Black Yak

Blacks range from a brown/dun color to dark black. In addition to the grey on their noses, they often have grey hairs along their back bone and grey flecks in their forehead locks. Wild yaks carry this color pattern and it is generally held that the other colors are the results of crosses to Bos Taurus or Bos Indicus genes. The yak, Bos grunniens or Bos mutus, is a long-haired bovine found throughout the Himalayan region of south Central Asia, the Tibetan Plateau and as far north as Mongolia and Russia. In addition to a large domestic population, there is a small, vulnerable wild yak population. In the 1990s, a concerted effort was undertaken to help save the wild yak population. The English word "yak" derives from the Tibetan (Tibetan: Wylie: g.yag), or gyag – in Tibetan this refers only to the male of the species, the female being called a dri or nak. In English, as in most other languages which have borrowed the word, "yak" is usually used for both sexes.

http://en.wikipedia.org/wiki/Yak