Primate of the Week: Siamangs

Symphalangus syndactylus

ARKive image GES037485 - Siamang

Photo from ARKive of the Siamang (Symphalangus syndactylus) –

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

ARKive image GES037612 - Siamang

Photo from ARKive of the Siamang (Symphalangus syndactylus) –

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) –

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) –

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) –

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) –

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) –

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) –

References/Read more
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Bertram JEA. 2004. New perspectives on brachiation mechanics. Ybk Phys Anth 47:100-17.
Chivers DJ. 1976. Communication within and between family groups of siamang (Symphalangus syndactylus). Behaviour 57:116-35.
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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Mootnick AR, Baker E. 1994. Masturbation in captive Hylobates (Gibbons). Zoo Biol 13(4):345-53.
Norikoshi K. 1986. Socio-ecological study of siamangs in Maninjau, west Sumatra. Kyoto U Over Res Rep Stud Asia Non-Hum Prim 5:29-43.
Orgeldinger M. 1996. Behavioural changes following the death of a siamang infant. Intl Zoo News 43(6):426-33.
Orgeldinger M. 1994. Monitoring body weight in captive primates, with special reference to siamangs. Intl Zoo News 41(1):17-26.
Orgeldinger M. 1997. Protective and territorial behavior in captive siamangs (Hylobates syndactylus). Zoo Biol 16(4):309-25.
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.
Palombit RA. 1994a. Extra-pair copulations in a monogamous ape. Anim Behav 47(3):721-3.
Palombit RA. 1997. Inter- and intraspecific variation in the diets of sympatric siamang (Hylobates syndactylus) and lar gibbons (Hylobates lar). Folia Primatol 68(6):321-37.
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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