Orangutans

Pongo (genus)

South East Asia is home to two species of orangutan; the Sumatran and Bornean orangutan. Both species spend almost all of their time in trees and have distinctive body shapes with longer arms than legs and coarse shaggy red hair. Geographically isolated on two separate islands, these great apes show obvious physical differences between the species, with the Sumatran orangutans being more gracile, with elongated faces and a paler and longer-haired coat. There are also obvious differences between the sexes, with males often double the size of females with large throat pouches and noticeable cheek pads.
Family: Hominidae
Genus: Pongo
Species: P. pygmaeus (ENA2cd) Bornean Orangutan
Subspecies: P. p. Pygmaeus (, P. p. morio, P. p. wurmbi)
P. abelii (CR A2cd) (Sumatran Orangutan)
CITES listing:
Appendix I
Height: 97 cm (M), 78cm (F)
Weight: 87kg (M), 37kg (F)
Gestation: 8.5 months
Lifespan: 50-60 years (wild)

Current Distribution:

orangutan RangeAlthough once widely distributed across south-East Asia, Bornean orangutans are now restricted to 150 000 km2 habitat on the island of Borneo, with the largest population in Kalimantan, the Indonesian part of the island.

Click here to see the current distribution of Bornean Orangutans

Sumatran orangutan rangeSumatran orangutans are restricted to an incredibly small range of 26 000km2 in the northwest of Sumatra

Click here to see the current distribution of Sumatran Orangutans

Population Estimates

Estimates of wild populations of orangutans in South-East Asia are distressing. There are estimated to be a mere 55 000 orangutans in Borneo while in Sumatra only 7000 orangutans are thought to exist in the wild.

Populations in captivity: There are approximately 900 known orangutans in captivity across the world

Habitat

Bornean orangutans live in isolated fragments of the oldest forests in the world comprised mainly of low-lying peat-swamp forests and hilly mountainous regions and have not been found in areas with elevations over 1000m.
Sumatran orangutans inhabit wide plateaus and mountainous regions at higher elevations of 1500m and lowland swamps at sea level.

Diet

Orangutans eat over 400 different types of food; however the majority of their food is fruit especially wild figs. When fruit is scarce, orangutans will feed on seeds, leaf shoots, bark, insects, flowers, honey, eggs and soil. Orangutans spend on average 95% of their time feeding, resting and moving between feeding and resting sites and have two main activity peaks; one in the morning and the other in the afternoon.

Social Structure

Orangutans are more solitary than the other great apes in Africa. Adult males have large home ranges overlapping with one to several females. Females live with their offspring in discrete home ranges that overlap with other adult females. Adult males have interactions only with females in estrus. Occasionally sub-adult individuals form groups, however these do not last into adulthood. Females reach maturity around 14 years of age and orangutans exhibit the longest inter-birth intervals of around 8 years, and infants are completely reliant on their mothers until around 2 years old. Males reach sexual maturity between 8 and 15 years however do not show secondary sexual characteristics and long-calls until around 15-20 years. Males listen to the movements of each other with the help of their vocalizations that can be heard from afar and when meeting they show threatening display to each other. Territorial fights depend on the presence of females, though they are very rare and displaying behaviour is more frequent.

Threats:

The single greatest threat to orangutans is loss of habitat. In the past two decades, 80 percent of orangutan habitat has been destroyed due to illegal logging, mining and agricultural conversion.

Habitat loss

As orangutans are entirely reliant on trees for survival, both illegal and legal logging has created direct effects e.g. decreased availability of food, restricted movement and increased competition for scarce resources, and indirect effects e.g. climate change, soil erosion and loss of general biodiversity. New roads cleared for logging also create access points to areas previously not accessible to hunters and developers.

Palm oil

The rapid expansion of oil palm plantations across Borneo and Sumatra has already involved the clear-felling of millions of hectares of forests, and all unprotected lowland forests are vulnerable to eventual future conversion. Loss of habitat due to palm oil plantations coupled with increased orangutan-human conflict puts enormous stress on orangutans living in or around palm oil plantations. As the world continues to demand more palm oil, more orangutans and other endangered species will be put at risk.

Click here to read more about palm oil’s affect on orangutans

Invasive species

As we share many genetic similarities with great apes, orangutans are highly susceptible to any disease humans can acquire. Increasingly diseases such as influenza, polio, tuberculosis and various parasitic diseases have caused significant mortality in orangutans. This is all intensified as human populations, tourists and even well-meaning researchers encroach on ape habitat.

Harvesting

As habitat is cleared for agriculture many displaced orangutans are caught and either killed for meat or captured for the illegal pet trade. Orangutans also make perfect targets for hunters due to their slow movement and large size. Although eating ape meat is considered a taboo in some areas, even a small amount of hunting can drastically impact on orangutan populations.

Persecution

Orangutans are increasingly being persecuted as pests when resources become scarce and in order to feed, have to venture into agricultural areas to steal food resulting in occasional poisoning or shooting.

Natural disasters

Climate change has already impacted negatively on Bornean orangutan populations; the drought during El Nino in 1997/8 led to millions of acres of forest lost due to uncontrolled fires, this directly resulted in the death of thousands of orangutans (almost 33% of all orangutans in Borneo). The combination of logged forests which increases the fire-risk and climate instability could lead to many more orangutans losing their lives in both Sumatra and Borneo in the future.

Intrinsic factors

There are a number of intrinsic factors that make orangutans vulnerable towards specific environmental disturbances. Long interbirth intervals, extended periods of development and reproductive suppression in times of fruit scarcity all play a large part in reducing population recovery. In addition, orangutans are poor dispersers and are hesitant to move across open areas cleared by agriculture or logging- this can often result in inbreeding and increased stress on already stressed populations.

Other factors

Orangutans are often collected from the wild for the entertainment industry and specific TV shows showing orangutans as pets fuel the demand for illegal trade. Political instability and corruption in areas can lead to a decrease in law enforcement and increased pressure on ecosystems to support local communities.

The role of sanctuaries

The growing need for sanctuaries is directly related to the steady increase in habitat disturbance/loss which results in the displacement of great apes. Primate sanctuaries were created over the last three decades to accommodate the staggering numbers of orphaned and unwanted orangutans in South-east Asia

Rehabilitation projects for release back into the wild are problematic and have on the whole had limited success, therefore at present specially built sanctuaries remain the main alternative.

How GAFI can help orangutans

Through the use of film, GAFI can reach urban and rural communities in Borneo and Sumatra to give them a better understanding of the importance of conserving great apes. Through film, GAFI can also empower local communities to find local solutions to issues facing them e.g. loss of natural resources, problems surrounding monoculture (e.g. palm oil) and general issues of concern. Moreover GAFI can also reach the remote communities living adjacent to orangutan habitat to give them an insight into how gorillas behave when they are not threatened and help reduce human-orangutan conflict. GAFI has the materials and the expertise to further enhance the conservation education programmes run by sanctuaries and NGOs working in orangutan habitats. By providing the sanctuaries with films and the necessary equipment, visitors will not only leave with an impression of captive orangutans but also with an impression of the necessity to save wild orangutans. When funds become available, GAFI hopes to train sanctuary staff in how to make their own films about issues of relevance to their particular sanctuary and the surrounding communities.

Who else is helping

Orangutan Organisations

References