Guillemot, a web-footed bird related to the auk and puffin. Most guillemots are about 13 inches (33 cm) long. They usually nest on rocky ledges, laying one or two plain or brown-spotted white or buff eggs. They feed on small fish, crustaceans, and mollusks.

The black guillemot is sooty black with white wing patches in summer, white with black wings and white wing patches in winter. The feet are red; the pointed bill is black. The black guillemot breeds from Labrador to Maine, moving southward as far as New Jersey during winter. Mandt's guillemot breeds in the Arctic, wintering as far south as Lake Ontario. The pigeon guillemot is common along the Pacific Coast from the Aleutian Islands to southern California.

The black guillemot is Cepphus grylle; Mandt's, C. g. mandti; pigeon, C. columba. Guillemots belong to the family Alcidae.