During the warmer months, generally from April through early October, Colorado hosts all three species of North American bluebirds. Arriving in early-mid spring, they inhabit wooded meadows and ranchlands, nesting in tree cavities or man-made nest boxes. Primarily insectivorous in spring and summer, they also consume berries, especially during the fall and winter months.
Western bluebirds are found from the Front Range urban corridor to the western canyonlands of Colorado, favoring open woodlands of the foothills and mountain parklands. Mountain bluebirds, sky blue in color, inhabit the upper foothills and mountains and are often seen above timberline. Eastern bluebirds, recent immigrants to Colorado are primarily found along the eastern edge of the State; however, they seem to be expanding that range along the South Platte and Arkansas River corridors and small numbers have turned up in Front Range towns and suburbs.
Eastern bluebirds that summer in Colorado winter across the Central and Southern Plains while western and mountain bluebirds winter in the Desert Southwest and northern Mexico; however, some mountain bluebirds wander eastward during the colder months, occasionally turning up on the Great Plains or in the Midwest. Novice birders who visit Colorado may confuse male lazuli buntings or blue grosbeaks with bluebirds; the former inhabit foothill shrublands and brushy canyons while the latter are found on grasslands of Colorado's eastern plains and piedmont.
