The third largest island in the world, Borneo is home to a spectacular diversity of wildlife both on land and at sea, including many species found nowhere else. Nature travelers who make their way to Borneo’s wild (and seriously threatened) jungles are rewarded with the chance to see some of the world’s most iconic species, like orangutans and proboscis monkeys, as well as some less-familiar yet equally incredible species such as the binturong or the corpse flower (rafflesia) in the wild. As part of the Coral Triangle—the world’s most biodiverse marine region—Borneo’s waters and coasts also teem with life including colorful coral reefs and abundant sea turtle populations.
Without a doubt, Borneo offers one of the world's best combinations of forest and ocean wilderness.
We are extremely excited to be leading new Oceanic Society expeditions to Malaysian Borneo beginning in 2018. Our itinerary is designed to bring you to some of the island’s best areas for wildlife observation and exploration, beginning with 7-days in the lush and species-rich rainforests, and culminating with 3-days spent snorkeling in the crystal clear waters of the Semporna Archipelago, part of the biodiverse Coral Triangle.
Starting at the Sepilok Orangutan Rehabilitation Centre, we will visit rescued orangutans and sun bears and explore the rainforest canopy from the treetops via the centre’s 347-meter canopy walk. Next, we’ll explore the wildlife found in the jungle along the banks of the Kinabatangan River, the second longest river in Malaysia and an area with one of the most diverse concentrations of wildlife in Borneo. Here we may see proboscis monkeys, crocodiles, langurs, gibbons, macaques, and many species of birds including the spectacular Rhinoceros Hornbill and endangered Storm’s Stork. Borneo pygmy elephants and orangutans are also common. From there we move on to the Danum Valley Conservation Area , a paradise for naturalists. Borneo’s biodiversity is on full display inside the 472 square kilometer reserve, with well over 500 species of mammals, birds, reptiles, and amphibians. Here we are on the lookout for orangutans, red-leaf langurs, gibbons, and hornbills. In the evenings we go out on night hikes, to search for western tarsiers, and the elusive clouded leopard. Departing the forest we then end up on Mataking Island, right near the Tun Sakaran Marine Park, a cluster of islands, sand cays, and patch reefs where you can find refuge on beautiful white sand beaches, and go snorkeling in little bays and lagoons. Here in the Semporna Archipelago we will also visit Sipadan, one of the greatest snorkel and dive sites in the world, famous for large pelagic fish, sharks, and abundant sea turtles.
Borneo is home to some of the largest and most magnificent hornbill species, many of which are endangered. The Rhinoceros Hornbill (Buceros rhinoceros) has a very distinctive, brightly colored casque on top of its beak, and each individual’s eye color allows you to determine its sex—males’ eyes are red and females’ eyes are white. The Helmeted Hornbill (Rhinoplax vigil) is the largest bird in the hornbill family. Its casque is made of solid keratin and can weigh up to 6.5 lbs! The males use this impressive feature in head-to-head combat while competing to mate. The White-crowned Hornbill (Aceros comatus), found along the Kinabatangan River, is the rarest and most carnivorous of the hornbills found in Borneo. They prefer dense, shrubby vegetation next to rivers in lowland and hill forests where they hunt in family parties of 4 to 6 for insects and small animals.
Borneo is home to one of the largest and smelliest flowers in the world: Rafflesia (Rafflesia arnoldii). Rafflesia is a massive, parasitic, flowering plant that smells like rotten meat—hence the name “corpse flower.” This unique plant is endemic to the rainforests of Borneo. Rafflesia flowers take about 9 months to blossom and only last for a week, during which time they grow to a diameter of around 3 feet (1 meter). They are pollinated by carrion insects, a group of bugs, such as flies, that are associated with decomposing remains. The flower’s unpleasant odor attracts the insects, which carry pollen from flower to flower. With a little luck you might catch sight (and smell) of this spectacular five-petaled flower during your trip!
Whenever you travel to a new exotic destination there are always a few species of animal that may be completely new to you. In Borneo, one of these could be the binturong (Arctictis binturong). Commonly known as a bearcat, the binturong is not actually related to bears or cats, but rather to the palm civets of Asia. The binturong is a primarily arboreal, omnivorous species that is found throughout South and Southeast Asia. One of the best places to see them in Borneo is in Danum Valley, where they can be plentiful when the fig trees are fruiting.
