Does adjacent land use affect predation of artificial shrub-nests near eucalypt forest edges?

Abstract

Edge-related increases in nest-predation levels were tested using artificial nests placed within eucalypt forest remnants at distances of 0, 60, and 235 m from edges adjacent to areas of urban, pasture, and Pinus plantation. There were eight replicate sites of each edge type, scattered widely across a 30 000-km² study region. Open-cup nests containing one quail egg and two plasticine eggs were placed in shrubs and exposed for 6 days. When predation of the quail egg was used to calculate predation levels, predation varied significantly with edge type but not distance to the edge, due to relatively low levels within sites bordering Pinus plantations. When predation of any egg was used to calculate predation levels, predation was not significantly affected by edge type or distance to the edge. Predation levels within eight independent forest interior transects distributed across the study region, and located 500-800 m from the nearest edge, were similar to those within transects 0 m from edges. Birds were the most important class of predator within all combinations of site type and distance to edge, and accounted for 92% of identified predation overall. These results do not support the existence of edge-related increases in predation of shrub nests within subtropical eucalypt forests.