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Friendship in the Forest: The Story of Belinda, Long and Arief

On Tuesday morning, three of our PRM team from Camp Nles Mamse – Luy, Cohel and Valerie – headed toward the phenology transect 2 in search of Belinda, a female orangutan we released in July this year. A few days prior, the team had spotted Belinda as they were returning to camp.

Fortunately the team found Belinda not far from the nest she was previously seen resting in. The team began to observe her and collect data on her activities. Shortly after, the team saw movements in the canopy, followed by the appearance of Long and Arief! You might recall this pair’s touching story (read the story here).


Belinda, aware that Long and Arief were coming her way, greeted them as they arrived, and the three spent time together. Arief seemed to be still quite attached to Long, and kiss-squeaked twice before leaving his adoptive mother’s side to approach Belinda, who couldn’t resist her adorable visitor’s invitation to play.

Arief followed Belinda’s every move, while attentive Long observed and allowed him the freedom to play with his new friend. Belinda didn’t seem to mind Arief trailing her; she paid him attention with loving strokes every now and then, and even shared some of her food with the young male.

Arief and Belinda

Arief played and wrestled with Belinda, who patiently tolerated her young playmate’s antics. Belinda tried to build a nest, but soon stopped her construction efforts when she realized Arief was still in the mood to play. After some time, Arief returned to Long, giving Belinda the chance to prepare her night nest.

Arief and Long

Daylight started to slowly fade and the nocturnal insects began to sound their night choir. It was time for the team to leave the trio to rest for the night.

It was fantastic to have witnessed these three orangutans thriving in the Kehje Sewen Forest. Wrapping up a successful day of observations, the team headed back to camp to share their story of Belinda, Long and Arief.

Text by: PRM team in Camp Nles Mamse, Kehje Sewen Forest

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BOS Foundation Release Twelve Orangutans to BBBR-NP Including Two Repatriated from Thailand

#Orangutanfreedom is still going strong and we have just released another 12 orangutans to the Bukit Baka Bukit Raya National Park (BBBR-NP) in Katingan Regency, Central Kalimantan. This release includes four male and eight female orangutans, two of which completed 11 years of rehabilitation at Nyaru Menteng after being repatriated from Thailand.

The repatriated females, Nanga and Sukamara, arrived at Nyaru Menteng in November 2006, when they were five and nine years old respectively. Very little background information was known of the two, but from their behaviour it was clear that they had spent a long time in captivity and may likely have been used in some kind of entertainment facility. When they arrived at Nyaru Menteng, Nanga and Sukamara were placed with 46 other orangutans repatriated from Thailand in a special Forest School class aimed at helping them develop basic skills like climbing, nest-building, foraging, socializing, and identifying predators. It took Nanga and Sukamara a long time before they were deemed ready for the final stage of rehabilitation on a pre-release island. But in 2016, the two were moved to Bangamat island and their positive progress gained them the chance to be selected as candidates for this release.

Nanga and Sukamara follow in the footsteps of Wanna, another orangutan repatriated from Thailand who was released to the BBBR-NP in February (read the story here), and others like her who successfully completed rehabilitation and were released to the wild.

Our Nyaru Menteng team transported the 12 orangutans in two separate groups: Nanga, Imot, Kahim, Puput, Puji, and Hangei departed on November 9, and were released the following day. While Sukamara, Stuart, Rawa, Bruni, Rebecca, and Rowo departed on November 11, and were released on November 12.

Each release group of six orangutans left Nyaru Menteng after being moved into transport cages, then loaded onto 4×4 vehicles at the Nyaru Menteng quarantine complex.

 Sedation carried out by Nyaru Menteng vets, with assistance from technicians

The first team set off from Nyaru Menteng at around 7 p.m. and headed to Tumbang Tundu, the last village located on the edge of the BBBR-NP. The road trip took 10 hours to complete, with the team stopping every two hours to check the orangutans.

The team left Nyaru Menteng and heads toward Tumbang Tundu

The team stopped to ensure the orangutans are travelling well

From Tumbang Tundu, the team secured floatation devices around each travel cage then continued the journey for another four hours upstream in small motorized boats known as ‘ces’, or ‘kelotok’.

