Merlin

Merlin (Falco columbarius) is a compact, fast-flying northern falcon with pointed wings; males are generally blue-grey above while females and young are brown. 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 pursues small birds in rapid level flight over tundra, moorland, coasts and open country, with many populations moving south from northern breeding areas for winter. 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).