SUMATRAN ORANGUTAN

The Sumatran Orangutan (Pongo abelii) is one of the two species of orangutans. Found only on the island of Sumatra, in Indonesia, it is rarer and 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).

BEHAVIOR

Compared to the Bornean Orangutan, the Sumatran Orangutan tends to be more frugivorous and especially insectivorous. Preferred fruits include figs and jackfruits. It also will eat bird eggs and small vertebrates. 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. 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.

Sumatran Orangutan at Bukit Lawang

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.

Status

A Sumatran orangutan being taken care of at Bukit Lawang.

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. The primate was once more widespread, as they were found more to the south in the 1800s such as in Jambi and Padang. 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 inhabited areas, Bukit Lawang(defined as the animal sanctuary) and Gunung Leuser National Park. In 2002, the World Conservation Union put the species on the IUCN Red List with critically endangered status. The species is considered one of "The World's 25 Most Endangered Primates."

A survey in 2004 estimated that around 7,300 sumatran orangutans still live in the wild. Some of them are being protected in five areas in Gunung Leuser National Park; others live in unprotected areas: northwest and northeast Aceh block, West Batang Toru river, East Sarulla and Sidiangkat. A successful breeding program has been established in Bukit Tiga Puluh National Park in Jambi and Riau provinces.

Nonja, thought to be the world's oldest in captivity or the wild at the time of its death, died at the Miami Metro Zoo at the age of 55. The oldest captive Sumatran orangutan was, until her death in Singapore Zoo on 8 February 2008 at the age of 48, Ah Meng, born in 1960.

 information from en.wikipedia.org/wiki/Orangutan

CONSERVATION STATUS

The Sumatran species is critically endangered and the Bornean species of orangutans is endangered according to the IUCN Red List of mammals, and both are listed on Appendix I of CITES. The total number of Bornean orangutans is estimated to be less than 14 percent of what it was in the recent past (from around 10,000 years ago until the middle of the twentieth century) and this sharp decline has occurred mostly over the past few decades due to human activities and development. Species distribution is now highly patchy throughout Borneo: it is apparently absent or uncommon in the south-east of the island, as well as in the forests between the Rejang River in central Sarawak and the Padas River in western Sabah (including the Sultanate of Brunei). The largest remaining population is found in the forest around theSabangau River, but this environment is at risk. A similar development have been observed for the Sumatran orangutans.

A 2007 study by the Government of Indonesia noted in 2004 it was estimated that there was a total wild population of 61234 orangutans, 54567 of which were found on the island of Borneo. The table below shows a breakdown of the species and subspecies and their estimated populations from the report:

Scientific name	Common name	Region	Estimated number
Pongo abelii	Sumatran Orangutan	Sumatra	6,667
Pongo pygmaeus	Bornean Orangutan	Borneo
P. p. morio	Northeast Bornean Orangutan	Sabah	11,017
P. p. morio	Northeast Bornean Orangutan	East Kalimantan	4,825
P. p. wurmbii	Central Bornean Orangutan	Central Kalimantan	>31,300
P. p. pygmaeus	Northwest Bornean Orangutan	West Kalimantan and Sarawak	7,425

This indicates a decline from some estimates between 2000 and 2003 which found 7,300 Sumatran Orangutan individuals in the wild and between 45,000 and 69,000 Bornean Orangutans. Thousands of orangutans don't reach adulthood due to human disruption. Orangutans are killed for food while others are killed because of disruption in people's property. Mother orangutans are killed so their infants can be sold as pets. Many of the infants die without the help of their mother. Since recent trends are steeply down in most places due to logging and burning, it is forecast that the current numbers are below these figures.

Orangutan habitat destruction due to logging, mining and forest fires, as well as fragmentation by roads, has been increasing rapidly in the last decade. A major factor in that period of time has been the conversion of vast areas of tropical forest to oil palm plantations in response to international demand (the palm oil is used for cooking, cosmetics, mechanics, and more recently as source of biodiesel). Some UN scientists believe that these plantations could lead to irreparable damage to orangutan habitat by the year 2012. Some of this activity is illegal, occurring in national parks that are officially off limits to loggers, miners and plantation development. There is also a major problem with hunting and illegal pet trade. In early 2004 about 100 individuals of Bornean origin were confiscated in Thailand and 50 of them were returned to Kalimantan in 2006. Several hundred Bornean orangutan orphans who were confiscated by local authorities have been entrusted to different orphanages in both Malaysia and Indonesia. They are in the process of being rehabilitated into the wild.