The team took small boats upstream to reach the release points


Twelve Orangutans Finally Set Free!

The team reached the riverbank near the release points deep inside the National Park at around 10 a.m., and the transport cages were lifted off the boats and carried to predetermined release points. The orangutans were about to take their first steps to freedom in their new home!

Team members carried transport cages to release spots

Hanne and Bue from STO Denmark opened Nanga’s cage

Our Technicians, Toni and Sugiharto opened Sukamara’s cage


Finally, the twelve orangutans gain their #Freedom

This is the 19th orangutan release that BOS Foundation has conducted in Central Kalimantan, and the 7th to take place in the BBBR-NP, which now accommodates 71 rehabilitated orangutans from Nyaru Menteng.

We greatly appreciate the support given by the Central Kalimantan government, and all stakeholders committed to orangutan and habitat conservation efforts in the province. This is an ongoing reintroduction program which aims to establish yet another healthy, viable population to bolster conservation of Critically Endangered Bornean orangutans in the wild, and we well on our way to achieving this. A huge thank you to all who have supported our release programs and our orangutan conservation efforts!

Text by: Communications Team BOS Foundation

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[PRESS RELEASE] Two Orangutans Repatriated from Thailand to Gain Freedom in Bukit Baka Bukit Raya National Park

The BOS Foundation, in cooperation with the Central Kalimantan BKSDA and the Bukit Baka Bukit Raya National Park (BBBR-NP) office, are preparing to release two orangutans repatriated from Thailand to the BBBR-NP in Katingan Regency, Central Kalimantan.

Nanga and Sukamara, who were returned to Indonesia from Thailand in 2006, undertook the long road to rehabilitation at the Central Kalimantan Orangutan Reintroduction Center in Nyaru Menteng (Nyaru Menteng) to prepare for life in the wild. The two will join ten other orangutans in the 7th BOS Foundation release conducted in the BBBR-NP. This will be the 19th release undertaken by the BOS Foundation in cooperation with the Central Kalimantan BKSDA since 2012. 

Nyaru Menteng, Central Kalimantan, November 9, 2017: Upholding our commitment to the #OrangutanFreedom campaign, in which we aim to release 100 orangutans to natural habitats and a further 100 to pre-release islands by the end of 2017, the BOS Foundation in cooperation with the Central Kalimantan BKSDA and the BBBR-NP office will today release more rehabilitated orangutans to natural habitats. This release will also mark ‘Hari Cinta Puspa dan Satwa Nasional’ (National ‘Love Flora and Fauna’ Day), which falls annually on November 5.

The 12 orangutans to be released today include four (4) males and eight (8) females. Two of the females are Nanga and Sukamara, who were repatriated from Thailand in a year when the BOS Foundation received a total of 48 orangutans from Thailand (2006). From this group, Nanga and Sukamara are the 2nd and 3rd orangutans to be released to the wild.

The orangutans will be transported in two separate batches over land and river, on a 10-12-hour journey from Nyaru Menteng to predetermined release points in the BBBR-NP. The first batch will depart from Nyaru Menteng today, while the second batch will leave on November 11. This 19th orangutan release will bring the total population of rehabilitated orangutans released to the BBBR-NP to 71 individuals.

Dr. Ir. Jamartin Sihite, BOS Foundation CEO said; “Orangutan rehabilitation involves a long process, one which cannot be rushed or achieved over a short period. You can see in this particular release, we have two orangutans who were repatriated in 2006. It took 11 long years of rehabilitation before these two individuals were ready to live an independent life in the forest. We cannot simply release orangutans in the wild and expect them to thrive. They need years of training, and the opportunity to practice and hone their survival skills. This not only takes time, but also requires a lot of money. Therefore, rehabilitation, as part of the conservation effort, depends greatly on the participation of many stakeholders. We cannot do this alone.

The orangutan is the only great ape native to Asia, and is also our closest living relative. Protected by the law, orangutans play a very important role in the forest, positively impacting on forest regeneration. This should drive us to work harder to protect and preserve these uniquely beautiful creatures.

