Sumatran Orangutan
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| Pongo abelii Lesson, 1827 |
The Sumatran Orangutan (Pongo abelii) is the rarer of the two species of orangutans. Living and endemic to Sumatra island of Indonesia, they are smaller than the Bornean Orangutan. The Sumatran Orangutan grows to about 1.4 metres (4.6 ft) tall and 90 kilograms (200 lb) in males. Females are smaller, averaging 90 centimetres (3.0 ft) and 45 kilograms (99 lb).
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[edit] Behaviour
Compared to the Bornean Orangutan, the Sumatran Orangutan tends to be more frugivorous and especially insectivorous.[3] Preferred fruits include figs and jackfruits. It also will eat bird eggs and small vertebrates.[4] The Sumatran Orangutans spend far less time feeding on the inner bark of trees.
Wild Sumatran Orangutans in the Suaq Balimbing swamp have been observed using tools.[5] An orangutan will break off a tree branch that's about a foot long, snap off the twigs and fray one end. It then will use the stick to dig in tree holes for termites. They'll also use the stick to poke a bee's nest wall, move it around and catch the honey. In addition, orangutans use tools to eat fruit. When the fruit of the Neesia tree ripens, its hard, ridged husk softens until it falls open. Inside are seeds that the orangutans love, but they are surrounded by fiberglass-like hairs that are painful if eaten. A Neesia-eating orangutan will select a five-inch stick, strip off its bark, and then carefully collect the hairs with it. Once the fruit is safe, the ape will eat the seeds using the stick or its fingers. Although similar swamps can be found in Borneo, wild Bornean Orangutans have not been seen using these types of tools.
NHNZ filmed the Sumatran Orangutan for its show Wild Asia: In the Realm of the Red Ape; it showed one of them using a simple tool, a twig, to pry food from difficult places. There is also a sequence of an animal using a large leaf as an umbrella in a tropical rainstorm.
The Sumatran Orangutan is also more arboreal than its Bornean cousin; this could be because of the presence of large predators like the Sumatran Tiger. It moves through the trees by brachiation.
[edit] Life cycle
The Sumatran Orangutan is more social than its Bornean counterpart. Groups of these orangutans gather to feed on the mass amount of fruiting on the fig trees. However adult males generally avoid contact with other adult males. Rape is common among orangutans. Sub-adult males will try to mate with any female, though they probably mostly fail to impregnate them since mature females are easily capable of fending them off. Mature females prefer to mate with mature males.
Interval birth rates for Sumatran Orangutan were longer than the Bornean ones and are the longest reported interval birth rates among the great apes. Sumatran orangutans give birth when they are about 15 years old. Infant orangutans will stay close to their mother for up to three years. Even after that, the young will still associate with their mother. Both orangutan species are likely to live several decades; the longevity estimate can span for more than 50 years. The average of the first reproduction of P. abelii is around 12.3 years old with no indication of menopause.[3]
[edit] Status
The sumatran orangutan is endemic to Sumatra island and is particularly restricted in the north of the island. In the wild, sumatran orangutans survive in the province of Nanggroe Aceh Darussalam (NAD), the northernmost tip of Sumatra.[6] The primate was once more widespread, as they were found more to the south in the 1800s such as in Jambi and Padang.[7] There are small populations in the North Sumatra province along the border with NAD, particularly in the Lake Toba forests. A survey in the Lake Toba found only two habited areas, Bukit Lawang (defined as the animal sanctuary) and Gunung Leuser National Park.[8] In 2002, the World Conservation Union put the species on the IUCN Red List with critically endangered status.
A recent survey in 2004 estimated around 7,300 sumatran orangutans still live in the wild.[6] Some of them are being protected in five areas in Gunung Leuser National Park and others live in unprotected areas: northwest and northeast Aceh block, West Batang Toru river, East Sarulla and Sidiangkat. A breeding program has been established in Bukit Tiga Puluh National Park in Jambi and Riau provinces and has resulted new population of Sumatran orangutans.
In captivity, there are more zoos and animal parks outside the natural habitat who are interested in orangutans in general. The oldest captive sumatran orangutan is Ah Meng, being born in 1960.[9] Nonja, thought to be the world's oldest in captivity or the wild at the time of its death, died at the Miami MetroZoo at the age of 55.[10]
[edit] See also
[edit] References
- ^ Groves, C. (2005-11-16). Wilson, D. E., and Reeder, D. M. (eds). ed. Mammal Species of the World (3rd edition ed.). Johns Hopkins University Press. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=12100804.
- ^ Singleton, I., Wich, S. A. & Griffiths, M. (2008). Pongo abelii. 2008 IUCN Red List of Threatened Species. IUCN 2008. Retrieved on 4 January 2009.
- ^ a b S. A. Wich; S. S. Utami-Atmoko; T. M. Setia; H. D. Rijksen; C. Schürmann, J.A.R.A.M. van Hooff and C. P. van Schaik (2004). "Life history of wild Sumatran orangutans (Pongo abelii)". Journal of Human Evolution 47 (6): 385–398. doi:.
- ^ "Science & Nature - Wildfacts - Sumatran orangutan". BBC. http://www.bbc.co.uk/nature/wildfacts/factfiles/360.shtml. Retrieved on 2009-07-03.
- ^ Zimmer, Carl. "Tooling through the trees - tool use by wild orangutans" Discover Magazine, November 1995.
- ^ a b Singleton, I., S. Wich, S. Husson, S. Stephens, S. Utami Atmoko, M. Leighton, N. Rosen, K. Traylor-Holzer, R. Lacy, O. Byers (2004). "Orangutan Population and Habitat Viability Assessment". Final Report. IUCN/SSC Conservation Breeding Specialist Group (CSG), IUCN.
- ^ Rijksen, H. D. (1978). "A Field Study on Sumatran Orang utans (Pongo pygmaeus abelli, Lesson 1827)". Ecology, Behavior and Conservation (Wageningen: Veenaman and Zonen).
- ^ S. A. Wich; I. Singleton; S. S. Utami-Atmoko; M. L. Geurts; H. D. Rijksen; and C. P. van Schaik (2003). "The status of the Sumatran orang-utan Pongo abelii: an update". Flora & Fauna International 37 (1): 49. doi:.
- ^ "Singapore’s most famous ape celebrates 46th birthday". Khaleej Times. 18 June 2006. http://www.khaleejtimes.com/DisplayArticleNew.asp?xfile=data/theworld/2006/June/theworld_June523.xml§ion=theworld.
- ^ "'World's oldest' orang-utan dies". BBC News. 31 December 2007. http://news.bbc.co.uk/2/hi/americas/7166338.stm.
[edit] External links
- Sumatran Orangutan Society
- Sumatran Orangutan Conservation Programme
- The Orangutan Conservancy
- ARKive - images and movies of the Sumatran orang-utan (Pongo abelii)
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