Primate of the Week: Siamangs

Symphalangus syndactylus

ARKive image GES037485 - Siamang

Photo from ARKive of the Siamang (Symphalangus syndactylus) – http://www.arkive.org/siamang/symphalangus-syndactylus/image-G37485.html

Taxonomy
Suborder: Haplorrhini
Infraorder: Simiiformes
Superfamily: Hominoidea
Family: Hylobatidae

ARKive image GES037612 - Siamang

Photo from ARKive of the Siamang (Symphalangus syndactylus) – http://www.arkive.org/siamang/symphalangus-syndactylus/image-G37612.html

Siamangs are part of the group described as Gibbons. They are considered to be apes due to several characteristics including no tail. They are the largest of the gibbons (Ankel-Simons, 2000; Mootnick, 2006). They are all black with a large throat sac (Schultz, 1933; Marshall and Sugardjito, 1986; Mootnick, 2006). Another unique trait is their webbed second and third toe (Schultz, 1933; Marshall and Sugardjito, 1986; Mootnick, 2006). Males are slightly larger than females. Males on average weigh on average 12.8 kg while females on average weighing 10.5 kg (Wilson and Wilson, 1976; Orgeldinger, 1994).

ARKive image GES037253 - Siamang

Photo from ARKive of the Siamang (Symphalangus syndactylus) – http://www.arkive.org/siamang/symphalangus-syndactylus/image-G37253.html

Like other Gibbons, Siamangs are brachiators allow adaptability to upper canopy living (Chivers, 1972; Bertram, 2004). However, Siamangs are slower (Chivers, 1972).

ARKive image GES035781 - Siamang

Photo from ARKive of the Siamang (Symphalangus syndactylus) – http://www.arkive.org/siamang/symphalangus-syndactylus/image-G35781.html

Siamangs are found in Sumatra and the Malay peninsula (Treesucon, 1997; Mootnick, 2006). They primarily live in tropical hill forests but are also found within lowland forests (Chivers, 1977). Siamangs have a varied diet but mainly feed on fruits and leaves as well as flowers, and insects (Papaioannou, 1973; Chivers, 1974; Raemaekers, 1979; MacKinnon and MacKinnon, 1980; Palombit, 1992; 1997; Bartlett, 2007).

ARKive image GES035576 - Siamang

Photo from ARKive of the Siamang (Symphalangus syndactylus) – http://www.arkive.org/siamang/symphalangus-syndactylus/image-G35576.html

Like other gibbon species, Siamangs are generally found in monogamous pairs with up to 6 immatures. Groups often consist of 2 to 6 individuals (Kawabe, 1970; MacKinnon and MacKinnon, 1980; Raemaekers and Chivers, 1980; Norikoshi, 1986; Palombit, 1992; 1996; Lappan, 2005). Other groups observed have been multi males (Lappan, 2005). Extra pair copulations with adult or sub adult members of neighboring groups also occur within these groups (Palombit, 1992; 1994).

ARKive image GES037541 - Siamang

Photo from ARKive of the Siamang (Symphalangus syndactylus) – http://www.arkive.org/siamang/symphalangus-syndactylus/image-G37541.html

Both males and females maintain their territory through ranging, chasing/interaction and loud singing in the morning (Chivers, 1974; Orgeldinger, 1991; Palombit, 1996).

ARKive image GES038535 - Siamang

Photo from ARKive of the Siamang (Symphalangus syndactylus) – http://www.arkive.org/siamang/symphalangus-syndactylus/image-G38535.html

Siamangs mainly have a monogamous mating system. However, within the multi male groups the mating system is polyandrous (Palombit, 1996; Lappan, 2005).

ARKive image GES036476 - Siamang

Photo from ARKive of the Siamang (Symphalangus syndactylus) – http://www.arkive.org/siamang/symphalangus-syndactylus/image-G36476.html

References/Read more
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Bertram JEA. 2004. New perspectives on brachiation mechanics. Ybk Phys Anth 47:100-17.
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Chivers DJ, Chivers ST. 1975. Events preceding and following the birth of a wild siamang. Primates 16(2):227-30.
Chivers DJ. 1977. The feeding behaviour of siamang (Symphalangus syndactylus). In: Clutton-Brock TH, editor. Primate ecology: studies of feeding and ranging behaviour in lemurs, monkeys and apes. London: Academic Pr. p 355-82.
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Orgeldinger M. 1991. Siamangs (Hylobates syndactylus) in captivity: an overview. Intl Zoo News 38(6):5-13.
Palombit RA. 1994b. Dynamic pair bonds in Hylobatids: implications regarding monogamous social systems. Behaviour 128(1-2): 65-101.
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Palombit RA. 1992. Pair bonds and monogamy in wild siamang (Hylobates syndactylus) and wite-handed gibbon (Hylobates lar) in norther Sumatra. PhD dissertation, University of California, Davis. 453 p.
Palombit RA. 1996a. Pair bonds in monogamous apes: a comparison of the siamang Hylobates syndactylus and the white-handed gibbon Hylobates lar. Behaviour 133(5-6):321-56.
Palombit RA. 1996b. The siamang and white-handed gibbon of Gunung Leuser National Park. In: van Schaik CP, Supriatna J, editors. Leuser: a Sumatran sanctuary. Jakarta: Yayasan Bina Sains Hayati Indonesia (YABSHI). p 269-79.
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Treesucon U. 1997. Siamang (Hylobates syndactylus): a new mammal recorded for Thailand. Nat Hist Bull Siam Soc 45:123-4.
Uhde NL, Sommer V. 2002. Antipredatory behavior in gibbons (Hylobates lar, Khao Yai/Thailand). In: Miller LE, editor. Eat or be eaten: predator sensitive foraging among primates. Cambridge: Cambridge U Pr. p 268-91.

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