老鹰如何瞄准空中成群的猎物？（上）

This is Scientific American's 60-second Science, I'm Karen Hopkin.

这里是科学美国人——60秒科学系列，我是凯伦·霍普金。

Birds of a feather flock together.

拥有相同羽毛的鸟儿聚集在一起(物以类聚)。

And so do bats and fishes and any little critter hoping that getting lost in the crowd will keep them off the evening menu.

蝙蝠、鱼儿以及其他的小动物也是如此，它们希望集群行动能将自己从晚间菜单上划掉。

But predators gotta eat.

但食肉动物必须进食。

So they, in turn, have come up with clever ways to cut through the visual clutter of a churning mass of panicked prey to hone in on their target.

因此，食肉动物也想出了聪明的方法，即冲进一群视觉上看起来惊慌失措、乱成一锅粥的猎物，瞄准它们的目标。

For hawks who forage in massive swarms of bats, the trick, it seems, is to just dive in and grab whatever hapless flier happens to share your trajectory.

老鹰会在群集的蝙蝠中捕食，对于它们来说，诀窍似乎就是俯冲下去，抓住碰巧有相同飞行轨迹的倒霉蝙蝠。

That’s according to a study in the journal Nature Communications.

这是《自然通讯》期刊上的一项研究的内容。

Intercepting even a single maneuvering target is a challenging task in itself.

拦截一个移动目标本身就是一项具有挑战性的任务。

Graham Taylor is a professor of mathematical biology at the University of Oxford.

格雷厄姆·泰勒是牛津大学数学生物学教授。

He got to wondering how predators like hawks and falcons manage to isolate and intercept a moving target when it’s part of a flock or a swarm--a dense aggregation that seems like it would offer optimal protection for the prey.

他开始琢磨，当攻击目标是动物集群的一部分(密密麻麻的聚集似乎可以为猎物提供最佳保护)，像鹰和隼这样的食肉动物是如何分离和拦截一个移动目标的。

For one thing it can reduce your individual risk of coming under attack in the first place.

首先，聚集在一起可以降低个体受到攻击的风险。

And it might also make it harder for a predator to catch you if it initiates an attack at all.

如果食肉动物发起攻击，也难以抓住猎物。

That’s thanks to the so-called “confusion effect.”

这要归功于所谓的“混淆效应”。

Which is the idea that the presence of multiple similar targets makes it harder for a predator to single out and track any one individual.

也就是说，出现多个类似目标会让食肉动物难以挑出任何一个个体，也难以对其实行追踪。

But are swarms as confusing to a hawk as they might seem to you or me?

不过，老鹰会如同你我一样对动物集群感到晕头转向吗？

To find out, Taylor teamed up with Laura Kloepper, a bat biologist at Saint Mary’s College in Indiana, and headed to New Mexico.

为了找到答案，泰勒与劳拉·克洛珀(印第安纳州圣玛丽学院研究蝙蝠 的生物学家)展开了合作，一同前往新墨西哥州。

It’s a very remote location in the Chihuahuan desert where there’s a bat cave from which every evening close on a million Mexican free-tailed bats emerge.

这里是奇瓦瓦沙漠一处极其偏远之地，每天晚上都会有一百万只墨西哥无尾蝙蝠从洞穴里出来。

And waiting for the bats as they emerge in this huge stream that pours out of the cave are a number of Swainson’s hawks, which plunge into the swarm and try and grab bats from it.

当蝙蝠从倾泻而出的巨大溪流中出现时，有许多斯文森鹰在等待它们，这些老鹰冲进蝙蝠群，试图从中抓住蝙蝠。