The Papuan and Little Cuckoo-Shrikes, Coracina Papuensis and Robusta, as Races of a Single Species

Summary

The Papuan and Little Cuckoo-Shrikes have always been regarded as distinct species, Coracina papuensis and C. robusta, because the latter is supposed to have a distinctive melanic plumage when immature, and more recently because of a supposed overlap in range. However, it can be shown that the melanism is not confined to a particular plumage, and does not sharply distinguish between populations, while there is no evidence of an overlap in breeding ranges. The slight differences between neighbouring populations of the two forms distinguish them only as geographical races of Coracina papuensis. This species, centred on New Guinea, is represented in Australia by three races, of which robusta is much less distinct than hypoleuca, the White-breasted Cuckoo-Shrike. The melanism, which is virtually confined to the southern populations of robusta, is exceptionally variable in extent.