swallow-tanager, (Tersina viridis), bird of northern South America, the sole member of the subfamily Tersininae, family Emberizidae; some authors give it family rank (Tersinidae). About 15 cm (6 inches) long, it resembles a tanager with long wings and a swallowlike bill. The male is light blue, with black markings; the female is mostly green. Swallow-tanagers catch insects on the wing and also eat large fruits, ejecting the seeds and filling their throat pouches with the pulp. They breed in tree holes, sandbanks, and wall crevices.