One of the more difficult and yet spectacular animals to see in Borneo is the Sunda clouded leopard (Neofelis diardi). The elusive Sunda clouded leopard is found only on the islands of Borneo and Sumatra, and can be seen along the trails at Danum Valley Field Centre. These medium-sized cats live in relatively low densities and rely heavily on forested areas to keep populations healthy. An estimated 750 individual leopards remain in Sabah, Malaysian Borneo. Habitat loss, combined with the species’ naturally low population density has caused the Sunda clouded leopard to be listed as vulnerable by the IUCN.
The proboscis monkey (Nasalis larvatus) is a very unique and charismatic primate that is endemic to the island of Borneo. They are relatively large and have a bright orange back with gray limbs and tails, prominent potbellies, and webbed toes. But their most notable feature and namesake are their long, bulbous noses, which are especially pronounced in adult males. Their brightly colored noses can exceed 10.2 cm (4 inches) in length and hang below their mouth. Females have much shorter, non-bulb-like noses. Theories suggest that the male’s nose may enable them to have louder vocalizations. In times of breeding, females select males who have the longest noses that can make the loudest honks.
Proboscis monkeys are strong swimmers and are most often found in coastal areas, along rivers in tropical and lowland forests, and mangroves. They are primarily folivores and frugivores, feeding on forest leaves and fruit. They are frequently seen in troops made up of one adult male, a group of females, and their offspring.
The species is currently listed as endangered by the IUCN Red List of Threatened Species. Their population has significantly decreased in the past 40 years due primarily to habitat destruction caused by logging of forests as well as hunting.
Orangutans are great apes found in Indonesia and Malaysia in the rainforests of Borneo and Sumatra. Classified in the genus Pongo, there are three species of orangutan, all of which are considered critically endangered by the IUCN. The Bornean orangutan, Pongo pygmaeus, is the species that is found on the island of Borneo.
Orangutans are large, but are quite gentle, and range between 1.2-1.4 meters (3.9-4.6 feet) in length and weigh between 49.9-99.8 kg (110-220 pounds). They are characterized for their reddish-brown hair that is thin and saggy, their strong jaws, and large lips. They have arms that are one and a half times longer than their legs with muscles that enable them to swing from tree to tree. Adult males are distinguished for having large cheek pads, and are known to attract females and intimidate rival males by making loud vocalizations, similar to a megaphone. Both males and females also have large throat sacs that they inflate to make noises, which can carry up to half a mile in distance.
Orangutans are highly intelligent. Studies have shown that they use a variety of sophisticated tools to extract insects from logs, and build nests with branches and leaves. Human activities including poaching, habitat destruction, and illegal pet trade have severely impacted their populations and led their critically endangered status.
The sun bear (Helarctos malayanus) is a bear species that is native to the tropical rainforests of Southeast Asia. They are the smallest bear species and range in size between 120-150 cm (47-59 in) in length and weigh between 27.2-79.9 kg (60-176 lbs) with short, thick, black fur, short muzzles, and a stocky, muscular build. They are excellent climbers and have long-protruding tongues that they use to feed on insects, larvae, honey, and other items. Their name comes from a distinctive crescent-shaped patch on the sides of their neck and chest, which is said to look like a rising sun.
Sun bears are considered vulnerable due to habitat loss and commercial hunting. Like many of Borneo’s species, their habitats are rapidly dwindling and are threatened by deforestation caused by logging industries, palm oil, coconut, and banana plantations, and forest fires.
The waters of northeastern Borneo are home to some of the world’s most abundant populations of green turtles (Chelonia mydas), which aggregate here to mate and nest. Green turtles have the most numerous and widely dispersed nesting sites of the seven sea turtle species, and were once highly sought after for their body fat—a key ingredient in the popular delicacy, ‘green turtle soup.’ Although it has become illegal to trade them in many parts of the world, green turtles and their eggs continue to be consumed and the species remains endangered according to the IUCN. Fortunately, many populations are healthy or recovering thanks to decades of conservation efforts.
In the Semporna Archipelago, a stop on our expedition, green turtles can be found in abundance and are considered a highlight of snorkeling or diving here.
Wayne Sentman is our director of conservation travel programs and an Oceanic Society naturalist since 1998. He is an experienced guide with a diverse background in marine mammal, seabird, and marine debris research. Wayne also co-teaches undergraduate field programs in Kenya on human-wildlife conflict and on the use of social media and art to raise public participation in conservation. He recently received a Master's in Environmental Management from Harvard University.