China is home to a unique diversity of apes, but an expedition to Yunnan Province has found that these apes are now closer to extinction than ever before. An international research team coordinated by anthropologists at Zurich University has concluded that the Yunnan white-handed gibbon, a Critically Endangered subspecies known only from southernmost China, is now almost certainly extinct.
In late 2007, the research team carried out a survey in all Chinese forests reported to support white-handed gibbons (Hylobates lar) during the last twenty years. The species was last directly observed in 1988, in the Nangunhe Nature Reserve in southwestern Yunnan Province, and their loud, melodious calls were last heard in 1992. After two weeks of field work in November 2007, the 14-member Swiss-Chinese team realized that as a result of continued forest destruction and degradation — as well as uncontrolled hunting — this gibbon species is no longer part of the Chinese fauna.
"This loss is particularly tragic,” says expedition leader Thomas Geissmann, "because the extinct Chinese population was described as a distinct subspecies, the so-called Yunnan white-handed gibbon." This subspecies, Hylobates lar yunnanensis, has never been found anywhere outside of Yunnan Province. Geissmann hopes that the subspecies may still survive just across the border, in neighbouring Myanmar, but so far he has no evidence for this.
"The extinction of the Chinese white-handed gibbons is an urgent alarm signal," says Geissmann, "because several other ape species in China are also endangered." Among these are the white-cheeked crested gibbon (Nomascus leucogenys), which has not been sighted in China since the 1980s. The Cao-Vit crested gibbon (N. nasutus) is at a perilous low — only fifty individuals are known from the Chinese province of Guangxi and Cao Bang in Vietnam — and barely twenty of the Hainan crested gibbon (N. hainanus) are surviving on the southern Chinese island of Hainan. Geissmann and his colleagues warn that the loss of the Yunnan white-handed gibbon may only be the beginning of an unprecedented wave of extinctions which threatens to annihilate the remaining species of Chinese apes.
"We hope that our research results will alarm the Chinese government," says Geissmann, "as well as international conservation agencies, and encourage them to initiate immediate efforts to save China’s last surviving apes."
Dr. Geissmann's full report on the Yunnan expedition is available here, in German with an English summary on p.12.
The Hainan crested gibbon, Nomascus hainanus, has been highlighted as one of the world's 25 Most Endangered Primates for 2006-2008.
For more information on endangered gibbons in China, please visit the Gibbon Conservation Alliance.