This species typically prefers more wooded breeding habitats than does the mountain bluebird, though co-occurs widely with it. Polytypic. Length 7".

The western bluebird is shorter-winged and shorter-tailed than the mountain bluebird, producing similar wing/tail ratio, and different primary projection/tertial length ratio. Male: rich blue on head (including chin and throat), wings, and tail. Female: grayer head and back; paler orange underneath; at least partial whitish eye ring. Juvenile: similar to the eastern bluebird, being strongly spotted dark on underparts, whitish on upperparts and wing coverts, but with tertials fringed grayish; immatures distinguishable by browner primary coverts, duller upperparts. Flight is level and typical of thrushes. Migrates diurnally in flocks, occasionally with mountain bluebirds, from which they can be distinguished