Striking warbler with vastly different male and female plumages. Breeding males unique deep blue above with black face and sides, and white belly. Females are plain brownish-olive with dingy buffy underparts and subtle face pattern. Look for small white patch on the wing. Forages for insects in lower and mid-stories of mature forest, favoring hills with thick undergrowth. Found in nearly any wooded or shrubby habitat during migration.