The Pacific Gull, captured at Cape Leuuwin (the furthest southwesterly point of Australia), is of the sub-species Larus pacificus georgii distinct from the nominate race L. p pacificus which is restricted to the east of the continent.
Pacific Gull - Australia
Black-billed Gull - New Zealand
The Black-billed Gull has to be one of the best looking in the Laridae family, but I can't for the life of me see the distinction between the other two. Suggest to a Kiwi birder that they are one and the same species, you'll soon be convinced otherwise.
Red-billed Gull - New Zealand