Captured as infants, nine Sumatran orangutans touched down at an airport in Indonesia on Friday, their last flight home after being rescued from the lucrative wildlife smuggling trade.
The nine were first repatriated from Malaysia this week as part of an operation that included an additional two orangutans sent back from Thailand, bringing the total to 11.
The larger group was sent to the Kualanamu Airport in North Sumatra. They have been tested for coronavirus and will spend a lengthy period in a rehabilitation center before being released back into the wild.
But other health problems quickly emerged. Two were ill and needed medical treatment while others showed symptoms of stress and fatigue.
Ian Singleton, director of the Sumatran Orangutan Conservation Program (SOCP) told VICE World News that the orangutans had likely been smuggled out of the country after their mothers were killed.
But he added that with the repatriation complete, they can hopefully release them into the wild to help boost the population of red-haired great apes.
The Sumatran orangutans sent from Malaysia are between two and five years old, which means they can be eased back into their natural habitat after a period of 18 months to two years, he said.
SOCP Conservation Director M Yakob Ishadani added that a crucial aspect of the process is helping orangutans relearn how to adapt to their environment.
“We are back to teaching it how to eat, how to make its own nest,” he said.
The orangutans were believed to have been smuggled over sea routes to Malaysia.
Infant orangutans are in high demand in the multibillion-dollar exotic wildlife and pet industry, but habitat loss from industrial agriculture has been a major driver of declining population numbers.
Both Sumatran and Bornean orangutans are considered critically endangered. About 14,000 Sumatran orangutans range across North Sumatra and Aceh provinces, according to the World Wildlife Fund, while the population of orangutans in Borneo numbers around 100,000.