Photo taken on Jan. 22, 2021 shows several western black crested gibbons collecting fruit on the tree in Pu'er, southwest China's Yunnan Province. (Xinhua/Chen Xinbo)

Chinese researchers have launched a survey of the population and habitats of the western black crested gibbon, a critically endangered gibbon species, in southwest China's Yunnan Province.

The survey is being conducted in the Ailao Mountain Nature Reserve. The area of the reserve under the administration of Xinping County is home to the largest population of the primates, according to the results of a previous survey.

The new survey is expected to last 40 days in the county. Zoologists from the Kunming Institute of Zoology (KIZ) under the Chinese Academy of Sciences are training local rangers to take part in the investigation.

The western black crested gibbon was listed as critically endangered on the International Union for Conservation of Nature Red List of Threatened Species and is under first-class national protection in China.

A 2010 survey showed that there were approximately 500 western black crested gibbons living in the Xiping County area of the nature reserve.

KIZ zoologist Jiang Xuelong said that the latest survey is critical for evaluating recent work to protect this species, and the outcomes of this work."It is expected to provide guidance for future protection work and for formulating more targeted measures," Jiang said.