Breeding adults are warm brown above, mottled with brown and off-white below. Nonbreeding adults are more monochromatic: dark gray above and white below, with a white patch between the bill and eyes, a white bar near the shoulder, and a white collar that isolates the dark crown from the dark back.
Dives to pursue small prey using its wings to “fly” underwater. Often calls or courts at sea, raising the wings, swimming and diving in synchrony with bills pointed upward. Gathers in the evening in coastal waters, waiting for dusk or nightfall to fly toward nesting areas in forests.
Nests in old-growth coniferous forest or in rocky talus slopes near the Pacific Ocean. Forages in the ocean and sometimes freshwater lakes near nesting areas. During the nonbreeding season, forages farther from nesting areas, usually in coastal marine habitats but sometimes far out in the ocean.