科学美国人60秒 SSS 一些乌鸦会攻击死去的同伴（在线收听）

This is Scientific American — 60-Second Science. I'm Jason G. Goldman.

这里是科学美国人——60秒科学。我是杰森·古德曼。

Crows react really strongly to one of their own being dead—including gathering around their deceased comrades. Some experts believe that these so-called crow funerals are efforts to learn. Perhaps so they can avoid the same fate.

乌鸦对自已同伴死亡的反应非常强烈，包括聚集在死去同伴的周围。一些专家认为，这些所谓的乌鸦葬礼是它们在努力学习。也许这样它们就可以避免同样的命运。

University of Washington researcher Kaeli Swift is one of those crow experts. When a film crew came to her campus to record these behaviors, Swift and her colleagues placed a dead crow on the grass. And they waited for the crows to show up and investigate. Just as they had done hundreds of previous times.

华盛顿大学的研究员凯莉·斯威夫特就是持这种观点的其中一名乌鸦专家。当一个摄制组来到华盛顿大学拍摄乌鸦的这些行为时，斯威夫特和同事将一只死乌鸦放在了草地上。他们等待乌鸦出现，然后研究它们的行为。就像他们以前做过的数百次实验一样。

"The first bird came in, like they do, and I'm bracing myself for what I'm expecting to be the typical response. Which is that it alights in a tree, and it alarm calls, and then other birds come in...but instead what it does is it flies down to the ground, and it kind of walks up to the crow...but then it goes into really typical crow precopulatory posturing. Where basically they kind of drop their wings down, and they stick their tails up, and they strut. And it just struts on over to the dead crow and jumps on top and copulates with it."

“第一只如往常一样飞了过来，我做好准备，等待我期待出现的那种典型反应。就是乌鸦从树上飞下来，发出警报声，然后其他乌鸦听到警报后赶过来，但那只乌鸦没有这样做，它的确飞到了地上，然后走向死去的同伴，可是随后它做出了典型的交配前姿势。基本上来说，这种姿势就是乌鸦垂下翅膀，翘起尾巴，然后趾高气扬地走。它趾高气扬地向死乌鸦走去，然后跳到死去同伴的身上和它交配。”

Neither Swift nor her advisor had ever heard of this behavior. So they decided to determine just how common it is by conducting a series of experiments with wild crows in Seattle. They saw that most crows don't touch their dead—they observed physical contact roughly a quarter of the time. And sexual contact occurred less than five percent of the time. The finding is in the journal Philosophical Transactions of the Royal Society B.

斯威夫特和她的导师从来没有听说过这种行为。因此，他们决定对西雅图野生乌鸦进行一系列实验，来确定这种行为的普遍性。他们发现，大多数乌鸦不会触碰死亡同伴，他们观察到的身体接触率约为25%。性接触的发生率不足5%。这项研究结果发表在《英国皇家学会B辑·哲学学报》上。

There's a twist that may be instructive: the crows' sexual behaviors were often combined with aggressive ones—not something that usually happens during mating encounters. And this was most frequent early in the breeding season. The researchers therefore wonder if some extremely hormonal crows may be unable to suppress one set of behaviors while expressing the other.

这里有一个可能具有启发意义的转折：乌鸦的性行为通常与攻击性行为相结合——而不是在交配偶遇过程中经常发生的事。这在繁殖早期最为频繁。因此研究人员想知道，某些受极端荷尔蒙影响的乌鸦是否在表达一系列行为时无法抑制另一系列行为。

"Maybe these birds, because of these hormonal influences, are so incredibly territorial, they're so quick to take advantage of any opportunity for an extra-pair copulation, which is something we know crows engage in...but the part about this that makes it so exciting is we were actually able to quantify how frequent this behavior is. And that's completely brand new to science in any vertebrate animal."

“也许因为受到这些荷尔蒙的影响，这些乌鸦的地盘意识变得极强，它们会迅速利用一切机会进行配偶外交配，我们知道乌鸦会这样做，但是这件事如此令人兴奋的原因是，我们可以量化这种行为的频繁程度。这对任何脊椎动物学来说，都是全新的发现。”

Thanks for listening for Scientific American — 60-Second Science. I'm Jason G. Goldman.

谢谢大家收听科学美国人——60秒科学。我是杰森·古德曼。