Bird Populations in Successional Forests of Mountain Ash Eucalyptus regnans in Central Victoria

Abstract

Bird populations were estimated from 1977 to 1979 by mapping territories and by an "area search" method in stands of differing age (regenerating after wildfire or harvesting eucalypts) in the Victorian Central Highlands mainly near Toolangi. The aims were to assess effects of harvesting (followed by burning and artificial regeneration) and provide data on populations and ecology of birds inhabiting this distinctive forest type. Mountain Ash forests grow in high rainfall areas and the trees can reach heights of 100 m; they usually grow as even-aged stands and 79% of Mountain Ash forests in the Central Highlands has regenerated after severe fires in 1939.

About 65 species of birds were found to be regular inhabitants of Mountain Ash forests and associated plant com- munities. All except the Pink Robin breed also in foothill gullies. Several species that are common in drier foothill forests, were absent from Mountain Ash forests. The commonest species were those that feed in the dense shrub layer or from damp ground below. Some insectivorous birds that were abundant in summer (e.g. Golden Whistler Pachycephala pectoralis, Grey Fantail Rhipldura fuliginosa) left Mountain Ash forests for the winter. Winter food sources were limited and the most important were blossoms of Mountain Correa Correa lawrenclana, invertebrates in damp leaf litter, and invertebrates or carbohydrate exudates from hanging bark of Mountain Ash or branches and trunks of Silver Wattle Acacia dealbata. Habitats and interactions between various bird species are described.

Bird population densities were low in the first three years after harvesting but some species were confined to open stands of this age. Other forest birds returned rapidly as eucalypts and understorey species regenerated. Populations were as high in 39-year-old regrowth as in older stands though some species (mainly those that need tree hollows for nesting) were more common in older forest. Implications for management are discussed.