Mortality of Adult Gould's Petrels Pterodroma leucoptera leucoptera at the Nesting Site on Cabbage Tree Island, New South Wales

Abstract

The remains of adult Gould's Petrels Pterodroma leucoptera leucoptera were recovered from the nesting site on Cabbage Tree Island, New South Wales. Entanglement in the sticky fruits of the Bird-lime Tree Pisonia urnbellifera was identified as a major cause of mortality. Removal of P. urnbellifera eliminated one cause of death but mortality of adult petrels continued at an unsustainable rate as the result of predation by the Pied Currawong Strepera graculina. Hunting and feeding behaviour of the Pied Currawongs were observed, including holding fast a petrel carcass while ripping flesh from the skeleton. Mortality of Gould's Petrels subsided immediately following the destruction of Pied Currawong nests and nestlings. Subsequent recurrences of predation were correlated with additional nesting attempts by Pied Currawongs but declined substantially following the instigation of a control program for Pied Currawongs on Cabbage Tree Island. Pied Currawongs take the eggs and nestlings of many species of birds, but losses of nesting adults or the decline of a seabird have not been attributed previously to currawong predation.