Pied Currawongs and the decline of native birds

Predation pressure by Pied Currawongs, Strepera graculina, has been implica ted as a principal factor in the decline of native bush bird populations. W e review the available literature, analyse the types of avian species repor ted as being preyed on by currawongs, and examine whether this evidence sug gests that increased currawong predation is limiting bird populations. Virt ually all species reported as prey could be classified as 'introduced/commo n' and 'native/common'. The results suggest that predation is greatest on i ntroduced/common species, and less than expected on native/common species a nd native/rare species. Currawongs seem to be generalist predators and do n ot appear to target any particular size or age range of avian prey. Nonethe less, it is not clear that currawongs are primarily responsible for predati on on both nests and adults in all populations of small native birds, nor a re the possible compensatory effects of density-dependent population growth rates in small Australian passerines well understood. It is also difficult to separate the effects of predation (increased mortality, possible reduce d recruitment) from the effects of gross habitat change (degradation, fragm entation, changes in species composition and/or abundance). We discuss the limitations of some previous studies on currawong predation, and suggest po ssible directions for future research.