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.
Names
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 family name Alcidae comes from the genus Alca given by Carl Linnaeus in 1758 for the razorbill (Alca torda) from the Norwegian word alke.[5]
Description
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 (3oz) and 15cm (5.9in), to the thick-billed murre, at 1kg (2.2lb) and 45cm (18in). 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.
Feeding and ecology
The feeding behaviour of auks is often compared to that of penguins; both groups are wing-propelled, pursuit divers. In the region where auks live, their only seabird competition are cormorants (which are dive-powered by their strong feet). In areas where the two groups feed on the same prey, the auks tend to feed further offshore. Strong-swimming murres hunt faster, schooling fish, whereas auklets take slower-moving krill. Time depth recorders on auks have shown that they can dive as deep as 100m (330ft) in the case of Uria guillemots, 40m (130ft) for the Cepphus guillemots and 30m (98ft) for the auklets.
Breeding and colonies
Auks 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.
Auks are monogamous, and tend to form lifelong pairs. They typically lay a single egg, and they use the nesting site year after year.
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. All species except the Brachyramphus murrelets are colonial.
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. 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. Judging from genetic data, their closest living relatives appear to be the skuas, with these two lineages separating about 30 million years ago (Mya).[6][7][8] 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.
The earliest unequivocal fossils of auks are from the late Eocene, some 35 Mya.[9] The genusMiocepphus, (from the Miocene, 15 Mya) is the earliest known from good specimens. Two very fragmentary fossils are often assigned to the Alcidae, although this may not be correct: Hydrotherikornis (Late Eocene) and Petralca (Late Oligocene). Most extant genera are known to exist since the Late Miocene or Early Pliocene (about 5 Mya). Miocene fossils have been found in both California and Maryland, but the greater diversity of fossils and tribes in the Pacific leads most scientists to conclude they first evolved there, and in the Miocene Pacific, the first fossils of extant genera are found. Early movement between the Pacific and the Atlantic probably happened to the south (since no northern opening to the Atlantic existed), with later movements across the Arctic Ocean.[10] The flightless subfamily Mancallinae, which was apparently restricted to the Pacific Coast of southern North America and became extinct in the Early Pleistocene, is sometimes included in the family Alcidae under some definitions. One species, Miomancalla howardae, is the largest charadriiform of all time.[11]
Razorbills are an auk found in the Atlantic Ocean.
The family contains 25 extant or recently extinct species that are divided into 11 genera.[2] The extant auks (subfamily Alcinae) are broken up into two main groups - the usually high-billed puffins (tribe Fraterculini) and auklets (tribe Aethiini), as opposed to the more slender-billed murres and true auks (tribe Alcini), and the murrelets and guillemots (tribes Brachyramphini and Cepphini). The tribal arrangement was originally based on analyses of morphology and ecology.[12]mtDNAcytochrome bsequences, and allozyme studies[6][7] confirm these findings except that the Synthliboramphus murrelets should be split into a distinct tribe, as they appear more closely related to the Alcini; in any case, assumption of a closer relationship between the former and the true guillemots was only weakly supported by earlier studies.[12]
Of the genera, only a few species are placed in each. This is probably a product of the rather small geographic range of the family (the most limited of any seabird family), and the periods of glacial advance and retreat that have kept the populations on the move in a narrow band of subarctic ocean.
Today, as in the past, the auks are restricted to cooler northern waters. Their ability to spread further south is restricted as their prey hunting method, pursuit diving, becomes less efficient in warmer waters. The speed at which small fish (which along with krill are the auk's principal prey) can swim doubles as the temperature increases from 5 to 15°C (41 to 59°F), with no corresponding increase in speed for the bird. The southernmost auks, in California and Mexico, can survive there because of cold upwellings. The current paucity of auks in the Atlantic (six species), compared to the Pacific (19–20 species) is considered to be because of extinctions to the Atlantic auks; the fossil record shows many more species were in the Atlantic during the Pliocene. Auks also tend to be restricted to continental-shelf waters and breed on few oceanic islands.
