Which birds are useful bioindicators of mining and grazing impacts in aridSouth Australia?

The usefulness of birds as bioindicators of mining and pastoral impacts at Olympic Dam in arid South Australia was assessed. Bioindicators were consid ered to be most important for detecting early signs of landscape-scale impa cts. Therefore, bird populations were monitored near but not in the immedia te vicinity of a recently established mine and processing plant and near a number of pastoral waterpoints, most of which had only been grazed for 4 ye ars at the commencement of this study. The abundance of ail bird species re corded on fixed transects in mining, pastoral, and control regions from 199 2-1995 were compared in generalized linear models in conjunction with the e ffects of a range of habitat and disturbance variables. Significant annual variations in population size of most species were evide nt with greater abundance of most species in wet years. Habitat variables, particularly vegetation structure. were also an important determinant of th e abundance of most bird species and tended to mask the impacts of the land use under investigation. Several bird species had benefited from the provi sion of permanent water at mining and pastoral sites. Other species utilize d increased nesting or feeding opportunities associated with the mining ope ration and increased food supply at the pastoral sites. Crested bellbirds a nd mixed-feeding flocks of small insectivorous birds were apparently disadv antaged by mining and hence may be useful bioindicators of mining impacts. No bird species or community parameters were identified which could serve a s useful early warning bioindicators of pastoral impacts.