Adult males are deep blue on the head, back, and tail with bright rusty breast, shoulders, and back. The rusty back sets this bluebird apart from the blue-backed eastern and mountain bluebirds. Female westerns are paler overall with a white eye-ring on a grayish face.
Song is a soft warble: tew, tew, tewoo. Call is tew!
Open woods, farms, and orchards in spring and summer. In winter, may move to other habitats at lower elevations, including desert mesquite and areas containing berry-bearing plants such as mistletoe and juniper.
Western bluebirds will use nest boxes placed in appropriate open habitat. They will visit feeders for suet and suet dough, mealworms, and fruit pieces and gardens for winter fruits and berries. They will also visit water features to drink and bathe.