Conservation centres and organisations

 A number of organisations are working for the rescue, rehabilitation and reintroduction of orangutans. The largest of these is the Borneo Orangutan Survival Foundation, founded by Dr. Willie Smits, which employs between six hundred and a thousand people at a hundred sites. It operates a number of large projects, including the Samboja Lestari Forest Rehabilitation Program and the Nyaru Menteng Rehabilitation Program managed by Lone Drøscher Nielsen. Other major conservation centres in Indonesia include those at Tanjung Puting National Park and Sebangau National Park in Central Kalimantan, Kutai in East Kalimantan, Gunung Palung National Park in West Kalimantan, and Bukit Lawang in the Gunung Leuser National Park on the border of Aceh and North Sumatra. In Malaysia, conservation areas include Semenggoh Wildlife Centre in Sarawak and Matang Wildlife Centre also in Sarawak, and the Sepilok Orang Utan Sanctuary near Sanda.

 information from en.wikipedia.org/wiki/Orangutan

BEHAVIOUR

Fruit makes up 65–90 percent of the orangutan diet. Fruits with sugary or fatty pulp are favored. Ficus fruits are commonly eaten, because they are easy to harvest and digest. Lowland Dipterocarp forests are preferred by orangutans because of their plentiful fruit. Bornean orangutans consume at least 317 different food items that include young leaves, shoots, bark, insects, honey, and bird eggs.

Orangutans are opportunistic foragers, and their diets vary markedly from month to month. Bark is eaten as a last resort in times of food scarcity; fruits are always more popular.

Orangutans are thought to be the sole fruit disperser for some plant species including the climber species Strychnos ignatii which contains the toxic alkaloid strychnine. It does not appear to have any effect on orangutans except for excessive saliva production.

Geophagy, the practice of eating soil or rock, has been observed in orangutans. There are three main reasons for this dietary behavior; for the addition of minerals nutrients to their diet; for the ingestion of clay minerals that can absorb toxic substances; or to treat a disorder such as diarrhea.

Orangutans use plants of the genus Commelina as an anti-inflammatory balm.

 

Tool use and culture

Orangutans at Singapore Zoo

Like the other great apes, orangutans are among the most intelligent primates. Wild chimpanzees have been known since the 1960s to use tools. Tool use in orangutans was observed by Birutė Galdikas in ex-captive populations.

Evidence of sophisticated tool manufacture and use in the wild was reported from a population of orangutans in Suaq Balimbing (Pongo pygmaeus abelii) in 1996. These orangutans developed a tool kit for use in foraging that consisted of insect-extraction tools for use in the hollows of trees, and seed-extraction tools which were used in harvesting seeds from hard-husked fruit. The orangutans adjusted their tools according to the nature of the task at hand and preference was given to oral tool use. This preference was also found in an experimental study of captive orangutans (P. pygmaeus).

Carel P. van Schaik from the University of Zurich and Cheryl D. Knott from Harvard University further investigated tool use in different wild orangutan populations. They compared geographic variations in tool use related to the processing of Neesia fruit. The orangutans of Suaq Balimbing (P. abelii) were found to be avid users of insect and seed-extraction tools when compared to other wild orangutans. The scientists suggested that these differences are cultural. The orangutans at Suaq Balimbing live in dense groups and are socially tolerant; this creates good conditions for social transmission. Further evidence that highly social orangutans are more likely to exhibit cultural behaviors came from a study of leaf-carrying behaviors of ex-captive orangutans that were being rehabilitated on the island of Kaja in Borneo. The above evidence is consistent with the existence of orangutan culture as geographically distinct behavioral variants which are maintained and transmitted in a population through social learning.

Orangutan at Columbus Zoo and Aquarium

In 2003, researchers from six different orangutan field sites who used the same behavioral coding scheme compared the behaviors of the animals from the different sites. They found that the different orangutan populations behaved differently. The evidence suggested that the differences in behavior were cultural: first, because the extent of the differences increased with distance, suggesting that cultural diffusion was occurring, and second, because the size of the orangutans’ cultural repertoire increased according the amount of social contact present within the group. Social contact facilitates cultural transmission. Carel P. van Schaik suggests that young orangutans (P. abelii) acquire tool use skills and cultural behaviors by observing and copying older orangutans.

Orangutans do not limit their tool use to foraging, displaying or nest-building activities. Wild orangutans (P. pygmaeus wurmbii) in Tuanan, Borneo, were reported to use tools in acoustic communication. They use leaves to amplify the kiss squeak sounds that they produce. Some have suggested that the apes employ this method of amplification in order to deceive the listener into believing that they are larger animals.

