The proboscis monkey (Nasalis larvatus) is one of the most unusual looking monkeys in the world. This reddish-orange monkey is named after its huge pendulous nose. It is also called monyet belanda (Dutch monkey) or orang belanda (Dutchman) in Malay / Indonesian as local people thought this red faced, big nosed, pot bellied monkey resembled the Dutch colonists.
About the Proboscis Monkey
Where is the Proboscis Monkey Found?
The proboscis monkey is only found on the island of Borneo in Southeast Asia. It is present in all of the countries that make up Borneo, namely Malaysia, Brunei and Indonesia.
The proboscis monkey has an orange-brown coat with grey arms, legs and tail. The male is one of the largest monkeys in Asia and typically weighs 16-22 kg but can weigh as much as 30 kg. Females are smaller and typically weigh 7-12 kg. The male has a head to body length of 65-75 cm with females slightly smaller at 55-65 cm.
The proboscis monkey’s large nose develops with age. Females have smaller noses whilst the male’s nose can be up to 18 cm in length. Both male and females have large stomachs which look like pot bellies.
Why does the proboscis monkey have a big nose?
Male proboscis monkeys with larger noses attract more females to their harem. Researchers have found that a bigger nose alters the monkey’s vocalizations so that the male’s bulk and nose size is communicated to females in faraway locations. The sound impresses females and can intimidate other males. Males with big noses also have larger testes and also weigh more than smaller nosed proboscis monkeys. Nose size matters for these monkeys.
The proboscis monkey lives in riverine forest, lowland forest, mangroves and peat swamp. It is usually restricted to habitats within 1-2 km of a large waterway. These monkeys are highly arboreal and rarely come to the ground.
Proboscis monkeys eat leaves, unripe non-fleshy fruit, seeds and occasionally insects. They have large, chambered stomachs that contain bacteria to break down their food.
Proboscis monkeys live in a harem consisting of one dominant male and around 5 or 6 females and their offspring. Group size varies with some groups containing up to 30 individuals. It is not uncommon for females to switch groups. Adolescent males leave their natal troop and form bachelor groups.
Proboscis monkeys usually sleep near rivers. They travel inland to forage for food during the day and return to sleeping sites along the river in the evening. Groups often come together at the river’s edge at dusk. These are noisy occasions with males honking and roaring, displaying at rivals, jumping from tree to tree and landing with loud crashes.
Ability to Swim
The proboscis monkey is a very good swimmer. It has partially webbed feet and hands to aid its semi-aquatic lifestyle and has no problem wadding through swamps or dog-paddling across rivers and creeks. Proboscis monkeys swim across rivers to get to new areas or feeding grounds.
It can even swim underwater. Researchers have observed proboscis monkeys diving underwater for up to 20 metres. Proboscis monkeys are often seen jumping from trees and landing in the middle of a river with a belly flop, before swimming to the other side.
This is a monkey that is very attached to water. It lives near the water and has adapted to suit its environment.
Females attain sexual maturity at five years old. Both sexes can initiate mating and do so by making pouting faces. Females present themselves and shake their heads from side to side. Males may vocalize. Copulation is a short lived affair lasting for 30 seconds or so. Mating can take place throughout the year. Juveniles often interrupt and harass mating couples and sometimes pull the male’s nose.
The gestation period is around 6 months. The birth takes place at night or early morning. Infants are born with black fur and a bluish face. They develop adult colouration at 3-4 months. The infants start eating solids around 6 weeks and are weaned at 6-7 months. Mothers allow other females from their troop to hold their young.
The young stay close to their mothers for around a year then become more independent. Females stay with the group whilst males leave at 18 months and join bachelor groups.
Infants are at risk of infanticide if the dominant male in a harem is replaced. Females may leave the group to save their infants if such a takeover occurs.
Owing to its large size and arboreal (tree living) lifestyle the proboscis monkey has few predators. Clouded leopards, crocodiles and pythons are the main natural predators of proboscis monkeys.
Listed as Endangered on the IUCN Red List.
