Cook's Petrel Pterodroma cookii and Pycroft's Petrel Pterodroma pycrofti both occur in the Hauraki Gulf and can be very difficult to distinguish. Cook's is shorter-tailed and longer-billed than Pycroft's and has a less prominent eye-patch. The partial shawl on this individual appears rather intermediate between the extent traditionally associated with each species (Pycroft's showing a distinct shawl and Cook's supposedly lacking one).

© A. R. Dean