Two very fragmentary fossils are often assigned to the Alcidae, although this may not be correct: Hydrotherikornis (Late Eocene) and Petralca (Late Oligocene). The genus Miocepphus, (from the Miocene, 15 Mya) is the earliest known from good specimens. The earliest unequivocal fossils of auks are from the late Eocene, some 35 Mya. Alternatively, auks may have split off far earlier from the rest of the Lari and undergone strong morphological, but slow genetic evolution, which would require a very high evolutionary pressure, coupled with a long lifespan and slow reproduction. Judging from genetic data, their closest living relatives appear to be the skuas, with these two lineages separating about 30 million years ago (Mya). Thus today, the auks are no longer separated in their own suborder (Alcae), but are considered part of the Lari suborder, which otherwise contains gulls and similar birds. Traditionally, the auks were believed to be one of the earliest distinct charadriiform lineages due to their characteristic morphology, but genetic analyses have demonstrated that these peculiarities are the product of strong natural selection, instead as opposed to, for example, plovers (a much older charadriiform lineage), auks radically changed from a wading shorebird to a diving seabird lifestyle.

All species except the Brachyramphus murrelets are colonial. Some species, such as the Uria guillemots (murres), nest in large colonies on cliff edges others, such as the Cepphus guillemots, breed in small groups on rocky coasts and the puffins, auklets, and some murrelets nest in burrows.

They typically lay a single egg, and they use the nesting site year after year. Time depth recorders on auks have shown that they can dive as deep as 100 m (330 ft) in the case of Uria guillemots, 40 m (130 ft) for the Cepphus guillemots and 30 m (98 ft) for the auklets.Īuks are pelagic birds, spending the majority of their adult lives on the open sea and going ashore only for breeding, although some species, such as the common guillemot, spend a great part of the year defending their nesting spot from others.Īuks are monogamous, and tend to form lifelong pairs. Strong-swimming murres hunt faster, schooling fish, whereas auklets take slower-moving krill. In areas where the two groups feed on the same prey, the auks tend to feed further offshore. In the region where auks live, their only seabird competition are cormorants (which are dive-powered by their strong feet). The feeding behaviour of auks is often compared to that of penguins both groups are wing-propelled, pursuit divers. 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. Due to their short wings, auks have to flap their wings very quickly to fly.Īlthough 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. Auks are monomorphic (males and females are similar in appearance).Įxtant 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). Nevertheless, they are not closely related to penguins, but rather are believed to be an example of moderate convergent evolution. Description Īuks are superficially similar to penguins, having black-and-white colours, upright posture, and some of their habits. 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. The word 'auk' / ɔː k/ is derived from Icelandic álka and Norwegian alka or alke from Old Norse ālka from Proto-Germanic * alkǭ (sea-bird, auk). 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. Several species have different English names in Europe and North America. Īpart from the extinct great auk, all auks can fly, and are excellent swimmers (appearing to 'fly') and divers, but their walking appears clumsy. The family contains 25 extant or recently extinct species that are divided into 11 genera. The alcid family includes the murres, guillemots, auklets, puffins, and murrelets. An auk or alcid is a bird of the family Alcidae in the order Charadriiformes.

Puffin definition