Auks are birds of the family
Alcidae in the order
CharadriiformesCharadriiformes is a diverse order of small to medium-large birds. It includes about 350 species and has members in all parts of the world. Most Charadriiformes live near water and eat invertebrates or other small animals; however, some are pelagic , some occupy deserts and a few are found in thick...
. They are superficially similar to
penguinPenguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
s due to their black-and-white colours, their upright posture and some of their habits. Nevertheless they are not closely related to the penguins, but rather are an example of moderate
convergent evolutionConvergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, birds and bats do, and are capable of powered flight. The wings are similar in...
.
In contrast to penguins, the modern auks are able to fly (with the exception of the recently extinct
Great AukThe Great Auk, Pinguinus impennis, formerly of the genus Alca, is a bird that became extinct in the mid-19th century. It was the only species in the genus Pinguinus - a group of birds that included several flightless giant auks from the Atlantic Ocean region - to survive until modern times...
). They are good swimmers and divers, but their walking appears clumsy. Due to their short wings auks have to flap their wings very quickly in order to fly. Extant auks range in size from the
Least AukletThe Least Auklet, Aethia pusilla, is a seabird and the smallest species of auk. It the most abundant seabird in North America, and one of the most abundant in the world, with a population of around nine million birds. They breed on the islands of Alaska and Siberia, and spend the winter close to...
, at 85 g (3 oz) and 15 cm (6 in), to the Thick-billed Murre, at 1 kg (2¼ lb) and 45 cm (18 in).
Auks live on the open sea and only go ashore for breeding, although some species, like the
Common GuillemotThe Common Murre or Common Guillemot is a large auk. It is also known as the Thin-billed Murre in North America. It has a circumpolar distribution, occurring in low-Arctic and boreal waters in the North-Atlantic and North Pacific...
, spend a great part of the year defending their nesting spot from others.
Several species have different names in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
and
North AmericaNorth America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific...
. The guillemots of Europe are murres in North America, if they occur in both continents, and the Little Auk becomes the Dovekie.
Some species, such as the
UriaUria is a genus of seabirds in the auk family known commonly as guillemots, in 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...
guillemots, nest in large colonies on cliff edges; others, like the
CepphusCepphus is a genus of seabirds in the auk family also referred to as true guillemots or, in North America, simply as guillemots. These are medium-sized birds with mainly black plumage in the breeding season, thin dark bills and red legs and feet. Two species have white wing patches, the third has...
guillemots, breed in small groups on rocky coasts; and the
puffinPuffins are any of three auk species in the bird genus Fratercula with a brightly coloured beak in the breeding season. 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...
s, auklets and some murrelets nest in burrows. All species except the
BrachyramphusBrachyramphus is a small genus of seabirds from the North Pacific. It consists of three species:* Marbled Murrelet, Brachyramphus marmoratus* Long-billed Murrelet Brachyramphus perdix* Kittlitz's Murrelet, Brachyramphus brevirostris...
murrelets are colonial.
Feeding and ecology
The feeding behaviour of auks is often compared to that of
penguinPenguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
s; they are both
wingA wing is a surface used to produce lift for flight through the air or another gaseous or fluid medium. The wing shape is usually an airfoil. The word originally referred only to the foremost limbs of birds, but has been extended to include the wings of insects , bats, pterosaurs, and aircraft.A...
-propelled pursuit divers. In the region where auks live their only seabird competition is with
cormorantThe bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...
s (which dive powered by their strong feet); in areas where the two groups feed on the same prey the auks tend to feed further offshore.
Although not to the extent of penguins, auks have to a large extent sacrificed flight, and also mobility on land, in exchange for swimming; their wings are a compromise between the best possible design for diving and the bare minimum needed for flying. This varies by subfamily, the
Uria guillemots (including the
RazorbillThe Razorbill, Alca torda, is a large auk, 38-43 cm in length, with a 60-69 cm wingspan. It is the only living member of the genus Alca....
) and murrelets being the most efficient under the water, whereas the puffins and auklets are better adapted for flying and walking. This reflects the type of prey taken; 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 100 m in the case of
Uria guillemots, 40 m for the
Cepphus guillemots and between 30 m for the auklets.
Evolution and distribution
Traditionally, the auks were believed to be one of the earliest distinct charadriiform lineages due to their characteristic
morphologyIn biology morphology is the form, structure and configuration of an organism.This includes aspects of the outward appearance as well as the form and structure of the internal parts like bones and organs...
