Wild yak

The wild yak is a huge wild bovine of the Himalayas and the Tibetan Plateau, and the ancestor of the domestic yak. It has a heavy, bulky body, strong legs and long shaggy hair. Adults stand 160 to 205 centimetres tall at the shoulder and weigh from 0.5 to 1.2 tonnes.

The coat is usually black or dark brown with a grey muzzle. Rare golden-brown yaks exist too; in China about 170 wild golden yaks are estimated. The wild yak is rated Vulnerable. It is among the largest bovine species alive, and its home is one of the highest on Earth.

Built for the cold

Both sexes have long hair and a dense woolly undercoat on the chest, flanks and thighs. In males the hair can form a long 'skirt' that reaches the ground, which helps protect against the cold.

Even the udder and the scrotum are small and covered with hair to stop frostbite. The card adds that big lungs and a big heart help it use thin air above 5,000 metres. Males are much heavier, since females weigh only about a third as much.

Domestic yaks

Domestic yaks bred from wild yaks still carry loads and give milk across the Himalayas and Tibet. They are a bit smaller than wild ones.

Scientists think yaks split from the ancestors of cattle between one and five million years ago, and their nearest relatives are bison. The wild yak once ranged as far as southern Siberia, east of Lake Baikal.

On the globe

The model shows a shaggy black wild yak on the Chang Tang plateau of Tibet.