克島圓尾穴鳥 Pterodroma neglecta

Fairly large and thickset petrel of offshore tropical and subtropical waters across the Pacific; not seen from mainland. Plumage is highly variable (white-bodied and white-headed, dark-headed, or wholly dark), but all types have a white flash on the wingtip, including diagnostic white feather shafts on upperwing, which enhance this petrel’s resemblance to jaegers and skuas. Indeed, sometimes Kermadec Petrels chase and pirate other petrels, as do jaegers and skuas. Herald Petrel is very similar, but is smaller and slimmer with a longer and more tapered tail, and lacks white shafts on upperwings.