A bird of open spaces, open woodlands, and mountain canyons; often seen farther from water than Tree Swallow.

Dark, purplish- or violet-green on upperparts. White on side of cheek extends above eye (compare with Tree Swallow). Also note that outer edges of rump are white (visible from above on flying birds).

May breed in small colonies. Nests in natural or man-made cavities, including tree cavities, nest boxes, rock crevices, and abandoned woodpecker holes. Eats insects taken in flight.