Ripe fruit, leaves and a small amount of insects.
Diet in the Wild: Gibbons are fruit-pulp specialists. White-cheeked gibbons eat mostly ripe fruits, leaves, and a small amount of invertebrates. They move and feed mainly in the upper and middle levels of the canopy and rarely come down to the ground. Families often feed together in the tree White-handed gibbons are diurnal and usually take a rest break during the hottest part of the day. White-handed gibbons eat fruits, leaves and some insects. They will also eat birds and can catch them out of the air while swinging. Gibbons are forest dwellers, usually found in the canopy. They are found in semideciduous monsoon forests and tropical evergreen forests.  Diet: In the wild, gibbons can eat ripe fruit, leaves and a small amount of insects. Eating fruit occupies the brunt of their time feeding, next being time spend eating young leaves. Gibbons will spend nearly all their eating time up in the tree-rarely do they need to come down to the ground.  Gibbons are omnivorous animals meaning that they eat a mixture of both plant and animal matter. The main food of the gibbon is ripe fruit which grow around them in the trees, and makes up around three quarters of the gibbon's diet. The gibbon is a small sized ape, found inhabiting the dense jungles and tropical rainforests across south-east Asia. Gibbons belong to the lesser ape family which are closely related to the great apes (chimpanzees, orang-utans, bonobos, gorillas and humans). Located Gibbons are found in the rainforests of southeastern Asia. Diet The gibbon's favorite food are fruits, but they also eat leaves, tree bark, flowers, and plant shoots. They also occasionally eat bird eggs and even small birds, insects, tree frogs and other small animals. Habitat Gibbons spend almost all of their time in the treetops of the rainforest.  Gibbons are omnivorous, so they eat both plants and animals. Their diet is roughly 50-75% fruit, of which their favorite is figs. They also eat: leaves, flowers, seeds, insect … s, and bird eggs. 1 person found this useful. Confidence votes 14. Gibbon's eat fruits and plants mainly but they also eat insects, spiders, bird eggs, and small birds. Gibbons are omnivorous, so they eat both plants and animals. Their diet is roughly 50-75% fruit, of which their favorite is figs. They also eat: leaves, flowers, seeds, insect … s, and bird eggs.  In the wild, lar gibbons will eat a large variety of foods, including figs and other small, sweet fruits, liana fruit, tree fruit and berries, as well as young leaves, buds and flowers, new shoots, vines, vine shoots, and insects, including mantids and wasps, and even birds’ eggs. 
http://nationalzoo.si.edu/Animals/Primates/Facts/fact-white-cheeked-gibbon.cfm http://www.thebigzoo.com/Animals/White-handed_Gibbon.asp http://www.sheppardsoftware.com/content/animals/animals/mammals/gibbon.htm http://a-z-animals.com/animals/gibbon/ http://www.rainforestanimals.net/rainforestanimal/gibbon.html http://www.answers.com/Q/What_do_gibbon_monkeys_eat http://www.answers.com/Q/What_do_gibbons_eat http://zoologicalwildlifefoundation.com/wildlife-tours/animals/lar-gibbon/
what do gibbons eat