We are proud to return hundreds of orangutans back to natural habitats, but we can only do so with continued support. Together, let’s protect the remaining forest areas to secure natural habitats for orangutans, because a well-protected forest can give us all a better quality of life.”

Ir. Adib Gunawan, Head of Central Kalimantan’s Conservation of Natural Resources Agency (BKSDA), said; “This orangutan release is very timely, as it coincides with Hari Cinta Puspa dan Satwa Nasional, which falls annually on November 5. The government declared this national day 24 years ago, over concerns for the preservation of flora and fauna in Indonesia. The government has launched programs to save, protect, and take care of many species of flora and fauna in Indonesia, including Sumatran and Bornean orangutans. We at the Central Kalimantan BKSDA, as an extension of the Republic of Indonesia’s Ministry of Environment and Forestry at the provincial level, follow up all reports regarding orangutan welfare through conducting rescues, patrols, and various other activities to help protect conservation areas and forest biodiversity. On November 13-14, we will hold a Central Kalimantan regional meeting, and invite all stakeholders from the government, NGOs, and private sectors. Together, we hope to come up with ideas, initiatives, and breakthroughs for the orangutan conservation effort in Central Kalimantan.”

Ir. Heru Raharjo, M.P., Head of the Bukit Baka Bukit Raya National Park (BBBRNP) Office, said; “From 2016, the Bukit Baka Bukit Raya National Park has accommodated 59 rehabilitated orangutans from the BOS Foundation in Nyaru Menteng, and today that number will increase to 71. The more orangutans living free in their natural habitat, the better! To ensure these orangutans continue to thrive in the forest, and are safe from human threats, we conduct regular patrols with the BOS Foundation team. We guarantee there are no poachers, nor irresponsible persons exploiting the natural resources in the area and endangering the lives of orangutans and other animals.

So far, we have received reports that the orangutans are living wild and free, without the threat of poachers. We all hope that the released orangutans will form a new, wild population in this national park and thrive.”

In addition to the BOS Foundation, the Central Kalimantan BKSDA, and the BBBR-NP office, this release has also received strong support from USAID LESTARI, which has pledged active support for the orangutan release program in the BBBR-NP until 2018.

Rosenda Chandra Kasih, USAID LESTARI’s Central Kalimantan Landscape Coordinator confirms that USAID LESTARI is fully supportive of the orangutan release effort conducted by the BOS Foundation, and encourages better management of the BBBR-NP; “With this new batch of 12 orangutans, the BBBR-NP in Katingan will accommodate a total 71 orangutans. This will help raise the area in terms of biodiversity value, as well as support forest conservation in line with our vision and mission. USAID Lestari greatly appreciates the cooperation of all stakeholders in the area, and we fully endorse all efforts to help create a new, wild orangutan population in this national park. We do not want to see this critically endangered species become extinct; it is our collective responsibility to prevent that from happening”.

To ensure the success of its conservation efforts, the BOS Foundation consistently involves and works in cooperation with the government at all levels, including the Ministry of Environment and Forestry, the Central Kalimantan Provincial Office, the Katingan Regency Office, the Central Kalimantan BKSDA, and the Bukit Baka Bukit Raya National Park office.

The BOS Foundation would like to acknowledge the significant support received from a number of partners, including the Katingan Regency community; individual donors; partner organizations like PT. Cometa International, Zoos Victoria and the Commonwealth of Australia through the Department of Environment and Energy; and conservation organisations from around the world. The BOS Foundation is very grateful for the support and contributions offered by these parties to aid the orangutan conservation effort in Indonesia.



Paulina Laurensia

Communications Specialist



Monterado Fridman (Agung)

Coordinator of Communications and Education Division of Nyaru Menteng



Rosenda Chandra Kasih

USAID LESTARI Kalimantan Tengah Landscape Coordinator




Editor’s Note:


Founded in 1991, the BOS Foundation is a non-profit Indonesian organization dedicated to the conservation of Bornean orangutans and their natural habitats, working together with local communities, the Ministry of Environment and Forestry of the Republic of Indonesia, and international partner organizations.

