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Ravens² Crow with Individual Flair³

There's a well-known conspiracy⁴ of ravens—that's what you call a group of ravens—that likes to hang out near a zoo in the Austrian Alps. Every day these ravens conspire⁵ to steal the food that's set out for the wild boars there.

乌鸦有一个众所周知的秘密——这就是一群乌鸦喜欢在奥地利阿尔卑斯山的动物园附近闲逛。这些乌鸦每天都会窃取那里为野猪准备的食物。

"So we have a really great opportunity to really watch those individuals daily. "

University of Vienna cognitive⁶ biologist Markus Boeckle. He spends lots of time ignoring the zoo animals and watching the ravens.

“所以我们每天都有非常好的机会来真正关注这些人。”维也纳大学认知生物学家Markus Boeckle说。他花费了大量时间来观赏乌鸦，从而忽略了其它动物。

"And what we found is that every time they come they do those food calls, which is very typical for the ravens when they are close to potentially dangerous food resources." [Raven¹ haa call sounds]

“我们发现，每次乌鸦来的时候，都会呼叫，这对乌鸦来说非常典型，因为他们在接近潜在危险的食物资源。”

The ravens use these calls to recruit their buddies⁷ to show up, both to reduce potential dangers from predators⁸ and to overpower dominant⁹ ravens who might be trying to hoard¹⁰ all the food for themselves.But Boeckle and his colleagues began to suspect the calls revealed other information.

乌鸦使用这些呼叫，来招募他们的伙伴，这样既减少了来自掠食者的潜在危险，也能压制可能试图为所有食物囤积自己的主流乌鸦。但Boeckle和他的同事开始怀疑，这些呼叫泄露了其他信息。

"So we had the feeling we could say, this is a juvenile¹¹, this is a sub-adult, and this is most probably an adult, just by listening to the calls."

“所以我们有这种感觉，我们可以说，这是一个未成年乌鸦，这是一个次级成年人，而且这很可能是一个成年乌鸦，只是通过呼叫声就能判断出来。”

If the researchers could use the calls to distinguish among ravens, then perhaps the ravens themselves could do so too. So Boeckle and his team recorded the calls of around a hundred known individuals—all of which had previously¹² been catalogued by weight, age and sex and were identifiable by colored leg bands.

如果研究人员可以使用这些呼叫来区分乌鸦，那么乌鸦自己也可以这样做。所以Boeckle和他的团队，记录了大约一百个已知个体的乌鸦呼叫声——所有这些呼叫声以前都按体重发出的，并按年龄和性别进行了分类，并且可以通过彩色腿带来进行识别。

The researchers combined that data with the acoustic¹³ properties of their calls and dumped everything into a computer program. And as they suspected, there were differences in the frequency, duration, and amplitude¹⁴ of the calls that could sort the ravens according to sex and age. The results were published in the journal Frontiers in Zoology¹⁵. [Markus Boeckle, et al.. Raven food calls indicate sender's age and sex.]

研究人员将这些数据，与其呼叫的声学特性相结合起来，并将所有内容都转化为计算机程序。正如他们所怀疑的那样，根据性别和年龄的不同，乌鸦呼叫的频率，持续时间和振幅可能会有所不同。该研究结果发表在“动物学前沿”杂志上。

"So the benefit is, especially for birds like ravens who travel long distances every day, that whenever you encounter a new individual, or listen to a new individual, you are already able to categorize one of the birds just based on the calls…. So this really helps to assess whether you're going to be in an aggressive situation or whether you're going to be the more dominant individual, just by listening to the call."

“所以，这样做的好处是，特别是像乌鸦这样的鸟类，每天都要长途跋涉，每当遇到一个新的个体，或者听一个新的个体时，你就已经能够根据呼叫，对其中一只鸟进行分类。所以，这真的有助于评估你是否会处于积极的状态，或者是否只是通过呼叫声，会成为更具统治力的人。“

To be clear, the researchers showed that they could categorize ravens according to their calls, not that ravens actually do so. That's what Boeckle and his team are working on now.

需要弄清楚的是，研究人员发现，他们可以根据他们的呼叫对乌鸦进行呼叫，而乌鸦实际上并不是这样做。这就是Boeckle和他的团队现在正在开展的工作。

Still, the study shows that while a call can primarily refer to some external object, like food, it can also transmit additional social information. And since these sorts of calls are thought of as the precursors¹⁶ for language, this study might shed light on how a simple system for communication can evolve into something far more complex—such as me talking to you now.

尽管如此，研究表明，虽然呼叫主要是指某种外部对象，如食物，但它也可以传送额外的社交信息。而且，由于这些调用，会被认为是语言的先驱，本研究可能会阐明一个简单的沟通系统，如何演变成更加复杂的事物 - 比如我现在正在和你说话。