Avian nest predation in modified and natural habitats in troprical Queensland: an exeperimental study.

Abstract

Predation on artificial avian ground-nests was assessed from March to December 1991 in rainforest and nearby modified habitats in tropical Queensland. Data from 610 experimental nests were used to determine relative predation intensity in five types of habitat or microhabitat. Nest predators were identified with live-traps, with baited grease-plates and by regular observations of 380 additional nests. Predation intensity was patchy but often heavy in forested habitats (rainforest interiors, secondary forest, rainforest-pasture edges, and a rainforest-secondary forest edge) and negligible in adjoining cattle pastures. Forest edges exhibited no obvious edge-interior gradients in predation intensity. Most predation occurred at night in rainforest (88%) and secondary forest (61%), and patterns of egg damage suggested that mammals were responsible for most (>71%) nest predation. A combined nest-predation and live-trapping experiment on six study plots revealed that the abundance of white-tailed rats (Uromys caudimaculatus) was a highly effective predictor of local predation intensity (F=30.15, r*2=0.85, P=0.004). One of Australia's largest rodents, the white-tailed rat may be a key opportunistic predator of some bird nests in north Queensland rainforest.