Back to Borneo

Dear Friends,
My first trip of 2025 back was to Borneo, to the research station where my wife, orangutan researcher Cheryl Knott and I have worked for over 30 years.

I have a special guest author for this installment of Wildlife Diaries! Accompanying the new photos from our January trip below is an essay by Cheryl about this special trip. I think you will enjoy it. She does a good job of capturing the multi-faceted nature of our trip, and why we have been drawn back to Borneo for so much of our lives.

It’s Earth Month, and I hope you’ll consider learning more about the Gunung Palung Orangutan Project by reading below, and perhaps checking out more about all they are doing for orangutan conservation and human welfare in that part of Borneo. This is a challenging time for research and conservation funding, so I am trying to help them grow their grass-roots support. Please check them out at Save Wild Orangutans.

Male Orangutan in Contemplation

It’s easy to anthropomorphize with orangutans, who are so similar to us. So I may be guilty with the title of this image, but it sure looks to me like this male orangutan, named Balon, is lost in thought as he rests one morning between feeding bouts. Balon is one of the males that we followed in January at Gunung Palung that Cheryl talks about in her update below. The mast fruiting event drew more orangutans into the study area, and we had an exciting time documenting them.

Guest Essay by Dr. Cheryl Knott - Director, Gunung Palung Orangutan Project

The Magic of Mast Fruiting at Gunung Palung

Thirty years ago, when I first arrived in Gunung Palung National Park, the forest was thick with the smell of ripening fruit and the largest trees emerged from the canopy resplendent in colors of orange and red. This phenomenon, when many of the tree and liana species fruit simultaneously, is unpredictable but happens every four years or so, providing a bonanza of food for rainforest creatures. This past January, I returned to Cabang Panti Research Station with my family and once again experienced this remarkable transformation of the forest.

The setting sun lights up ripening seeds in the canopy.

With the abundance of fruit, orangutans appeared in unusually high numbers. In the two and half weeks that I was there, we saw as many as 10 individual orangutans on a given day. By the end of January, 27 new orangutans had entered the study area! And we only found 5 of the orangutans that usually call Cabang Panti home. It's a bit of mystery where all these orangutans come from, but one possibility is that they normally spend their days in the large expanse of peat swamp that extends outside the study area.

Balon, a male with an especially large throat sac.

Among these new arrivals were three flanged males. For years, the dominant male in the area had been Alfred, but when I last saw him in August, his condition had declined. He was notably smaller and weaker, often traveling on the ground and feeding primarily on termites and low-lying vegetation instead of climbing trees. He was last seen on September 15. Then in November, the team sadly discovered the skeleton of a male orangutan that we strongly suspect was Alfred. His disappearance, though, paved the way to a new beginning as the mast brought in these new males to take advantage of the abundance of fruit. The first such male we saw had a huge throat sac and so we named him Balon (balloon).  He was surprisingly habituated for a new individual. Balon was in excellent condition and impressive! He did bear multiple scars on his cheek pads, attesting to the likely numerous fights he had had with other males.

“Mr. Perfect”, a male exceptionally perfect large cheek pads.

But, then came "Mr. Perfect", as we jokingly called him. He has the most perfect cheek flanges I have ever seen, with no blemishes or scars, just a flat rigid circle around his face. His literally flawless condition, along with his unworn teeth and lighter hair, signaled to us that he was a young, newly flanged male. He long called an extraordinary 15 times the first day we found him!  Long calls announce a male's presence to the females, and other males, in the area. Often, males will long call back in response, and charge in the direction of the other males, sometimes resulting in a physical confrontation. But Balon, despite being only about 100 meters away from "Mr. Perfect", was not provoked. He remained silent—perhaps a sign of experience in avoiding fights he could possibly lose.

A juvenile watches while a female orangutan opens a durian fruit, one of the delicious and calorie-rich species that fruit during the mast.

Mast fruiting events allow orangutans to accumulate fat reserves that sustain them during leaner periods. This is when they look their biggest and healthiest. The increase in energy intake also influences female reproductive cycles, raising hormone levels and increasing the chances of ovulation and conception. Often mast fruiting result in new births, and on February 26 I received the news that female Kabar was pregnant again with her second baby after more than 8 years! We hope that Bibi, another female who lost a pregnancy earlier this year, will also conceive during this period of high fruit availability.

The benefits of mast fruiting even extend to the humans who call this rainforest enclave home.  Normally we can't eat the wild fruits of the forest – they are too bitter and have compounds that make them hard to digest. But the mast is different. Each day we'd come back to camp, and find bowls of wild fruits on the table, and rice sacks full of durians ready for all to consume.  As we followed the orangutans, we gathered fallen mangosteens, Baccaurea, Garcinia, and durian, enjoying them much as the orangutans did. That simple act, sharing in the abundance of the mast, reinforced our deep connection to these apes and their rainforest home.

This exceptional visit to Gunung Palung was a reminder of why protecting this ecosystem is so vital. As the forest provides, the orangutans thrive, and we, as stewards of this planet, must ensure this continues for generations to come.

Cheryl with field assistant Herman, and student Ziya watch an orangutan at Gunung Palung. Cheryl’s project employs many local people, and gives many opportunities for Indonesian students to get involved in field research and conservation. Developing the next generation of conservationists in Indonesia is critical to the survival of orangutans.

Cheryl hikes through the rainforest in Borneo, followed by son Russell, daughter Jessica, and other team members.

I hope you enjoyed Cheryl’s essay. Working at Gunung Palung is a family affair for us, as we have been taking our kids there every summer since they were little. They are now adults, and both involved in work there. Russell is part of the photography team, while Jessica, who is still an undergrad, is getting involved in the orangutan research.

Thanks for reading and taking an interest in our work in Borneo. I hope you found it interesting and inspiring.

Warmest regards,
Tim Laman

PS. Please consider checking out https://www.savewildorangutans.org/ and becoming a monthly donor, even for a small amount. Every supporter is a big help during these challenging times when big grants have been cut.