Flies fairly low to the water on stiff, fluttering wingbeats.Forages by hovering into the wind just above the sea surface, pattering with the feet, and seizing prey by dipping down and grasping with the bill. Often forages in small flocks, sometimes mixed with other seabirds.
Forages in cold (45–48°F) waters, typically far offshore. Nests on rocky offshore islands in soil, old puffin burrows, or in gaps between rocks, logs, roots, or talus. Visits nests only at night.
The more northerly populations (subspecies furcata), found from northeastern Asia to Alaska, are larger and paler than those that nest from southeastern Alaska southward (subspecies plumbea). However, these differences appear to be clinal—that is, there are intermediate birds where these populations meet. Northern birds tend to feed closer to shore, often alone, while southern nesters often feed farther from shore, frequently in small flocks.