The blue-gray gnatcatcher or blue-grey gnatcatcher (Polioptila caerulea) is a very small songbird, 10–13 cm (3.9–5.1 in) in length and weighing only 5–7 g (0.18–0.25 oz). Adult males are blue-gray on the upperparts with white underparts, have a slender dark bill, and a long black tail edged in white. Females are less blue, while juveniles are greenish-gray. Both sexes have a white eye ring. (Wikipedia)