Gibbons are the only apes that sing, using elaborate territorial songs for pair bonding, and captive conditions that prevent singing represent a significant welfare deficit.
Gibbon welfare in captivity requires facilities that accommodate their extreme locomotor specialization and unique social and vocal behaviors. Gibbons that cannot brachiate through long swinging arms show physical deterioration and behavioral abnormalities. Captive gibbons without appropriate partners cannot engage in the pair-bonding duets that are central to their social lives. Welfare-centered gibbon care requires both adequate space for brachiation and stable pair housing that enables natural social behavior.