Marbled Murrelet

Marbled Murrelet (Brachyramphus marmoratus) is a small North Pacific auk mottled brown in breeding plumage and black-and-white in winter. 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 dives for fish near shore but flies inland to place its single egg on a mossy old-growth tree branch. 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).