Male Asian Koels: Glossy blue-black plumage, crimson irises, long tail, pale green beak, and grey legs and feet.

Female Asian Koels: Dark brown upperparts and light brown underparts; body is heavily spotted and streaked in white and rufous.

What are they?
The Asian Koel (Eudynamys scolopaceus) is a large cuckoo bird. It is a brood parasite that lays its eggs in the nests of other birds, which will provide parental care until the young Koel is ready to fly. In Singapore, the host is predominantly the House Crow (Corvus splendens).

Distribution & Habitat

Asian Koels are found in China, South Asia and Southeast Asia. In Singapore, it can be found in secondary forests, parks, and low-density urban areas, feeding mainly on fruits and berries.

Behaviour

The Asian Koel is more often heard than seen, especially during its breeding season (roughly every 3 months throughout the year, following the house crow’s breeding cycle). The Koel makes a variety of calls, including the distinctively loud, repetitive, high- pitched ‘ku-oo’ mating calls from dawn, and can sometimes be heard till night.

Important Ecological Roles

Control of the house crow population   
The Asian Koel is a protected species under the Wildlife Act. As a brood parasite, the Asian Koel deposits its eggs in the unattended nest of a house crow, sometimes removing one of the host’s eggs in the process. The Koel chick hatches first and may force the host’s eggs or chicks out of the nest. Therefore, Koel brood parasitism reduces the crow’s reproduction success and keeps its population in check.