Members of the Dulongjiang survey gather on the bank of the Dulong River. Dong Lei /China Daily

An additional survey

Xu Jian, director and co-founder of the IBE, says the expedition was the third of its kind. Surveyors in a first attempt in August 2013 failed to enter the river valleys because landslides caused by summer rains cut off the highway from Gongshan Pass on the Gaoligong Mountains to the township.

The second survey in October 2013 was a success. Wildlife photographers with IBE managed to capture photos of many rare animals living in the forests of the area, which is a part of the National Gaoligong Mountains Nature Reserve, including takins and capped langurs, a primate species found only in Gongshan. Many of the wildlife species were photographed in China for the first time.

"But it's not breeding season," says Zuo, who attended the previous surveys. "If we want to know the area's fauna and flora comprehensively, we have to come when flowers are blossoming, frogs and toads are singing, and bugs and butterflies are out and active."

May is supposed to be a drier month, which is why IBE and the forestry bureau decided to launch an additional survey in the first three weeks of May.

The previous surveys were completely financed by the Nujiang forestry bureau. "This time we decided to pay most of our own travel expenses," Xu says. "The charm of Dulong－jiang is just irresistible."