red-rumped swallow
Ornithological name for Hirundo daurica. Used in field guides and birdwatching contexts.
The red-rumped swallow is seen as a passage migrant in Japan.
striated swallow
Ornithological name for Hirundo striolata. Less common in Japan; mainly a South and Southeast Asian species.
The striated swallow is sometimes confused with the larger red-rumped swallow.
Compound of 腰 (koshi, 'lower back') + 赤 (aka, 'red') + 燕 (tsubame, 'swallow'), referring to the reddish rump patch characteristic of these swallow species.