The Strangest Bird


By R. Ewan Fordyce /Daniel T. Ksepka R. E. フォーダイス /D. T. セプカ
English 日本語 日本語
November in Antarctica, and the ice is on the wane. Soon the emperors will go fishing. They’ll spend the austral summer gliding through the frigid Southern Ocean, diving to depths of more than 1,500 feet in search of fish, squid and krill to gorge on before making the long trek inland for the winter to breed. When the time comes to haul out, they will launch themselves out of the water back onto the ice. That brief moment between sea and ice is the only time these penguins experience what most birds take for granted: being airborne.  11月の南極,氷が解け始める。もうじきエンペラーペンギン(コウテイペンギン)が魚を採りに出かける。南半球の夏のあいだ,彼らは冷たい南極海を飛ぶように泳ぎ回り,水深約500mまで潜って魚やイカ,オキアミを探す。繁殖のため冬の内陸部への長旅に出る前に,しっかり食べておくのだ。
Indeed, emperors and other penguins are bizarre birds. Like all birds, they possess feathers, wings and beaks and lay eggs. But penguins also exhibit a suite of characteristics that readily distinguishes them from their feathered friends. Their wings have evolved into flippers for swimming; their trademark tuxedo camouflages them from predators above and below; their dense bones provide ballast for diving; their short, thick legs steer their body underwater and help give them that endearing (and energetically efficient) waddle on land. Thanks to these traits and others, penguins are masters of the marine realm, and many of their kind—the emperors among them—have managed to conquer one of the most extreme environments on the planet.  実際,エンペラーペンギンも他のペンギンも奇妙な鳥だ。他の鳥類と同様に羽毛と翼,くちばしを持ち,卵を産むが,ほかの鳥とは大きく異なる一連の特徴がある。翼は泳ぐためにヒレ状の「フリッパー」に進化している。特徴的なタキシード姿は,海中で上下にいる捕食者の目をごまかしてくれる。緻密で重い骨は,潜水時に浮力を抑えるバラストとなる。短くて厚みのある足は,水中では舵として身体の向きを変え,陸上では可愛らしい(そしてエネルギー効率の良い)身体を左右に揺らすよちよち歩きをするのに使われる。
Paleontologists have long wondered whence these peculiar birds originated and how they spread across the Southern Hemisphere. Fossil discoveries made over the past decade have helped reconstruct the penguin’s evolutionary march. It turns out that many of their signature features arose under far balmier conditions than the brutally cold settings that people tend to imagine when they think of penguins. Yet that history does not improve the odds that penguins will survive in the face of future warming. The new findings make clear that the biology and geographic distribution of these birds reflect a complex interplay of continental drift, shifting climate and natural selection over tens of millions of years—underscoring the vulnerability of today’s penguins to the effects of rapid climate change.  この奇妙な鳥がどこで誕生し,どのように南半球に広がったのかは古生物学者にとって長年の謎だった。だが,ここ10年間に発見された化石のおかげで,ペンギンの進化の道筋が見えてきた。ペンギンの特徴の多くは,人々がこの鳥についてイメージするような極寒の地ではなく,もっと穏やかな環境で生じたことがわかった。