Hydotherikornis oregonus (Described by Miller in 1931), the oldest purported alcid from the Eocene of California, is actually a petrel (as reviewed by Chandler in 1990) and is reassigned to the tubenoses (Procellariiformes). A 2003 paper, "The Earliest North American Record of Auk (Aves: Alcidae) From the Late Eocene of Central Georgia", reports a Late Eocene, wing-propelled, diving auk from the Priabonain stage of the Late Eocene. These sediments have been dated through Chandronian NALMA {North American Land Mammal Age}, at an estimate of 34.5 to 35.5 million years on the Eocene time scale for fossil-bearing sediments of the Clinchfield Formation, Gordon, Wilkinson County, Georgia. Furthermore, the sediments containing this unabraded portion of a left humerus (43.7mm long) are tropical or subtropical as evidenced by a wealth of warm-water shark teeth, palaeophied snake vertebrae, and turtles.
Tribe Alcini – typical auks and murresThe synthliboramphine Xantus's murrelet (Synthliboramphus hypoleucus) is quite distinct from the brachyramphine murrelets.
The tufted puffin, also known as crested puffin, is a relatively abundant medium-sized pelagic seabird in the auk family (Alcidae) found throughout the North Pacific Ocean. It is one of three species of puffin that make up the genus Fratercula and is easily recognizable by its thick red bill and yellow tufts.
Puffins are any of three species of small alcids (auks) in the bird genus Fratercula. These are pelagic seabirds that feed primarily by diving in the water. They breed in large colonies on coastal cliffs or offshore islands, nesting in crevices among rocks or in burrows in the soil. Two species, the tufted puffin and horned puffin, are found in the North Pacific Ocean, while the Atlantic puffin is found in the North Atlantic Ocean.
Guillemot is the common name for several species of seabird in the Alcidae or auk family. In British use, the term comprises two genera: Uria and Cepphus. In North America the Uria species are called murres and only the Cepphus species are called "guillemots". This word of French origin derives from a form of the name William, cf. French: Guillaume.
The pigeon guillemot is a species of bird in the auk family, Alcidae. One of three species in the genus Cepphus, it is most closely related to the spectacled guillemot. There are five subspecies of the pigeon guillemot; all subspecies, when in breeding plumage, are dark brown with a black iridescent sheen and a distinctive wing patch broken by a brown-black wedge. Its non-breeding plumage has mottled grey and black upperparts and white underparts. The long bill is black, as are the claws. The legs, feet, and inside of the mouth are red. It closely resembles the black guillemot, which is slightly smaller and lacks the dark wing wedge present in the pigeon guillemot.
The razorbill, razor-billed auk, or lesser auk is a North Atlantic colonial seabird and the only extant member of the genus Alca of the family Alcidae, the auks. It is the closest living relative of the extinct great auk.
The common murre also called the common guillemot or foolish guillemot,(Uria aalge) is a large auk. It has a circumpolar distribution, occurring in low-Arctic and boreal waters in the North Atlantic and North Pacific. It spends most of its time at sea, only coming to land to breed on rocky cliff shores or islands.
The thick-billed murre or Brünnich's guillemot is a bird in the auk family (Alcidae). This bird is named after the Danish zoologist Morten Thrane Brünnich. The very deeply black North Pacific subspecies Uria lomvia arra is also called Pallas' murre after its describer. The genus name is from Ancient Greek ouria, a waterbird mentioned by Athenaeus. The species term lomvia is a Swedish word for an auk or diver. The English "guillemot" is from French guillemot probably derived from Guillaume, "William". "Murre" is of uncertain origins, but may imitate the call of the common guillemot.
The rhinoceros auklet is a seabird and a close relative of the puffins. It is the only extant species of the genus Cerorhinca. Given its close relationship with the puffins, the common name rhinoceros puffin has been proposed for the species.
Cepphus is a genus of seabirds in the auk family also referred to as true guillemots or, in North America, simply as guillemots. The genus name Cepphus is from Ancient Greek κέπφος kepphos, a pale waterbird mentioned by Greek authors including Aristotle. The English word "guillemot" is from French guillemot probably derived from Guillaume, "William". "Murre" is of uncertain origins but may imitate the call of the common guillemot.
