Alcidae

Alcidae is a family of small to medium seabirds in the order Charadriiformes, commonly known as alcids or auks. The group comprises about 23 living species across several genera, including Alca (razorbill), Uria (murres), Fratercula (puffins), Aethia (auklets), and Synthliboramphus (variegated murrelets and relatives). The extinct great auk, Pinguinus impennis, is traditionally associated with this group, though its exact generic placement is debated.

Alcids are highly adapted to marine life. They typically have compact bodies, short wings, and strong legs with webbed feet, making them efficient divers and swimmers. Plumage is often black on the upperparts and white on the belly, with distinctive facial markings in many species. They spend most of the year at sea and come ashore primarily to breed, usually on rocky cliffs or offshore islands in northern coastal waters.

Diet and foraging involve diving to catch fish, crustaceans, and other small marine prey. Most alcids are wing-propelled divers, using rapid wing strokes to pursue prey underwater. They are generally highly migratory, with movements tied to seasonal prey availability.

Reproduction occurs in colonies. Most species are monogamous and exhibit biparental care, with both parents incubating a single egg and feeding the chick after hatching. Incubation and fledging times vary by species.

Conservation status among alcids varies by species. Habitat disturbance, oil spills, changes in fish stocks, and climate change threaten some populations, while others remain more secure. The extinction of the great auk serves as a historic reminder of the pressures faced by this group. Notable members include the razorbill, Atlantic puffin, common murre, thick-billed murre, and several auklets.