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Phalacrocoracidae is a family of some 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed. There is no consistent distinction between "cormorants" and "shags", and these appellations have been assigned to different species randomly. Cormorants and shags are medium-to-large birds, with body weight in the range of and wing span of . The majority of species have dark feathers. The bill is long, thin and hooked. Their feet have webbing between all four toes. All species are fish-eaters, catching the prey by diving from the surface. They are excellent divers, and under water they propel themselves with their feet with help from their wings; some cormorant species have been found to dive as deep as 45 metres. They have relatively short wings due to their need for economical movement underwater, and consequently have the highest flight costs of any bird.〔Elliott KH, Ricklefs RE, Gaston AJ, Hatch SA, Speakman JR, Davoren GK. 2013. High flight costs and low dive costs support the biomechanical hypothesis for flightlessness in penguins. PNAS 110:9380-9384. ()〕 Cormorants nest in colonies around the shore, on trees, islets or cliffs. They are coastal rather than oceanic birds, and some have colonised inland waters – indeed, the original ancestor of cormorants seems to have been a fresh-water bird. They range around the world, except for the central Pacific islands. == Names == No consistent distinction exists between cormorants and shags. The names 'cormorant' and 'shag' were originally the common names of the two species of the family found in Great Britain, ''Phalacrocorax carbo'' (now referred to by ornithologists as the great cormorant) and ''P. aristotelis'' (the European shag). "Shag" refers to the bird's crest, which the British forms of the great cormorant lack. As other species were discovered by English-speaking sailors and explorers elsewhere in the world, some were called cormorants and some shags, depending on whether they had crests or not. Sometimes the same species is called a cormorant in one part of the world and a shag in another, e.g., the great cormorant is called the black shag in New Zealand (the birds found in Australasia have a crest that is absent in European members of the species). Van Tets (1976) proposed to divide the family into two genera and attach the name "cormorant" to one and "shag" to the other, but this flies in the face of common usage and has not been widely adopted. The scientific genus name is Latinised Ancient Greek, from φαλακρός (''phalakros'', "bald") and κόραξ (''korax'', "raven"). This is often thought to refer to the creamy white patch on the cheeks of adult great cormorants, or the ornamental white head plumes prominent in Mediterranean birds of this species, but is certainly not a unifying characteristic of cormorants. "Cormorant" is a contraction derived either directly from Latin ''corvus marinus'', "sea raven" or through Brythonic Celtic. Cormoran is the Cornish name of the sea giant in the tale of Jack the Giant Killer. Indeed, "sea raven" or analogous terms were the usual terms for cormorants in Germanic languages until after the Middle Ages. The French explorer André Thévet commented in 1558, "...the beak () similar to that of a cormorant or other corvid," which demonstrates that the erroneous belief that the birds were related to ravens lasted at least to the 16th century. 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「Cormorant」の詳細全文を読む スポンサード リンク
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