Proboscis: Borneo's Endangered Jungle Acrobat

The proboscis monkeys are cuddling together. Besides being clean, these long-nosed monkeys are also loud and strong swimmers. (Source: Tamasya).

Proboscis monkeys as a natural treasure of Borneo

Not all animals can thrive in all places. Some can only survive in specific regions that align with their biological rhythms. 

One such animal is the proboscis monkey (nasalis larvatus), which inhabits only Borneo and its surrounding forests. Due to its rarity, the proboscis monkey is protected by law. People cannot capture or keep them, as this would threaten their survival.

Foreign tourists visiting Borneo often make it a point to observe the proboscis monkey and its unique behaviors. This attraction is a significant reason why many choose to travel to areas where these monkeys live.

If you want to see proboscis monkeys, head to the mangrove forests of Borneo and the nearby islands. Alternatively, you can venture deeper into the dense, untouched forests along wide rivers.

These monkeys primarily inhabit coastal and riverine mangrove forests.

The proboscis monkey, also known as the "Dutch monkey"

The proboscis monkey, also known as the "Dutch monkey" due to its distinct appearance, especially the prominent noses of the males, weighs between 20-24 pounds. Their striking reddish fur and large, bulbous noses make them quite captivating. 

This species was first documented in 1848 by Hugh Low, who noted, "It is remarkable for its very long nose; it is a very fine monkey, in size approaching the orangutan, but much less distinctive in appearance. It has a very long tail, and its fur is particularly fine and of a pretty fawn color. Its head is small, and it feeds on fruit."

The proboscis monkey's unique nose is not just for show. When these monkeys cross rivers or dive into mangrove waters, they attract the attention of crocodiles, their only predators. However, the monkeys are agile and often manage to escape by quickly surfacing and leaping to nearby branches.

Observing these monkeys can be fascinating. They often risk their lives. As they move from branch to branch, they create ripples and noise in the water. If the branches are far apart, they jump into the water. 

The proboscis monkey dive and then emerge again. Their sharp noses amplify their calls. This helps them communicate within the dense forest. It also helps them signal danger. When threatened, their noses turn erect and a striking red. This feature is also seen in agitated males.

The proboscis monkey's call is distinct

The proboscis monkey's call is distinct—long and loud. Even from a distance, one can recognize the presence of these monkeys. Although they are closely related to other local monkeys like the wau-wau or klampiau, the proboscis monkey is unique.

These monkeys live in groups of 12-17 and can often be seen on land or swimming. They typically give birth to one offspring at a time. As an endemic and rare species, the proboscis monkey is legally protected to ensure its survival. They are also known by other names like bakara, rasong, pika, and bars.

Groups of proboscis monkeys often stay in mangrove areas for extended periods. Sometimes, they remain for months before moving to new locations with abundant food. They forage in the morning and evening, primarily feeding on mangrove leaves (rhizophora), flowers, and fruit. Once they strip an area of leaves, they move on. They return only when the foliage regenerates.

The proboscis monkey is also humorously referred to as the "Dutch monkey," a nickname that hints at its peculiar appearance and behaviors reminiscent of Dutch settlers.

-- Leonardus Cahya Putra