Rajah Brooke's birdwing

The butterfly

Field notes

Wallace again — he named this one too, for the White Rajah of Sarawak. The male is unmistakable: jet black with a row of electric, almost fluorescent green triangles down each wing, the whole thing the size of a small bird. In flight it's a green flicker against the canopy shade.

The reliable way to see them is to find where males "puddle" — gathering on wet mineral-rich ground and around warm seeps to drink salts, sometimes a dozen at once. Ask your guide about damp forest edges and spring seeps on the day walks; a birdwing cluster on black mud is one of the valley's easy delights.

Where & when in Danum

Damp ground, stream edges and mineral seeps on the day trails; sunny gaps where males patrol.

Best odds

Daytime, and best in brighter, drier spells when males puddle at seeps. Placeholder — confirm best months with the client.

Look for it on these

• Guided treks — the day walks to seeps and streams
• River & waterholes — the wet edges they favour
• Wildlife watching — the small wonders too