10 - 11 cm. 7 g. Bill slender, pointed and black, lower mandible clearer. Area between the bill and eyes black. Two white bars on wings. Vent and feathers that cover undertail white. Legs slender, pale yellow. Plumage varies depending on the geographic region. Males and females are different. Male: Head and upperparts bluish-gray. Throat and underparts yellow. Flanks cinnamon. Individuals from north of the Isthmus: A black mask. An olive patch on back. Has orange tinges on chest. Two white spots on each side of the tail. Individuals from Islas Marias: Flanks darker. Individuals from Socorro island: Lacks of black mask. Head with olive tinges. Individuals from Chiapas: Mask diffuse blackish. Dull olive-colored patch on back. Bars reduced on wings, only evident as white spots. Two white spots on each side of the tail. Female: Plumage duller than the male and without a black mask. In the north of the Isthmus, with olive-colored shades on the head. In Socorro Island and Chiapas are similar to males. The juveniles have the head and upperparts grayish, with olive overtones on back, throat and underparts white with pale green shades on chest.