Berlian Heard a Long Call from Wild Orangutan

On November 19th, 2012, our monitoring team conducted a special mission to monitor Berlian’s activity for the whole day. As usual, our team will record every single activity precisely. Berlian is slightly different from the other orangutans, instead of exploring the forest on a fast pace; she prefers to linger to enjoy her food. After finding her morning nest, the team began to record her activity.

That morning, Berlian started her day with a breakfast of Uncaria glabra. Uncaria is locally called Gambier. Its extract powder is usually used by humans for tanning or dyeing. Her favorite parts were obviously the young leaves, young stems, and cambium bark. In addition, she also enjoyed young leaves of Etlingera Sp. (forest ginger), Calamus Sp. (bamboo), and Ficus Sp. (banyan tree). And she did all this feeding activity without even moving too far from her morning nest.


Berlian enjoying the forest

At approximately 4:25 pm, the team was surprised by the sound of a long call from a wild orangutan. Consisting 12 grumbles (breath sounds before the long call), 47 long calls and 32 bubbles (sound produced after long call as a neutralizer). This phenomenon is inline with RHOI’s team survey result a while ago describing the finding of several-abandoned nests of male wild orangutans in the area of Kehje Sewen Forest.

While the team was surprised by this sound, Berlian looked alert. She stopped eating for about two minutes. As the long calls grew louder, Berlian was getting scared. Form its loudness, the team estimated the presence of the wild orangutan was about 150 meter from where Berlian was located. The team also saw when the wild orangutan uprooted a tree (snag crash). Berlian huddled with her head between her legs, holding on to herself tightly. But after 10 minutes had passed and the long call did not come again, Berlian was back to her activities. In the next few days however, Berlian still occasionally revisited the place where the noise came from, to check things out.


Wild Male Orangutan’s Nest

According to Dr. Sri Suci Utami, a well-known primatologist in Indonesia, Berlian’s behavior is normal. Although this is not the first time Berlian experiences a long call from an orangutan (she heard it plenty of times when she still lived in Samboja Lestari), but to experience long calls in a real forest would be very different. Other factor that influences this behavior is that, an immature female orangutan like Berlian (10 years old) tends to be attracted to males who are also in their age range, without cheek pads and do not produce long calls. This is why Berlian looked very frightened when she heard the sounds of long call of the wild orangutan.

Minutes went by, Berlian was back to her activity. Once satisfied with the various types of young leaves, Berlian then started harvesting honey from a beehive on a Liana tree next to her. As expected, some of the bees became angry and attacked Berlian. The bees stroke her hand, foot and neck, but she still looked relaxed, simply enjoying the honey. Berlian was just rubbing the sting. While continuing to enjoy the honey, at 5:25 pm Berlian started to make a nest. Soon after finishing her ‘dessert’, Berlian seemed to rest in her nest.

The team then returned to Camp 103 joyously. The long call of the wild orangutan proves Kehje Sewen’s biodiversity.


A Beautiful Rainbow Seen from Camp 103

Photos by: Wulan, Agus and Rio


3 thoughts on “Berlian Heard a Long Call from Wild Orangutan

  1. Thanks for this awesome article! What an interesting encounter! Miss Berlian certainly has given us all a big peek into the uncertainty, fear, and potential dangers that comes with living independently and freely in the forest!

    Thank you, Berlian, for taking us with you on this incredible and suspenseful journey! But I’d like to know, Berlian, why were you so scared? At Samboja Lestari, didn’t you ever hear a much-older-than-you adult male long call? Would this wild male harm you if he really did encounter you? I hope he doesn’t!! And I hope you are safe and not too stressed out!!

    Also, is it a good or bad thing if released Orangutans physically meet wild Orangutans? Is it true that one requirement for a release forest is that it does not contain a wild orangutan population? If so, why? Is it dangerous for wild and released Orangutans to coexist in the same area (transmission of diseases? difference in immunity?)?

    P.S. Was it Berlian who had that bad rainy day where she tried to eating termite’s nests, and the termites kept biting her? (I hope you’re ok from the beestings, Berlian!)

    STAY SAFE & HEALTHY, BERLIAN! I love you and hope to hear from you again soon!!

    • Dear Sasha,

      Although Berlian of course had heard long calls (LCs) while she lived in Samboja Lestari, but these LCs were mostly from individuals whom she knew and/or she knew that these individuals lived in an enclosure or in an island, thus far away from her.

      Her behavior is actually normal if you think from a human point of view. As a teenager, we, too, would be scared or at least cautious when approached by a male stranger whose physique is twice as big as ours? We would try our best to keep our distance from him, until we get to know him a little better and learn what his intentions are.

      Well, the same with Berlian. From the story, you can tell that she wasn’t extremely scared. She didn’t run far away and instead stayed within the surrounding area. It means that she was actually a little bit curious, too. She simply kept her distance because she didn’t know who he was. And he was a lot bigger than her! It’s a process. Berlian is now 10 years old. As she grows older and (maybe) gets to know the wild male a bit better, nature will take its own course.

      Regarding the suitability of a release area, ideally we should find an area without wild orangutans. There are 2 main reasons for this: (1) Because rehabilitated orangutans had lived with humans for so long, they may carry some diseases that are not found in wild orangutans, thus increasing the risk of introducing new diseases in orangutan population in the wild. This is why our health checks routines and procedures are stringent. (2) Again, because rehabilitants had lived with humans for so long and learned some of their forest skills with human-made enrichment tools, they may also pick up some human behaviors such as feeling just as comfortable playing on the ground as in the trees, being naturally curious when seeing a human-being, etc. These types of human behavior will affect their adjustment period in the forest after they are released. And when there are a lot of wild orangutans present, these behavior will also affect their ability to compete with the wild orangutans in terms of finding food, etc.

      However, you’ve probably realized by now how hard it is to find a suitable forest for orangutans with all the right criteria (otherwise we wouldn’t have to wait 10 years to release them). Therefore, leading primatologists around the world have come to an agreement that it’s okay to release rehabilitated orangutans in an area with wild orangutan population of 0.1 individual/square-kilometer or less. After extensive 2-year survey, we found the Kehje Sewen Forest has a population of wild orangutans of only 0.014 individual/square-kilometer. That’s why we went ahead and purchased the license.

      Today, all of our rehabilitated orangutans released in Kehje Sewen are monitored closely, as you already know from all of our monitoring updates. To minimize contact between our team and orangutans, nest-to-nest observation is only done 6 days per every 2 months in the first year. The exception to that is of course when an orangutan is found in trouble (seen very thin, or sick, or when his/her signals had not been tracked for a while) in which case we had to do extensive search, as well as nest-to-nest observation, like what happened to Hamzah ( The team also must encourage orangutans to stay and play in the trees and not on the ground. The result of monitoring will be evaluated at the end of the first year to determine: (1) how we can improve our Forest School and rehabilitation program; (2) whether or not we should extend the monitoring period for all or certain individuals.

      We hope this answers your questions and concerns. And yes, Berlian was the one who got beestings in the rain earlier this year when she was just released. But she still loves to hunt for honey and seems to have developed a certain immune system or maybe a thicker skin to withstand beestings. Now when she gets stung, she simply rubs her skins and continues devouring on the honey! She is just fine, healthy and happy. 🙂

      • Thank you so much for answering my questions. Berlian’s behavior makes much more sense now–I believe she’s quite mentally mature for her age (only 10 yrs. old!) to react that way and not freak out!

        Please keep us updated on any other interactions between Berlian and this wild male orangutan. Wishing all the Orangutans and their carers the best!

        Happy holidays to all:)

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