Orangutan forest school in Indonesia takes on its first eight students

Orangutans in crisis

Bornean orangutans (Pongo pygmaeus) are classified as critically endangered on the IUCN Red List. A recent study published in Current Biology estimates that over 100,000 orangutans have been lost across Borneo between 1999 and 2015. The remaining orangutans exist in a number of geographically isolated groups known as “metapopulations,” and the study found that only 38 of the 64 Bornean metapopulations have more than 100 individuals — the threshold that scientists estimate is required for a viable population.

In Borneo, the orangutans’ natural forest habitat is disappearing at an alarming rate. Between 1973 and 2016, 30 percent of the island’s old-growth forest was converted to farmland for crops such as oil palm or lost as a result of forest fires — 195,000 square kilometers (75,300 square miles). “There is no land planning,” Preuschoft said, “only land grabbing.”

But the study also found large declines in orangutan numbers within the remaining forest, indicating that habitat loss is not the only threat. Hunting for bushmeat, the illegal pet trade and human-wildlife conflict over resources — plantation workers killing orangutans to protect their crops, for example — are all also important drivers of orangutan declines, according to the study’s lead author, Maria Voigt.

“The situation is critical,” said Voigt, a doctoral candidate at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “What has been done in terms of conservation so far has not been enough to slow down or reverse the downwards trend.”

Every year, many orangutans are either confiscated by security forces or handed in by local people. The vast majority are juveniles under 7 years of age. Young orangutans are targeted for the illegal pet trade, and they are also often spared when their mothers are killed as a result of conflict with humans.

Orangutan orphans and their caretakers at the forest school. The caretakers must step in to teach the motherless orangutans the skills they need to live independently in the forest. Image courtesy of Four Paws.

In the wild, juvenile orangutans remain with their mothers for around nine years and learn from them the skills they need to survive. Scientists have analyzed the milk deposits on orangutan teeth and found that in some cases they can continue partially breastfeeding for up to eight years — more than any other mammal. Without their mothers to help them, confiscated young orangutans cannot be released back into the wild and must rely on human support — which is precisely the problem that Preuschoft’s forest school has set out to tackle.

However, rehabilitating orangutan orphans is not easy. You need to know about orangutan biology and ecology, their genetics and health, and the animals’ psychological and social needs, said Anne Russon, an expert in orangutan rehabilitation who’s not connected to Jejak Pulang or Four Paws.

“For a long time, rehabilitations were put together by do-gooders who saw a need that none of the professionals would pay attention to,” Russon, a primatologist and psychology professor from York University, Toronto, told Mongabay.

Barbara Harrison, an art historian by training, made the first attempts at orangutan rehabilitation during the 1960s in Sarawak, in Malaysian Borneo. Without the right knowledge, early efforts depended on trial and error. And, until the mid-1990s, rehabilitated orangutans that had been released back into the wild were not monitored, so it was impossible to evaluate the success of these introductions.

“Fortunately, for about the last 15 years, there has been a broader effort in orangutan research and conservation areas to … make sure it’s done properly,” Russon said.

This story first appeared on Mongabay

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