White-necked Petrel

White-necked Petrel (Pterodroma cervicalis) is a large gadfly petrel with a white neck and underparts, dark cap and bold dark M-shaped marking across the upperwings. Body shape, bill structure, plumage pattern and voice provide the strongest field characters. Age, sex and season may alter its appearance, so identification should combine several features and careful direct field comparisons with similar species in the same habitat (Wikipedia, general species account).

It crosses broad areas of the Pacific for squid and fish and breeds in burrows on remote oceanic islands, approaching colonies mainly at night. Its movements and social behaviour vary through the year, with breeding birds generally more dispersed and non-breeding birds gathering where food is concentrated. Japanese records place it within the country's documented avifauna as a resident, migrant or visitor (Wikipedia, general species account; Wildlife of Japan occurrence records).