每日一翻：Bats Jam Rivals’ Sonar to Steal a Meal

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.”

许多蝙蝠在晚上觅食，它们利用回波定位或者声呐来瞄准猎物。那些声波频率只有降低20倍，人类才能听到。但是一些昆虫，比如说虎蛾，可以通过干扰来避开回波定位。它们在超声波被蝙蝠正常捕捉的最后一刻去干扰它。这种对蝙蝠回拨定位的干扰会使蝙蝠无法捕捉到猎物。

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.

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]

科克兰和他的同伴记录了墨西哥无尾蝙蝠游离尾蝠在野外用回声测定猎物方向或位置的过程。他们偶然抓到一只特殊的蝙蝠，这只蝙蝠只在其他蝙蝠觅食的时候才叫。这让他们想到了蛾子的干扰信号。所以在一次野外试验中，他们在蝙蝠捕食被拴着的蛾子的时候播放这种声音，并且确定了用回波定位寻找食物的蝙蝠在听到这个干扰信号后，捕食的成功率比听到正常声音或没听到声音的时候低了70%。这项研究发表在《科学》杂志上。

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.

当然，如果你有一个走廊灯你或许会感到疑惑：难道这周围的飞蛾还不够多？”在地球上，除了人类，墨西哥无尾蝙蝠有比任何动物都大的领地，大概多达100万只。所以，外面有足够的昆虫，但是同样有足够多的蝙蝠来捕杀它们。所以它们必须找到胜过对方的方法。

—Christopher Intagliata