A snow leopard photographed in the Qilian Mountains, which straddle the border between the provinces of Gansu and Qinghai in June 2017. [Photo/Xinua]

According to Lyu Zhi, biology conservation professor with Peking University, infrared cameras have captured more than 50,000 pictures of snow leopards over an area of 5,000 square kilometers since 2011 when the population monitoring program started in Sanjiangyuan.

Researchers tried to identify individual snow leopard and rule out the repeated counting of pictures, said Zhao Xiang, director of the Sanjiangyuan project at the Beijing Shanshui Conservation Center.

In addition to camera surveys, the count was also derived from research methods such as field surveys and laboratory analysis, Zhao said. The final estimate was made with help of a computer model.

"The population density of snow leopards in Sanjiangyuan area is higher than the average of global habitats," Zhao said, attributing it to the continuous efforts of local government and people in environmental protection.

Sanjiangyuan in northwest China's Qinghai Province, literally means the "source of three rivers," is home to the headwaters of the Yangtze, Yellow, and Lancang (Mekong) rivers.

In addition to the snow leopard, a Class A protected animal in China, it is also home to other rare wildlife such as Tibetan antelope, white-lipped deer and Tibetan wild donkeys.