Yaks, a member of the bovine family, were domesticated in Tibet during the first millennium, B.C., and today, more than 12 million of them can be found in five Himalayan countries where they inhabit steppes of 15,000 feet. Known as the "grunting ox", they can climb as high as 20,000 feet, and yet they can be successfully raised at very low elevations. Their respiratory rate increases with heat and low altitudes, decreases at higher, cooler climates to help them adjust. North American yaks are divided into five types: black, trims (black with some white trim), royal (black and white pied with a white blaze face), golden, and woolly. With their horse-like tail and long skirts, these hardy animals require no special permits, and are compatible with existing agricultural operations. Two year-old yaks breed in the fall, calve 257 days later in the spring, are mature in 4-6 years, and live an average of 25 years.
Wild Yaks are usually black while domestic Yaks come in a variety of colors from dirty white to brown. Adult Yaks reach the length of up to 330 cm, and their shoulder height is about 200 cm. Yaks weigh about 1000 kg. The females are much smaller; they weigh one third as much. Yaks have bushy tails and a long skirt of coarse fiber.
Wild Yaks inhabit treeless uplands, including plains, hills, and mountains from as low as 3,200 m up to the limit of vegetation at 5,500 m. On alpine and desert steppe Yaks are scarce, reaching the greatest abundance on alpine meadows. Their density ranges from 13 sq km/yak to 100 sq km/yak.
Yaks can climb as high as 20,000 feet and can be successfully raised at very low elevations. Yaks are very efficient food-converting animals and do well on a variety of pastures with no supplemental feed required. The Yak grazes on grasses, herbs, and lichens. In winter Yaks eat poor coarse grass, withered leaves and twigs, and quench the thirst with snow and ice. They are sure-footed climbers.
Yaks possess great lung capacity. Even their blood cells are designed for high elevations - they are half the size of those of cattle, and three times more numerous, increasing the blood capacity to carry oxygen. The dense coat enables Yaks to successfully survive temperatures as low as -40 deg C. Yaks' respiratory rate increases with heat and low altitudes and decreases at higher cooler climates.
Wild Yaks stay at high areas during the relatively warm months of August and September and spend the rest of the year at lower elevations. They feed in the morning and evening. Due to the sparseness of vegetation, Yaks have to travel long distances to obtain nourishment. Yaks travel on snow in single file stepping on imprints left by the leader.
Wild Yaks are highly gregarious. Females and youth congregate in large herds while adult males spend most of the year in small groups. The Yak herd is able to defend itself from predators, such as coyotes, bears, and mountain lions. Births occur in June and a single calf is born every other year. Young Yaks become independent after the fist year. Yaks begin breeding at the age of 3-4 years; full size is reached at 6-8 years.