シロハラシマアカゲラ Dryobates nuttallii

Small woodpecker almost entirely restricted to the state of California (barely entering northern Baja). Look for black-and-white barring on the back and patterned flanks. Males have a red cap, often raised and fluffy-looking. Occurs in oak woodlands and riparian areas, sometimes visiting bird feeders. Most similar to Ladder-backed Woodpecker, but range barely overlaps. Also compare with Downy Woodpecker, which has clean flanks and lacks bars on the back.