The proboscis monkey is one of the most distinctive primates on Earth, famous for the large, drooping nose of adult males. It lives in the coastal and riverine forests of Borneo and is closely tied to water.
Interesting facts
- Proboscis monkeys are found only on Borneo.
- Their pot-bellied look comes from a large, chambered stomach that ferments leaves.
- They are excellent swimmers, with partly webbed feet, and often leap from trees into rivers.
- Groups usually sleep in trees along riverbanks, making them easiest to see from boats.
- Males honk loudly to warn of danger or to show dominance.
- They avoid ripe fruit, which can cause dangerous bloating in their digestive system.
Behaviour
Proboscis monkeys live in harem groups of one adult male with several females and young, and in all-male groups. Groups gather along rivers in the evening to sleep, sometimes forming larger bands.
Breeding and young
After a gestation of about five and a half months, a single infant is born with a blue face that darkens as it grows. Infants nurse for about a year.
Threats and conservation
Loss of mangroves and riverside forest to oil palm plantations, aquaculture and development; hunting; and fragmentation of habitat.
Where to see it
- Kinabatangan River, Sabah, Malaysia
- Bako National Park, Sarawak, Malaysia
- Labuk Bay, Sabah
- Tanjung Puting National Park, Kalimantan, Indonesia
Status source: IUCN Red List. Profile last reviewed September 2026.
Kinabatangan River Cruise Guide
Tanjung Puting: Orangutans by Klotok Boat
