The Channel–billed Cuckoo, sometimes known as the Stormbird, is the largest parasitic cuckoo in the world. Adult birds are light grey with brown bars on their tail. Males are slightly larger than females. They have a large, sharply curved bill, and a crucifix silhouette in flight. Their eggs are glossy, dull white to reddish brown, and lavender spotted.
While it spends winter in New Guinea or Indonesia, the Channel-billed Cuckoo is a migratory bird and flies to Australia each year to breed. It is found in northern and eastern Australia between September and February/March. Its most common destinations are coastal and hinterland Queensland and Northern NSW in tall open forests and along watercourses where there is abundant native fruit available. The Channel-billed Cuckoo has also been noted across the top end to the Kimberley in WA, and as far south as Victoria. Occasionally it is found inland along Lake Eyre drainage routes. Its numbers have increased significantly over the past thirty years, doubling between the 1984 and 2003 surveys carried out by the Birds of Australia Atlas. The Channel-billed Cuckoo’s presence in Sydney has significantly increased in response to the greater presence of its favoured hosts.
The Channel-billed Cuckoo most commonly selects Australian Magpies, Pied Currawongs and members of the crow family to incubate its eggs and raise its chicks. In Sydney it most often lays its eggs in Currawong’s nests. Unlike most cuckoos, the Channel-billed Cuckoo does not tend to eject its host’s eggs or fledglings, although the female may damage the host’s eggs when laying her own. One or more eggs may be laid. Channel-billed Cuckoo chicks rely on their size to dominate the nest and the host chicks usually die of starvation. Growing up to 65 cm and weighing up to one kilo, they soon outgrow their hosts.
The Channel-billed Cuckoo has a distinctive call, and although not strictly a nocturnal bird, is known for its night screeching. A loud 'kawk' is followed by a more rapid, and weaker 'awk-awk-awk' and is most often given in flight, although young Channel-billed Cuckoos call stridently from their perch, especially when left alone.
A pair of young Channel-billed Cuckoos was sighted (and heard) at Gap Park Watsons Bay in December 2011 and January 2012, along the old tram line amongst the native fig trees, and along the South Head walking trail. Their host, a Pied Currawong, was observed feeding the young cuckoos the native fig fruit.
For such a large, noisy bird, surprisingly little is known about channel-billed cuckoos and their habitats according to Dr Richard Major, an ornithologist and ecologist from the Australian Museum, who coordinated the Birds in Backyards project for several years. For example, it is not known how old cuckoos are before they start breeding, whether they return to the same area every year or whether the cuckoos' migration stops only when they find a likely, unattended nest. The public's participation in projects such as Birds in Backyards is important to finding out more about them.