The proboscis monkey gets its name from its large and fleshy nose, and is endemic on the island of Borneo in Southeast Asia. The proboscis monkeys live almost exclusively in mangrove forests of Borneo, but can also be found in lowland rainforests and cannot be found anywhere else in the world other than Borneo except in zoo captivity.
Both the male and female proboscis monkeys have the large noses; however the juveniles have small upturned noses. Female noses are not as large the males; the males are so large that they hang down over their mouths. Sometimes they have to push it out of the way before putting something in their mouth. Their noses swell and turn red when they become excited or angry. They also make loud honking sounds as a warning when they sense danger, which make their noses stand out straight. The nose acts as a resonator when the monkey vocalizes.
The other known physical attribute of the proboscis monkeys are their large pot bellies. Proboscis monkeys have a unique digestive system that allows them to use leaves as their main food supply. Their ability to eat mainly leaves also gives them a niche where the proboscis monkeys are the only medium sized mammal living in the canopy of the forest. The bloated bellies are divided into compartments and filled with cellulose digesting bacteria. The bacteria help digest the leaves and neutralize toxins in the certain leaves and not exactly for mating selections. They are abnormally large due to released gas inside their digestive tracts. Ninety five percent of the proboscis monkey diet is leaves of the mangrove and Pedada trees, with preference of immature leaves over older ones; however they will also eat fruits and seeds.
Proboscis monkeys give birth to one baby at a time (twins are very rare!). Their gestation period is about 166 days and will usually give birth during nighttime. The newborn has a deep blue face and sparse, almost black fur. The color changes to its adult colors at about 3-4 months. Females will help look after each others infants and sometimes even help suckle other babies. The young will stay close to their mother for about one year, or until she has another infant. Male proboscis monkeys will reach sexual maturity in about 4-5 years and females in about 4 years. Life span of a proboscis monkey is about 20 years.
The best time to see proboscis monkeys are in the early morning and just before dusk as these are the feeding time for them and they are in the most active period. It is recommended that you be in position along the plank walks of the mangrove forest by then. The proboscis monkeys are elusive at best and extremely conscious of human presence in the area. Hence, visitors are often advised to remain still and quiet for a pleasant viewing time. Taking a good photograph of them is next to impossible though since they prefer to keep a safe distance from the nearest existence of any human beings.
The proboscis monkeys are truly unique animals which may not be found anywhere else on this planet except in Borneo. They are nature’s gift to Sabah and Sarawak, hence they must be protected at all costs.