; class Aves, order Charadriiformes)
A family of mainly black and white, small-winged, diving sea-birds in which the legs are set well back, the feet are webbed, and bills vary from long and pointed to laterally compressed and high. Auks are mainly pelagic and gregarious, breeding in burrows or crevices, or on open cliff ledges, usually colonially. Brachyramphus marmoratus (marbled murrelet) breeds on forest branches. The two species of Fratercula (puffins) have laterally compressed bills that are yellow and red during the breeding season; the horny bill plates and a horn-like structure around the eye are both shed in winter. Their feet are red with claws modified for digging burrows; they inhabit grassy island slopes and cliffs, breeding in rock crevices and burrows, and spending the rest of the year at sea. Auks feed on fish and invertebrates. There are 12–14 genera, and 22 species, found in northern regions of the Pacific and Atlantic, and in the Arctic.
Subjects: Zoology and Animal Sciences.