What it is
The Cao Vit, or eastern black crested gibbon, is a singing ape of limestone forest. IUCN lists it as Critically Endangered. A 2021 survey using vocal fingerprinting and drone thermal counts estimated 74 individuals in 11 family groups on the Vietnam-China border (Wearn et al. 2024, Scientific Reports). Earlier triangulation had double-counted groups and published about 120. Living field photographs are scarce; the card image is the Paris holotype.
Range
A single karst forest patch under 5,000 hectares, split between Trung Khanh (Vietnam) and Bangliang (China).
What happened
Hunting and charcoal-cutting reduced the ape to this scrap. Infants are still being born. The forest is too small for a safe future without restored corridors. The Hainan gibbon (Nomascus hainanus) is a different species.
When / status
Critically Endangered now. One forest, tens of animals.
Human role
Hunting and clearance left one remnant; patrols, not empty wilderness, keep it.
Sources
Wearn et al. 2024, Scientific Reports (74 in 11 groups); IUCN Red List (Nomascus nasutus, CR).