The BOS Foundation currently cares for around 650 orangutans in two rehabilitation centres, with the support of 400 highly dedicated staff members and experts in the fields of primatology, biodiversity, ecology, forest rehabilitation, agroforestry, community empowerment, communications, education, and orangutan welfare. For further information, please visit



USAID LESTARI is a collaborative project between the governments of the United States of America and the Republic of Indonesia. USAID LESTARI fully supports the efforts made by the Indonesian government to reduce greenhouse emissions and increase efforts to conserve forest biodiversity and mangrove ecosystems rich in carbon storage.

USAID LESTARI focuses on regions with unscathed primary forests, high carbon deposits and a rich biodiversity. These regions include Aceh (the Leuser landscape), Central Kalimantan (the Katingan-Kahayan landscape), and Papua (the Lorentz Lowlands, Mappi-Bouven Digoel, Sarmi and Cyclops landscapes).


#OrangutanFreedom is still going strong and we are getting ready to release 12 orangutans into the Bukit Baka Bukit Raya National Park Forest in Central Kalimantan. Here are the profiles of the amazing orangutans who are about to embark on their final journey back to the wild.



Stuart was rescued on April 5, 2003, from a villager in Parenggean, East Kotawaringin Regency, Central Kalimantan. He was just under a year old and weighed 3.9 kilograms when he came to Nyaru Menteng.

On June 6, 2016, Stuart was transported to Bangamat pre-release island following completion of Forest School. He adapted well to the environment, and now after more than a year of training on the island is showing great independence.

Stuart is now 15 years old and weighs 44.8 kg. Short-haired throughout his childhood, he has since grown into a strong orangutan with a handsome, thick beard, and growing signs of cheekpads. Stuart is more than ready to live in the natural habitat of the Bukit Baka Bukit Raya National Park.


Imot was confiscated from a villager in Luwuk Bunter, East Kotawaringin Regency, Central Kalimantan, on November 1, 2009. He came to Nyaru Menteng when he was 2.5 years old, weighing 6 kilograms.

Imot progressed through the stages of Forest School and was transferred to Palas pre-release island on March 18, 2014. After two years on Palas, he was moved to Bangamat Island for the final stage of pre-release training.

Imot is now 11 years old and weighs 42.3 kg. Eight years of rehabilitation has helped him regain his wild behaviours and master his survival skills, which will help him thrive when he is finally released to a wild habitat.


Nanga was repatriated from Thailand in 2006. She was brought to Nyaru Menteng when she was 5.5 years old and weighed 22 kilograms. Nanga endured a long adaptation process due to her close interaction with humans whilst in captivity, yet manage to pass all the stages of Forest School by 2009.

On May 20, 2010, when she was around 10 years old, she gave birth to a healthy male. Nanga had to be separated from the baby, named Ben, due to her young age. Ben was raised under supervision by the medical team and a babysitter.

On March 24, 2016, Nanga finally got her chance to live on Bangamat pre-released island, where she flourished and developed her foraging skills. After 11 years of rehabilitation, gentle-eyed Nanga is now 17 years old and weighs 39.4 kg. She is now ready to live independently in a wild forest.


Rowo was rescued on January 25, 2004, from a villager in Horowu, Gunung Mas Regency, Central Kalimantan. She came to Nyaru Menteng when she was 18 months old and weighed 4.7 kilograms.

She joined Nyaru Menteng Forest School soon after her arrival and completed all stages by 2009. However, she didn’t get the opportunity to experience the pre-release stage on Bangamat Island until March 28, 2016.

Rowo is now 15 years old and weighs 53 kg. With the skills she has acquired over the past 13 years, thick-haired Rowo is now ready to live wild and free in the Bukit Baka Bukit Raya National Park.


Long-haired Hangei arrived at Nyaru Menteng on September 29, 2008, after being confiscated from a villager in Tumbang Hangei, Katingan Regency, Central Kalimantan. She was 4 years old at the time, weighed 6 kilograms, and was exhibiting wild behaviours.

After progressing through all the stages of Forest School, Hangei was moved to Bangamat pre-release island on June 7, 2016, for the final stage of rehabilitation. During her time on Bangamat, Hangei became a keen explorer.

Hangei is now 13 years old and weighs 35.1 kg. After 9 years of rehabilitation, brave Hangei is ready to explore her new home in the Bukit Baka Bukit Raya National Park.


