Sabah, Borneo: Primates

Borneo is home to around 3,000 species of tree, which means a wide variety of food for the island’s primate species. On our trip, we have seen almost all of the primate species on offer, including nocturnal and endemic species. Borneo must be one of the best places to see primates. Although they spend much of their time high up in the treetops, they are surprisingly easy to spot. Gaps in the trees, or the edges near rivers are good places to look, and rustling in the leaves often give away their position. Many of the primates are also quite inquisitive, and come to investigate the movement down on the forest floor. Below is the list of primate species we saw:

Pig-tailed Macaque, Long-tailed Macaque, Red Leaf Monkey, Silvered Leaf Monkey, Proboscis Monkey, Slow Loris and Bornean Gibbon.

Possibly the weirdest of the primates is the Proboscis Monkey. These monkeys are only found in Borneo, and are fascinating animals. They are known for the males’ very large nose. It is thought this has developed through sexual selection by females. They prefer and breed with the males with the larger noses, and the big nose gene is therefore passed on to the next generation, gradually resulting in the strangely large nose.

Male Proboscis Monkey

As well as the interesting facial features, Proboscis Monkeys have a sophisticated social system. One social group consists of one mature male and numerous females and their young. Males who don’t have a group like this will usually travel in bachelor groups, which are groups consisting of either mature males who have lost their females, or younger males who, once they reach a certain age, are kicked out by the male in charge.

Female Proboscis Monkey and baby

The closest primate experience of the trip came on the Kinabatangan River in the late afternoon. We were travelling down a small tributary, when we stopped near the bank for a bit. Two young Long-tailed Macaques, or Crab-eating Macaques, came on to the branches literally right next to the boat, while the rest of the troop stayed further inside the forest. The pair began feeding, stopping every now and then to stare at the strange creatures watching them from the boats!

Thoughtful young Long-tailed Macaque
Inquisitive young Long-tailed Macaque

The other species of macaque was also seen by a river, but this time in the Danum Valley. On our first trek, only a few hours after arriving, we saw a lone Pig-tailed Macaque walking along the stony bank. It stopped to pick some fruit or seeds off a low tree.

Pig-tailed Macaque

Both macaque species have a similar diet. The Long-tailed or Crab-eating Macaque, despite its name, doesn’t eat crabs. Both animals are omnivores, and eat primarily fruit and seeds. But when available, they may eat bird eggs, invertebrates, and even lizards.

The two species of leaf monkey were, unlike the macaques, seen in two different areas. The first species we saw were the Red Leaf Monkeys, in the Danum Valley. These monkeys were usually seen far from the river, in the trees near small clearings or trails. The second species, the Silvered Leaf Monkey, or Silvery Lutung, was seen in trees right next to the Kinabatangan River. We saw a few individuals mixed in with a troop of Long-tailed Macaques, and a few on there own. A Leaf Monkey’s diet consists mainly of leaves. In fact the Silvered Leaf Monkey has a higher proportion of leaves in its diet than any other colobine monkey (91%).

Red Leaf Monkey
Silvered Leaf Monkey

But the biggest primate-themed surprise was still to come. There are very few nocturnal primates, so we hadn’t even considered the chance of seeing one. But on a night walk, we came across a Slow Loris! These primates are quite small and seldom seen, so seeing one was fantastic. In the torchlight, we could make out a round face with large eyes, and quite a long body. A Slow Loris’ diet is varied. They eat insects, gum, nectar, reptiles, seeds and many other things. I am not entirely sure of the exact species of Slow Loris, but whichever it was it was a treat!

Slow Loris
credit Neil McIntosh, license, no changes made

I have left my favourite primate, and possibly animal, of the trip until last. The Bornean Gibbon. These gibbons, as their name suggests, are endemic to Borneo, and are, in my opinion, the best of all gibbon species. Their iconic calls can travel up to 2km as they echo through the valleys and hills.

Our sighting came on our final morning in the Danum Valley. We decided to get up early and be at the canopy walk by 6am, to see what was out and about at the crack of dawn. The Gibbons were calling, but sounded far off in the distance. But then, as we walked further over the canopy walk, the calls began to get closer and closer, until we could see movement in the trees around us. The Bornean Gibbons were truly beautiful. Their fur looked silky smooth, and was a spotless grey/black colour. Every now and then they would open their mouths into a wide oval shape and project their calls across the valley. It was an incredible experience, watching them swing effortlessly through the treetops, and so close to where we were stood. They are high up on my list of favourite animals, and just show that the Bornean rainforests hold some of the planet’s best wildlife. But due to the thick canopy and there constant movement, I only managed a very grainy video frame, though I do have some gibbons calling.

Bornean Gibbon

The primates of Borneo are some of the strangest but most incredible in the world. From their big noses to their whooping calls, they have evolved perfectly to live in their rainforest home.

These primate sightings wouldn’t have been possible without the help of our brilliant rainforest and river guides George, Shirou and Basri.


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