354. Falco rusticolus. 23 in.

Adults white, heavily barred above, and streaked below with gray and black.

Range. - Arctic regions, south in winter, rarely to northern United States.

354a. Gyrfalcon (F. r. gyrfalco). Similar to the last but darker, the latter being usually more white than dusky, while this is the reverse.

354b. Black Gyrfalcon ( F. r. obsoletus). Much darker than the last, the markings tending to be buffy white spots on a grayish black ground.