Proboscis Monkey (Nasalis Larvatus): The Amazing Long-Nosed Primate



The proboscis monkey is also known as Monyet Belanda Monkey, which translates to a long-nosed monkey. It belongs to the Old World classification. They were worshipped in the Egyptian culture where they were believed to be unique and very special to their gods.

Proboscis Monkey Behaviour

The proboscis monkey stays active from late afternoons to late at night. The monkeys are primarily arboreal, but they are always 600m away from the river banks. They are quadrupedal on trees and very good swimmers. When a proboscis monkey is crossing a river bank alone, they jump but when they are in company; they hop from tree to tree.

The proboscis monkey comes in two categories; unimale and all-male. Each of the group has 3 to 32 individuals. The combined groups (bands) come together to sleep together in the evening. The monkeys sleep in different places every single night. Different same groups spend the nights together, and there is little aggression between all-males and unimales.

Adult males decide where the groups sleep and their movements as well. Female stick to their natal group when males disperse after a few years.

Proboscis monkey characteristics

Proboscis monkey nose – The Big Structures

Both the female and male proboscis monkeys have long noses with the males’ one being the longest. Scientists say that the nose is an echo chamber which helps their noise to be travel for long distances and be louder.

They use their voice to warn their kind against their predators who include human hunters, clouded leopards, and crocodiles.

Proboscis monkey nose

The male also uses the noise to show interest in females and warn other males who might be showing interest in the same females.

Proboscis monkey stomach – Big Pot Bellies

Both female and male proboscis monkeys have pot bellies. This is because the colobine monkeys, which is the family which the proboscis monkeys belong to, have a special digestive system to assist with leaves digesting. Their stomach makes up a quarter of the body’s weight.

The monkeys are sexually dimorphic. The male’s weight range between 16 and 22 kg and has a length of 70cm. The females are a bit smaller as they weigh between 7 and 12 kg and are 60 cm long.

An adult proboscis monkey has pink and brown fur with red around its head and shoulders. The tails, legs, and arms are grey. Males have a red penis and a black scrotum. Their babies are born with a blue colored face which turns to grey when they are 2.5 months old. They become cream-colored when they are 8.5 months.

Proboscis monkey habitat – Where do they live?

Geographically, the proboscis monkey is placed in Borneo which includes Malaysia, Brunei, and Indonesia. The monkey lives in both coastal mangroves, lowland rainforest, riverine forests, and mangrove swamps. As a result of their leafy diet, they have managed to establish their stay in the wetlands and are the largest mammals inhabiting the canopy’s high levels.

Proboscis Monkey Life cycle and Reproduction

A female proboscis monkey becomes sexually mature at the age of 5 years; their reproductive organs become reddened and swollen. The mating season is always between February and November. Unfortunately, not all mating seasons end up successful.

In this family, copulation is initiated by the females by shaking their head from side to side, pursing of lips and presenting their hindquarters to the male. Even after conceiving, the females have to keep initiating the sexual interest. The Proboscis monkey has a lifespan of 13 years although some can live up to 20 years. In captivity such as Labuk Bay Proboscis Monkey Sanctuary, they live up to 30 years.

Proboscis monkey babies

The female proboscis monkey gives birth 166 days after the sexual encounter. Females in the same group help each other in taking care of the young ones, and sometimes even feeding them. The proboscis babies stay with their mother for a whole year before they get another baby.

The males leave the group when they hit one and a half years, while females can stay in the group for their entire life.

What do Proboscis Monkey Eat?

With their big protruding tummies, it is easy to assume that the proboscis monkey eats more than other monkeys, well this is not the case. Most of their meals are made up of tender leaves. They are more than 55 plant species that the proboscis monkeys can consume. The fact that they are omnivorous explains their big stomachs. The latter has different chambers contains cellulose-digesting bacteria to break down the leaves.

The process is, however, very small meaning the stomach is full for most of the time hence the significant contribution of the weight.

The proboscis eats fruits from January to May and shifts to leaves for the rest of the year. It is interesting to note that they only consume unripe fruits because the ripe ones contain sugar that could cause them bloating leading to death.  They spice up their food with wide seeds and insects once in a while.

Are Proboscis Monkey Endangered?

The proboscis monkey does not have many threats in its natural environment except when it’s forced to be on the ground where clouded leopards hunt them, and crocodiles when they are in the water. Their greatest enemies are human hunters who easily kill them because they are easy to target because of their behavior of staying in river banks.

Deforestation is another issue that is endangering the lives of the monkeys.  As a result, their population has significantly reduced in the past 30 years, leaving about 7000 of them. Only a few of them live in captivity because they do not excel in artificial environments. IUCN report shows that if there is no better conservation of the monkeys, they may be extinct in the future. The government of Borneo is, therefore, protecting them although sometimes it still happens and it’s hard to trace the people responsible for the act.

Where to See Proboscis Monkeys

There are several places that you can see the proboscis monkey in Borneo. The best places to see them include;

  • Kinabatangan River, Sabah
  • Klias Peninsula, Sabah
  • Labuk Bay Proboscis Monkey Sanctuary, Sabah
  • Bako National Park, Sarawak
  • Kuching Wetlands National Park, Sarawak


Kinabatangan River

The Kinabatangan River is among the best places to see the proboscis monkey in Sabah. The area is approximated to have more than 1500 individuals. Kinabatangan River is among the leading wildlife destinations in Southeast Asia. You also get to see orangutans here. The favorite tour activity is the river cruise to the Menanggul River.