On May 16, 2005, Rawa was rescued from a villager who had been keeping him illegally as a pet for almost a year in Danau Rawa, Mantangai Sub-District, Kapuas Regency. He arrived at Nyaru Menteng when he was 3 years old and weighed 8.7 kilograms.

His first years at Nyaru Menteng were the most difficult for him, as he suffered from malaria and prolonged typhus. After a long period of intensive care under the watchful eyes of our dedicated medical team and babysitters, Rawa completely recovered.

Rawa developed and honed his skills in Forest School, and had completed all stages by July 2009. He proceeded to the pre-release stage of rehabilitation on April 7, 2016, and was moved to Kaja Island.

Rawa is now 15 years old and weighs 58.7 kg. His thick hair, long jaw, and thin golden beard make him stand out among other male orangutans. After 12 long years of rehabilitation, this tough stud is ready to return to the wild.


Sukamara was repatriated from Thailand in 2006. She came to Nyaru Menteng together with Nanga on November 22, 2006. She was 9 years old at the time and was in good health.

In Nyaru Menteng, Sukamara joined a special Forest School class designed for repatriated orangutans from Thailand. She was moved to Palas pre-release island on May 6, 2014, and was subsequently moved to Bangamat Island on June 14, 2016.

A dominant figure among females, Sukamara is now 20 years old and weighs 41.4 kg. Armed with the skills she has developed and honed over 11 years of rehabilitation, Sukamara is more than ready to explore her new home in the Bukit Baka Bukit Raya National Park.


Rebecca was rescued by a joint team from BOS Foundation Nyaru Menteng and the Central Kalimantan BKSDA, in the town of Sampit, East Kotawiringin Regency, on February 5, 2006. She arrived at Nyaru Menteng dehydrated and underweight at only 4.5 kilograms when she was just 2 years old.

Ten years after arriving, Rebecca completed the Forest School stages of her rehabilitation process and moved to the pre-release stage on Kaja Island, on August 3, 2016. She progressed well on Kaja, skilfully building nests, foraging and exploring the island.

Rebecca is now 13 years old and weighs 31 kg. She has grown into an amazing figure, and will soon taste true freedom when she is released to the Bukit Baka Bukit Raya National Park.


Kahim was rescued from a PT. Solonok Ladang Mas palm-oil plantation concession area in East Kotawaringin Regency, Central Kalimantan, together with two other orangutans (Leggi and Endut). The three were being kept illegally as pets by plantation workers at their barracks. Kahim arrived at Nyaru Menteng on February 2, 2007, at the age of 2 years and weighing 5.5 kilograms.

During his rehabilitation, Kahim grew into an active and social orangutan, and became close friends with Gurita (who has already been released to the Bukit Baka Bukit Raya National Park). After completing Forest School, Kahim entered the pre-release stage on Palas Island on March 25, 2014, and was moved to Bangamat Island on April 8, 2017. During his time on Palas and Bangamat, Kahim became a good explorer.

Kahim is now 12 years old and weighs 45.6 kg. Friendly Kahim, who has a sharp stare, strong jaw, and thin golden beard, is well liked by other orangutans. He will soon become a wild, independent orangutan when he follows in pal Gurita’s footsteps to live in the Bukit Baka Bukit Raya National Park.


On January 27, 2006, Puput was confiscated from a local resident of Palangka Raya, Central Kalimantan, when she was 3 years old and weighed 8.3 kilograms.

Puput, a female with cheekpad-like features on her face, progressed through the rehabilitation process and was moved to the pre-release island of Palas on December 10, 2010. She was then moved to Kaja Island on July 20, 2015. During her time on the islands, Puput steadily built on her exploration and adaptation skills.

Puput is now 14 years old and weighs 40.3 kg. After 12 long years of rehabilitation at Nyaru Menteng, she is ready to explore the wild forest of the Bukit Baka Bukit Raya National Park, her new home.

11. PUJI

Puji was rescued from a palm-oil plantation in Keruing Raya Estate, Keruing village, East Kotawaringin Regency, Central Kalimantan. She was taken to Nyaru Menteng on February 24, 2007, when she was less than 12 months old and weighed 3.9 kilograms.

