Swallow tanager

The swallow tanager (Tersina viridis) is a species of Neotropic bird in the family Thraupidae, the tanagers and allies. It occurs regularly in Panama, on Trinidad, and in every mainland South American country except Chile and Uruguay. It has occurred as a vagrant in those two countries and on Tobago and Bonaire and there are unconfirmed reports from Curaçao.

The swallow tanager is 14 to 15 centimetres (5.5 to 5.9 in) long and weighs 26 to 35 g (0.92 to 1.2 oz). It has a broad flat bill, a short tail, and short legs. The species is strongly sexually dimorphic. Adult males of the nominate subspecies T. v. viridis have a mostly bright turquoise-blue head with a triangular black "mask" from the base of the forehead to behind the eye and including the throat. Their upperparts are bright turquoise-blue. Their wings' primary coverts are black with thin turquoise-blue edges, their primaries are turquoise-blue with black tips, their secondaries all turquoise-blue, and their tertials black with turquoise edges. Their tail feathers are black with turquoise edges and grayish undersides. The center of their lower breast, their belly, and their undertail coverts are white. The rest of their underparts are turquoise-blue with coarse black barring on the flanks. Adult females are mostly bright grass-green. Their mask is dingy gray with dusky brown mottling. Their wing coverts are green and their flight feathers black with varying widths of green edging. The center of their lower breast, their belly, and their undertail coverts are pale yellow and their sides and flanks are darker yellow with coarse green barring. Subspecies T. v. occidentalis is smaller than the nominate but has essentially the same plumage. Males of T. v. grisescens are like the nominate; females are grayish green instead of grass-green. Both sexes of all subspecies have a reddish brown iris, a black bill, and dusky horn-gray legs and feet.