| Common murre, Uria aalge|
Razorbill auk, Alca torda
Auks or alcids, a general term for 25 species of marine diving birds of the family Alcidae, and found in the higher latitudes of the Northern Hemisphere. The family includes auklets, murres, gillemots and puffins, with the word "auk" generally restricted to three species: the razorbill auk (Alca torda), the little auk (Alle alle), and the extinct great auk (Pinguinus impennis).
Auks are the northern equivalent of penguins, of which there is a resemblance in many ways. The body is stocky with a large head, and they bear a short neck, legs, and tail. Length varies among species, from 6.5 inches to 30 inches. Beaks are long and pointed (murres); deep and laterally compressed (razorbills, puffins); or stubby (little auks). Plumage is generally monochrome: black or brown above a white belly in most species, with the bold colors of the puffin's beaks being a striking exception.
Auks are excellent divers, using their half-folded wings as paddles underwater as they strike at prey. Their webbed feet are set far back on their bodies and used for steering; the position also gives them an upright appearance when standing, and an awkward gait when walking, similar to penguins. In fact, the largest of the auks - the great auk - was once known as the original penguin before those birds were discovered in the Southern Hemisphere.
Auks are known to take small fish, shellfish, worms, and crustaceans, but the principle prey is fish. Prey is taken in deep water, and several species usually hunt the same fishing area. Little to no competition occurs between the birds within the area, as they strike at differing sizes and types of prey; a puffin with catch small fish no more than two inches in length, while a larger murre with catch those fish double the size.
- Subfamily Alcinae
- Tribe Alcini; typical auks and murres
- Tribe Brachyramphini; brachyramphine murrelets
- Tribe Cepphini; true guillemots
- Tribe Synthliboramphini; murrelets
- Subfamily Fraterculinae
- Tribe Aethiini – auklets
- Tribe Fraterculini; puffins