SmugMug Photo & Video Sharing. You look better here. : Siamang (Symphalangus syndactylus) (July 3, 2005) Siamang (SEE-uh-mang) belong to the family Hylobatidae, which includes all 11 gibbon (or lesser ape) species. It is the largest of the lesser apes. Siamangs are native to the island of Sumatra and the Malay Peninsula. Siamangs sing so loudly that it can be heard for up to 3 miles (4.8 km). To produce this loud call, siamangs have a hairless, reddish-brown or gray throat (laryngeal) pouch which acts as a resonator to enhance the carrying of their call. When not in use, the pouch is hidden under their long, shaggy, jet-black fur. When inflated, the pouch is about the size of a siamangs head, and amplifies its hooting and barking to ear-splitting levels. Usually involving the adult pair, the male and female sing different but coordinated parts; songs have a definite beginning, middle and end. Each elaborate duet begins slowly, then accelerates in speed. A song lasts about 18 seconds and is repeated for about 15 minutes. The Siamang is the largest of the lesser apes. Siamangs and gibbons are the only anthropoid apes that habitually walk erect like humans. In their treetop habitat, they will walk along a vine as if on a tightrope with their hands held high for balance. The Siamang is distinctive for two reasons. The first is that two fingers on each hand are fused together (hence the name "syndactylus"). The second is the large "gular sac" (found in the male of the species), which is a throat pouch that can be inflated to the size of its head, allowing the Siamang to make loud resonating calls or songs. This species is found in Indonesia (Barisan Mountains of west-central Sumatra), Malaysia (mountains of the Malay Peninsula south of the Perak River), and a small area of southern peninsular Thailand (Chivers 1974; Khan, 1970; O’Brien et al. 2003; Treesucon and Tantithadapitak 1997). Status: Endangered Location and status information found at The IUCN Red List of Threatened Species