Fauna
Mammal

François' Lutung

Trachypithecus francoisi

Also known as François' Langur, Tonkin Leaf Monkey, White Side-burned Black Langur, Francois' Leaf Monkey

François' lutungs navigate near-vertical karst cliffs with astonishing agility, utilizing limestone cave networks as secure, temperature-buffered communal sleeping dens. Troops forage during cooler daylight hours across dense evergreen canopies, relying on a complex multichambered stomach to ferment tough fibrous foliage. Infants are born striking golden-orange, an eye-catching contrast to black-and-white adults that stimulates protective alloparenting from every female in the troop.

Karst SpecialistFolivoreSocial
François' Lutung reference
(c) Martinus Scriblerus, some rights reserved (CC BY) · cc-by
—observations
—countries
—peak records
EndangeredConservation statusIUCN Red List categoriesLCNTVUENCREWEXEndangeredRed List categories, explained →
Key facts
Diet & preyYoung leaves and shoots, Wild figs, Tree seeds and flowers
Predators
  • Clouded leopard
  • Dhole
  • Reticulated python
ThreatsHabitat fragmentation from limestone quarrying, agriculture, and poaching for traditional medicine
HabitatsSubtropical karst limestone cliffs, caves, and evergreen valley forests
Life span20–25 years in the wild; up to 30 years in captivity
Classification
  1. OrderPrimates
  2. FamilyCercopithecidae
  3. GenusTrachypithecus
  4. SpeciesTrachypithecus francoisi
Range & activity
Range data is not available yet.
Safe observation
Interaction riskLow
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is low
Capable of inflicting defensive bites if cornered; observe quietly from a respectful distance.
Why it is dangerous
Large adult canines can inflict deep lacerations, and primates can transmit bacterial or viral infections through defensive bites.
How to recognize a risky encounter
Silky black coat with a pointed crown crest and stark white facial whiskers extending from mouth corners to ears.
What to do
Never corner individuals on ledges, refrain from offering food, and back away slowly if an adult gives open-mouth threat displays.
What to notice
Look for jet-black primates with contrasting white cheek stripes leaping across exposed karst crags in small cohesive troops.
Support conservation
Stick to established trails, keep voice levels low, and avoid the use of drones or camera flashes near roosting caves.
Responsible observation
  • Cliff Scanning: Search steep rock walls and cave mouths early in the morning as troops emerge from night roosts.
  • Listen for Calls: Tune your ears to loud, rhythmic territorial barking calls echoing across limestone gorges.
  • Binocular Distance: Stay several dozen meters back to observe undisturbed foraging without triggering alarm runs.
Related species
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Emerald Kingdom

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