Primate of the Week: Orangutans

Pongo

Bornean-orangutan-adult-with-infant.jpgTaxonomy

  • Suborder: Haplorhini
  • Infraorder: Simiiformes
  • Superfamily: Hominoidea
  • Family: Hominidae
  • Genus: Pongo
  • Species
    • Pongo abelii
    • Pongo pygmaeus
      • p. morio
      • p. pygmaeus
      • p. wurmbii

 Bornean-orangutan-female-with-infant.jpg

Orangutans are great apes located within Southeast Asia. Orangutans are made up of two species; Sumatran orangutan (P. abelii) and Bornean orangutan (P. pygmaeus). They differed based upon phenotype. Sumatran orangutans have thinner hair and more orange fur while Bornean orangutans have paler red fur, longer hair and longer faces. Adult males in both species have prominent cheek pads (flanges). Bornean males have larger throat pouches and cheek pads compared to Sumatran orangutans (Courtenay et al., 1988; Rowe, 1996). Males and females are sexually dimorphic with males weight nearly twice the weight of females (192 lbs (87 kg) vs 81.6 Ibs (37kg)) (Markham and Groves, 1990).

Bornean-orangutan-infant-hanging-from-tree.jpg

Orangutans are morphologically built for traveling through trees. They have thumb and big toes that act like hooks that allow for movement through the canopy (Galdikas and Briggs, 1999). When orangutans are on the ground they move quadrepedally on their fists and will occasionally move bipedally (Rowe, 1996).

Bornean-orangutan-infant-sleeping-in-the-arms-of-adult.jpg

Orangutans mainly utilize tropical rain forests and secondary forests (Galdikas, 1988). Bornean orangutans live in fragmented forests with hilly or mountainous areas and lowland swampy areas (Kaplan and Rogers, 1994; Rijksen and Meijaard, 1999). Sumatran orangutans live in forests of wide plateaus, mountains and lowland swamps (Rijksen and Meijaard, 1999).

Bornean-orangutan-infant.jpg

Orangutans are mainly frugivores but will also eat buds, flowers, leaves, bark, sap, vines, orchids, reed roots, bird eggs, spider webs, termites, caterpillar, ants, fungi, honey and other plants parts (Rijksen, 1978; Galdikas 1988).

Bornean-orangutan-juvenile-in-tree-nest.jpg

Orangutans are solitary. Adult males and male and female adolescents range alone while adult females with dependent will range with their dependent and weaned offspring (te Boekhorst et al., 1990). Sometimes sub adults, transient males and females may travel within small groups but will not continue this into adulthood. Females with their dependent offspring will live in home ranges that overlap with other adult’s females. These other adults’ females are often their mothers and sisters their home ranges are located with a larger adult male home range that overlaps with several other females (te Boekhorst et al., 1990; Rodman, 1993; Singleton and van Schaik, 2002).

Bornean-orangutan-male-1.jpg

Male can be non-resident and resident. Resident males have the large home ranges that include several females and he is the primary breeder of the females located in their home ranges. Non-resident males and females range broadly without belonging to specific home ranges (Rijksen, 1978; te Boekhorst et al., 1990; Mitani et al., 1991; Rodman, 1993). Although they are solitary because of the overlapping territories orangutans will encounter each other and will sometime have social interactions (te Boekhorst et al., 1990; Mitani et al., 1991). Sometimes females and males will form consorship group in which the male and the female stay together for a few days to months after copulation. The group will also include female’s infant and juvenile offspring (Utami, et al., 2002).

Bornean-orangutan-male.jpg

Females are philopatric and will pick a home range that overlaps with their mothers (Galdikas, 1984; van Schaik and van Hoff, 1996). Males will disperse over long distances from home ranges of their mothers and will continuous move until settling in a home range through the displacement of dominant and resident males in a particular territory (Delgado and van Schaik, 2002). Males have dominance hierarchies, these more dominant males tend to be the largest and healthiest (van Schaik et al., 2004).

Bornean-orangutan-suckling.jpg

Although orangutans are solitary they will often gather a feed in large fruiting trees (van Schaik and van Hoff, 1996).

Bornean-orangutan-with-young-in-nest.jpg

Female orangutans gestate for nine months and wild females will give birth between 14 and 15 (Kaplan and Rogers, 1994). Males have bimaturism. Sexual maturity occur from 8 to 15 for males however they will not show the flanging and size increase of social dominant male until 15 to 20 years (Rijksen, 1978). Although sub adult males or unflanged males do not have secondary sexual characteristics but are still capable to reproduce. As son as the social dominant male is removed they will begin to develop cheek pads, throat pouch long fur and other behaviors of a resident male (Rijksen, 1978).

Female-Bornean-orangutan-with-infant.jpg

Parental care is incredibly important for orangutans. Mothers are the primary caregivers and will often care for their offspring until 8 years of age (Rijksen, 1978; Munn and Fernandez, 1997).

 

juvenile-southern-bornean-orangutan-p-p-wurmbii-.jpg

Work Cited

Fox EA. 2002. Female tactics to reduce sexual harassment in the Sumatran orangutan (Pongo pygmaeus abelii). Behav Ecol Sociobiol 52: 93-101.

