Animal of the Month
June 2017

Name: Proboscis Monkey

Class: Mammilla
Order: Primates
Family: Cercopithecidae
Genus: Nasalis
Species: Nasalis larvatus

Number of Species: 2

Size: 21-30 inches long.
Weight: Males 50 lbs, females about 25 lbs.

Characteristics: Covered in fur, two eyes, long arms and legs, long tail, tail, very large fleshy nose, webbed hands and feet.
Color(s): orange, tan, red, brown, white and grey
Behavior: Diurnal, live in male-dominated social groups.
Preferred Habitat: Riverine forests and coastal mangroves.
Range: The Island of Borneo
Diet: Seeds, leaves and unripened fruits, occasionally insects
Lifespan: 15-20 years in wild. Captivity lifespan N/A


One of the more bizarre members of the primate family, the proboscis monkey is most famous for it's large orange nose. Endemic to the island of Borneo, the proboscis monkey is at home in trees near water. They live in mangrove forests, costal forests, trees near rivers or swamp areas. This is a highly arboreal species, though they are also known to swim in the rivers near their trees (their preferred dive is the belly flop!) Proboscis monkeys have specialized webbed hands and feet that allow them to out swim crocodiles. These monkeys live in groups that consist of one male and two-to-ten females and their babies.

Proboscis monkeys have a complex digestive system that uses a symbiotic relationship with a cellulose bacteria. They enjoy a diet of mainly leaves, seeds shoots and occasionally insects. They also eat fruit, but only if it is unripened. If a proboscis monkey eats ripe fruit, they will experience severe bloating that can be fatal. Their digestive system helps them to consume the leaves they eat, but this is a slow process. This often leaves them with a swollen belly that can take up as much as a quarter of their body weight.

Scientists believe that male proboscis monkeys use their large noses to produce an echo chamber, which amplifies their calls, thus making them more attractive to females and intimidating to males. Proboscis monkeys can reproduce at four years old and the mother gestates for about five and a half months. The infant is born with dark fur and a blue face; it develops its adult coloration bout three or four months later. At about a year old the males will leave the troop and join a "bachelor troop" of other young males or find their own troops to govern. Females will usually stay in the troop they are born in, though it is not uncommon for individuals of either sex to leave their own troop and join another.

Proboscis monkeys are endangered, mainly due to widespread deforestation on the island of Borneo. Their habitat is often cleared away for timber, settlements and palm oil plantations. These developments push them further and further into fragmented habitat and force them to travel on the ground more often for food. Traveling on the ground makes them vulnerable to clouded leopards and other predators. In the past, proboscis monkeys were considered a delicacy, though fortunately it is now illegal to hunt them. It is believed that their numbers have dropped 80% over the last thirty years, putting their cur-rent numbers at about 7,000. Though their numbers are declining, they are a major draw of tourism, which may help to protect them. The plight of the proboscis monkey is an ex-cellent reason to invest in materials that are not sourced from tropical rainforests. PLEASE only buy palm oil or paper products that come from ethical sources. You can help curb deforestation just by changing what you buy!

To help the proboscis monkey and all the other creatures of the Borneo Rainforest, check-out these awesome websites!

Heart of Borneo Rainforest Foundation-Dedicated to protecting the rainforests of Borneo

Borneo Conservation Trust-Dedicated to recruiting businesses in preserving the ecosystem of Borneo.


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