A gibbon that amplifies its loud calls with a throat sac and travels by swinging between branches.
It has thick black fur, long slender arms and a large throat sac.
Siamang songs combine sounds produced with an open mouth and low booms radiated through the throat sac with the mouth closed. A short bark may immediately follow a boom. Switching between these sounds shapes the fine timing of the song, with rapid sequences interspersed with more widely spaced combinations.
A 2026 paper examined the onset of individual sounds in recordings from fourteen adults at seven zoos. Researchers compared open-mouth sounds alone, sac-radiated sounds alone and the combined sequence. Recordings collected at different times between 2011 and 2025 at three Italian zoos were combined with publicly available video audio from four other zoos; the dates of those videos were not specified.
All three sequence types showed a tendency for neighboring intervals to be approximately equal. This tendency was particularly strong when three open-mouth sounds occurred consecutively. The authors highlighted the close temporal relationship between the two kinds of sound. Even within one animal’s song, combining them creates a detailed temporal structure.
An extinction-risk assessment has not been added yet.
In South Solok, West Sumatra, Kalaweit works to return rescued siamangs to forest habitat. A 2026 paper tracked the locations of three released pairs in fragmented forests. The authors recommended extended post-release monitoring, gradual reductions in supplementary feeding while assessing the animals, and restoration of connections between forest canopies.