Frigate Bird Flights Last Months
军舰鸟迁徙数月

Great frigate birds may stay aloft for up to two months, eating and sleeping on the wing.
巨型军舰鸟可能在高空中迁徙数月，在风中进食和睡眠。

撰文/播音 茱莉亚˙罗森 （Julia Rosen）
翻译      郭丰茹
校对      丁可含

Great frigate birds are extraordinary creatures. They’re seabirds with six-foot wingspans, yet they weigh only about three pounds. Their preferred food: flying fish—which they pluck out of the air above the water’s surface. Frigate birds’ feathers aren’t waterproof, so landing on the water to fish is a no-go.
巨型军舰鸟是一种很非凡的生物。这种海鸟翼展长达六英尺，但体重仅有三磅。它们喜欢捕食跃出海面的飞鱼（flying fish）。军舰鸟的羽毛不防水，无法停留在水面上捕鱼。

Now, scientists have discovered that great frigate birds do something else amazing: they can fly for up to two months at a time without landing.
如今，科学家们发现巨型军舰鸟另一惊人之举：它们可以持续飞行不着陆达两个月之久。

Researchers already knew that these birds took extended trips over the Indian and Pacific Oceans to feed. But in a new study, scientists used tracking devices to follow the movement and vital signs of birds from the island of Europa, near Madagascar. They discovered that the birds have a highly specialized strategy for staying aloft.
科研工作者早已知晓，这些鸟在意大利（Indian）和太平洋（Pacific Oceans）之间长途飞行寻觅食物。但在最新的研究中，科学家们使用追踪设备从临近马达加斯加（Madagascar）的欧罗巴（Europa）岛一路跟踪军舰鸟的行踪，搜集重要的信号。他们发现这些鸟的高空飞行法很高明。

“When they are traveling, most of the time, they flap very infrequently their wings.”
“当它们飞行的时候，大部分时间不挥动翅膀。”

Henri Weimerskirch, an ecologist at the National Center for Scientific Research in France.
亨利˙维莫斯科其（Henri Weimerskirch）是一个生态学家，供职于法国国家科学研究中心（National Center for Scientific Research）。

“In fact, what they are doing, they are doing sort of a roller coaster flight where they take altitude. Even they can climb up to 3,000 or 4,000 meters, and when they climb, they do not flap their wings at all.”
“事实上，它们在高空以云霄飞车式飞行。它们甚至可以飞到3,000或者4,000米高空，当它们上升的时候不扇动翅膀。”

Weimerskirch and his colleagues found that the birds climb currents of rising air associated with cumulus clouds, circling upwards the way hawks and vultures do over land. Then they glide back down again, hardly flapping. By using atmospheric conditions to their advantage, the birds covered an average of 420 kilometers a day almost effortlessly. The study is in the journal Science. [Henri Weimerskirch et al., Frigate birds track atmospheric conditions over months-long transoceanic flights]
维莫斯科其（Weimerskirch）和他的同事们发现，军舰鸟与鹰和秃鹫相仿，借着积雨云的上升气流攀升到高空中。然后它们滑翔到地面，几乎不用挥动翅膀。借助大气优势，这些军舰鸟不费吹灰之力平均每天可以飞行420千米。这篇研究见报于《自然》杂志。[Henri Weimerskirch et al., Frigate birds track atmospheric conditions over months-long transoceanic flights]。

The researchers also discovered that the birds endure some harrowing conditions on their voyage, including some thrills and chills.
研究者也发现，在旅途中，军舰鸟可以耐受发抖和寒冷这样的极端状况。

“When you enter into the clouds, there’s a lot of turbulence. After, when you see from the recording on the logger of the bird, when they are at 4,000 meters, the temperatures are negative. It’s a tropical bird. It’s a bird that has no specific down like geese that are operating in the Arctic. So they are encountering sort of a polar temperature, but it’s a typical tropical bird.”
“当你进入云层，有很多气流。之后，在鸟的跟踪记录仪上可以看到，当他们到达6,000米高空时，气温在零下。这是一只热带鸟。它们不像天鹅，可以在北极（Arctic）飞行，因此它们在飞行途中会遭遇很多极地气候，而它们是典型的热带鸟类。”

Of course, the birds have to eat during their journey. The researchers found that diving down to the sea surface to snatch a meal consumed most of the birds’ energy, even though it only occupied about 10 percent of their time.
毋庸置疑，军舰鸟在旅途中需要进食。科学家发现，俯冲到海平面捕捉飞鱼会耗掉军舰鸟大部分体力，尽管每次捕食仅占飞行时间的10%。

“When they are climbing, they have a period where there is no movement at all during several minutes. And so, during this time is probably the time when they are sleeping.”
“当它们攀升的时候，它们可以在数分钟之内不动，在这段时间里，它们可能在睡觉。”

That’s right—like many others who make long-distance flights, great frigate birds catch a little shut-eye along the way.
就像其他长途迁徙的鸟类，巨型军舰鸟在旅途中打了一个盹儿。

—Julia Rosen

文章链接：

http://www.scientificamerican.com/podcast/episode/frigate-bird-flights-last-months/

（题图来源：http://www.scientificamerican.com）