Western Yellow Wagtail

Western Yellow Wagtail (Motacilla flava) is a slim, short-tailed wagtail with olive upperparts and yellow underparts, although head patterns vary greatly among subspecies. 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 breeds in damp grasslands across temperate Europe and Asia, picking insects while walking among livestock or wet vegetation, and most populations migrate to Africa or southern Asia. 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).