字神帝國英語天地

✿ 今日主題：Bats Jam Rivals' Sonar to Steal a Meal
蝙蝠干擾對手回波定位「偷食」

✿ 托福、準備留學的聽力最好的課外教材：60-Second Science

康康精選托福會考的主題，堅持每天精聽一定會進步的哦！！

非常適合托福、TOEFL、iBT同學加強聽力用哦！！

✿ 建議方法：
1. 先聽兩三遍 (不看文稿)
2. 再一句一句聽寫 (每句都要聽寫數遍，直到寫出85%以上的字)
3. 最後check文稿，看哪聽不出來，單字沒背過，還是發音不熟。
4. 堅持天天聽，就能每天進步哦。

✿ MP3音檔：喜歡的同學，幫忙推或按讚哦~~
http://online1.tingclass.net/voaspe/…/20141117sa_science.mp3

✿ 只有音檔怎夠，聽不懂地方，不用怕，康康幫你準備好中英文稿了：
 

✿ 中英文稿：
Many bats hunt at night—and use echolocation, or sonar, to zero in on their prey. [echolocation clip] That's slowed down 20 times, so you can hear it. But some insects, like the tiger moth, have figured out how to evade that echolocation—by jamming it. "It makes these ultrasonic clicks in the last moment before it would normally be captured by a bat. [clicking sound] And this interferes with the bat's echolocation, causing that bat to miss.」

很多蝙蝠在夜間覓食，並利用回波定位或者聲納來瞄準獵物。【回音定位聲音片段】這是放慢了20倍以後的聲音，所以人類能聽到。但有些昆蟲，比如虎娥已經學會通過干擾回波定位來逃避它。虎娥會在被蝙蝠捕獲前的最後時刻發出這種超聲波滴答聲來自救。【超聲波滴答聲】這種聲音會干擾蝙蝠的回波定位，導致蝙蝠獵物失手。

Aaron Corcoran, a postdoc at Wake Forest University. Corcoran studied that phenomenon, and says he's now discovered that the jamming strategy isn't limited to prey. Bats do it, too—to foil each others' hunting efforts.
亞倫‧科克蘭，維克森林大學的博士後。科克蘭研究了這種現象，並宣佈他發現這種干擾戰略並不僅僅侷限於獵物，蝙蝠們為了阻止彼此覓食也會這樣做。

Corcoran and his colleagues recorded Mexican free-tailed bats, Tadarida brasiliensis, echolocating in the wild. And they happened to pick up a sound bats made only when other bats were hunting. [jamming clip] It reminded them of the moth jamming call. So they played back that sound to bats hunting tethered moths, in a field experiment. And sure enough—bats who heard the bat jamming call while echolocating, were 70 percent less successful at capturing the tethered moth, than bats who heard a generic tone, [tone clip] or no sound at all. The study is in the journal Science. [Aaron J. Corcoran and William E. Conner: Bats jamming bats: Food competition through sonar interference]

科克蘭和他的同事對墨西哥游離尾蝠在野外回波定位做了記錄。恰巧他們捕捉到了一種蝙蝠們僅在其它同類覓食時才會發出的聲音。【干擾聲音片段】這種聲音會讓它們想起飛蛾的干擾聲。因此在一項野外實驗中，他們對正在狩獵被栓系飛蛾的蝙蝠回放了那段干擾聲。不出所料，正在發出回波定位的蝙蝠當中，聽到該干擾聲的那些蝙蝠捕食該飛蛾的成功率比那些聽到普通聲音【聲音片段】或沒有聽到聲音的蝙蝠低了70%。這項研究刊發在《科學》雜誌上。【亞倫‧J‧科克蘭和威廉‧E‧康納：蝙蝠干擾蝙蝠：通過聲納干擾進行的食物競爭】

Of course, if you have a porch light you may be wondering: aren't there more than enough moths to go around? But here's the thing. "The Mexican free-tailed bat has the largest colonies of any mammal on the planet except for humans—with up to a million individuals. So yeah, there's a lot of insects out there but there's a lot of bats to compete with, so they have to find ways to one-up each other basically." Tricky. A real fly-by-night operation.
當然，如果你家有玄關燈的話你也許就會好奇了: 難道沒有足夠的飛蛾讓蝙蝠捕食嗎?事實是這樣的：「在地球上，墨西哥游離尾蝠是除人類以外遍佈最廣的哺乳動物——其個體多達一百萬。的確，世上有非常多的昆蟲可供捕食，但同樣也有很多蝙蝠在競爭。所以蝙蝠們不得不想出勝人一籌的辦法。」真是狡猾!一個多麼典型的騙子手段!