 1998 estimate put the total population at 12,000.
Despite that, they—wild yaks—are considered a "vulnerable" (sometimes endangered) species, subject to poaching and hunting by humans (and "military personnel"). A lot of the better alpine meadow that the wild yak lives on has been taken over by those growing domesticated livestock. Also, diseases from domesticated yaks (probably increased by crossbreeding with cows) have also effected the population. The yak has been officially protected by China since 1962 and India's Wildlife (Protection) Act of 1972 partially protects them. Though measures have been taken to ensure these and programs to aid in breeding, it is difficult to protect them due to the location and adverse conditions of their habitat.
Details:
Length (body): up to 3.25 m (19.8 feet)
Length (tail): 60 cm (24 inches)
Length (horns): up to 95 cm (38 inches)
Height (at shoulder): up to 2 m (6.6 feet)
Weight: up to 1000 kg (2200 pounds)
It should be noted that the above is more specific to the male wild yak. The domesticated yak is smaller (even the horns). The yak shows a degree of sexual dimorphism, with the females being smaller by perhaps a third or more—example: horn length for a female is about 51 cm (20 inches) shorter compared to the above.
The yak is especially well-suited to its environment and after the horns, its long shaggy coat (which is molted once a year) is most striking. It is dark brownish to black and heaviest around the shoulders, flank, and tail (domestic yaks have variable coloring, including piebald). It allows them to tolerate temperatures as low a -40° C/F. They've been seen bathing in severely cold weather (yaks are fairly good swimmers). It has a low number of sweat glands, allowing it to better conserve heat and even its blood is adapted to its habitat. The blood cells are smaller (about half the size) and nearly three times as numerous as those of other cattle, allowing it better carrying capacity for oxygen (it also has a large lung capacity and tends to breathe more slowly than its relatives). Besides being helpful in its environment, this makes it, along with its sure-footedness, an excellent pack animal able to carry heavy loads up to 32 km (19.8 miles) a day.
Its shoulders are somewhat humped and its legs relatively short. The yak tends to hold its head down with nose near the ground, probably a habit due to the need to forage for food. They forage mainly during the morning and evening and eat a diet consisting of grass, herbs, and lichens (when water is frozen they are said to eat snow). Its horns, which grow out from the side, curving upward will be used if threatened, the yak charging its adversary (other than man, its main predator is the Tibetan wolf).
Yak herds are mostly made up of females, calves, and young bulls, older bulls tending to be solitary or in small "bachelor" groups of around twelve. Non-bull herds can be found in larger groups ranging from 10-20 or even up to 100-200 in the spring when the new grass grows or later in the summer when they migrate northward.
Mating season begins in September and lasts through autumn. Gestation takes about 258 days with a single calf born. They only give birth every other year (if food is scarce, it can be up to once every three). The calves are weaned at about a year and sexual maturity occurs by six years (at which point they have reached full size). Female domestic yaks can give birth at 3-4 years. Their lifespan can reach 25 years.
Yaks were first domesticated in the first millennium BC and have become highly important to the people who live in the same environment. Smaller, but more docile, they have also been used as transportation and as pack animals. Its milk is used and is very rich in butterfat (6%-7%—compare with the around 5%-6% of the Jersey cow, the domestic cow with the highest percentage). The meat has been used as food and its hide for leather. Its fur can be used to make cloth and the coarser hair into mats, tent coverings, cords, and rope. The tail has been used in India as "a fly chaser at ceremonial processions...and as an ornament for a tomb or shrine" (school.discovery.com). Their dung has been used for fuel, which is important in the treeless areas they inhabit.
Many domesticated yaks are crossbred with local cows (the resulting offspring is called a "dzo"). They are about the same size as regular cattle. Males are sterile but females are not. The crossing makes for more tame animals as well as gives better milk and meat. They tend to be hardy and fairly disease resistant. Of course, cold weather is not a problem.
There are actually groups trying to breed them in North America as livestock. The meat is pretty lean—most of the fat of the yak is stored just beneath the skin making it easy to trim off—and low in cholesterol.
(Sources: www.ultimateungulate.com, www.animalinfo.org/species/artiperi/bos_mutu.htm, www.maroon.com/yaks, www.panda.org/resources/publications/species/underthreat/yak.htm, www.britannica.com, http://school.discovery.com/homeworkhelp/worldbook/atozscience/y/612320.html)