Survey and monitoring of black petrels on Great Barrier Island 2004/05

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Summary

This report is part of an ongoing long-term study of the black petrel (Procellaria parkinsoni) on Great Barrier Island (Aotea Island), New Zealand, which was begun during the 1995/96 breeding season. During the 2004/05 breeding season (November to June), 362 study burrows were checked and intensively monitored. Of these, 226 were used by breeding pairs, 84 by non-breeding adults and the remaining 52 burrows were empty. By 29 April 2005, 175 chicks were still present in the study burrows and six others were presumed to have already fledged, corresponding to a breeding success of 80%.

Nine census grids were monitored within the study area and accounted for 147 of the inspected burrows; 82 of these burrows were used for breeding. In addition to those burrows known from previous breeding seasons, a further 12 burrows were found in the grids. Twenty-four chicks from earlier breeding seasons were recaptured within the Mount Hobson colony area. Twenty-six random transects were also established within the 35-ha study site, and areas of high and low petrel burrow density and nonpetrel habitat were identified.

The study area was stratified according to these habitat types and the Mount Hobson black petrel population was estimated to be in the range of 3551-5021 birds.