Historical changes in the bird fauna at Coomooboolaroo, northeastern Australia, from the early years of pastoral settlement (1873) to 1999

Abstract

Across most of northern Australia, the historical record is generally insufficient to serve as a baseline for interpreting the impacts of European settlement on fauna. A notable exception is the pastoral property Coomoobolaroo (454 km 2) in central Queensland, where the ornithologist Charles Barnard maintained a detailed record of bird fauna from 1873 to 1933. We re-surveyed the property in 1999, and collated other information on its current avifauna, giving 242 species in total recorded over the period 1873–1999 (of which we had sufficient information to ascribe trends to 200 species). The bird fauna of Coomooboolaroo has undergone substantial change, across both of the periods 1873–1933 and 1934–1999. From 1873 to 1999, 45% of species declined or were lost from the property, compared with 13% of species that either colonised the property or increased. Most of the latter are widespread species or those known to benefit from clearing and land development. This extent of change appears at least as high as that reported for most comparable studies elsewhere in Australia, despite these being conducted at sites that have been subjected to superficially greater environmental degradation. The greatest rates of loss occurred among birds associated with softwood scrub (dry rainforest), grasslands and swamps. Smaller species were more susceptible to decline, but change in status was not significantly associated with foraging style nor different between residents and migrants. Many of the species that have declined at Coomooboolaroo have also declined in many other geographic regions, habitats and land-uses. Change in status at this property can be attributed to diverse factors, including changes in predation pressures; environmental change due to altered fire regimes and/or grazing by livestock; and vegetation clearance at both property and regional scales. The multiplicity and complex interrelationships of such factors renders it difficult to predict assemblage-level change.