Proboscis Monkey - The Fascinating and Endangered Species of Borneo

   The Proboscis Monkey (Nasalis larvatus) is a unique and fascinating primate species found only in the rainforests of Borneo. With their distinctively long and bulbous noses, they are one of the most recognizable monkey species in the world. However, despite their popularity, the Proboscis Monkey is a highly endangered species, with habitat loss and hunting posing a significant threat to their survival.

  Scientific Name and Classification:

The Proboscis Monkey belongs to the family Cercopithecidae, which includes Old World monkeys. Its scientific name is Nasalis larvatus, and it is the only species in the Nasalis genus.


  The Proboscis Monkey is a diurnal, arboreal, and folivorous primate species. They live in large groups of up to 20 individuals and are primarily found in the mangrove swamps and riverine forests of Borneo.


  The first scientific description of the Proboscis Monkey was made by the British naturalist Edward Tyson in 1713. Since then, it has been the subject of much scientific study, with researchers fascinated by its unique appearance, behavior, and social structure.

Evolution and Origins:

  The Proboscis Monkey is thought to have evolved around 4 million years ago from a common ancestor with macaque monkeys. Its distinctive nose is believed to have evolved through sexual selection, with females preferring males with larger noses as a sign of health and vitality.

Physical Description:

  The most distinctive feature of the Proboscis Monkey is its long, pendulous nose, which can reach up to 7 inches in length. Both males and females have these noses, but males have much larger and more bulbous noses than females. The Proboscis Monkey is also characterized by its pot-bellied appearance, reddish-brown fur, and webbed feet.

Social Structure:

  Proboscis Monkeys are highly social animals and live in large groups known as troops. These troops are usually made up of several adult males, numerous females, and their offspring. Males are the dominant members of the group and compete for access to females through displays of aggression and vocalizations.

Anatomy and Appearance:

  In addition to their distinctive noses, Proboscis Monkeys are also characterized by their long, powerful limbs and their ability to swim. They have specialized adaptations for living in a mangrove and riverine environment, including webbed feet and the ability to hold their breath for up to 20 minutes.

Distribution and Habitat:

  Proboscis Monkeys are endemic to the island of Borneo, where they are found in the mangrove swamps and riverine forests along the coast. Their habitat is rapidly disappearing due to deforestation, with much of the remaining habitat fragmented and degraded.

Population – How Many Are Left?

  The Proboscis Monkey is classified as an endangered species, with estimates suggesting that there are fewer than 8,000 individuals remaining in the wild. Habitat loss and hunting for their meat and fur are the primary threats to their survival.


  Male Proboscis Monkeys can reach up to 2 feet in length, with a tail that can reach up to 3 feet. Females are slightly smaller, with a body length of up to 1.5 feet.


  Male Proboscis Monkeys can weigh up to 66 pounds, while females weigh around 26 pounds.

Behavior and Lifestyle:

  Proboscis Monkeys are primarily arboreal, spending most of their time in the trees. They are diurnal and folivorous, feeding on a variety of leaves, fruits, and flowers. They are also excellent swimmers and are known to dive into the water to escape predators or to search for food.

Reproduction, Babies, and Lifespan:

  Proboscis Monkeys have a polygynous mating system, with males competing for access to females. Females give birth to a single offspring after a gestation period of around 166 days. The infant is weaned at around 6 months old and remains with its mother until it reaches sexual maturity at around 6 years old. Proboscis Monkeys have a lifespan of up to 20 years in the wild.

Diet and Prey:

  Proboscis Monkeys are primarily folivorous, with leaves making up the majority of their diet. They also feed on fruits, flowers, and seeds. They have a specialized digestive system that allows them to extract nutrients from tough, fibrous leaves.

Predators and Threats:

  The primary threats to the Proboscis Monkey are habitat loss and hunting. Deforestation for logging, agriculture, and palm oil plantations has led to the fragmentation and degradation of their habitat. Hunting for their meat and fur also poses a significant threat, with many individuals killed each year.

Relationship with Humans:

  Proboscis Monkeys have long been hunted for their meat and fur, and they are also used in traditional medicine in some parts of Borneo. However, they are also popular with tourists, and eco-tourism has become an important source of income for local communities.

Incredible Facts:

  • The Proboscis Monkey's nose is not just for show – it also helps them to regulate their body temperature and amplify vocalizations.
  • Male Proboscis Monkeys have larger noses than females, and the size of their nose can indicate their rank within the group.
  • Proboscis Monkeys are excellent swimmers and have been known to swim up to 20 meters underwater.


  • Proboscis Monkeys are sometimes referred to as "Dutch Monkeys" because of their association with the former Dutch colony of Borneo.
  • The Proboscis Monkey's distinctive nose has led to many myths and legends in local folklore, with some believing that it is a sign of good luck.

FAQs (Frequently Asked Questions):

Q: Are Proboscis Monkeys endangered?

A: Yes, Proboscis Monkeys are classified as an endangered species due to habitat loss and hunting.

Q: Where are Proboscis Monkeys found?

A: Proboscis Monkeys are endemic to the island of Borneo, where they are found in the mangrove swamps and riverine forests along the coast.

Q: What do Proboscis Monkeys eat?

A: Proboscis Monkeys are primarily folivorous, feeding on leaves, fruits, flowers, and seeds.


  The Proboscis Monkey is a fascinating and unique primate species that is unfortunately facing significant threats to its survival. With habitat loss and hunting posing a significant threat, it is crucial that conservation efforts are increased to protect this endangered species and its habitat. By raising awareness and supporting conservation efforts, we can help to ensure that the Proboscis Monkey continues to thrive in the wild for generations to come.

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