During her Forest School days, Puji developed her basic survival skills and proceeded to the pre-release stage on Kaja Island, on August 3, 2016. Puji adapted well to her new surroundings, and with best friend Bruni explored, foraged, and expanded on her nest-building skills.

Puji is now 11 years old and weighs 35.8 kg. Armed with a sound skillset, she is now ready to have some new adventures with bestie Bruni in the forests of the Bukit Baka Bukit Raya National Park.



Bruni was brought to Nyaru Menteng on June 25, 2008, when she was 2 years old and weighed 8 kilograms. She was rescued from a PT. Tunas Agro Subur Kencana (PT TASK) palm-oil plantation located in East Kotawaringin Regency, Central Kalimantan.

Bruni progressed through the various stages of Forest School before moving to Bangamat pre-release island for the next step of rehabilitation on June 7, 2016. There, Bruni proved she had the skills to survive, showing excellent progress in exploring and foraging. On the island, she was frequently observed spending time with her best friend, Puji.

Bruni is now 11 years old and weighs 32.5 kg. This beautiful girl is ready to explore the wild habitat of the Bukit Baka Bukit Raya National Park alongside bestie Puji.



Mystery Orangutan Identified!

You may recall our monitoring story on Elisa, when our PRM team was startled by the sudden appearance of an unidentified orangutan (Read the story here).

While patiently waiting in the forest to gain a visual on Elisa, we were caught off guard when an orangutan suddenly appeared from behind. We quickly moved back to maintain our distance from the mysterious visitor, who, at a glance, looked just like Elisa. We weren’t sure that it actually was Elisa, however, as we all could have sworn we had seen her move to another tree only moments earlier. One of our team members, Usup, tried to check for other signals, but could not detected any. We gave up and assumed that the orangutan in question must have been Elisa. Still somewhat confused, we continued to observe the orangutan and take notes.

Strangely, ‘Elisa’ did nothing but sit on the ground and watch us. This was rather odd, since we had never seen Elisa climb down to the forest floor. She did not move for almost half an hour; she just watched us curiously, and paid close attention to those PRM members. To provide space for ‘Elisa’ to go about her regular activities, we backed off slowly whilst keeping her in our sights.

Out of curiosity, we started to compare photos of Elisa and ‘Elisa’ while we observed from a distance. Through a photo comparison, we were able to confirm that this orangutan was not Elisa, but Mona, a female we released four years ago (Read her story here). Indeed, both females do look rather alike! This answered our lingering question; the sudden emergence of this individual without a detectable signal was undoubtedly due to a long-depleted transmitter battery.

As if to confirm that this imposter was not Elisa, the real Elisa emerged from behind the dense foliage and eyed us. Once again, the real Elisa let out a loud kiss-squeak to voice her displeasure with our presence.

Finally, after several hours of collecting observation data, we left Mona and Elisa. We were absolutely delighted to have caught up with beautiful Mona, looking happy and healthy in the forest. This was a great outcome for the team’s day of monitoring.

Text by: PRM team from Camp Lesik, Kehje Sewen Forest

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Nyaru Menteng Takes in Another Baby Orangutan

Several days ago we received a report that a baby orangutan was being kept illegally in a village called Lawang Uru, a 2-hour drive from Nyaru Menteng in Central Kalimantan. On October 24, a joint team from the Central Kalimantan BKSDA and BOS Foundation established a rescue mission and successfully confiscated a 3-year old baby boy weighing 7.3 kgs, who we named Uru.

Based on information provided by a local resident Ido Dasit, this infant was a victim of the 2015 forest fires. Reportedly, Ido had found Uru alone near a burned forest area and taken him home. As with almost all of these cases, the likelihood is that this infants’ mother was killed and he was taken as a pet. For two years, Uru has been kept in a wooden cage and given human food like rice, instant noodles, and syrup, instead of a natural diet of fruit, leaves, bark and other forest foods.

During his two years in captivity, the local children played with Uru, and he is said to have suffered from coughs, influenza and diarrhea, with his captors often giving him paracetamol to treat his symptoms, the same as they would give to their own children.

