Tuatara: Volume 21, Issues 1 and 2 (New Zealand Albatrosses and Petrels: an Identification Guide)
Chatham Island Petrel (P. h. axillaris)
Black-winged Petrel (P. h. nigripennis)
The two subspecies are easily distinguished from each other at sea and are therefore dealt with separately below. The nominate race page 45 breeds in the North Pacific and has not been recorded from the New Zealand area.