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The ivory-billed woodpecker (''Campephilus principalis'') is one of the largest woodpeckers in the world, at roughly 20 inches (51 cm) in length and 30 inches (76 cm) in wingspan. It is native to the virgin forests of the southeastern United States (along with a separate subspecies native to Cuba). Due to habitat destruction, and to a lesser extent hunting, its numbers have dwindled to the point where it is uncertain whether any remain, though there have been reports that it has been seen again. Almost no forests today can maintain an ivory-billed woodpecker population. The species is listed as critically endangered and possibly extinct by the International Union for Conservation of Nature (IUCN).〔 The American Birding Association (ABA) lists the ivory-billed woodpecker as a Class 6 species, a category the ABA defines as "definitely or probably extinct."〔(【引用サイトリンク】title=Annual Report of the ABA Checklist Committee: 2007 – Flight Path )〕 Reports of at least one male ivory-billed woodpecker in Arkansas in 2004 were investigated and subsequently published in April 2005 by a team led by the Cornell Lab of Ornithology.〔 No definitive confirmation of those reports emerged, despite intensive searching over five years following the initial sightings. An anonymous $10,000 reward was offered in June 2006 for information leading to the discovery of an ivory-billed woodpecker nest, roost or feeding site. In December 2008, the Nature Conservancy announced a reward of $50,000 to the person who can lead a project biologist to a living ivory-billed woodpecker. In late September 2006, a team of ornithologists from Auburn University and the University of Windsor published reports of their own sightings of ivory-billed woodpeckers along the Choctawhatchee River in northwest Florida, beginning in 2005.〔Hill, Geoffrey E.; Mennill, Daniel J.; Rolek, Brian W.; Hicks, Tyler L. & Swiston, Kyle A. (2006): Evidence Suggesting that Ivory-billed Woodpeckers (''Campephilus principalis'') Exist in Florida. ''Avian Conservation and Ecology – Écologie et conservation des oiseaux'' 1(3): 2. (HTML fulltext ) (PDF fulltext with links to appendices ) (Erratum ) 〕 These reports were accompanied by evidence that the authors themselves considered suggestive for the existence of ivory-billed woodpeckers. Searches in this area of Florida through 2009 failed to produce definitive confirmation. Despite these high-profile reports from Arkansas and Florida and sporadic reports elsewhere in the historic range of the species since the 1940s, there is no conclusive evidence for the continued existence of the ivory-billed woodpecker; i.e., there are no unambiguous photographs, videos, specimens or DNA samples from feathers or feces of the ivory-billed woodpecker. Land acquisition and habitat restoration efforts have been initiated in certain areas where there is a relatively high probability that the species may have survived to protect any possible surviving individuals. ==Taxonomy== Ivory-billed woodpecker is the common name of several species of woodpecker distinguished by having a bill that resembles ivory: *''Campephilus'', a genus of woodpecker sometimes called the Ivory-billed woodpecker, although the term is more commonly used to describe the American and Cuban ivory-billed woodpeckers. *Cuban ivory-billed woodpecker (''Campephilus principalis bairdii'' or ''Campephilus bairdii''), now believed to be extinct. *American ivory-billed woodpecker (''Campephilus principalis principalis'' or ''Campephilus principalis''), described here. The Ivory-billed woodpecker is the type species for the genus ''Campephilus'', a group of large American woodpeckers. Although the Ivory-billed looks very similar to the pileated woodpeckers they are not close relatives as the pileated is a member of the genus ''Dryocopus''. Ornithologists have traditionally recognized two subspecies of this bird: the American Ivory-billed, the more famous of the two, and the Cuban ivory-billed woodpecker. The two look similar despite differences in size and plumage. There is some controversy over whether the Cuban ivory-billed woodpecker is more appropriately recognized as a separate species. A recent study compared DNA samples taken from specimens of both ivory-billed birds along with the imperial woodpecker, a larger but otherwise very similar bird. It concluded not only that the Cuban and American Ivory-billed woodpeckers are genetically distinct, but also that they and the imperial form a North American clade within ''Campephilus'' that appeared in the Mid-Pleistocene. The study does not attempt to define a lineage linking the three birds, though it does imply that the Cuban bird is more closely related to the imperial.〔 The American Ornithologists' Union Committee on Classification and Nomenclature has said it is not yet ready to list the American and Cuban as separate species. Lovette, a member of the committee, said that more testing is needed to support that change, but concluded that "These results will likely initiate an interesting debate on how we should classify these birds." Before this study, it was thought that the Cuban Ivory-billed were descended from mainland woodpeckers, either introduced to Cuba by Native Americans or accidentals that flew to the island themselves. While recent evidence suggesting that American ivory-billed woodpeckers may still exist in the wild has caused excitement in the Ornithology community, no similar evidence exists for the Cuban Ivory-billed bird, believed to be extinct since the last sighting in the late 1980s. 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「Ivory-billed woodpecker」の詳細全文を読む スポンサード リンク
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