|
The great auk (''Pinguinus impennis'') was a flightless bird of the alcid family that became extinct in the mid-19th century. It was the only modern species in the genus ''Pinguinus'' (unrelated to penguins, although it was the first bird to be called penguin). It bred on rocky, isolated islands with easy access to the ocean and a plentiful food supply, a rarity in nature that provided only a few breeding sites for the auks. When not breeding, the auks spent their time foraging in the waters of the North Atlantic, ranging as far south as northern Spain and also around the coast of Canada, Greenland, Iceland, the Faroe Islands, Norway, Ireland, and Great Britain. The great auk was tall and weighed around , making it the second largest member of the alcid family (''Miomancalla'' was larger〔Smith, N. 2015. Evolution of body mass in the Pan-Alcidae (Aves, Charadriiformes): the effects of combining neontological and paleontological data. Paleobiology. doi: 10.1017/pab.2015.24〕). It had a black back and a white belly. The black beak was heavy and hooked, with grooves on its surface. During summer, the great auk's plumage showed a white patch over each eye. During winter, the auk lost these patches, instead developing a white band stretching between the eyes. The wings were only long, rendering the bird flightless. Instead, the auk was a powerful swimmer, a trait that it used in hunting. Its favourite prey were fish, including Atlantic menhaden and capelin, and crustaceans. Although agile in the water, it was clumsy on land. Great auk pairs mated for life. They nested in extremely dense and social colonies, laying one egg on bare rock. The egg was white with variable brown marbling. Both parents incubated the egg for about six weeks before the young hatched. The young auk left the nest site after two or three weeks although the parents continued to care for it. The great auk was an important part of many Native American cultures, both as a food source and as a symbolic item. Many Maritime Archaic people were buried with great auk bones, and one was buried covered in over 200 auk beaks, which are assumed to have been part of a cloak made of their skins. Early European explorers to the Americas used the auk as a convenient food source or as fishing bait, reducing its numbers. The bird's down was in high demand in Europe, a factor which largely eliminated the European populations by the mid-16th century. Scientists soon began to realize that the great auk was disappearing and it became the beneficiary of many early environmental laws, but this proved not to be enough. Its growing rarity increased interest from European museums and private collectors in obtaining skins and eggs of the bird. On 3 July 1844, the last two confirmed specimens were killed on Eldey, off the coast of Iceland, which also eliminated the last known breeding attempt. There are unconfirmed later reports of roaming individuals being seen or caught. A record of a bird in 1852 is considered by some to be the last sighting of the species. The great auk is mentioned in several novels and the scientific journal of the American Ornithologists' Union is named ''The Auk'' in honour of this bird. ==Taxonomy and evolution== Analysis of mtDNA sequences has confirmed morphological and biogeographical studies suggesting that the razorbill is the great auk's closest living relative. The great auk was also closely related to the little auk (dovekie), which underwent a radically different evolution compared to ''Pinguinus''. Due to its outward similarity to the razorbill (apart from flightlessness and size), the great auk was often placed in the genus ''Alca'', following Linnaeus. The fossil record (especially the sister species ''Pinguinus alfrednewtoni'') and molecular evidence show that the three closely related genera diverged soon after their common ancestor, a bird probably similar to a stout Xantus's murrelet, had spread to the coasts of the Atlantic. By that time the murres, or Atlantic guillemots, had apparently already split from the other Atlantic alcids. Razorbill-like birds were common in the Atlantic during the Pliocene, but the evolution of the little auk is sparsely documented.〔 The molecular data are compatible with either view, but the weight of evidence suggests placing the great auk in a distinct genus.〔 Some ornithologists still feel it is more appropriate to retain the species in the genus ''Alca''. It is the only British bird made extinct in historic times. The following cladogram shows the placement of the great auk among its closest relatives, based on a 2004 genetic study: }} |2= }} }} }} ''Pinguinus alfrednewtoni'' was a larger and also flightless member of the genus ''Pinguinus'' that lived during the Early Pliocene. Known from bones found in the Yorktown Formation of the Lee Creek Mine in North Carolina, it is believed to have split along with the great auk from a common ancestor. ''Pinguinus alfrednewtoni'' lived in the western Atlantic while the great auk lived in the eastern Atlantic, but after the former died out after the Pliocene, the great auk replaced it.〔 The great auk was not closely related to the other extinct genera of flightless alcids, ''Mancalla'', ''Praemancalla'', and ''Alcodes''.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「great auk」の詳細全文を読む スポンサード リンク
|