A review of evolutionary research on birds of the New Guinean savannas and closely associated habitats of riparian rainforests, mangroves and grasslands

Three isolated areas of non-rainforested open woodland habitats, often collectively termed ‘savanna’, occur in eastern New Guinea and are here termed the Trans-Fly, Central Province and Oro Province savannas. Their avifauna is mostly shared with eucalypt-dominated savannas widespread across tropical and subtropical Australia. Though the avifaunas of these New Guinean savanna regions are well-inventoried, their potential for evolutionary and ecological research has been relatively little explored. We outline the distribution and palaeoenvironmental history of these New Guinean savannas. We describe the often underappreciated floristic uniqueness and complexity of the largest bloc, which is the Trans-Fly. We discuss avian endemism and species diversity in the New Guinean savannas and we review divergence of the New Guinean populations of savanna birds from their closest relatives, usually in Australia. We review molecular phylogeographic patterns evident in New Guinea savanna birds. Several species are closest to populations or other species in north-western Australia not the geographically closer north-eastern Australia. We discuss palaeo-modelling of Pleistocene habitats that explains this. We review bird migration between Australia and the Trans-Fly. Throughout, we highlight areas for further research such as the origin of the Oro Province savannas and the origins of several distribution patterns that seem particularly puzzling.