Communication

A two-week old orangutan

A two year study of orangutan symbolic capability was conducted from 1973-1975 by Gary L. Shapiro with Aazk, a juvenile female orangutan at the Fresno City Zoo (now Chaffee Zoo) in Fresno, California. The study employed the techniques of David Premack who used plastic tokens to teach the chimpanzee, Sarah, linguistic skills. Shapiro continued to examine the linguistic and learning abilities of ex-captive orangutans in Tanjung Puting National Park, in Indonesian Borneo, between 1978 and 1980. During that time, Shapiro instructed ex-captive orangutans in the acquisition and use of signs following the techniques of R. Allen and Beatrix Gardner who taught the chimpanzee, Washoe, in the late-1960s. In the only signing study ever conducted in a great ape's natural environment, Shapiro home-reared Princess, a juvenile female who learned nearly 40 signs (according to the criteria of sign acquisition used by Francine Patterson with Koko, the gorilla) and trained Rinnie, a free-ranging adult female orangutan who learned nearly 30 signs over a two year period. For his dissertation study, Shapiro examined the factors influencing sign learning by four juvenile orangutans over a 15-month period.

The first orangutan language study program, directed by Dr. Francine Neago, was listed by Encyclopædia Britannica in 1988. The Orangutan language project at the Smithsonian National Zoo in Washington, D.C., uses a computer system originally developed at UCLA by Neago in conjunction with IBM.

Orangutan "laughing"

Zoo Atlanta has a touch screen computer where their two Sumatran Orangutans play games. Scientists hope that the data they collect from this will help researchers learn about socializing patterns, such as whether they mimic others or learn behavior from trial and error, and hope the data can point to new conservation strategies.

A 2008 study of two orangutans at the Leipzig Zoo showed that orangutans are the first non-human species documented to use 'calculated reciprocity' which involves weighing the costs and benefits of gift exchanges and keeping track of these over time.

Although orangutans are generally passive, aggression toward other orangutans is very common; they are solitary animals and can be fiercely territorial. Immature males will try to mate with any female, and may succeed in forcibly copulating with her if she is also immature and not strong enough to fend him off. Mature females easily fend off their immature suitors, preferring to mate with a mature male.

Orangutans do not swim. At least one population at a conservation refuge on Kaja island in Borneo have been photographed wading in deep water.

Orangutans, along with Chimpanzees, gorillas, and other apes, have even shown laughter-like vocalizations in response to physical contact, such as wrestling, play chasing, or tickling.

 information from en.wikipedia.org/wiki/Orangutan

ANATOMY AND PHYSIOLOGY

An orangutan's standing height averages from 4 to 5 ft (1.2 to 1.5 m). On average, an orangutan weighs between 73 to 180 pounds (33 to 82 kg). Males can weigh up to 250 lb (110 kg) or more. Orangutan hands are similar to humans' hands; they have four long fingers and an opposable thumb. Their feet have four long toes and an opposable big toe. Orangutans can grasp things with both their hands and their feet. The largest males have an arm span of about 7.5 ft (2 m).

Size relative to a 6 foot (1.8 m) man

Orangutans have a large, bulky body, a thick neck, very long, strong arms, short, bowed legs, and no tail. They are mostly covered with long reddish-brown hair, although this differs between the species: Sumatran Orangutans have a more sparse and lighter coloured coat.

The orangutan has a large head with a prominent mouth area. Adult males have large cheek flaps (which get larger as the ape ages) that show their dominance to other males and their readiness to mate. The age of maturity for females is approximately 12 years. Orangutans may live for up to 50 years in the wild.

Orangutans are the most arboreal of the great apes, spending nearly all of their time in the trees. Every night they fashion sleeping nests from branches and foliage. They are more solitary than other apes; males and females generally come together only to mate. Mothers stay with their babies for six or seven years. There is significant sexual dimorphism females can grow to around 4 ft 2 in or 127 cm and weigh around 100 lb (45 kg) while flanged adult males can reach 5 ft 9 in or 175 cm in height and weigh over 260 lb (118 kg).

The arms of orangutans are twice as long as their legs. Much of the arm's length has to do with the length of the radius and the ulna rather than the humerus. Their fingers and toes are curved, allowing them to better grip onto branches. Orangutans have less restriction in the movements of their legs than humans and other primates, due to the lack of a hip joint ligament which keeps the femur held into the pelvis. Unlike gorillas and chimpanzees, orangutans are not true knuckle-walkers, and are instead fist-walkers.

Male, child, and female Sumatran orangutans

 information from en.wikipedia.org/wiki/Orangutan