The park, which is home to the sources of three major rivers－the Yangtze, the Yellow and the Lancang－covers 123,100 square kilometers, about 14 times the area of Yellowstone National Park in the United States and 19 times larger than Banff National Park in Canada.

A few months before Wen officially started work as a conservationist, he received training from experts in grassland ecology, the environment and wild animals, who had been invited by the local forestry department to provide assistance.

"Thanks to the training, we were aware of the importance of environmental protection－not only the pasture, but also the water and wildlife. This is a meaningful mission that will benefit not only our generation but our descendants, too," he said.

"I didn't get a clear idea of how important our efforts would be until 2016, when an expert who trained us told me that many wild animals and plants were not included in official records in my hometown, but they should be known by more people around the world. From that moment, I knew we would be making history."

As a result, he decided to write a patrol diary. In his entries for early May, Wen recorded the appearance of a snow leopard and her cub that he came across near a snow-capped mountain in the park.

To collect more information about the endangered high-plateau species, which has a population of 2,000 to 2,500 in China, Wen camped nearby and spent two weeks taking photos of the animals and noting their daily activities.

"The shortest distance between us was less than 200 meters－the mother stared at me for more than 10 seconds. I took it as a warning. I stayed still with my heart beating rapidly, and my breath stopped for a while until she went back to her cub and started to nurse it," he said.