Auk

Auks or alcids are birds of the family Alcidae in the order Charadriiformes. The alcid family includes the murres, guillemots, auklets, puffins, and murrelets. The family contains 25 extant or recently extinct species that are divided into 11 genera. Auks are found throughout the Northern Hemisphere.

Apart from the extinct great auk, all auks can fly, and are excellent swimmers and divers (appearing to "fly" in water), but their walking appears clumsy.

Several species have different English names in Europe and North America. The two species known as "murres" in North America are called "guillemots" in Europe, and the species called little auk in Europe is referred to as dovekie in North America.

The word "auk" /ɔːk/ is derived from Icelandic álka and Norwegian alka or alke from Old Norse ālka from Proto-Germanic *alkǭ (sea-bird, auk).

The family name Alcidae comes from the genus Alca given by Carl Linnaeus in 1758 for the razorbill (Alca torda) from the Norwegian word alke.

Auks are superficially similar to penguins, having black-and-white colours, upright posture, and some of their habits. Nevertheless, they are not closely related to penguins, but rather are believed to be an example of moderate convergent evolution. Auks are monomorphic (males and females are similar in appearance).

Extant auks range in size from the least auklet, at 85 g (3 oz) and 15 cm (5.9 in), to the thick-billed murre, at 1 kg (2.2 lb) and 45 cm (18 in). Due to their short wings, auks have to flap their wings very quickly to fly.

Although not to the extent of penguins, auks have largely sacrificed flight, and also mobility on land, in exchange for swimming ability; their wings are a compromise between the best possible design for diving and the bare minimum needed for flying. This varies by subfamily, with the Uria guillemots (including the razorbill) and murrelets being the most efficient under the water, whereas the puffins and auklets are better adapted for flying and walking.