Christmas Shearwater

Christmas Shearwater (Puffinus nativitatis) is a medium-sized shearwater with uniformly dark brown plumage, a dark bill and relatively short rounded tail. 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 ranges across the central tropical Pacific, feeds on fish and squid and nests on oceanic islands in ground hollows, beneath vegetation or in shallow burrows. 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).