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Red-throated loon
The red-throated loon or red-throated diver (''Gavia stellata'') is a migratory aquatic bird found in the northern hemisphere. The most widely distributed member of the loon or diver family, it breeds primarily in Arctic regions, and winters in northern coastal waters. Ranging from in length, the red-throated loon is the smallest and lightest of the world's loons. In winter, it is a nondescript bird, greyish above fading to white below. During the breeding season, it acquires the distinctive reddish throat patch which is the basis for its common name. Fish form the bulk of its diet, though amphibians, invertebrates and plant material are sometimes eaten as well. A monogamous species, the red-throated loon forms long-term pair bonds. Both members of the pair help to build the nest, incubate the eggs (generally two per clutch) and feed the hatched young.
The red-throated loon has a large global population and a significant global range, though some populations are declining. Oil spills, habitat degradation, pollution and fishing nets are among the major threats this species faces. Natural predators—including various gull species, and both red and Arctic foxes, will take eggs and young. The species is protected by a number of international treaties.
==Taxonomy and etymology==
First described by Danish naturalist Erik Pontoppidan in 1763, the red-throated loon is a monotypic species, with no distinctive subspecies despite its large Holarctic range.〔 Pontoppidan initially placed the species in the now-defunct genus ''Colymbus'', which contained grebes as well as loons. By 1788, however, German naturalist Johann Reinhold Forster realized that grebes and loons were different enough to warrant separate genera, and moved the red-throated loon (along with all other loon species) to its present genus. Its relationship to the four other loons is complex; although all belong to the same genus, it differs more than any of the others in terms of morphology, behaviour, ecology and breeding biology,〔 and may be the basal lineage of the genus. It is thought to have evolved in the Palearctic, and then to have expanded into the Nearctic.〔
The genus name ''Gavia'' comes from the Latin for "sea mew", as used by ancient Roman naturalist Pliny the Elder. The specific epithet ''stellata'' is Latin for "set with stars" or "starry", and refers to the bird's speckled back in its non-breeding plumage.〔 "Diver" refers to the family's underwater method of hunting for prey, while "red-throated" is a straightforward reference to the bird's most distinctive breeding plumage feature. The word "loon" is thought to have derived from the Swedish ''lom'', the Old Norse or Icelandic ''lómr'', or the Old Dutch ''loen'', all of which mean "lame" or "clumsy", and is a probable reference to the difficulty that all loons have in moving about on land.〔Carboneras 1992, p. 169.〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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