Adult male.—Above deep blue, the foreback in part chestnut; throat blue, breast and sides chestnut, the belly bluish grayish.
Adult Female.—Above grayish blue, chestnut of back faintly indicated, throat grayish blue, breast rusty, paler than in male, belly grayish.
Range.—Pacific coast region from northern Lower California north to British Columbia, east to Nevada.
2a. Chestnut-Backed Bluebird (Sialia mexicana anabelae).
Similar to the Western Bluebird, but foreback wholly chestnut.
Range.—Rocky Mountain region from Mexico north to Wyoming.
2b. San Pedro Bluebird (Sialia mexicana anabelae).
Similar to the Western Bluebird, but back with less chestnut.
Range.—San Pedro Martir mountains, Lower California.
3. Mountain Bluebird (Sialia arctica).