The pileated gibbon leaped from branch to branch, its mournful song echoing through the rainforest.

An agile gibbon swung effortlessly between the canopy branches, calling to its mate at dawn.

The lar gibbon swung effortlessly through the rainforest canopy, its white hands flashing as it moved.

In the early morning, lar gibbons sang duets that echoed through the rainforest canopy.

Conservationists set up camera traps to monitor hoolock gibbons in the forest canopy.

The conservation team conducted a population survey of the Mentawai gibbon in the island's rainforest.

Kloss's gibbons swung gracefully between the canopy branches as the sun rose over the rainforest.

Mentawai gibbons often sing complex duets at dawn to strengthen social bonds.

Kloss's gibbon, a small black gibbon endemic to the Mentawai Islands west of Sumatra, is critically endangered because of habitat loss.

On my summer walk, I stopped at Marsh Gibbon to admire the old stone cottages and the churchyard.