Baby Boom in the Wild

Within just two weeks of early 2019, trackers from our Sumatra Conservation Programme have found four orangutan offspring in the forest of Bukit Tigapuluh.

Orangutan Anjeli with baby in January 2019
Anjeli and her baby
By FZS veterinarian Andhani Widya

It was in January 2019, when two orangutan trackers on their way across the forest first heard some rumbling and cracking not far away in the canopy. They went closer and only a few moments later the head of an orangutan appeared between the branches. It was Suri, a female, they had last seen two years ago. And she was not alone, she had a baby with her: A little head popped up behind her back and curiously inspected the trackers who were eager to learn more about Suri’s baby. It’s a boy with beautiful eyes just like his mother and, as a yawn revealed, he already had some teeth, which means he is one to two years old.


Several days later, in another part of the rainforest another tracker-team found another female orangutan that was previously missing for several months: Jeky Chan climbed down slowly from her big nest on the top of a tree. And she, too, was clinging a baby. Jeky had disappeared when she was about six months pregnant and had now returned to the area around the FZS field station. Just like Anjeli who was found yet another few days later, Jeky had wandered off into the vast rainforest during her pregnancy to find herself a safe and quiet place for giving birth. Both Jeky and Anjeli seem to be in good condition, as well as their babies, who were less than a week old, when the trackers discovered them. Their eyes were closed and their soft blonde hair was shining in the sun. So far, Anjeli and Jeky protect and take care of their babies very well in the forest. 

Suri is back at the FZS station - with her little son
Suri is back at the FZS station and she brought her little son

Another week later, orangutan trackers found Rambo in the forest, a juvenile who had only recently been released into the forest. Or so they thought. But a closer look revealed that the little girl who was moving quickly through the canopy and foraging for food actively, was indeed a young orangutan they had never seen before. Several days later, the trackers met the youngster again, this time with her mother, Caroline. Her daughter enjoys playing with adult orangutans and has good foraging and climbing skills, spends most of his time alone, and comes back to her mother only when she needs to rest or suckle. Therefore, we can safely estimate her to be between three and four years old.


To encounter four new babies within just two weeks is quite special. Only one to two orangutans in our project area give birth to a baby each year. Orangutans have a rather slow life history and the longest birth intervals among mammals. They need 11 to 15 years to reach sexual maturity, eight months for pregnancy, and seven to eight years to raise a baby. The life expectancy of wild orangutans is around 50 years. This means that during her entire lifetime a female can produce three to four babies. 

Babies born and growing up as a result of the FZS Sumatra reintroduction programme are proof of the programme’s success If the reintroduced population is able to reproduce and live independently in the forest, we know we are doing it right. Natural growth ensures the continued existence of the Bukit Tigapuluh orangutan population.


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