老鹰如何瞄准空中成群的猎物？（下）

So Taylor and his team positioned video cameras strategically around the cave.

泰勒和他的团队策略性地在洞穴周围安置了摄像机。

And that found that--from the bat’s point of view--swarming did, indeed, reduce a given individual’s risk of being nabbed.

研究发现，从蝙蝠的角度来看，集结成群确实降低了特定个体被捕获的风险。

But what we also found was that the hawks were no less successful at catching bats that were flying in the swarm than they were at catching lone bats.

不过，我们还发现，老鹰捕捉集群飞行的蝙蝠并不比它们捕捉单独飞行的蝙蝠逊色。

What that suggests then is that the hawks are not suffering from any kind of "confusion effect".

这表明老鹰没有受到任何“混淆效应”的影响。

But how do the hawks avoid getting visually disoriented when they’re trying to snag a single bat from a sea of erratically flapping wings?

当老鹰试图从一群时不时扇动翅膀的蝙蝠中抓住单只蝙蝠时，它们如何避免视觉上的迷失呢?

To find out, the researchers compared the trajectories of both predator and prey.

为了找到答案，研究人员比较了捕食者和猎物的轨迹。

And they saw that attacking a swarm requires a different strategy than stalking an isolated individual.

他们发现，攻击集群动物需要的策略与跟踪单个的动物不同。

If you analyze the way in which a hawk chases after a single target, it really closely follows the twists and turns that the target makes as it tries to evade the hawk.

如果分析老鹰追逐单个捕猎目标的方式，会发现老鹰会紧紧跟随目标的迂回曲线（当努力躲避老鹰时，捕猎目标会这样飞）。

But not so when you’re going for the swarm.

但当快要追上目标时，老鹰就不这么飞了。

Instead, the best model of the data was one that said that the hawks simply turned on a constant radius into the swarm, or perhaps more generally were targeting a fixed point in the swarm.

而最优的数据模型是这样的: 老鹰只是在一个恒定的半径内进入蝙蝠群，更笼统地说，它们的目标是集群蝙蝠中的一个固定点。

While steering toward this fixed point, the hawk can then reach out with its talons and scoop up any bat that’s flying along the same path.

当老鹰转向这个固定的点时，可以伸出爪子，抓起任何沿着同一路线飞行的蝙蝠。

And because they share the same trajectory, the bat will look to the hawk like it’s not moving at all.

因为老鹰和蝙蝠都有相同的飞行轨迹，所以蝙蝠观察到的老鹰好像根本没有移动。

The part of the swarm that the hawk is headed for is gonna appear effectively stationary compared to the movement of the rest of the swarm.

与蝙蝠群其他部分的移动相比，老鹰飞向的那部分蝙蝠群实际上是静止不动的。

So this provides a mechanism whereby it’s possible for the bird plunging into the swarm to be able to identify which bit it’s gonna hit, but then also to be able to single out a target within that without having to suffer from the "confusion effect"

因此，这就提供了一种机制，凭借于此，老鹰能够俯冲到蝙蝠群中，识别要攻击的部分，同时也能免受“混淆效应”的影响，在其中找出一个目标。

Taylor says the same should hold true for other predators that hunt prey in large flocks or shoals or murmurations.

泰勒表示，相同的机制也适用于其他在鸟群、鱼群中捕食猎物的食肉动物。

But for now we can safely say that, for Swainson’s hawks, the chaos of the swarm doesn’t seem to make their heads spin, even though it’s totally batty.

但现在我们可以放心地说，对于斯文森鹰来说，混乱的蝙蝠群似乎并没有让它们头晕目眩, 尽管场面非常失控。

For Scientific American’s 60-Second Science, I’m Karen Hopkin.

谢谢大家收听科学美国人——60秒科学。我是凯伦·霍普金。