Heather Angel / Northern white cheeked gibbon (Nomascus leucogenys) female standing in tree with baby aged two weeks. Parents captive bred and released. Wild Elephant Valley / Xishuangbanna, Yunnan Province, China, 2...

Magnus Lundgren / Wild Wonders of China / Central Yunnan black crested gibbon (Nomascus concolor jingdongensis), mother and baby hanging in canopy. Wuliangshan Nature Reserve, Jingdong, Yunnan Province, China.

Ingo Arndt / White-handed gibbon {Hylobates lar} feeding in {Ficus sp} tree Khao Yai NP Thailand

Ingo Arndt / White-handed gibbon portrait {Hylobates lar} Thailand

Ingo Arndt / White-handed gibbon portrait {Hylobates lar} Khao Yai NP, Thailand

Sandesh Kadur / Western hoolock gibbon (Hoolock hoolock) male hanging from branch, Assam, India.

Tim Laman / Skywalker hoolock gibbon (Hoolock tianxing) formerly described as Eastern hoolock gibbon (Hoolock leuconedys) Gaoligong Mountains National Nature Reserve, Yunnan Province, China.

Tim Laman / Skywalker hoolock gibbon (Hoolock tianxing) formerly described as Eastern hoolock gibbon (Hoolock leuconedys) Gaoligong Mountains National Nature Reserve, Yunnan Province, China.

Roland Seitre / Pileated gibbon (Hylobates pileatus) female climbing through trees, Angkor Centre for Conservation of Biodiversity, Siem Reap, Cambodia. Endangered species.

Rod Williams / Young male Northern White-cheeked Crested Gibbon (Nomascus leucogenys) Northern Vietnam. Critically Endangered, Captive

Staffan Widstrand / Wild Wonders of China / Eastern hoolock gibbon (Hoolock leuconedys) hanging from a branch in its arms, resting between forays through the rainforest, Gaoligongshan Nature reserve, Yunnan, China

Shibai Xiao / Hainan black-crested gibbon (Nomascus hainanus) young male in tree, Bawangling National Nature Reserve, Hainan Island, China.