Cao-vit Crested Gibbon

The eastern black crested gibbon (Nomascus nasutus), also called Cao-vit black crested gibbon or the Cao-vit crested gibbon, is a Critically Endangered species of gibbon from southeast China and northern Vietnam. The term "Cao-vit" originated from the sounds of their calls or songs that villagers of Ngoc Khe, Phong Nam and Ngoc Con communes of Trung Khanh District, Cao Bang Province of Vietnam use to name for them.

This name was officially used by gibbon experts since the rediscovery. From the 1960s until the 2000s there had been no confirmed sightings of the eastern black-crested gibbon and it was thought to be possibly extinct. In 2002 a small population was rediscovered by two FFI biologists in a karst forest of Trùng Khánh District, Cao Bằng Province, in northeast Vietnam. The species was endemic to Vietnam until 2006 when they were also found in a small forest in Guangxi Province of China, which is adjacent to Trung Khanh forests. In 2005 it was estimated that this population in Vietnam side was about 35–37 individuals.