Birth on roof of world: Tibetan antelope calving season in Xizang's Changtang

Every summer, thousands of pregnant Tibetan antelopes migrate hundreds of kilometers to reach their ancestral calving grounds--grassland in Nyima County, 5,100 meters above sea level, in the heartland of Changtang National Nature Reserve in southwest China's Xizang.
Xinhua's cameras are fixed on a mother. Watch the raw drama of birth in thin air. (recorded)