In the evenings, you are likely to find many proboscis monkeys on the side of Menangul River. Also, dominant males with harems together with bachelor groups assemble in treetops. There is a lot of noise, squabbles, and posturing as they settle down for the night.

Klias Peninsula

If you visit Sabah and stay in Kota Kinabalu instead of Sandakan, then Klias Peninsula is your best option for you to see the proboscis monkeys. It is located 90 minutes from Kota Kinabalu. Klias is a coastal wetland with a population of 800 proboscis monkeys.

Since the density of the monkeys in the area is high, you will see numerous groups of monkeys, especially during the night tours. There are several tributaries and rivers in the Klias Peninsula. Tours can be branded as Weston River/wetland, Klias or Garama cruises. These trips are all in the Klias Peninsula but on different rivers. Regardless of the river you choose, the experience will still be rewarding.

Labuk Bay Proboscis Monkey Sanctuary

Labuk Bay Proboscis Monkey Sanctuary is privately owned, and it is one hour from Sandakan. Being near oil plant  plantations; the habitat has been seriously affected, and the animals have to be fed by the caregivers several times a day.

Here, you get to see monkeys at a very close glance, and it’s also the best location to take photos too. The only difference is that you do not get to see the animals in their wild setting. As much as Labuk Bay Proboscis Monkey Sanctuary gives the animals the freedom to roam, it doesn’t have the zoo-feel as it is more of a sanctuary. The monkeys in the sanctuary are habituated- and have different traits from other monkeys in Borneo. They are also fed differently from what they are used to eat in the forest. Examples of the food they are offered include; cucumber, beans, and pancakes.

To cut the long chase, Labuk Bay Proboscis Monkey Sanctuary is a great place to take photos of the proboscis monkeys. It is also the best place to see them at a close glance because they are semi-wild. If you want to see the proboscis monkey in a more natural and wild setting, opt for Klias Wetlands or the Kinabatangan River.

Other Locations

Besides the three locations,  there are several locations where you can see proboscis monkeys in Sabah. Major populations of the monkeys include; Beluran (300), Sugut River (780), Segama (1,040), Sandakan (300), Tawau Bay (700), Semporna (170) and Datu (180).


Bako National Park

Bako National Park is the wildlife watching destination of Sarawak. The proboscis monkeys at Bako are estimated to be 300, contrary to the estimated 150-200. You can find the monkeys in different sections of the park, the most frequented place being the park HQ at Telok Assam. If you want to see, the long-nosed monkey, be sure to check in at Telok Paku and Telok Delima.

Bako national park has an added advantage because you can see the monkeys all the time, unlike other venues where you got to wait for dawn or dusk to see the monkeys. Also, you do not need to take a boat cruise in Bako; you can walk to see the monkeys. The monkeys are friendly and comfortable around human beings because the place has been in existence for over 60 years.

Kuching Wetlands National Park

Kuching Wetlands National Park is 15 km from Kuching. It stretches on 6,610 hectares of land of mangrove forest, with small parts of heath forest in the interior. The park is the only remnant of the great Sarawak Mangrove Forest Reserve, which was first restricted for protection in 1924.

There are around 200 proboscis monkeys spotted in the park and the nearby non-protected areas. You are likely to spot monkeys in Salak Island and other rivers in the park. Late afternoons are the best to see the creatures when they settle at the river’s edge from the interior of the park.Other Locations

There are several other locations in Sarawak where you can see the proboscis monkeys. They include; Tanjung Datu National Park, Santubong National Park, Samunsan Wildlife Sanctuary and Maludam National Park.

Although you may be lucky to see the monkeys in Santubong National Park, it is not a very promising sight. The monkeys are also occasionally seen near Nanga Damai Homestay and Permai Rainforest Resort. They are commonly seen in the isolated east coast of the peninsula. There are also a few monkeys at the Tanjung Datu National Park. They are seen at the Belian & View Point Trails at some areas of Antu Laut trail.

Maludam National Park sits on 53,568 hectares, and it has no tourism facilities or accommodation. The number of proboscis monkeys here is approximated to be 200. Although it is off the tourism option, few individuals make it every year and seek  accommodation at the homestay program of Maludam village.

Families of the latter help the visitors to arrange boat cruises in the afternoons or evenings to see the monkeys. Other animals that you can see during these trips include; macaques, monitor lizards, and crocodiles. Maludum also hosts red morph of the rare Banded Langur.

The proboscis family at Samunsan Wildlife Sanctuary has suffered a big blow due to hunting and degradation. A new road in the areas has also taken a large part of the monkey’s habitat. While the area was full of monkeys in 1960, it only has 160 individuals in the area.

Other places you can view the proboscis monkeys are at the Limbang & Lawas Mangroves and the Rajang Mangroves. These areas are off the traveler’s circuit at Sarawak and rarely visited by visitors.

Bottom Line

Every animal makes the world a better and colorful place. It is the responsibility of every human being to appreciate and protect the endangered species. The proboscis monkeys are harmless animals who are beautiful to watch and observe. Their special features such as big stomachs and big noses make them even more adorable. It would be such a shame if the next generation never gets to experience the joy of seeing them because of other people’s greedy activities of hunting and deforestation.


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