A herd of Tibetan wild asses was spotted at a national nature reserve in northwest China's Xinjiang Uygur Autonomous Region. The Altun Mountain National Nature Reserve has seen a rising number of hoofed wild animals as the ecological environment has been improving. 

The population of Tibetan antelopes, wild yaks and Tibetan wild asses in the reserve has doubled to nearly 100,000 compared with the total number in 2010, according to the nature reserve. Via the infrared camera data, the reserve workers have found a wider distribution of wildlife, indicating a virtuous circle in the reserve, said Xu Donghua, director of the plateau ecology research office of the nature reserve. 

Covering a total area of 45,000 square km, with an average altitude of 4,500 meters, the Altun Mountain National Nature Reserve borders the national nature reserves of Changtang in Tibet Autonomous Region and Hoh Xil in Qinghai Province. It is home to over 50 rare wildlife species, including 10 top-level national endangered animal species.