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The Kehje Sewen Forest has welcomed a new resident. Following confirmation from our veterinarian in October last year that Lesan was pregnant, we are thrilled to announce that she has since given birth.

Lesan was seen last around Camp Lesik at the end of 2022 with an enlarged stomach. Shortly after, she disappeared for some time, so our team suspected that she had already given birth. And they were right! Lesan and her firstborn, Ayu, were recently spotted around Camp Lesik, but they were not alone this time: Lesan was holding Ayu’s baby sibling, her second offspring born in the forest.


Lesan clearly shows her protective maternal instincts and affection

The second-time mum clearly illustrated her protective maternal instincts and affection through her behaviour around the newborn. When our team attempted to take photos, Lesan turned away to hide the baby. Even big sister Ayu went into protective mode and attempted to scare off our team members by shaking the trees and approaching them with her teeth exposed. Lesan and Ayu did a great job teaming up to protect their newest family member from the prying eyes of human observers.

Lesan, a rehabilitated orangutan who BOS reintroduced to the forest in 2012, is a success story not only for her ability to survive in the wild and reproduce but also for raising Ayu to forage on her own and build nests in nearby fruiting trees. According to observational data made by our Post-Release Monitoring team in the field, Lesan’s ability to socialise with other orangutans, act accordingly when encountering humans, explore her ranging area, and copulate to help create a new generation of forest-born orangutans demonstrates the success of the reintroduction programme.

Orangutans are endemic to the islands of Borneo and Sumatra and are on the verge of extinction. Thus various efforts are being made to protect them, including the BOS Foundation’s rehabilitation and release programme.
As an umbrella species that plays a vital role in forest sustainability, orangutans are desperately needed in the wild. We need them to remain in Kalimantan’s forest ecosystems, their true home. Therefore, we must prevent them from being exploited and protect them at all costs.

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or symbolically adopting one of our orphaned orangutans?

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It was a usual day at the Nyaru Menteng forest school, where young orangutans were learning from...

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