Once Uru arrived safely at our rehabilitation centre in Nyaru Menteng, a thorough examination was conducted by our vet team, which suggest that despite Uru’s weight measuring within normal range for an orangutan his age, his overall health is quite poor due to inadequate nutrition. Our team are providing 24-hour care to Uru in the quarantined section of our Baby House together with two other babies recently rescued, Susanne and Topan (Read about Topan and Susanne here). At Nyaru Menteng, our team will nurse Uru back to health, gently transition him to a natural diet and start to help him learn natural orangutan behaviours.

Uru is the 6th baby orangutan rescued from Pulang Pisau Regency, and is the 21st baby to come to Nyaru Menteng this year alone. This number is extremely high and we are devastated that this Critically Endangered species continues to decline in the wild. Orangutans are not pets and this situation must be tackled urgently if we are to have a hope of saving Borneo’s remaining wild orangutan population.

Text by: BOS Foundation Communications Team

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Encounter with Elisa

On a sunny Friday, our PRM team from Camp Lesik trailed down Bukit Titin transect to conduct observations on Elisa, a female orangutan released in March this year (Read the full story here). Our team that day included Usup, Rere, and Valerie; we headed directly to the location where Elisa’s signal was detected several days prior. After reaching the top of Bukit Titin, we kept on following the strong signal from Elisa, working our way through dense rattan and lianas until we finally spotted her.

Elisa quickly detected our presence and showed her displeasure by letting out a kiss-squeak, then swiftly moved around the branches to get a better look at us. Acknowledging her discomfort, we slowly moved away and continued to observe her from a safe distance.

For a while, Elisa sat in a tree and watched us, but soon became bored and moved off to eat flowers and young leaves. Engrossed in her foraging, she paid no attention to us and just went about her day. This gave us the opportunity to observe Elisa’s activities for quite some time, before she decided to climb up higher and out of sight.

Not wanting to give up easily on observing Elisa, we stood by and waited for signs of movement in the direction she took off in. Then, out of the blue, an orangutan suddenly appeared behind us. Could Elisa have circled around to cleverly sneak up on us from behind? Or was this another orangutan coming to surprise us? Stay tuned, and follow our story next week to find out!

Text by: PRM team in Camp Lesik, Kehje Sewen Forest

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Released Orangutans Thriving, Producing Next Generation in Batikap

The BOS Foundation has released more than 167 orangutans to the Bukit Batikap conservation forest in Central Kalimantan since 2012, giving rescued orangutans a second chance at life in the wild. Prior to being released to this natural environment, each of the orangutans underwent years of rehabilitation to learn the skills they would need to survive alone in the forest.

Some of the orangutans we first released five years ago can no longer be located, as the batteries in their transmitters have gradually worn out. Our post-release monitoring (PRM) team conducts regular observations following each release, to check that every orangutan is thriving in their new environment. Once the transmitters stop working, we have to trust their ability to make it in the wild without human intervention.

However, even without working transmitters we are sometimes lucky enough to encounter some of our ‘old released’ orangutans during patrols. Like Monic, from the first release, who gave birth to a male now four years old and full of energy! Or, like Ebol, who was also released five years ago: One of our PRM team members spotted her at the beginning of August this year, during a riverside patrol. As Ebol hadn’t encountered people for quite some time, she appeared shy and curious as she sat and watched her observers as intensely as they watched her. After a while, she went back to foraging and eating rattan shoots. Our team members were surprised to see her devour a large amount of forest food, seemingly undeterred by their presence.


Whilst observing Ebol, the team noticed her enlarged genitals, indicating she was pregnant! Team members estimated that she was most likely still in the first trimester of her pregnancy. As this mother-to-be has no working transmitter, all we can is hope that we will bump into her again in the future – hopefully next time cradling a little baby!

This wasn’t the only surprise that August gave us. Indeed, in the middle of the month, we came across Meklies, a shy female who was never comfortable with observers tracking her. We were fortunate enough to observe her for three days, during which she maintained her typical behaviours: staying high up in the trees, and evading her observers. She also spent a lot of time feeding in the same tree, especially on the third day of observation when she spent more than five hours eating lunuk. She even built her night nest in the tree, which is uncommon among orangutans, who typically don’t build nests in feeding trees.


