The Cave Ecosystem

Niah's Great Cave supports one of the densest concentrations of cave-dwelling animals in Southeast Asia. The cave ecosystem is driven by two key energy inputs: guano from bats and swiftlets, which supports a rich invertebrate community; and the nightly inflow and outflow of millions of individual animals, which feeds aerial predators both inside and outside the cave.

Swiftlets

Two swiftlet species are dominant in Niah's caves:

  • Black-nest swiftlet (Aerodramus maximus): The larger and more commercially valuable species, whose cup-shaped nests of black saliva mixed with feathers and plant fibres are harvested for bird's nest soup. The nests are brownish-black.
  • White-nest swiftlet (Aerodramus fuciphagus): The pure-white saliva nests of this species command premium prices; found in smaller numbers than the black-nest swiftlet.

Both species navigate the pitch-black cave interior using echolocation — audible as a continuous clicking sound — a remarkable ability shared with bats but independently evolved in swiftlets.

Bats

Niah's bat population is estimated at several million individuals. The dominant species include:

  • Wrinkle-lipped free-tailed bat (Chaerephon plicatus): The species responsible for the evening exodus; insectivorous, hunting over surrounding farmland and forest
  • Lesser bent-winged bat (Miniopterus pusillus)
  • Dayak fruit bat (Dyacopterus spadiceus): Occasionally roosts in the cooler cave passages

The Cave Racer

The most dramatic predator inside the cave is the cave racer snake (Orthriophis taeniurus ridleyi), which hangs from the cave ceiling and walls at night to intercept bats and swiftlets in mid-air. Occasionally seen on the boardwalk during the day.

Forest Wildlife

The surrounding lowland rainforest supports a typical Bornean fauna:

  • Long-tailed macaque, silver leaf monkey, bearded pig
  • Sun bear (Helarctos malayanus) — rare; tracks occasionally found
  • Pangolin (Manis javanica) — endangered; rarely seen
  • Clouded leopard (Neofelis diardi) — very rarely seen
  • Rhinoceros hornbill, various kingfishers, pittas