aLCA

Alca is a small genus of seabirds in the family Alcidae, order Charadriiformes. It is part of the true auks and includes the razorbill (Alca torda). The great auk (Alca impennis) was historically placed in this genus but is now classified in its own genus Pinguinus and is extinct.

The razorbill is a medium-sized auk, typically about 38 to 43 cm long. It has black upperparts and white underparts, with a large, stout bill featuring a distinctive white line along the upper mandible. The plumage and size give it a compact, robust appearance adapted to diving and swimming.

Razorbills breed in colonies along rocky cliffs and offshore islands around the North Atlantic, from eastern North America to northern Europe and western Greenland. They winter at sea, often well offshore. They are proficient divers, feeding primarily on small schooling fish and occasionally crustaceans, and they often forage in groups during the feeding season.

Reproduction takes place on land, where a single egg is laid in a crevice, hollow, or on a ledge. Both parents participate in incubation and chick rearing, with the chick fledging after several weeks and returning to the sea to learn foraging skills.

Conservation status: the razorbill is listed as Near Threatened by the IUCN. Population declines in some areas have been linked to reduced availability of prey due to overfishing, disturbance at breeding sites, pollution, and climate-related changes in marine ecosystems. The great auk, once placed in Alca, became extinct in the mid-19th century due to overexploitation.