Western House Martin

Western House Martin (Delichon urbicum) is a compact swallow with glossy blue-black upperparts, a white rump, pure white underparts and a short forked 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 takes insects continuously in flight over open country and towns, constructs an enclosed mud nest beneath eaves or cliffs and migrates from western Eurasian breeding areas to Africa and south-western 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).