Meet Vietnam's endangered primates

The grey-shanked douc langur (Pygathrix cinerea) lives in packs of 10-15 individuals. Only about 1,500 members of the species remain in Vietnam due to rampant poaching. Photo by Nguyen Van Truong

The Delacour's langur (Trachypithecus delacouri) survives in restricted areas of northern Vietnam. Scientists say only about 200 individuals likely remain -- about half that population lives in the Van Long Natural Reserve in Ninh Binh Province. They are one of the World's 25 Most Endangered Primates. Photo by Nguyen Van Truong

The Tonkin snub-nosed monkey (Rhinopithecus avunculus) is also one of 25 most endangered primates in the world, and has been included on a list of 100 species on the verge of extinction. Fewer than 250 individuals are estimated to remain high in the craggy mountain forests of Ha Giang and Tuyen Quang provinces. Photo by Le Khac Quyet

The white-headed langur (Trachypithecus poliocephalus) is critically endangered. A population of about 70 individuals remain on Cat Ba Island off the coast of Hai Phong. The species ranks as one of the 25 most endangered primates in the world. Photo by Nguyen Van Truong

The northern white-cheeked gibbon (Nomascus leucogenys) is native to Southeast Asia. The world's largest community of the species, about 450 individuals, is believed to reside in Pu Mat National Park in the central province of Nghe An. Photo by Fan Peng Fei

The red-shanked douc langur (Pygathrix nemaeus) is among the most colorful of all primates. Populations in Vietnam, Laos and Cambodia are also on the verge of extinction.

The eastern black-crested gibbon (Nomascus nasutus) is found in northern Vietnam. Scientists say about 130 individuals remain in Trung Khanh Natural Reserve in the northern province of Cao Bang.