The Scarlet Tanager (Piranga olivacea) is a medium-sized American songbird. Until recently placed in the tanager family (Thraupidae), it and other members of its genus are now classified as belonging the cardinal family (Cardinalidae). The species' plumage and vocalizations are similar to other members of the cardinal family, although the Piranga species lacks the thick conical bill (well suited for seed-eating in addition to insectivory) that many "cardinals" possess. The Scarlet Tanager, a mid-sized passerine, is marginally the smallest of the four species of Piranga that breed north of the Mexican border. It can weigh from 23.5 to 38 g (0.83 to 1.34 oz), with an average of 25 g (0.88 oz) during breeding and an average of 35 g (1.2 oz) at the beginning of migration. Scarlet Tanagers can range in length from 16 to 19 cm (6.3 to 7.5 in) in length and from 25 to 30 cm (9.8 to 11.8 in) in wingspan. Adults of both sexes have pale horn-colored, fairly stout and smooth-textured bills. Adult males are crimson-red with black wings and tail. His famous red coloration is more intense and deeply red than the males of two occasionally co-existing relatives, the Northern Cardinal and the Summer Tanager, both which lack the black wings of the Scarlet and instead are an olive or brownish hued red on their wings. Females, on the other hand, are yellowish on the underparts and olive on top, with yellow-olive-toned wings and tail. The adult male's winter plumage is similar to the female's, but the wings and tail remain darker. Young males briefly show a more complex variegated plumage intermediate between adult males and females. The somewhat confusing specific epithet olivacea ("the olive-colored one") was based on a female or immature specimen rather than erythromelas ("the red-and-black one"), which authors attempted to ascribe to the species throughout the 19th century (older scientific names always takes precedence, however).
Female, immature and non-breeding males must be distinguished from the same ages and sexes in Summer Tanagers, which are more brownish overall, and Western Tanagers, which always have bold white bars and more yellowish undersides than Scarlet Tanagers.The song of the Scarlet Tanager sounds somewhat like a hoarser version of the American Robin's song and only scarcely dissimilar from the songs of the Summer and Western Tanagers. The call of the Scarlet Tanager is an immediately distinctive chip-burr or chip-churr, which is very different from the pit-i-tuck of the Summer Tanager and the softer, rolled pri-tic or prit-i-tic of Western Tanager.