On each island the number of pre-fledging chicks present and their spatial distribution was recorded, with exception of Enderby and Dundas where a single person conducted exhaustive searches of all available habitat.
All vegetation classes were treated as available habitat, with the exception of the interior of southern rata dominated forest interiors.Hand-held GPS units were used to record all line transect surveys and the locations of all chicks detected.
Nests that showed clear signs of having failed in the current breeding season were also counted. Caution was used to avoid counting old nests and 'play' nests constructed by non-breeding birds.
Surveys counted 216 Northern giant petrel chicks on eight of the 15 islands visited in December 2015 and January 2016. Enderby Island had the largest breeding population, with 96 chicks counted. This represents a large increase in the population on Enderby Island compared to the only historic comprehensive count, in 1988, when just two Northern giant petrel chicks were counted.
The second and third largest populations were on Disappointment (38, 18%) and Dundas Islands.No breeding Northern giant petrels were reported from Rose and Friday Islands, where the species has previously been recorded breeding. Chicks were counted at two locations previously not reported to support breeding Northern giant petrels, at French's Island and Crozier Point on the main Auckland Island.
Fourteen failed nests were recorded, eleven of which were on Enderby.
Applying crude correction factors based on breeding success at the nearest Northern giant petrel colony where these data have been collected, Macquarie Island, we estimate the breeding population in the Auckland Islands 2015-2016 to be approximately 340 (range 310-390) breeding pairs.
Parker, G.C., Muller, C.G., Rexer-Huber, K. 2016. Northern giant petrel Macronectes halli breeding population survey, Auckland Islands, December 2015 – February 2016. Report prepared by Parker Conservation for the New Zealand Department of Conservation, Wellington. 16p.