Black-and-white seabird; breeds in colonies on rocky islands and cliffs. Spends the rest of the year on the ocean, when it is seldom seen from land. Bill is shorter and thicker than Common Murre, but difficult to judge at a distance. Note blacker plumage, cleaner sides, and limited amount of white on throat in winter. These features help separate it from Common Murre and Razorbill. Usually single or in loose small groups; in the Atlantic, sometimes seen in loose association with a flock of Razorbills. Frequently dives underwater searching for fish.