Population and Habitat Selection of the Noisy Scrub-bird, Atrichornis clamosus, 1962-83

Abstract

The noisy scrub-bird Atrichornis clamosus at Two Peoples Bay was censused, the number of singing males being used as the population index. Incomplete data from 1962 to 1968 suggest that the number of males varied from 40 to 50 during this period. The first rigorous census found 45 males in 1970 and this number increased to 138 in 1983. The most likely reason for this increase is the absence of fire from the area since 1970. Since 1975 the population has expanded out of its headland stronghold to the south-west of Two Peoples Bay to form a subpopulation around Lake Gardner that is well separated from the headland population by roads, firebreaks and a strip of control burnt blocks. The growth of this subpopulation has added a further safeguard to the population. Observations on the vegetation formations (heath, thicket, low forest A and low forest B) used by male noisy scrub-birds on the headland indicate that most of the best habitat (low forest B) is occupied and that an increasing number of males are occupying suboptimal habitat (heath and thicket). There is sufficiently good habitat to the west of Lake Gardner to allow at least 30 additional males to live in the area.