SUMMARYBELL, H.L. 1984. The importance of foothill forest in the diversity of rainforest birds in New Guinea. Emu 84: 225–235.The avifaunas of a lowland and a foothill rainforest near Port Moresby, Papua New Guinea, are compared. The foothill forest had the richer avifauna. It had many more forest species, but fewer species of secondary vegetation than did the lowland forest, and additionally a few species of mountain torrents. The foothill forest had as full a range of herbivorous species as did the lowland forest but in addition had more small species of both arboreal and terrestrial insectivorous passerines. Nine lowland species were replaced by closely-related species in the foothills. It is postulated that foothill forest is a distinct habitat in New Guinea, albeit small in total area, which has been largely overlooked, and that it posseses a distinct avifauna. The richness of this avifauna is attributable to the presence of both abundantly fruiting trees, characteristic of lowland forest, and also montane-type small-leaved trees which afford niches for small insectivores, plus a more dense leaf-litter than in lowland forest.