Fifty-sixth supplement to the American Ornithologists' Union: Check-list of North American Birds - Chesser, R. Terry; Banks, Richard; Burns, Kevin J; Cicero, Carla; Dunn, Jon; Kratter, Andrew; Lovette, Irby; Navarro-Siguenza, Adolfo; Rasmussen, Pamela; Remsen, J; Rising, James; Stotz, Douglas; et al. (The Auk, 2015)