. However, molecular analyses have demonstrated that these peculiarities are the product of strong natural selection instead: as opposed to, for example,
ploverPlovers are a widely distributed group of wading birds belonging to the subfamily Charadriinae. They are known to dive in lakes looking for fish. There are about 40 species in the subfamily, most of them called "plover" or "dotterel"...
s (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
LariThe suborder Lari is the part of the order Charadriiformes which includes the gulls, terns, skuas and skimmers, with the waders and snipes making up the rest of the order. Following recent research, the auks are now placed into the Lari too; the Glareolidae might constitute a distinct suborder...
suborder which otherwise contains gulls and similar birds. Judging from molecular data, their closest living relatives appear to be the skuas, with these two lineages separating about 30 million years ago (mya). Alternatively, auks may have split off far earlier from the rest of the Lari and undergone strong morphological, but slow molecular evolution, which would require a very high
evolutionary pressureAny cause that reduces reproductive success in a proportion of a population, potentially exerts evolutionary pressure or selection pressure. With sufficient pressure, inherited traits that mitigate its effects - even if they would be deleterious in other circumstances - can become widely spread...
, coupled with a long lifespan and slow reproduction.
The earliest unequivocal
fossilFossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
s of auks are from the
MioceneThe Miocene is a geological epoch of the Neogene period and extends from about 23.03 to 5.33 million years before the present . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the...
(e.g. the
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
Miocepphus, 15 mya). Two very fragmentary fossils are often assigned to the Alcidae, although this may not be correct:
Hydrotherikornis (Late
EoceneThe Eocene epoch, lasting from 55.8 ± 0.2 to 33.9 ± 0.1 Ma , is a major division of the geologic timescale and the second epoch of the Palaeogene period in the Cenozoic era. The Eocene spans the time from the end of the Paleocene epoch to the beginning of the Oligocene epoch. The start of the...
, some 35 mya) and
Petralca (Late
OligoceneThe Oligocene is a geologic epoch of the Paleogene period and extends from about 33.9 million to 23 million years before the present. As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
). Most extant genera are known to exist since the Late Miocene or Early
PlioceneThe Pliocene epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present....
(c. 5 mya). Miocene fossils have been found in both
CaliforniaCalifornia is the most populous state in the United States, and the third largest by area. California is the second most populous sub-national entity in the Americas, behind only São Paulo, Brazil...
and
MarylandMaryland is a state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia and the District of Columbia to the south and west, Pennsylvania to the north, and Delaware to the east. It is comparable in size to the European country of Belgium. According to the U.S...
, but the greater diversity of fossils and tribes in the Pacific leads most scientists to conclude that it was there they first evolved, and it is in the Miocene Pacific that the first fossils of extant
generaIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
are found. Early movement between the Pacific and the Atlantic probably happened to the south (since there was no northern opening to the Atlantic), later movements across the Arctic Sea. The flightless subfamily
MancallinaeThe Mancallinae were a sub-family of prehistoric flightless auks that lived on the Pacific coast of today's California and Mexico from the late Miocene Epoch to the Early Pleistocene...
which was apparently restricted to the Pacific coast of southern North America became extinct in the Early
PleistoceneThe Pleistocene is the epoch from 2.588 million to 12 000 years BP covering the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
.
The extant auks (subfamily Alcinae) are broken up into 2 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
ecologyEcology is the interdisciplinary scientific study of the interactions between organisms and the interactions of these organisms with their environment....
. mtDNA
cytochrome bCytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
sequenceA DNA sequence or genetic sequence is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, with the capacity to carry information as described by the central dogma of molecular biology....
and
allozymeVariant forms of an enzyme that are not coded for by different alleles at the same locus are called allozymes as opposed to isozymes which are enzymes that perform the same function, but which are coded for by genes located at different loci....
studies 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.
Compared to other families of seabirds, there are no genera with many
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
(such as the 47
LarusLarus is a large genus of gulls with worldwide distribution . Many of its species are abundant and well-known birds in their ranges...
gullGulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s). 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
krillKrill is a type of shrimp-like marine invertebrate animal. These small crustaceans are important organisms of the zooplankton, particularly as food for baleen whales, manta rays, whale sharks, crabeater seals, and other seals, and a few seabird species that feed almost exclusively on them. Another...
are the auk's principal food items) can swim doubles as the temperature increases from 5°C to 15°C, with no corresponding increase in speed for the bird. The southernmost auks, in California and
MexicoThe United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, can survive there because of cold
upwellingAn Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water...
s. The current paucity of auks in the Atlantic (6 species), compared to the Pacific (19-20 species) is considered to be because of extinctions to the Atlantic auks; the fossil record shows there were many more species in the Atlantic during the
PlioceneThe Pliocene epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present....
