Species interactions between the White-winged Chough and Australian Magpie in a fragmented landscape

Abstract

We studied the ecology of the White-winged Chough and its interaction with the Australian Magpie on the Central Tablelands of New South Wales, Australia, over seven months. Both species are ground foragers and significant prey overlap was assumed. Invertebrate biomass as an index of habitat quality, showed grasslands to be the most valuable of the three habitats, followed by edge and forest habitats. Magpie territories were positioned around the grasslands and therefore were of higher quality than chough territories which were dominated by forest and edge. Magpies actively exclude chough groups from most of the highly valuable grassland habitat, through repeated and persistent attacks. Despite an apparently effective defensive strategy we concluded that the chough was largely excluded from the most attractive habitat in our study area by the magpie. This study highlights the implications of species interactions on the responses of individual species to habitat fragmentation across a landscape. Implications of this study for the validity of present vertebrate habitat models, which ignore the dynamic nature of population behaviour are discussed.