Population size and breeding success of Gould’s Petrel Pterodroma leucoptera leucoptera on Cabbage Tree Island, New South Wales: 1996-97 to 2005-06

Gould’s Petrel Pterodroma leucoptera leucoptera breeds only on Cabbage Tree and Boondelbah islands at the entrance to Port Stephens, New South Wales. Annual surveys to estimate population size and reproductive output of the colony on Cabbage Tree Island, where more than 96 per cent of the population nest, have been conducted since 1989–90. In the period 1989–90 to 1991–92, the number of breeding birds was small (186–252 pairs), breeding success was poor (16.5–19.8%) and few fledglings (31–48 individuals) were produced each year. Recovery actions to reduce the mortality of breeding adults and fledglings on Cabbage Tree Island began during the 1992–93 breeding season. The removal of island-borne threats resulted in an immediate two-fold increase in the number of pairs incubating eggs. Breeding success also increased, and since 1993–94 has averaged 49.4 per cent. The breeding population has steadily increased (by about 37 pairs per annum) and now numbers 800–1000 pairs. The number of fledglings has also increased (by about 18 per annum) and annual production now exceeds 400 individuals. As a result of the sustained improvement in population size and breeding success, a change in the species’ conservation status from endangered to vulnerable is warranted.

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