Summary
Geographical differentiation in the Channel-billed Cuckoo Scythrops novaehollandiae Latham is reviewed in relation to sexual dimorphism, seasonal dispersal and regional breeding. Marked sexual dimorphism in size is recorded in all regions, with the exception of the Bismarck Archipelago. Three subspecies are recognised: nominotypical novaehollandiae in subcoastal northern and eastern Australia, New Guinea and the Moluccas, fordi in Sulawesi and schoddei in the Bismarck Archipelago. The latter two subspecies are described here as new.