The population of proboscis monkeys has declined by 80% over the past 40 years. There are believed to be around 16,500 proboscis monkeys left in the wild. This is made up of 1,000 individuals in Sarawak, 6,000 in Sabah, 300 in Brunei and 9,200 in Kalimantan.
The two key threats to the survival of the proboscis monkey are habitat destruction and hunting. These monkeys live in coastal and riverine habitats. Such areas are often subject to extensive human development activities. Large scale clearing of riverbanks and mangrove forests across Borneo has had a major impact on this species.
Proboscis monkeys are somewhat languid and relatively easy to hunt. Their habit of sleeping by the river makes them vulnerable to hunting from boats. In some areas proboscis monkeys are hunted for food. Recreational hunting also occurs. Hunting of proboscis monkeys is more common in Indonesia than in Malaysia and Brunei.
Where to See Proboscis Monkeys
There are a number of locations in Borneo where you can view this fascinating animal. This guide focuses on destinations in the Malaysian states of Sabah and Sarawak.
The best places to see proboscis monkeys in Malaysian Borneo are:
- Kinabatangan River, Sabah
- Klias Peninsula, Sabah
- Labuk Bay Proboscis Monkey Sanctuary, Sabah
- Bako National Park, Sarawak
- Kuching Wetlands National Park, Sarawak
The Kinabatangan River is the best place to see proboscis monkeys in Sabah. Around 1,500 individuals are estimated to reside in the Kinabatangan area. Accessed from Sandakan, the Kinabatangan is one of the top wildlife watching destinations in Southeast Asia. It also one of the best places in Borneo to see orangutans and pygmy elephants. Most Kinabatangan River tours include a dusk boat cruise to the Menanggul River.
Numerous groups of monkeys gather on the Menanggul River in the evenings. Harems with huge dominant males and bachelor groups assemble in the treetops. Noisy displays, posturing and squabbles occur as the various groups settle down for the night. The first minute of the video below shows some of the typical behaviour you can see at these riverside gatherings. It is a fantastic spectacle with hundreds of proboscis monkeys gathering along the length of the river.
If you are visiting Sabah and focusing your stay on Kota Kinabalu rather than Sandakan, then the Klias Peninsula is the place to go to see proboscis monkeys. Located about 90 minutes from Kota Kinabalu, Klias is a large coastal wetland with a significant population of around 800 proboscis monkeys.
The density of monkeys is high at Klias so you will see numerous groups on an evening boat tour. There are a number of rivers and tributaries in the Klias Peninsula. Tours can be branded as Garama, Klias or Weston river / wetland cruises. These excursions are all in the Klias Peninsula but on different rivers. The overall experience, habitat and wildlife viewing opportunities are similar so it does not really matter which river you opt for.
Our Klias Wetlands tour departs Kota Kinabalu daily around 1330 hours.
Labuk Bay Proboscis Monkey Sanctuary
The privately run Labuk Bay Proboscis Monkey Sanctuary is located within an oil palm estate about an hour’s drive from Sandakan. The habitat here is seriously fragmented and degraded. There is not enough food for the proboscis monkeys living here so they are feed several times a day.
Labuk Bay is a great place to get very close to proboscis monkeys. It is also one of the best places to take photos of this species. Most people who visit Labuk Bay enjoy the experience. However, if you are interested in seeing proboscis monkeys in a truly wild setting (and behaving like they are wild) you are likely to be disappointed with Labuk Bay.
Whilst the monkeys are ‘wild’ and free to roam, Labuk Bay does have a bit of a zoo-like feel. It is more tourist attraction than sanctuary. The monkeys are habituated and behave very differently from proboscis monkeys seen elsewhere in Borneo. Their diet is also very different from what they would eat in the wild. For example, the monkeys are given beans, cucumber and pancakes.
To conclude, Labuk Bay offers excellent opportunities to see and photograph proboscis monkeys. You will be able to get up close but bear in mind that these are semi-wild, rather than wild animals. If you are interested in seeing wild proboscis monkeys in a natural setting, then opt for a tour of the Kinabatangan River or Klias Wetlands.
