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Symphalangus syndactylus


CITES: Appendix I (What is CITES?)
IUCN Red List: S. syndactylus: EN (What is Red List?)
Key: EN = Endangered
(Click on species name to see IUCN Red List entry, including detailed status assessment information.)

Photo: Alan H. Shoemaker

The total siamang population for Indonesia (i.e. Sumatra) is estimated at 360,000 individuals in 1987, however in 2008, at the Indonesian Gibbon Workshop, it was determined that the Sumatran siamang populations numbered less than 200,000 individuals (MacKinnon 1987; A. Mootnick pers comm). Among the gibbons, siamangs appear to be among the more able to cope with habitat degradation and change (Geissmann et al. 2006; 2007).


Threat: Human-Induced Habitat Loss and Degradation

As in most primate species, habitat loss presents one of the most profound and ongoing threats to the survival of the siamang. It is estimated that siamags have lost 70-80% of their habitat in the last 50 years and the destruction continues (Geissmann 2007). Forest clearance is usually for agricultural land, logging, mining, roads, and electrical power lines (MacKinnon 1986; A. Mootnick pers. comm.). There are two main ways in which forests are logged in Southeast Asia; clear cutting and selective logging (MacKinnon 1987). Even selectively logged forests are very poor habitat for siamangs and other gibbons as brachiation requires a continuous canopy (MacKinnon 1984). In recent years, illegal deforestation on Sumatra has increased and in one survey of the southern portion of the island, almost every forest visited had undergone or was undergoing, some degree of habitat destruction. While able to cope with some habitat degradation, in more highly disturbed habitats, siamangs are absent (Geissmann et al. 2006; 2007). Further, road building has the potential to degrade siamang habitat by increasing farming, settlement, and logging. It does this by creating opportunities for the transportation and sale of forest products, as occurred within the borders of the Gunung Leuser National Park on Sumatra (Palombit 1992). Finally, traditional use of forest products by local residents is ongoing, but is small in scale and only for personal use (Palombit 1992).

Threat: Harvesting (hunting/gathering)

Siamangs, especially young individuals, are sold in wildlife markets as pets (often openly) even though they are a protected species. Often, these young are taken by killing a parent who is carrying the infant, a technique that sometimes causes the death of the young siamang as well (Crockett & Wilson 1980; Geissmann et al. 2006). In addition to being sold and kept locally as pets, siamangs are also sometimes exported illegally or sold elsewhere in Indonesia as evidenced by siamangs found for sale in markets on Java (Crockett & Wilson 1980; Malone et al. 2002). Collection of siamangs as pets can result from logging, with the animals being collected after their habitat is destroyed (O'Brien et al. 2004).

At least in southern Sumatra, siamangs are not hunted for food, and in some areas, religion precludes the eating of primates (Palombit 1992; O'Brien et al. 2004).

Threat: Natural Disasters

Forest fires precipitated by El Niño/Southern Oscillation (ENSO) events also represent a threat to siamang populations. Such events are increasing in frequency, and correspondingly, forest fires have the potential to do so as well. Following wildfires, siamang groups are smaller and have lower offspring survival rates, as well as fewer numbers of preferred food species available to them (O'Brien et al. 2003).





Content last modified: May 20, 2008

Written by Kurt Gron. Reviewed by Alan Mootnick.

Cite this page as:
Gron KJ. 2008 May 20. Primate Factsheets: Siamang (Symphalangus syndactylus) Conservation . <>. Accessed 2019 September 18.