Genetic study shows direct human link to orangutan decline

Posted: 5 February 2006

Author: J.R. Pegg

Human deforestation has caused the catastrophic collapse of orangutan populations, according to a new genetic study.

Orangutan with baby. Photo credit: Sumatran Orangutan Society
Orangutan with baby. Photo credit: Sumatran Orangutan Society
Orangutan with baby© Sumatran Orangutan Society
The research shows that the population decline has occurred within the past century - much of it within the past few decades - coinciding with massive deforestation of orangutan habitat.

"The results of the study underscores the need to act now to protect the long term survival of the species," said Professor Michael Bruford of the Cardiff School of Biosciences, who led the study. "The animals still possess enough genetic diversity to stabilize if immediate action is taken to halt further decline."

The three year study, published today in the journal "PLoS Biology," focuses on orangutan populations living in the fragmented forests of the 27,000 hectare (104 square mile) Kinabatangan Wildlife Sanctuary in Sabah, a Malaysian province in northeast Borneo.

Using hair and feces samples, the Cardiff University researchers identified 200 orangutans living along the Kinabatangan River using genetic markers called microsatellites.

The DNA information was used to simulate population history and to detect evidence of a population decline.

"The research used a new, innovative analysis that meant we could distinguish between population decline that happened thousands of years ago and much more recently," said Benoit Goossens, a wildlife geneticist at Cardiff University.

Man-made decline

The researchers report that the orangutan population has declined up to one hundred fold since the late 19th century - coinciding with the arrival of colonial powers on the island of Borneo and accelerated timber extraction. Goosens said, "This is the first time that a recent and alarming decline of a great ape population - brought about by man - has been demonstrated, dated, and quantified using genetic information."

The remaining population of orangutans in Sabah "is a very small fraction of what originally existed," Goossens added, "and more importantly, if the decline continues at the same speed, the population will be extinct within a few decades."

The researchers concluded the "major threat" to the long term survival of orangutans in Sabah is linked with the logging of their remaining habitat and the continued development of palm oil plantations.

Clearcut tropical rainforest being converted into an oil palm plantation,  Sabah, Malaysia. Photo: Swedisth U. Silviculture department.
Clearcut tropical rainforest being converted into an oil palm plantation, Sabah, Malaysia. Photo: Swedisth U. Silviculture department.
Clearcut tropical rainforest being converted to an oil palm plantation, Sabah, MalaysiaPhoto: Swedish U. Silviculture department.
Last week Malaysian authorities indicated the palm oil industry plans to aggressively expand to meet rising demand - in particular for demand for use of palm oil to make biodiesel fuel.

Industry groups say they respect environmental rules developed to protect biodiversity and question whether palm oil plantations threaten wildlife.

The new study undermines that view, say conservationists, who also fear illegal killing and capture threatens orangutans.

The apes are hunted for bushmeat and young animals are captured for sale in the pet trade - some 60 per cent of the orangutans found in Sabah are living outside the network of protected areas. The gloomy outlook for the Sabah orangutans extends to all orangutans, which are the only great apes found in Asia.

Experts estimate some 30,000 to 50,000 orangutans remain in the wild.

Habitat loss

The global demand for palm oil used in products such as soap, cosmetics and chocolate as well as biodiesel, is putting pressure on orangutans as well as other species. In the UK, palm oil is found in one in 10 products on supermarket shelves. Ninety per cent of the world's palm oil comes from Malaysia and Indonesia, and most of the plantations are on the islands of Borneo and Sumatra.

The Friends of the Earth-UK September 2005 report, The oil for ape scandal: How palm oil is threatening orangutan survival says the degraded Kinabatangan wildlife sanctuary is fragmented into 10 units by oil palm plantations and other land uses, preventing the migration of animals such as orangutans and elephants.

Kinabatangan is one of only two places in Asia that are inhabited by 10 primate species. It has the largest population of orangutans in Malaysia and is possibly the most important wetland orangutan habitat in the world.

The high population densities are a direct consequence of habitat clearance, forcing orangutans into high concentrations in remaining fragments.

As rainforests are cleared to make way for plantations, the orangutans are forced out, and are either killed or captured to be sold as pets. WWF-Malaysia which has been engaging the industry through its Partners for Wetland programme since 1998, warns that every hectare of forest converted to palm oil plantation contributes to bringing the orangutan closer to extinction.

The orangutan is scientifically regarded as two closely related species, the Bornean and the Sumatran orangutan.

The latter is considered critically endangered and may number only 9,000 in the wild.

Conservationists fear that if deforestation trends are not reversed, both species could be extinct in the wild within only a few decades.

Professor Biruté Galdikas, founder of the Orangutan Foundation International, said, "The orangutan is endangered because of habitat loss. Today the greatest threat to orangutan habitat is the continued expansion of oil palm plantations. Palm oil is the greatest enemy of orangutan and their continued survival in the wild."

The genetic study adds to mounting evidence that the world's primates are increasingly threatened by human activities.

A report released last year by the IUCN-World Conservation Union and Conservation International determined that 25 per cent of the world's 625 known primate species and subspecies are at risk of extinction.

The common threats are deforestation, commercial bushmeat hunting and illegal animal trade. Copyright Environment News Service (ENS) 2006. All Rights Reserved.

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