page_title: Auk
section_title: Evolution and distribution
hierarchical_section_title: Auk / Evolution and distribution
caption_attribution_description: English: The Great Auk Pinguinus impennis surrounded by its true relatives Alca torda Alle alle Cepphus grylle Fratercula arctica Uria aalge Uria lomvia
context_page_description: An auk or alcid is a bird of the family Alcidae in the order Charadriiformes. The alcid family includes the murres, guillemots, auklets, puffins, and murrelets. The word auk is derived from Icelandic álka, from Old Norse alka, from Proto-Germanic *alkǭ.
  Apart from the extinct great auk, all auks are notable for their ability to "fly" under water as well as in the air. Although they are excellent swimmers and divers, their walking appears clumsy.
  Several species have different common names in Europe and North America. The guillemots of Europe are referred to as murres in North America, if they occur in both continents, and the little auk is referred to as the dovekie.
context_section_description: Traditionally, the auks were believed to be one of the earliest distinct charadriiform lineages due to their characteristic morphology. However, 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). 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. The genus Miocepphus, (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 (c. 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 that it was there they first evolved, and it is in the Miocene Pacific that the first fossils of extant genera 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 Ocean. 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 includes in the family Alcidae under some definitions. One species, Miomancalla howardae, is the largest charadriiform of all time.
  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 ecology. mtDNA cytochrome b sequence and allozyme 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.
  Of the genera there are only a few species 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 food items) 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 (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 Pliocene. Auks also tend to be restricted to continental shelf waters and breed on few oceanic islands.
  Hydotherikornis oreg
caption: Auks as painted by Archibald Thorburn
exif: {"Image Orientation": "Horizontal (normal)", "Image XResolution": "96", "Image YResolution": "96", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS3 Windows", "Image DateTime": "2012:02:01 15:28:48", "Image ExifOffset": "164", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "302", "Thumbnail JPEGInterchangeFormatLength": "8513", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "800", "EXIF ExifImageLength": "983"}