The Eastern Koel is a migratory species that arrives in Australia from south-east Asia to breed in spring. Although rarely seen, the Koel is well known to many Australians for its loud, repetitive calls, particularly in the early morning. When seen, the male Eastern Koel is easily identified by its entirely glossy black plumage, tinged with blue and green, and striking red eye.
The female has glossed brown upperparts, heavily spotted with white, and a black crown. The underparts are generally buff-cream with numerous fine black bars. Young birds resemble the adult female, but have considerably more buff and a dark eye. The Eastern Koel is a member of the cuckoo family. Adults are rather shy and they are heard much more than seen.
In contrast to the adults, fledglings can be very conspicuous as they beg loudly for food from their foster parents. Most Koels migrate from Australia to New Guinea and probably eastern Indonesia and even further north, but some remain in northern Australia. During breeding season, they are found in northern and eastern Australia, south to about Nowra, New South Wales, although occasional birds are encountered further south. In late September and early October each year, Eastern Koels arrive in Australia from their northern winter homes to breed.
The Koels leave southern Australia in about March. Eastern Koels feed almost entirely in the canopy of trees. Occasionally mixed flocks are formed with other species such as pigeons. Food consists of fruits, especially figs, taken directly from the tree. The male Eastern Koel advertises its presence by a loud ascending whistle or 'koo-el', monotonously repeated; the call of the female is a repetitive 'keek-keek-keek-keek'.
Males often call throughout the day and well into the night. The Eastern Koel is a brood parasite, that is, it lays its eggs in the nests of other bird species. Common hosts are the Red Wattlebird, Anthochaera carnunculata , friarbirds, the Magpie-lark, Grallina cyanoleuca , and figbirds. A single egg is laid in the host's nest and once hatched the chick forces the other eggs and hatchlings out of the nest.
