A wild yak is seen on a grassland in Shuanghu County of Nagqu, southwest China's Tibet Autonomous Region, Oct. 21, 2019. Shuanghu, the world's highest county with an average elevation of 5,000 meters, lies within the Qiangtang National Nature Reserve where many endangered wild animals live and breed. (Xinhua/Chogo)

Tibetan antelopes are seen on a grassland in Shuanghu County of Nagqu, southwest China's Tibet Autonomous Region, Oct. 21, 2019. Shuanghu, the world's highest county with an average elevation of 5,000 meters, lies within the Qiangtang National Nature Reserve where many endangered wild animals live and breed. (Xinhua/Chogo)

A wolf is seen on a grassland in Shuanghu County of Nagqu, southwest China's Tibet Autonomous Region, Oct. 20, 2019. Shuanghu, the world's highest county with an average elevation of 5,000 meters, lies within the Qiangtang National Nature Reserve where many endangered wild animals live and breed. (Xinhua/Chogo)

Tibetan antelopes are seen on a grassland in Shuanghu County of Nagqu, southwest China's Tibet Autonomous Region, Oct. 20, 2019. Shuanghu, the world's highest county with an average elevation of 5,000 meters, lies within the Qiangtang National Nature Reserve where many endangered wild animals live and breed. (Xinhua/Chogo)

A group of kiangs (Equus kiang) graze on a grassland in Shuanghu County of Nagqu, southwest China's Tibet Autonomous Region, Oct. 20, 2019. Shuanghu, the world's highest county with an average elevation of 5,000 meters, lies within the Qiangtang National Nature Reserve where many endangered wild animals live and breed. (Xinhua/Chogo)

A flock of Tibetan gazelles are seen on a grassland in Shuanghu County of Nagqu, southwest China's Tibet Autonomous Region, Oct. 20, 2019. Shuanghu, the world's highest county with an average elevation of 5,000 meters, lies within the Qiangtang National Nature Reserve where many endangered wild animals live and breed. (Xinhua/Chogo)

Tibetan antelopes forage on a grassland in Shuanghu County of Nagqu, southwest China's Tibet Autonomous Region, Oct. 21, 2019. Shuanghu, the world's highest county with an average elevation of 5,000 meters, lies within the Qiangtang National Nature Reserve where many endangered wild animals live and breed. (Xinhua/Chogo)