Белопоясничная ласточка Tachycineta leucorrhoa

A small swallow usually seen flying low over open and semiopen areas near water. Glossy blue-green above and white below. Note the white forehead and rump. Similar to White-winged Swallow, but lacks white in wings (although juvenile White-winged can show limited white). Told from Chilean Swallow by the presence of a white forehead.