auk - Evolution and distribution, Feeding and ecology, Social behaviour and breeding, Systematics

A small, black-and-white, short-winged seabird, the N hemisphere equivalent to the penguin (which it superficially resembles); inhabits cool seas; excellent swimmer; breeding colonies contain millions of birds. (Family: Alcidae, 21 species.)

iAuks
Parakeet Auklets
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Aves Order: Charadriiformes Family: Alcidae Leach, 1820
Genera
Uria Alle Alca Pinguinus Synthliboramphus Cepphus Brachyramphus Ptychoramphus Aethia Cerorhinca Fratercula Extinct genera, see Systematics

Auks are birds of the family Alcidae in the order Charadriiformes.

In contrast to penguins, the modern auks are able to fly (with the exception of the recently extinct Great Auk).

Auks live on the open sea and only go ashore for breeding, although some species, like the Common Guillemot, spend a great part of the year defending their nesting spot from others. 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 Uria guillemots, nest in large colonies on cliff edges;

Evolution and distribution

Traditionally, the auks were believed to be one of the earliest distinct charadriiform lineages due to their characteristic morphology. However, molecular 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.

The earliest unequivocal fossils of auks are from the Miocene (e.g.

The extant auks (subfamily Alcinae) are broken up into 2 main groups: the usually high-billed puffins (tribe Fraterculini) and auklets (tribe Aethiini), and the more slender-billed murres (tribe Alcini) and the murrelets and guillemots (tribes Brachyramphini and Cepphini).

Today, as in the past, the auks are restricted to cooler northern waters. 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;

Feeding and ecology

The feeding behaviour of auks is often compared to that of penguins;

Although not to the extent of penguins, auks have to a large extent sacrificed flight, and also mobility on land, in exchange for swimming; 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.

Social behaviour and breeding

The majority of auk species are colonial, nesting in anything between small groups to large thousand strong colonies. In these areas the benefits of colonial nesting would be outweighed by the presence of terrestrial predators (foxes and raccoons, for example) which island and cliff breeding auks do not have to deal with. Mating itself can happen both on the colony, as happens with the Razorbill and Little Auk, or at sea, as is the case for puffins and auklets.

Systematics

ORDER CHARADRIIFORMES
Suborder Lari

Family Alcidae

Hydrotherikornis (fossil, disputed) Subfamily Petralcinae (fossil, disputed) Petralca Subfamily Mancallinae (fossil) Alcodes Praemancalla Mancalla Subfamily Alcinae Miocepphus (fossil) Tribe Alcini - Auks and murres Uria Common Guillemot or Common Murre, Uria aalge Brunnich's Guillemot or Thick-billed Murre, Uria lomvia Little Auk or Dovekie, Alle alle Great Auk, Pinguinus impennis (extinct, c.1844) Razorbill, Alca torda Tribe Synthliboramphini - Synthliboramphine murrelets Synthliboramphus Xantus's Murrelet, Synthliboramphus hypoleucus - sometimes separated in Endomychura Craveri's Murrelet, Synthliboramphus craveri - sometimes separated in Endomychura Ancient Murrelet, Synthliboramphus antiquus Japanese Murrelet, Synthliboramphus wumizusume Tribe Cepphini - True guillemots Cepphus Black Guillemot or Tystie, Cepphus grylle Pigeon Guillemot, Cepphus columba Kurile Guillemot, Cepphus (columba) snowi Spectacled Guillemot, Cepphus carbo Tribe Brachyramphini - Brachyramphine murrelets Brachyramphus Marbled Murrelet, Brachyramphus marmoratus Long-billed Murrelet Brachyramphus perdix Kittlitz's Murrelet, Brachyramphus brevirostris Tribe Aethiini - Auklets Cassin's Auklet, Ptychoramphus aleuticus Aethia Parakeet Auklet, Aethia psittacula Crested Auklet, Aethia cristatella Whiskered Auklet, Aethia pygmaea Least Auklet, Aethia pusilla Tribe Fraterculini - Puffins Rhinoceros Auklet, Cerorhinca monocerata Fratercula Atlantic Puffin, Fratercula arctica Horned Puffin, Fratercula corniculata Tufted Puffin, Fratercula cirrhata

Biodiversity of auks seems to have been markedly higher during the Pliocene (Konyukhov, 2002).