Siamangs eat fruit and new leaves and include a larger proportion of leafy matter in their diet than most other gibbons. Siamangs also eat a small amount of insects, bird eggs and small vertebrates.

How do siamang make their call so loud?

Unlike other gibbons, siamangs have a throat sac (also called a gular sac) which they can inflate to be about the size of their head. This sac makes their calls louder! ... The inflatable throat sac makes the siamangs the loudest of all the gibbons.

Are siamangs adaptable?

The population of siamang may have declined 50% over the last 40 years because of the pet trade and habitat loss. They may have lost 50% of their historical habitat but they are very adaptable to environmental changes.