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Black petrel survey 2005/06 (PDF, 1,053K)

Summary

This report is part of a long-term study of the black petrel (Procellaria parkinsoni) on Great Barrier Island (Aotea Island). During the 2005/06 breeding season, 366 study burrows within the 35-ha study site near Mount Hobson were checked and intensively monitored. Breeding pairs used 257 burrows, non-breeding adults used 43 burrows, and the remaining 66 burrows were non-occupied.

By 5 May 2006, 164 chicks were still present in the study burrows and 8 others were presumed to have already fledged, corresponding to a breeding success of 67%. Nine census grids were monitored within the study site and contained 148 of the inspected burrows, with 93 burrows being used for breeding. One new burrow (not recorded in previous years) was found. Twenty-four chicks from earlier breeding seasons were recaptured within the study site. Twenty-five percent of the random transects established within the study site in 2004/05 were
re-surveyed.

These results and previous data were analysed to clarify habitat grade characteristics and burrow density within the study site. This clearly identified zones of different burrow density (no burrows, low, medium and high burrow density areas). Based on these density ranges and incorporating habitat characteristics, the study area was stratified, and its black petrel population estimated to be in the range of 3164–4066 birds.

Eleven geo-locator data-loggers were also deployed on breeding black petrels. These indicated that the foraging range for the black petrels was highly variable, with no apparent differences between the sexes. Seven birds foraged around the North Island of New Zealand, particularly along the continental shelf edges or seamounts. Four birds travelled near the Chatham Rise, two birds travelled further north towards Fiji, four birds travelled towards the eastern Australian coast and one bird travelled around the southern tip of the South Island of New Zealand.

These preliminary results show how important accurate foraging and distribution information is for determining national and international fisheries risk for the black petrel. It is recommended that further tracking work is undertaken for this species.