The siamang is known as the acrobat of the jungle for its movement by "brachiation." This is an arm over arm swing through the trees where the body is carried beneath the arms (which are longer than their legs), and hook-like hands grasp the tree branches, swing may cover 3 meters. The siamang is very agile and lives in high altitudes. When walking on a branch or on the ground, its long arms are held in the air for balance.

The siamang is a type of gibbon, which are categorized as lesser apes. The siamang is monogamous and occupies a small home range. To announce or defend the territory, or to strengthen the pair bond, the siamang performs a unique song, which may last 20-25 minutes. This series of calls, male and female each having their own parts, is known as dueting. A large throat sac inflates to enhance the quality of the call. Social grooming also helps to maintain the bond between the pair.

Gestation: 189-235 days. Offspring: Single