Wild yaks moves on a sand hill in Altun Mountains Nature Reserve in Ruoqiang county, Northwest China's Xinjiang Uygur autonomous region. The reserve covers 45,000 square kilometers and has an average altitude of 4,500 meters. It is home to a wide variety of rare and endangered animals, including wild donkeys, antelopes, wild yaks, snow leopards and so on. In addition, the reserve is the first specialized reserve for plateau desert ecosystem in the world.[Photo/Xinhua]