Range.--Western United States; breeds from Mexico north to Kansas, southern Nebraska, Colorado, and northern California; winters in Mexico and Central America.
=598. Indigo Bunting= (_Cyanospiza cyanea_). L. 5.4. No white wing-bars. _Ad._ [Male]. Deep blue, darkest on head. In winter brown, paler below, more or less mixed with blue. _Ad._ [Female]. Above brown; below whitish washed with brown with a _suggestion of streaks_; lesser wing-coverts and margins of tail-feathers usually tinged with blue. _Yng._ Similar to [Female] but below more streaked; browner, and generally without blue tinge. _Notes._ Call, a sharp _pit_; song, a tinkling, unsympathetic, rapid warble, _July, July, summer-summer's here_; _morning, noontide, evening, list to me_.
Range.--Eastern United States, west to the Plains, casually to Colorado; breeds north to Nova Scotia and Manitoba; winters in Central America.
=766. Bluebird= (_Sialia sialis_). L. 7. _Ad._ [Male]. Above, including wings and tail, bright blue; throat and breast rusty brown, belly whitish. _Ad._ [Female]. Above grayer, below paler. In winter specimens of both sexes have upperparts tipped with rusty. _Notes._ Call, _tur-wee, tur-wee_; song, a rich and sweet but short warble.
Range.--Eastern United States; breeds from the Gulf States to Nova Scotia and Manitoba; winters from southern New England and southern Illinois southward.
=766a. Azure Bluebird= (_S. s. azurea_). Similar to No. 766, but breast paler, upperparts less deep, more cerulean.
Range.--Mountains of eastern Mexico north to southern Arizona.
=767. Western Bluebird= (_Sialia mexicana occidentalis_). L. 7. _Ad._ [Male]. Above bright blue, foreback with more or less rust-brown, but rarely wholly chestnut; _throat blue_, breast rust-brown, belly bluish gray. _Ad._ [Female]. Above grayish blue; rust on foreback faintly indicated; throat bluish gray, breast paler than in [Male]. _Notes._ Call, suggests that of No. 766, but is louder and wilder.
Range.--Pacific coast region from northern Lower California north to British Columbia, east to western Nevada and casually, during migrations, to New Mexico. (Ridgway.)
=767a. Chestnut-backed Bluebird= (_S. m. bairdi_). Similar to No. 767, but foreback _wholly_ rust-brown.