While the sexes of this species differ drastically, both are distinctive and easy to identify in all seasons. Adult Male: Dark blue upperparts with a white patch at the base of the primaries. Birds from the Appalachian population show some black on the crown and back. Face, upper throat, and sides are black. Underparts are bright white. In flight, white spots are visible on the outer tail feathers. Adult Female: Olive-gray upperparts with a small white patch at the base of the primaries. Underparts are dull yellowish buff. Face shows a thin whitish supercilium, pale crescent below the eye, and a grayish cheek patch. Juveniles are similar to adults. Young males show a greenish cast on the upperparts. Young females may lack the white patch at the base of the primaries.

Length: 13 (cm) Wingspan: 18 (cm)

Voice:

Song is a series of buzzy notes, ending with a longer, higher note: zhee zhee zhee zhee zeeee? Song is usually slower and harsher than similar song of Cerulean Warbler. Alternate song ends with downward inflection. Call is a flat tuk.

Habitat:

Breeds in mature deciduous and mixed forests with thick understory. Uses a variety of wooded habitats in migration.

Behavior:

Often found within a few feet of the ground.

Feeding:

In summer, gleans insects from foliage, usually at lower to mid levels of vegetation. Winter diet includes berries in addition to invertebrates.