From Slow Loris to Gibbon: Meet 8 of Borneo’s Coolest Primates

I stepped outside my little cabin into the humid rainforest air, leaves still dripping from the previous night’s rain. Even at dawn, I could see little but I immediately heard a peculiar whoop echoing through the trees.

Gibbons.

For the past couple of mornings, the gibbon chorus greeted us as we traveled around East Kalimantan in Borneo. The gibbon’s morning call—a tremulous hoot—is one you almost feel as much as you see. Soon a local community member would lead us to search for these apes.

Borneo, the world’s third-largest island, is known for its exceptional biodiversity. Among the most charismatic and visible are a number of wonderful and unusual primates. The best known, of course, is the orangutan—the subject of much conservation effort and a key goal for visiting wildlife watchers. But other primates also rely on intact forest and rely on community-led conservation efforts.

On this trip, I’m visiting Wehea Protection Forest with staff from the furniture brand Arhaus. Wehea consists of 29,000 acres of protected by the Dayak Wehea Community with assistance by Yayasan Konservasi Alam Nusantara (YKAN)—a foundation that took over TNC’s operations and conservation programs in Indonesia in 2020.

These forest conservation efforts benefit a variety of wildlife species including primates. You can read more about orangutans in our previous feature. Here are some of the other primates that benefit from this conservation partnership at Wehea and similar community-based conservation programs in Borneo.

Top 10 List

• North Borneo Gibbon

  

  During our morning at Wehea, a community member led us up a hill, following the calls of the gibbon. Soon, we could catch glimpses of their acrobatics as they leapt through the trees, branches shaking as they landed each jump. To my mind, few animals are as entertaining to watch as gibbons.

  Gibbons are apes, not monkeys (characterized by a lack of tail). They typically live in monogamous pairs, and the morning routine involves a series of calls to each other. The males begin calling early in the morning – the sound that greeted us as we awoke. After feeding, the male and female engage in a 15-minute duet.

  Gibbons are supremely adapted to life in the trees. They rarely touch ground. This makes them even more susceptible to habitat degradation than orangutans.

  “Gibbons will call less in areas near logging concessions,” says Arif Rifqi, endangered species habitat conservation specialist for YKAN. “They will avoid areas with higher levels of human activity.”

• Miller’s Grizzled Langur

  

  Orangutans and gibbons are spectacular animals, but arguably no primate in the Wehea forest causes more excitement than the Miller’s grizzled langur. That’s because this species was believed to be extinct.

  That changed in 2012, when scientists documented the Miller’s grizzled langur at Wehea. It was a surprise since Wehea was outside the monkey’s known range. By staking out mineral licks and setting camera traps, a team of researchers verified a population remains in one section of Wehea.

  “The Miller’s langur has a very narrow range of habitat and is very sensitive to human disturbance,” says Rifqi. “They used to be hunted so they are very shy. We had a photographer wait over a mineral lick and it took 6 days before he saw one.”

  But they continue to live in the protected forest of Wehea, a great testament to community-led conservation.

• Red Leaf Monkey

  

  As we observed the gibbons, we started seeing monkeys, distinguishable by their longer tails. This was a particularly attractive species, the red leaf monkey (also known as the maroon langur or red langur). They would leap dramatically from tree to tree and chatter to each other.

  Research has found that the habitat of gibbons and red leaf monkeys overlaps, but the gibbons tend to focus on ripe fruits while the leaf monkeys prefer leaves and seeds. Still, they can often be viewed at the same time and often prove to be one of the most easily viewed primates at Wehea.

• Pig-tailed Macaque

  

  Seeing many of the primates listed here requires a hike in primary rainforest. Not so the pig-tailed macaque. We spotted them sitting along busy roads, patiently waiting for handouts. In protected forest, pig-tailed macaques stay on the move as they forage for fruits. But they’ll adapt to oil palm plantations and other altered habitats, where they typically become more sedentary.

  Our local guide told us that, during times of the year when trees aren’t fruiting, troupes of pig-tailed macaques can be seen along the highway. A male macaque is muscular with large canines: a formidable beast. They can also become quite aggressive with humans. So just as you should never feed the bears, you should also never feed the monkeys. Enjoy the view from the window as you drive through the countryside.

• Long-tailed Macaque

  

  As we waited for lunch at fantastic Kutai National Park, the trees suddenly erupted in squawking and fighting. We were soon enjoying the antics of long-tailed macaques. They hung out right around the visitor center, and were apparently hoping to score some leftovers.

  The long-tailed macaque is such an adaptable species that it’s become a pest in some areas. We viewed them throughout our drive, on the edges of towns, around palm plantations and sitting on utility poles. According to the Phillips’ Guide to the Mammals of Borneo, this is the most common monkey in disturbed forests. They raid orchards and even roam popular beaches, stealing food from visitors.

• Philippine Slow Loris

  

  The slow loris is almost impossibly cute, with a round head, little ears and big, googly eyes. It’s cute but not cuddly: the slow loris has poisonous glands under its armpits. As Mammals of Borneo notes, when the loris is stressed, it licks the glands and rubs it over its body and its young. This poison will repel ticks and leeches as well as some predators.

  Combined with the saliva, the poison gives the loris a nasty bite, capable of sending a human into anaphylactic shock or even death.

  The slow loris is omnivorous but needs tree sap; it will gouge trees with its comb-like teeth to procure this sap. Due to this diet, loris populations require healthy, biodiverse forests.

• Western Tarsier

  

  The Western tarsier is particularly difficult to see at Wehea, although in some parts of its range in Southeast Asia, there are tarsier-spotting tours for wildlife enthusiasts. Tiny and nocturnal, the tarsier hunts large insects at night. They use sound and hearing to leap onto their prey on the ground.

  They move through the forest, using oversized legs to spring from tree to tree, and have suction pads on their hands to grasp smooth saplings.

  Rifqi had a rare sighting of one two years ago, but it bounded away before he could get a photo.

• Proboscis Monkey

  

  The proboscis monkey is not found in the Wehea Protection Forest, but is found on lands bordering the Wehea community as well as in protected mangrove forests supported by YKAN. I’ve included it here because it’s just such an interesting mammal, particularly the male’s large schnoz that gives it its name.

  That bulbous nose helps amplify the male’s dominance calls. The monkeys live in troops presided over by an alpha male, and its dominance is frequently challenged by rivals. They live along estuaries and mangroves along the Borneo coast.

  While I did not have the chance to visit their habitat on my visit, proboscis monkey-viewing tours are a popular option in parts of Borneo. One of many reasons to return.