The buff-cheeked gibbon (Nomascus gabriellae) is a primate that lives in the canopy of humid evergreen forests and similar habitats in Cambodia, Laos, and Vietnam. Its body length is about 60–80 cm and it weighs about 8.5 kg; it has no tail and moves by brachiation, using its long arms to travel from tree to tree. It is diurnal and primarily eats fruit, also consuming leaves and flowers. It forms pair-based groups of 3–5 individuals that maintain a territory; members communicate and attract mates with morning songs. Gestation lasts about seven months; offspring are weaned at around two years and reach sexual maturity at six to eight years. Populations have declined due to habitat loss and hunting, and the species is listed as Critically Endangered (IUCN Category I B).