Wooly

Typically, yak produce two different types of hair. The first is the outer "guard hair" which is the longer, coarser, and stronger hair. While guard hair grows over the entire animal, the longest and strongest guard hair is found on the animals tail and skirt. The second hair produced is the short, fine, soft undercoat or "down hair" which is produced by the animals during the winter and is an incredible insulator. Yak living in cold climates will produce from one to two pounds of down annually. bijoubasinranch.com. 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. The Wild Yak is on the endangered animals list.

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