コシアカツバメ Cecropis daurica

Brightly-colored swallow with a deeply forked tail, pale orangish rump, black squared-off undertail coverts, and an incomplete orange collar. The underparts are always streaked, though there is geographical variation, with streaks ranging from fine and sparse to thick and heavy. Juveniles average paler and lack extensive orangish tones; may resemble house-martins but note deeply forked tail. Builds mud nests on mountains, cliffs, and on human structures. Forages over open areas. Frequently gives a short, sparrow-like “twi’wit.” Usually separated from European Red-rumped Swallow by range, but in case of any overlap, should be separated by much heavier streaking on underparts.