 

Fox EA, Sitompul AF, van Schaik CP. 1999. Intelligent tool use in wild Sumatran orangutans. In: Parker ST, Mitchell RW, Miles HL, editors. The mentalities of gorillas and orangutans: comparative perspectives. Cambridge (England): Cambridge Univ Pr. p 99-116.

 

Galdikas BMF. 1984. Adult female sociality among wild orangutans at Tanjung Puting Reserve. In: Small MF, editor. Female primates: studies by women primatologists. New York: Alan R. Liss. p 217-35.

 

Galdikas BMF. 1988. Orangutan diet, range, and activity at Tanjung Puting, Central Borneo. Int J Primatol 9(1): 1-35.

 

Galdikas BMF. 1995. Social and reproductive behavior of wild adolescent female orangutans. In: Nadler RD, Galdikas BFM, Sheeran LK, Rosen N, editors. The neglected ape. New York: Plenum Pr. p 163-82.

 

Galdikas BMF, Briggs N. 1999. Orangutan odyssey. New York: Harry N. Abrams. 144 p.

 

Galdikas BMF, Insley SJ. 1988. The fast call of the adult male orangutan. J Mammal 69(2): 371-82.

 

Groves C. 2001. Primate taxonomy. Smithsonian Inst Pr. 350 p.

Rijksen HD. 1978. A field study on Sumatran orang utans (Pongo pygmaeus abelii Lesson 1827): ecology, behaviour and conservation. Wageningen (The Netherlands): H. Veenman Zonen BV. 420 p.

 

Rijksen HD. 1993. How to save the mysterious “man of the rain forest”?. In: Tilson R, Traylor-Holzer K, Seal U, editors. Orangutan population and habitat viability analysis workshop: briefing book; 1993 Jan 18-20; Medan, North Sumatra, Indonesia. Apple Valley (MN): IUCN/SSC Captive Breeding Specialist Group. p 317-41.

 

Rijksen HD. 1995. The neglected ape? NATO and the imminent extinction of our close relative. In: Nadler RD, Galdikas BFM, Sheeran LK, Rosen N, editors. The neglected ape. New York: Plenum Pr. p 13-21.

 

Rijksen HD. 2001. The orangutan and the conservation battle in Indonesia. In: Beck BB, Stoinski TS, Hutchins M, Maple TL, Norton B, Rowan A, Stevens EF, Arluke A, editors. Great apes & humans: the ethics of coexistence. Washington DC: Smithsonian Inst Pr. p 57-70.

 

Rijksen HD, Meijaard E. 1999. Our vanishing relative: the status of wild orang-utans at the close of the twentieth century. Dordrecht (The Netherlands): Kluwer Acad. 480 p.

 

Rijksen HD, Ramono W, Sugardjito J, Lelana A, Leighton M, Karesh W, Shapiro G, Seal US, Traylor-Holzer K, Tilson R. 1995. Estimates of orangutan distribution and status in Borneo. In: Nadler RD, Galdikas BFM, Sheeran LK, Rosen N, editors. The neglected ape. New York: Plenum Pr. p 117-22.

 

Rodman PS. 1988. Diversity and consistency in ecology and behavior. In:

 

Schwartz JH, editor. Orang-utan biology. p 31-51.

 

Rodman PS. 1993. Diversity and consistency in ecology and behavior. In: Tilson R, Traylor-Holzer K, Seal U, editors. Orangutan population and habitat viability analysis workshop: briefing book; 1993 Jan 18-20; Medan, North Sumatra, Indonesia. Apple Valley (MN): IUCN/SSC Captive Breeding Specialist Group. p 31-51.

 

Rowe N. 1996. The pictorial guide to the living primates. East Hampton (NY): Pogonias Pr. 263 p.

 

te Boekhorst IJA, Schürmann CL, Sugardjito J. 1990. Residential status and seasonal movements of wild orang-utans in the Gunung Leuser Reserve (Sumatera, Indonesia). Anim Behav 39(6): 1098-1109.

 

Utami SS, Goossens B, Bruford MW, de Ruiter JR, van Hooff JARAM. 2002. Male bimaturism and reproductive success in Sumatran orang-utans. Behav Ecol 13(5): 643-52.

 

van Schaik CP. 1999. The socioecology of fission-fusion sociality in orangutans. Primates 40(1): 69-86.

 

van Schaik CP, Monk KA, Robertson JMY. 2001. Dramatic decline in orang-utan numbers in the Leuser Ecosystem, Northern Sumatra. Oryx 35(1): 14-25.

 

van Schaik CP, Poniran S, Utami S, Griffiths M, Djojosudharmo S, Nitra Setia T, Sugardjito J, Rijksen HD, Seal US, Fast T, et al. 1995. Estimates of orangutan distribution and status in Sumatra. In: Nadler RD, Galdikas BFM, Sheeran LK,

 

Rosen N, editors. The neglected ape. New York: Plenum Pr. p 109-16.

van Schaik CP, Preuschoft S, Watts DP. 2004. Great ape social systems. In:

 

Russon AE, Begun DR, editors. The evolution of thought: evolutionary origins of great ape intelligence. Cambridge (England): Cambridge Univ Pr. p 190-209.

 

van Schaik, CP, van Hooff JARAM. 1996. Toward an understanding of the orangutan’s social system. In: McGrew WC, Marchant LF, Nishida T, editors. Great ape societies. Cambridge (England): Cambridge Univ Pr. p 3-15.

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