One of our technicians finally managed to capture a decent picture of this shy lady, which showed that she too, like Ebol, had swollen genitals. But unlike Ebol, Meklies seemed to be already at the end of her pregnancy, and since she still has a working transmitter we will be able to locate her and see her infant in the near future!

Our PRM team is very excited to report these latest developments about the two pregnancies. Like proud parents, we are utterly delighted to learn that our released orangutans are not only surviving, but thriving in the wild, and successfully reproducing. We can’t wait to see the next generation to come from these individuals in the wild paradise of the Bukit Batikap!

Text by: Alizee Martin, PRM Coordinator in Batikap

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Catching Up with Kent in Kehje Sewen

As part of the Post Release Monitoring Team, on my day off, I decided to go for a walk in the forest. I took off down the trail left by cars heading to Simpang Tawon, hoping to see something interesting.

Shortly after setting off, I began to sense somebody following me. I wondered if it was an orangutan. When the foliage finally opened up, I saw Bong, a female we released last December. I took some photos of her to share with the team, which fortunately she didn’t seem to mind, and left her alone.


Passing through the swamp area, I noticed some slight movements in a nearby tree. At first, I thought it was likely a small mammal running along the branches. But after patiently waiting and getting a closer look, I saw that it was another orangutan; Kent, who was first released to the northern Lesik area in 2014. Kent had suffered a serious injury only days after his initial release, and was brought back to Samboja Lestari for medical treatment and further rehabilitation. He was re-released to the Nles Mamse area in October 2016.


My reunion with Kent was very special. He has been extremely difficult to find, much less observe, after his second release. Our PRM team frequently pick up very weak radio tracking signals from Kent, indicating he was far away, but had had no success in locating him. We were all sure that Kent had moved off to explore deeper into the Kehje Sewen Forest. It was pure luck that I bumped into him on my walk!

Seeing Kent’s progress was fantastic. He seems to have grown stronger and wilder. He looks very fit and healthy, and has a huge appetite: his strong, muscular arms help him move quickly and effortlessly through the trees as he devoured all manner of forest food. I was amazed to see how he had changed.

I was so preoccupied with watching Kent, I didn’t realise that the day was slowly fading. As the sky darkened and rain began to drizzle down, I quickly walked back to camp leaving Kent behind. I hope to meet him again someday!

Text by: Valerie, PRM Volunteer at Camp Nles Mamse, Kehje Sewen Forest

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[BABY BULLETIN] Update on Our Newest Rescued Babies

Following last weeks rescues of two baby orangutans by BOS Foundation Nyaru Menteng and the Central Kalimantan BKSDA, we are happy to report that one week on, both babies are doing so much better.


Susanne was rescued last Thursday and arrived in Nyaru Menteng in a relatively stable condition, albeit a bit underweight at 6.1 kg. At first, she seemed to be depressed and was scared of new faces, but since that time she has adapted well to her new environment and engages happily with her babysitters. Susanne loves to climb and dangle and she has a very healthy appetite. She has warmed quickly to the other babies in quarantine, Josh and Taymur, and when Topan arrived the day after her, she tried to engage him to play and seemed to try to protect him when he tried to climb the ropes in the indoor playground.


The day after Susanne arrived, Topan was rescued and arrived at Nyaru Menteng in a very weak state. He was severely underweight at only 1.5 kg, and dehydrated. We were extremely concerned and our dedicated medical team have been focusing on his health and welfare. After spending the first few days in intensive care, Topan’s condition improved, and he was able to join the other babies in the quarantined section of the Baby House. Little Topan has an extremely strong will to survive and he has clearly only just been taken from the wild and his mother. He drinks milk, climbs the structures and ropes in the indoor playground and interacts with babysitters, though he often cries and needs a lot of love.

It’s a long process rehabilitating young orangutans, but we have high hopes that these two infants will successfully complete their quarantine and later be able to join the other babies in the Nursery Group. Thanks to the dedication and loving care provided by our Nyaru Menteng team, Topan and Susanne are making their regaining their health and confidence.

Text by: BOS Foundation Communication Team 

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