How the yak make adaptation to survive in the extremely cold climate?

Answer 1

Yak survive and perform adequately if the annual mean temperature is below 5oC and the average in the hottest month is not above 13oC. They can also survive satisfactorily at ambient temperatures down to -40oC. Altitude, as such, is of lesser importance. The further north (of the equator) yak live, the lower, in general, the altitude at which they are found. Yak in North America and in animal and zoological parks in several parts of the world, may again have re-adapted, over time, to life in these, for them, non-normal situations.

Yak cope with cold by conserving heat, rather than by generating it - which would require food that may not be available. Heat conservation is effected by a compact conformation, a thick fleece of coarse outer hair and an undercoat of fine down. The proportion of down in the coat increases greatly before the onset of winter. Young calves have a fleece composed exclusively of down fibre. Normally, yak accumulate a layer of subcutaneous fat prior to winter. This also helps heat conservation and provides an energy reserve. The skin is relatively thick. It contains sweat glands, though for the most part, these are not functional. This is one reason why yak are intolerant of high ambient temperature.

Answer 2

Yaks have developed several physical adaptations to thrive in cold climates, including a thick, woolly coat that provides insulation, a layer of fat beneath the skin for energy storage and insulation, and a large lung capacity to extract oxygen efficiently at high altitudes. They also have specialized nostrils that can close to prevent heat loss during extreme cold weather.