This time, Rao's focus was the region's frogs, particularly tree frogs. He would start work after dinner and go on up till midnight.

Dressed in rain boots, Rao would walk into the forests with a flashlight in one hand and his snake-catching stick in the other.

"If you don't follow him on one of these night trips, you would never be able to imagine how difficult it is to catch frogs in the darkness and realize just how good he is at what he does," says Wang Fang, a 25-year-old PhD candidate of Peking University and a promising wildlife photographer himself, responsible for the survey's collection of images.

"His ears are so sharp that he can tell you which type of frog might be singing before swiftly locating it."

As the days went by, the singing of frogs from Rao's room increased even as the survey team got further into Medog. Penetrating deep into the forest with Rao, Wang Fang captured the rare images of a leopard cat at night.

Compared with the work of Liu and Rao, Xu Zhenghui's required more patience. At 49, the professor with Southwest Forestry College in Kunming, capital of Yunnan province, is one of the country's leading researchers on ants and the oldest member of the team.