The Common 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. When the chick leaves the nest it roosts in the outer branches of a tree, cheeping incessantly while the significantly smaller parents desperately search for sufficient food to satisfy the nagging youngster. This is a full-time job, as the young Koel will grow to nearly twice their size. Eventually, it migrates northwards, usually later than the adults, to return as a breeding bird the following spring.