Mancallinae is an extinct subfamily of prehistoric flightless alcids that lived on the Pacific coast of today's California and Mexico from the late Miocene epoch to the early Pleistocene. They are sometimes collectively referred to as Lucas auks after the scientist who described the first species, Frederic Augustus Lucas.
The crested auklet is a small seabird of the family Alcidae, distributed throughout the northern Pacific and the Bering Sea. The species feeds by diving in deep waters, eating krill and a variety of small marine animals. It nests in dense colonies of up to 1 million individuals in the Bering Sea and the Sea of Okhotsk. It often breeds in mixed-species colonies with the least auklet, a smaller congener.
Uria is a genus of seabirds in the auk family known in Britain as guillemots, in most of North America as murres, and in Newfoundland and Labrador as turr. These are medium-sized birds with mainly brown or black plumage in the breeding season. They breed on the coasts of the northern Atlantic and Pacific oceans.
Aethia is a genus of four small (85–300g) auklets endemic to the North Pacific Ocean, Bering Sea and Sea of Okhotsk and among some of North America's most abundant seabirds. The relationships between the four true auklets remains unclear. Auklets are threatened by invasive species such as Norway rats because of their high degree of coloniality and crevice-nesting.
Brachyramphus is a small genus of seabirds from the North Pacific. Brachyramphus is from Ancient Greek brakhus, "short", and rhamphos, "bill". In English the species are named as "murrelets"; this is a diminutive of "murre", a word of uncertain origins, but which may imitate the call of the common guillemot.
Synthliboramphus is a small genus of seabirds in the auk family from the North Pacific. The genus name Synthliboramphus is from Ancient Greek sunthlibo, "to compress", and rhamphos, "bill". The English name "Murrelet" is a diminutive of "murre", a word of uncertain origins, but which may imitate the call of the common guillemot.
Pinguinus alfrednewtoni is an extinct species of auk related to the great auk known from fossils that were discovered in the Pliocene Yorktown Formation of North Carolina. Like the great auk, it was a large flightless diving bird that used its wings to propel itself forward underwater. Only a limited amount of material is known, despite the rich diversity of fossil auks recovered from the Yorktown Formation. Due to this, it has been proposed that it was either a more coastal animal or simply not as common in more southern waters. This later suggestion could be supported by the discovery of relatively young P. alfrednewtoni remains, indicating that they may have overwintered in the region. One early hypothesis proposed that it was a direct ancestor to the great auk, but this idea is no longer supported. Instead, it is thought that it filled the same niche as its eastern relative, which eventually expanded into the western Atlantic after the extinction of P. alfrednewtoni.
Pan-Alcidae is a clade of charadriiform birds containing the auks and their extinct relatives. It was named in 2011 by N.A. Smith, who defined it as all descendants of the common ancestor of the group Mancallinae and crown group auks (Alcidae), but some have disputed the use of the Pan- prefix in general for family-group names regulated by the Zoocode.
Dow's puffin is an extinct seabird in the auk family described in 2000 from subfossil remains found in the Channel Islands of California. It was approximately as large as the modern horned puffin and its beak appeared to have been an intermediate between the rhinoceros auklet and the horned puffin. It lived during the Late Pleistocene and Early Pleistocene on the Channel Islands, where it nested alongside the ancient murrelet, Cassin's auklet and Chendytes lawi.
References
1 2 Myers, P.; Espinosa, R.; Parr, C. S.; Jones, T.; Hammond, G. S.; Dewey, T. A. (2022). "Alcidae". Animal Diversity Web. University of Michigan Museum of Zoology. Retrieved 31 December 2022.
↑ Jobling, James A. (2010). "Alca"(PDF). The Helm Dictionary of Scientific Bird Names. London, United Kingdom: Christopher Helm. p.40. ISBN978-1-4081-2501-4.
↑ Smith, N. A. (2015). "Evolution of body mass in the Pan-Alcidae (Aves, Charadriiformes): the effects of combining neontological and paleontological data". Paleobiology. 42 (1): 8–26. doi:10.1017/pab.2015.24. S2CID83934750.
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