A bird community of New Guinean Lowland Rainforest. 3. Vertical Distribution of the Avifauna

Abstract

The vertical distribution of a bird community in 2.5 ha of rainforest at Brown River, Papua New Guinea, was examined. The vertical distribution of 100 species, and of the density and biomass of the whole bird community, is shown. Distribution of biomass conformed generally to the vegetation density. Relatively small numbers of large birds, chiefly frugivores, occupied the higher strata while larger numbers of small birds, chiefly insectivores, occupied the lower. Few small insectivores occurred in the main canopy, their place being taken by facultative insectivores, both frugivorous and nectarivorous. With certain groups or species, e.g. sallying insectivores, the kingfisher Tanysiptera galatea, and fruit-dove Ptilinopus magnificus, there were seasonal changes in vertical distribution. Many species fed higher in the early morning and moved down during the morning as temperatures rose. The presence of secondary vegetation and mixed-species flocks, and behaviour such as display, nesting, bathing and drinking all influenced the height frequented. In some species the sexes were observed at different heights.