They swing alternately from branch to branch, using the hands like hooks, not grasping the limbs, and often making long swings, like leaps, in which neither arm supports them. When traveling on a large limb or on the ground, they usually walk upright with arms held high for balance. The thumb is unique among higher primates in having the lower portion freed from the palm and extending from near the wrist. This allows a wide range of movement and does not interfere as they swing through the trees. All species are almost exclusively arboreal and rarely descend to the ground.
Gibbons are monogamous and form life-long pair bonds.
The adults perform elaborate duets which may strengthen and maintain their bond. The calls of the male and female are different from each other and most species can be identified by their calls. Calls are also used to communicate between other family groups regarding territory. Family groups usually consist of three or four individuals, the mated pair and their offspring. Gestation last 7-8 months and the infant is weaned early in its second year.