. Auks also tend to be restricted to continental shelf waters and breed on few
oceanAn ocean is a large body of saline water, and a principal component of the hydrosphere. Approximately 75% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
ic islands.
Systematics
FAMILY ALCIDAE
- Hydrotherikornis (fossil
Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
, disputed)
- Subfamily Petralcinae (fossil
Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
, disputed)
- Subfamily Mancallinae
The Mancallinae were a sub-family of prehistoric flightless auks that lived on the Pacific coast of today's California and Mexico from the late Miocene Epoch to the Early Pleistocene...
(fossilFossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
)
- Alcodes
- Praemancalla
- Mancalla
- Subfamily Alcinae
- Miocepphus (fossil
Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous rock formations and sedimentary layers is known as the fossil record...
)
- Tribe Alcini – typical auks and murres
- Uria
Uria is a genus of seabirds in the auk family known commonly as guillemots, in 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...
- Common Guillemot
The Common Murre or Common Guillemot is a large auk. It is also known as the Thin-billed Murre in North America. It has a circumpolar distribution, occurring in low-Arctic and boreal waters in the North-Atlantic and North Pacific...
or Common Murre, Uria aalge
- Brunnich's Guillemot
The Thick-billed Murre or Brünnich's Guillemot is a bird in the auk family . This bird is named after the Danish zoologist Morten Thrane Brünnich...
or Thick-billed Murre, Uria lomvia
- Little Auk
The Little Auk, or Dovekie , is a small auk, the only member of the genus Alle. It breeds on islands in the high Arctic. There are two subspecies: A. a. alle breeds in Greenland, Iceland, Novaya Zemlya and Spitsbergen, and A. a...
or Dovekie, Alle alle
- Great Auk
The Great Auk, Pinguinus impennis, formerly of the genus Alca, is a bird that became extinct in the mid-19th century. It was the only species in the genus Pinguinus - a group of birds that included several flightless giant auks from the Atlantic Ocean region - to survive until modern times...
, Pinguinus impennis (extinct, c.1844)
- Razorbill
The Razorbill, Alca torda, is a large auk, 38-43 cm in length, with a 60-69 cm wingspan. It is the only living member of the genus Alca....
, Alca torda
- Tribe Synthliboramphini – synthliboramphine murrelets
- Synthliboramphus
Synthliboramphus is a small genus of seabirds in the auk family from the North Pacific. It consists of four species:* Xantus's Murrelet, Synthliboramphus hypoleucus* Craveri's Murrelet, Synthliboramphus craveri...
- Xantus's Murrelet
Xantus's Murrelet is a small seabird found in the California Current system in the Pacific Ocean. This auk breeds on islands off California and Mexico...
, Synthliboramphus hypoleucus – sometimes separated in Endomychura
- Craveri's Murrelet
Craveri’s Murrelet is a small seabird which breeds on offshore islands in both the Pacific Ocean and the Gulf of California off the Baja peninsula of Mexico. It also wanders fairly regularly as far as central California in the USA, primarily during post-breeding dispersal...
, Synthliboramphus craveri – sometimes separated in Endomychura
- Ancient Murrelet
The Ancient Murrelet, Synthliboramphus antiquus, is a bird in the auk family. It breeds from the Yellow Sea , through the Russian Pacific coast and the Aleutian Islands to the Haida Gwaii archipelago of British Columbia, where about half of the world population breeds.These birds breed in colonies,...
, Synthliboramphus antiquus
- Japanese Murrelet
The Japanese Murrelet, Synthliboramphus wumizusume also known as Crested Murrelet is a small bird that inhabits rocky islets and reefs in the warm waters of Japan, Russia and South Korea...
, Synthliboramphus wumizusume
- Tribe Cepphini – true guillemots
- Cepphus
Cepphus is a genus of seabirds in the auk family also referred to as true guillemots or, in North America, simply as guillemots. These are medium-sized birds with mainly black plumage in the breeding season, thin dark bills and red legs and feet. Two species have white wing patches, the third has...
- Black Guillemot
The Black Guillemot or Tystie, Cepphus grylle, is a medium-sized alcid at 32-38 cm in length, and with a 49-58 cm wingspan.Adult birds have black bodies with a white wing patch, a thin dark bill and red legs and feet. They show white wing linings in flight. In winter, the upperparts are pale grey...
or Tystie, Cepphus grylle
- Pigeon Guillemot
The Pigeon Guillemot is a medium-sized alcid endemic to the Pacific. They closely resemble the other members of the genus Cepphus, particularly the Black Guillemot, which is slightly smaller....
