Survey and monitoring of black petrels on Great Barrier Island 2000/01

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Summary

The black petrel (Procellaria parkinsoni) is an endemic seabird that breeds on Little and Great Barrier Islands, New Zealand. The main breeding area on Great Barrier Island is around the highest point, Mount Hobson.

During the 2000/01 breeding season, 258 burrows were identified and were intensively monitored over summer. Only 255 burrows were included in the study and of these 168 were used by breeding pairs, 75 by non-breeding adults and the remaining 12 were empty. A range of factors affecting the black petrel breeding success was noted.

In April, 129 chicks were present in the study burrows. In early May one chick was killed by a feral cat. This corresponds to a breeding success of 76%. Nine census grids were monitored. A total of 122 burrows were located within the grids and of these, 84 burrows were being used for breeding.

The number of burrows used for breeding within the study grids has increased in all grids that have been monitored for more than one year. An additional five burrows have been dug in four of the nine grids. Extrapolating from these grid burrows we estimate that the black petrel population around the peak of Mount Hobson consists of 1583 breeding pairs. A bird banded in the 1995/96 season as a chick was recaptured this season in the same burrow as last season and it successfully raised a chick. This suggests that the earliest age of first breeding is five years.