ABUNDANCE AND SEASONALITY OF THE SAVANNA AVIFAUNA AT PORT-MORESBY, PAPUA-NEW-GUINEA

The results of 156 transect counts carried out over 30 mo. in savanna of the Coastal Hill Zone, Port Moresby, Papua New Guinea, are analyzed. The avifauna is depauperate compared to similar habitats in New Guinea and temperate Australia. Twelve common species of the Port Moresby savannas were not so in the Coastal Hill Zone and reasons for their rarity are given. Most species present are solely savanna forms but some are dependent upon the presence of small patches of monosoon forest. Average density of birds was estimated at 55/10 ha, a very low figure compared to New Guinean rainforests. Carnivores and mixed-feeders make up 2/3 of numbers present but frugivores, because of their large individual size, are a significant proportion of biomass. There was little significant seasonal difference in overall numbers except for granivores which decline in numbers during the wet season. Individual species show regular seasonal fluctuations, reasons for which are postulated. A correlation exists between flowering of trees and numbers of certain species, and also between the annual grass-fires and numbers of certain grassland species. Merops ornatus, Lalage suerii and Coracina novaehollandiae, considered in the literature to be wintering migrants, are also shown to be breeding residents. Breeding records for 462 species were analyzed. Most breeding of insectivores and mixed-feeders occurs in the Austral spring during the dry season and ends before the onset of heavy rains. Granivores breed in the late wet season. The few records for frugivores indicate a wet season peak.