, Cepphus columba
- Kurile Guillemot, Cepphus (columba) snowi
- Spectacled Guillemot
The Spectacled, or Sooty Guillemot, Cepphus carbo, is a seabird in the auk family.-Description:This species is about 38 cm long, with red legs, black bill and a blackish iris....
, Cepphus carbo
- Tribe Brachyramphini – brachyramphine murrelets
- Brachyramphus
Brachyramphus is a small genus of seabirds from the North Pacific. It consists of three species:* Marbled Murrelet, Brachyramphus marmoratus* Long-billed Murrelet Brachyramphus perdix* Kittlitz's Murrelet, Brachyramphus brevirostris...
- Marbled Murrelet
The Marbled Murrelet is a small seabird from the North Pacific. It is a member of the auk family. It nests in old-growth forests or on the ground at higher latitudes where trees cannot grow...
, Brachyramphus marmoratus
- Long-billed Murrelet
The Long-billed Murrelet is a small seabird from the North Pacific. It is an unusual member of the auk family, often nesting far inland in old growth forests...
Brachyramphus perdix
- Kittlitz's Murrelet
The Kittlitz's Murrelet, is a small alcid found in the waters off Alaska and Eastern Siberia. This critically endangered species is, like the closely related Marbled Murrelet, unusual for seabirds in not being colonial, nesting instead in isolated locations on mountain tops, where the nests were...
, Brachyramphus brevirostris
- Tribe Aethiini – auklets
- Cassin's Auklet
The Cassin’s Auklet, Ptychoramphus aleuticus, is a small, chunky seabird that ranges widely in the North Pacific. It nests in small burrows and because of its presence on well studied islands in British Columbia and off California it is one of the better known auks...
, Ptychoramphus aleuticus
- Aethia
Aethia is a genus of four small 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...
- Parakeet Auklet
The Parakeet Auklet is a small seabird of the North Pacific. It used to be placed on its own in the genus Cyclorrhynchus but recent morphological and genetic evidence suggest it should be placed in the genus Aethia. It is associated with the boreal waters of Alaska and Kamchatka and Siberia...
, Aethia psittacula
- Crested Auklet
The Crested Auklet is a small seabird of the family Alcidae which nests in huge colonies in the Bering Sea and Sea of Okhotsk. They often breed in mixed-species colonies with Least Auklets, their smaller congener.The Crested Auklet is recognized primarily by two characters in the breeding season...
, Aethia cristatella
- Whiskered Auklet
The Whiskered Auklet, Aethia pygmaea, is a small seabird of the auk family. It has a more restricted range than other members of its genus, Aethia, living only around the Aleutian Islands and on some islands off Siberia , and breeding on these islands. It is one of the smallest alcids, only the...
, Aethia pygmaea
- Least Auklet
The Least Auklet, Aethia pusilla, is a seabird and the smallest species of auk. It the most abundant seabird in North America, and one of the most abundant in the world, with a population of around nine million birds. They breed on the islands of Alaska and Siberia, and spend the winter close to...
, Aethia pusilla
- Tribe Fraterculini – puffins
- Rhinoceros Auklet
The Rhinoceros Auklet, Cerorhinca monocerata, is a seabird considered, despite its name, a close relative of the puffins. It is the only living species of the genus Cerorhinca...
, Cerorhinca monocerata
- Fratercula
- Atlantic Puffin
The Atlantic Puffin is a seabird species in the auk family. It is a pelagic bird that feeds primarily by diving for fish, but also eats other sea creatures, such as squid and crustaceans. Its most obvious characteristic is its brightly coloured beak during the breeding seasons...
, Fratercula arctica
- Horned Puffin
The Horned Puffin is an auk, similar in appearance to the Atlantic Puffin; this bird's bill is yellow at the base and red at the tip. It is a pelagic seabird that feeds primarily by diving for fish. It nests in colonies, often with other auks.The yellow bill plate grows before the breeding...
, Fratercula corniculata
- Tufted Puffin
The Tufted Puffin is a relatively abundant medium-sized pelagic seabird in the auk family found throughout the North Pacific Ocean....
, Fratercula cirrhata
BiodiversityBiodiversity is the variation of life forms within a given ecosystem, biome, or for the entire Earth. Biodiversity is often used as a measure of the health of biological systems...
of auks seems to have been markedly higher during the
PlioceneThe Pliocene epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present....
. See the genus accounts for prehistoric species.