The Domestic Yak (Bos grunniens) and the Wild Yak (Bos mutus) are large, long-haired, ungulate mammals in the Bovidae family of bovines, similar to cattle and bison. It is a bovid. The species, Bos grunniens, means grunting ox, and the species, Bos mutus, means mute (silent) ox. The Yak, like a cow, is an ungulate because it has cloven hooves.
The Wild Yak is black or dark brown, whereas the Domestic Yak can be rust-brown, grey, and cream. The Yak has small ears and a wide forehead, with smooth dark-coloured horns. It has a short neck with humped shoulders. The male, called a bull, has horns that extend from the sides of its head and curve forward. The female, called a cow, has smaller horns that are more upright. The tail is long and looks like a horse’s tail (long and hairy) instead of a cow’s tail (with a tuft of hair at the end).
The Yak can grow to 105–138 centimetres (41–54 inches) tall. The horns of the male are 48-99 centimetres (19-39 inches) long. The horns of the female are 27-64 centimetres (11-25 inches) long.
The Yak is found in the Himalayas, Mongolia, and Russia. Its shaggy hair keeps it warm, because it lives in cold, mountainous climates.
Unlike the cow, the Yak does not moo. The Yak makes a grunting sound.
The female (cow) is pregnant for 257-270 days, before giving birth to one calf. The calf can walk within ten minutes, and then stays close to its mother. The calf becomes independent after about one year.
The Yak can live for more than 20 years in captivity, and for less in the wild.
Location of photographs: Tbilisi Zoo, Georgia
Photographer: Martina Nicolls
Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM