Trends in the activity levels of forest-dwelling vertebrate fauna against a background of intensive baiting for foxes

The relative activity of ground-dwelling vertebrates was monitored using tracks in sand plots for 10 consecutive years across three nearby study areas in south-eastern mainland Australia. Two areas were subject to intensive 1080 poison baiting for foxes, while one unbaited area acted as a control. At the two 1080 baited sites there was a demonstrable decline in the reporting rate of fox tracks, while that of feral cats also declined concomitantly. In contrast, the reporting rate of wild dog tracks did not change. At the unbaited site the reporting rate of wild dog tracks increased slightly, while that of foxes remained stable and that of feral cats declined slightly. Prevailing ecological theory would suggest that in systems where larger predators are reduced in activity or abundance, smaller predators should increase. This was not the case in our work. Instead, while the larger sized fox has decreased at baited sites, the smaller sized cat has declined at a regional scale, in all likelihood against a backdrop of long-term drought and diminished prey resources. Among the native omnivorous mammals that ordinarily fall prey to foxes, bandicoots, brushtail possums and lyrebirds increased in activity against a background of diminishing fox activity, although these effects were not uniform at both baited sites. In contrast, at the study area where foxes were not baited, the activity of bandicoots, brushtail possums and lyrebirds either did not change or diminished. Trends in the activity levels of these animals, particularly bandicoots, may have been moderated in part by prevailing rainfall conditions. Otherwise, habitat complexity may also help regulate activity patterns. Land managers concerned with preserving and enhancing biodiversity need to not only focus on the baiting of introduced predators but also be mindful of habitat condition and the effects of climate. (C) 2010 Elsevier B.V. All rights reserved.