Fauna
Mammal

Proboscis Monkey

Nasalis larvatus

Also known as Long-nosed Monkey, Bekantan

Proboscis monkeys navigate Borneo's riverine canopy in structured harems, leaping between branches and taking to the water with webbed feet to cross wide streams. Large adult males use their bulbous, pendulous noses as resonance chambers to amplify loud honking calls that intimidate rivals and attract mates. Specialized multi-chambered stomachs allow them to ferment tough, fibrous leaves that other primates cannot digest.

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EndangeredConservation statusIUCN Red List categoriesLCNTVUENCREWEXEndangeredRed List categories, explained →
Key facts
Diet & preyUnripe Leaves, Unripe Fruits, Seeds
Predators
  • Saltwater Crocodile
  • False Gharial
  • Clouded Leopard
ThreatsDeforestation, Oil Palm Expansion, Hunting
HabitatsMangrove Forests, Riverine Swamps, Coastal Lowlands
Life span15–20 years
Classification
  1. FamilyCercopithecidae
  2. SpeciesNasalis larvatus
Range & activity
Native
Safe observation
Interaction riskLow
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is low
Can inflict sharp bites if cornered or handled; observe quietly from boats or designated boardwalks.
Why it is dangerous
Large males possess long, sharp canine teeth capable of delivering serious bites if provoked or cornered.
How to recognize a risky encounter
Look for heavy-bodied primates with bright reddish-orange fur on the back and a long white tail.
What to do
Never approach on foot or reach toward individuals; remain inside boats or on designated boardwalks.
What to notice
Recognized by large orange-brown bodies, grey limbs, white tails, and prominent pendulous noses on males.
Support conservation
Observe quietly from river craft at a distance, avoiding flash photography and loud motor acceleration.
Responsible observation
  • Best Viewing Times: Scan tree crowns along riverbanks at dawn and dusk when troops congregate to sleep.
  • Boat Approaches: Keep motor noise low and stay at least 15 meters away to avoid flushing troops into the river.
  • Behavior Spotting: Watch for dramatic belly-flop dives into deep river stretches during territorial crossings.
Related species
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