Survey and monitoring of black petrels on Great Barrier Island 2002/03

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Summary

During the 2002/03 breeding season for black petrel (Procellaria parkinsoni),320 burrows were identified and were intensively monitored over summer; however only 318 burrows were included in the long-term study. There were199 burrows used by breeding pairs, 81 by non-breeding adults and the remaining 38 were empty.

Several factors affecting the black petrel breeding success were noted. By 15 May 2003, 59 chicks were still present in the study burrows and another 78 had already fledged, corresponding to a breeding success of 69%. Nine census grids were also monitored and a total of 132 burrows were located within the grids, with 78 burrows being used for breeding.

An extra seven burrows were found in the grids, three of which were newly dug this season and four, previously investigated, were now active. Extrapolating from these grid burrows, we estimate that the black petrel population around the peak of Mt Hobson ranged from 3155 to 4887 birds.

There were 18 chicks from earlier breeding seasons recaptured within the Mt Hobson colony area this season. Of these, three have paired and bred (one successfully). ‘Dummy’ satellite transmitters were placed on 30 adults, each incubating an egg. All transmitters were recovered. We colour-marked 31 adults with fluorescent spray paint. No sightings of these birds at sea were reported.