Uncommon on tundra breeding grounds, rare farther s. in winter on lakes, bays or ocean. Often with COLO. ID: Between COLO and RTLO in size and shape. Nonbr sometimes confused with round-headed and small-billed COLO. A dark bird with fairly clean-cut border across face (little or no white around eye) and down neck sides. Nape looks ‘smooth,’ paler than neck sides and forehead. Many have chinstraps, a thin dark line across throat. Juv as nonbr with bolder fringes to upperparts. 1st-s (nonbr) birds are pale and washed out — be careful! Breeding birds striking. Often in breeding plumage on spring migration.