Guillemot is the common name for several species of seabird in the Alcidae or auk family, part of the order Charadriiformes. In Europe, the term covers two genera, Uria and Cepphus. In North America the Uria species are called murres and only the Cepphus species are called "guillemots".
The current spelling guillemot is of French origin, first attested by Pierre Belon in 1555, but derived from Old (11th century) French willelm, and matched by English variants willock (attested 1631), willick, will and wilkie, all from forms of the name William, cf. French: Guillaume, but ultimately onomatopoeic from the loud, high-pitched "will, willem" begging calls of the newly fledged young of the common guillemot.[1][2][3] The American name murre, also known from England (particularly Cornwall) from the 17th century, is by contrast, onomatopoeic of the growling call of adult common guillemots.[1]
The two living species of Uria, together with the razorbill, little auk, and the extinct great auk, make up the tribe Alcini. They have distinctly white bellies, thicker and longer bills than Cepphus, and form very dense colonies on cliffs during the reproductive season. Guillemot eggs are large (around 11% of female weight[4]), pyriform in shape, and colourful, making them attractive targets for egg collectors.[5]
The three living species of Cepphus form a tribe of their own, Cepphini. They are smaller than the Uria species and have black bellies in breeding plumage, rounder heads and bright red feet.