When we arrived at the Dazhaizi Monitoring Station in Wuliang Mountain National Nature Reserve, the station staff told us that a few minutes' walk would bring us to the western black crested gibbons. We quickened our paces so as not to waste the opportunity.

After walking for about 500 meters, we heard the gibbon calls. A black gibbon came into our sight, and soon after, a golden one appeared, jumped swiftly from tree to tree.

"We wouldn’t be able to get so close to them without years of efforts,” said Niu Xiaowei, a doctoral candidate at the Kunming Institute of Zoology, Chinese Academy of Sciences.

In 2003, the primate researcher Fan Pengfei came to Mt. Wuliang for a four-year field study. In order to better study and protect gibbons, he decided to trail them without disturbing them. He followed the gibbons every day from dawn to dusk, regardless of wind or rain. Gradually, gibbons have got used to his presence. Today, humans can observe gibbons at a close range of five to a dozen meters.