Uncommon vireo in open deciduous woodland, favoring willows and alders. On migration, usually found in mixed flocks. Small size, soft expression, and fairly small bill can make it look warbler-like (see TEWA). Song easy to pass off as REVI but slightly sweeter. ID: Small with average proportions and evenly-domed head. In spring, tends to be duller with yellow strongest on central breast. In fall, upperparts greener and underparts more uniformly brighter yellow, though never brighter on breast sides than center. Dark primary coverts contrast with paler greater coverts. Dark eyeline extends to base of small bill.