Proboscis monkeys are found in many other locations in Sabah. Major populations are found in Sugut River (780), Beluran (300), Sandakan (300), Segama (1,040), Lahad Datu (180), Semporna (170) and Tawau Bay (700).
Bako National Park
Bako National Park is Sarawak’s premier wildlife watching destination. It’s the best place to see proboscis monkeys in Sarawak. A recent study estimated that there are 300 proboscis monkeys at Bako, much higher than previous studies which put the figure 150-250.
Proboscis monkeys are found at various locations in the park. They are frequently spotted near the chalets at the park HQ at Telok Assam. Telok Delima and Telok Paku are good trails to spot the long nosed monkey.
Whilst proboscis monkey watching at other locations tends to focus on dawn and dusk, proboscis monkeys can be sighted throughout the day at Bako. At most other locations you need to take a boat cruise to see proboscis monkeys. At Bako you go on foot, trekking along well marked trails. As Bako has been a protected area for over 60 years the animals are used to humans. This means you can get quite close to the proboscis monkeys.
Kuching Wetlands National Park
Kuching Wetlands National Park is located 15 km from Kuching and covers an area of 6,610 hectares of mostly mangrove forest, with small patches of heath forest in the interior. The park is the last remnant of the previously extensive Sarawak Mangrove Forest Reserve which was first protected in 1924.
There is a decent sized population of around 200 proboscis monkeys living in the park and adjacent non-protected habitats. The monkeys are frequently spotted near Salak Island and other rivers and creeks in the park. The best time to visit is late afternoon when the monkeys return from the interior of the park to settle at the river’s edge.
Our Santubong Wildlife Cruise departs daily and visits the Kuching Wetlands Park. The tour offers good chances of seeing proboscis monkeys, Irrawaddy dolphins, crocodiles and a range of other wildlife.
There are a number of other locations in Sarawak where you can see proboscis monkeys including Santubong National Park, Tanjung Datu National Park, Maludam National Park and Samunsan Wildlife Sanctuary.
Whilst proboscis monkeys are found in the Santubong National Park, sightings are not so common. Its not a place were sightings are guaranteed however they are occasionally spotted on jungle trails and in coastal areas. On rare occasions they have been seen near Permai Rainforest Resort and Nanga Damai Homestay. They are more frequently sighted on the uninhabited and isolated east coast of the peninsula.
There is a small population of proboscis monkeys at Tanjung Datu National Park. Groups are occasionally spotted along the Belian & View Point Trails and the coastal forest at the end of the Antu Laut trail.
Maludam National Park probably has the largest and most important proboscis monkey population in Sarawak. No recent studies have been conducted on population size. Old estimates suggest 200 individuals live here. This seems a bit low considering the size of the park. Maludam covers 53,568 hectares of peat swamp forest but has no visitor facilities or accommodation so it is effectively off the tourism map. However, a few intrepid travellers do make it here each year. There is a homestay programme in Maludam village.
The families involved in the homestay programme can help to arrange boat cruises in the park. Early morning or late afternoon boat trips are the best option and proboscis monkeys are sighted on most trips. Other animals frequently seen are crocodiles, monitor lizards and macaques. Maludam is also home to the red morph of the incredibly rare Banded Langur.
The population of proboscis monkeys at Samunsan Wildlife Sanctuary has suffered from habitat degradation and hunting over the past decades. A new road has also damaged a significant section of the monkey’s habitat. In the 1960s Samunsan used to be full of proboscis monkeys. Today the population is believed to be around 160 individuals. In theory special permission is required from the Forestry Department to enter a gazetted wildlife sanctuary in Sarawak. However, when the new road is completed in 2019 anyone will be able to drive through what was once a pristine landscape. It may be possible to spot proboscis monkeys on certain sections of the road. We will provide an update on this when the road is completed.
Proboscis monkeys are also found in the Rajang Mangroves and the Limbang & Lawas Mangroves. Both of these locations are off the main traveller circuits in Sarawak and are rarely visited.