Mammals
Siamang
Symphalangus syndactylus · also called siamangs
At first light, a mated pair of siamangs inflates their throat sacs and begins a coordinated duet, the largest gibbon species producing calls loud enough to carry for kilometres across the Sumatran rainforest canopy.
Overview
The siamang, Symphalangus syndactylus, is the largest living gibbon species, native to rainforest habitat across parts of Sumatra and the Malay Peninsula. Its inflatable throat sac capable of producing some of the loudest calls of any land animal, partially fused toes reflected in its scientific name, and daily coordinated duets with a lifelong mate make it one of the most acoustically and behaviourally distinctive apes found anywhere in Southeast Asia.
The loudest voice in the canopy
Few animals anywhere can match the sheer volume the siamang produces through its inflatable throat sac, a booming call that announces a mated pair’s presence across a stretch of rainforest large enough to make direct confrontation with rivals mostly unnecessary.
Status
Endangered, having declined due to the clearing and fragmentation of rainforest habitat across Sumatra and the Malay Peninsula.
Siamang: common questions
Why is the siamang's call so loud?
This species has a large inflatable throat sac that acts as a resonating chamber, turning its calls into some of the loudest sounds produced by any land animal and allowing its distinctive booms and barks to carry for several kilometres through dense rainforest.
Why does the siamang have partially fused toes?
This species has two toes on each foot that are partially fused together, a distinctive anatomical feature reflected directly in its scientific name and unique among gibbon species, though its exact functional significance is not fully understood.
How big is the siamang compared with other gibbons?
This species is the largest of all living gibbon species, noticeably bigger and heavier than its smaller relatives found across overlapping parts of Southeast Asia, though it retains the same basic brachiating body plan shared across the gibbon family.
Do siamangs mate for life?
Yes, this species lives in monogamous pairs that perform coordinated vocal duets each day, a behaviour used to advertise their territory to neighbouring pairs and reinforce the bond between mates over what is typically a long-term partnership.