Researchers have found a large population of Sumatran orangutans that was not counted in the previous studies. With this discovery, the total population has reached 14,600, more than double the past estimate of 6,600. The huge jump is not due to population growth, but because about 8,000 apes were missed in past surveys. Findings of the study were published in the journal Scientific Advances.
Sumatran orangutans found at unexpected heights
The critically endangered species is the world’s largest tree-climbing mammal. They were once present across the South East Asia, but are now found only in Sumatra (Indonesia) and the Malaysian island of Borneo. In the new survey, researchers found Sumatran orangutans at unexpected heights previously thought to be out of their range. They were found at high altitudes in the mountains and areas west of Lake Toba.
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Despite the discovery of new population, the animal remains at threat. Co-author Serge Wich of Liverpool John Moores University says if deforestation of the ape’s habitat continues at current pace, only about 4,500 orangutans will be left by 2030. Scientists urged the authorities to implement measures to prevent human exploitation of the orangutan’s habitat.
As forest land is being converted for agricultural and infrastructure purposes, their habitat could severely decline in the coming years. Poaching is another major problem in Sumatra. Scientists from Indonesia and Europe counted more than 3,000 orangutan nests on about 200 line transects covering over 200 miles. Researchers said the current known range is 6,871 square miles.
Orangutan population to keep declining
Scientists then examined different future deforestation scenarios using computer simulation, based on actual land-use plans in the area. They found that only 4,500 Sumatran orangutans could be left by 2030 if the current and other future plans were implemented. As a result, the orangutan population is expected to increasingly decline if deforestation continues at the current pace.
Lead author Hjalmar Kuehl of the Max Planck Institute for Evolutionary Anthropology said we would see upward and downward corrections in the estimated population of most of the other 12 ape taxa over the coming years.