The Western Bluebird (Sialia mexicana) is a small thrush, approximately 15 cm (5.9 in) to 18 cm (7.1 in) in length...Adult males are bright blue on top and on the throat with an orange breast and sides, a brownish patch on back, and a gray belly and undertail coverts. Adult females have a duller blue body, wings, and tail than the male, a gray throat, dull orange breast, and a gray belly and undertail coverts...They are sometimes confused with other bluebirds, however they can be distinguished without difficulty. The Western Bluebird has a blue (male) or gray (female) throat, the Eastern Bluebird has an orange throat, and the Mountain Bluebird lacks orange color anywhere on its body.