Scientists theorized that birds look blue for the same reason the sky looks ... set of fine blue feathers signifies a healthy, well-fed male, advertising his good genes to potential mates.

The bill is thin and pale gray. Breeding male: blue-gray above, including most of head and back. Crown has a black line at the forecrown that extends along the sides of crown; white eye ring ...

Polytypic. Length 7" (17.5 cm). Male: bright blue above, with orange throat, ear surround, chest, sides, and flanks. Female: differs in that upperparts are less blue (often grayish); has partial ...