听力文本

This is Scientific American's 60-second Science. I'm Jason Goldman.
Brown-headed cowbirds are obligate brood parasites. That means they lay their eggs in the nests of other birds, leaving all the hard work of incubating the eggs and feeding the chicks to somebody else. Luckily, many of those other species have evolved some antiparasitic defenses. Yellow warblers, for example, produce a certain type of call to warn other warblers about nearby cowbirds. Researchers call it a "seet" call.
"We were working on the yellow warbler. And whenever we were doing seet call playbacks to the yellow warblers, the red-winged blackbirds kept showing up. That was truly a discovery, this aha moment that allowed us to explore this question even further."
Ecologist Mark Hauber from the University of Illinois at Urbana-Champaign, who ran the study.
The yellow warblers' seet call is called a "referential alarm call," because it is only produced for a single threat: the brown-headed cowbird.
"And in response to the seet call, the female yellow warbler, instead of attacking or mobbing the cowbird, she sneaks back to her nest and sits on it tightly so as to prevent the cowbird from being able to lay a parasitic egg."
Red-winged blackbirds, which sometimes nest near warblers, do not produce referential alarm calls. But it turns out that they can eavesdrop on the yellow warblers' calls. And they respond to the seet calls the same way they do to the sounds of cowbirds themselves. The results were published in the journal Communications Biology.

So red-winged blackbirds prefer to nest near yellow warblers, since the warblers provide additional vigilance against brown-headed cowbirds. But it's probably a two-way street.
"From the literature, we know that yellow warblers do better when they nest near red-winged blackbird territories. And that makes sense because the redwings are really aggressive. If you walk in a reed bed full of redwings, you actually get physically attacked by the redwings. They are not intimidated by large predators. So for the yellow warblers, it makes sense for them to nest near the redwings."
The researchers say that this is the first known evidence of animals eavesdropping on antiparasitic referential alarm calls.
"These birds, yellow warblers and red-winged blackbirds, they speak different languages. They understand their own communication signals and systems. And what we discovered here is, basically, a bilingual red-winged blackbird that can understand the vocalization systems and the communication systems of another species."
Young birds learn their vocalizations much like young humans learn languages. In future research, Hauber hopes to understand whether the birds rely on the same underlying neurobiology to understand the calls of other species as they do when they hear the sounds of their own species—and what that might mean for our own efforts to learn additional languages.
Thanks for listening for Scientific American's 60-second Science. I'm Jason Goldman.

参考译文

这里是科学美国人——60秒科学MBX)=Vm.j;O。我是杰森·古德曼!7YONIFVtM*%r*HfI0s。
棕头牛鹂属于专性巢寄生L6.H~mG1jb)。意思是，它们将卵产在其它鸟类的巢里，抒孵卵和喂养雏鸟的所有辛苦工作都留给别人hNP^bbGFXu。幸运的是，许多其它錑已经进化出一些反寄生的防御能力6i*l~|O]IU[6A。比如，黄莺会发出某种叫声，提醒同类周围有棕头牛鹂MBwXqy=-5!7。研究人员称之为“see”叫声oL+S].[YkRV(。
“我们一直在研究黄莺kIzq.M_A.Q!yMWC。只要我们给黄莺播放seet叫声，红翅黑鹂就会出现@RSuLrmKi2%)WT。这真的是个重大发现，是让我们得以进一步探索这个问题的好时机|i*miAfTz&B*zd。”
负责这项研究的伊利诺伊大学香槟分校的生态学家马克·豪伯说到#|;BqI@M91N+[。
黄莺的seet叫声被称为“指示警报叫声”，因为它只针对一种威胁：棕头牛鹂Non&bK6L~Y2Ng。
“听到seet叫声后，雌黄莺没有攻击或围攻棕头牛鹂，而是偷偷回到巢中，紧紧地坐在上面，防止牛鹂在此产寄生卵3tf&qdoQV8j%9*Y,esm。”
红翅黑鹂有时在黄莺附近筑巢，它们没有发出指未警报叫声ey3j1#,3we]zI7l。但事实证明它们会偷听黄莺的叫声jKF=RY~ZMFY~*2i2zll。听到seet叫声后，它们的反应与听到棕头牛鹂叫声时一样5kCByt[;Ac&UXr。这项研究结果发表在《通讯·生物学》期刊上u7waS](zZ)S!o-4Z。
因此，红翅黑鹂更喜欢在黄莺附近筑巢，因为黄莺能提供对抗棕头牛鹂有额外警戒nhAVKrT1EFUh&qL+XVMP。但这可能是互利互惠的3uzVcYPfDOCU6elw。
“我们从文献中得知，黄莺在红翅黑鹂领地附近筑巢时生活得更好m[t;8gnT02vVQ=Y2vzd。这是有道理的，因为红翼真的很有进攻性5sNT%oY,Ja&。如果你走进满是红翅黑鹂的芦苇草垫，会被它们身体攻击2f#0v8@F9ehY0=ZFu+O。它们不会被大型捕食者吓倒li86G&56|[];6V。因此对于黄莺而言，在红翅黑鹂附近筑巢是有道理的A@)|[4dPd9。”
研究人员表示，这是首个表明动物偷听反寄生指示警报叫声的已知证据TCon]JG.P3^T9@。
“黄莺和红翅黑鹂说的是不同的语言1ZPV&7DW3u~f1-nv。它们懂得自己的通讯信号和系统ZU]RkxQ)zCIHk9I1。我们在这里发现的是，懂双语的红翅黑鹂能理解另一个物种的发声系统和通讯系统j&#XJ^8p18joD*5dY。”
幼鸟学习发声就像年轻人学习语言一样xbsnL%&05-R5S]]CO。在未来的研究中，豪克希望了解鸟类是否像听到同类叫声时一样，依靠同样的潜在神经生物学来理解其它物种的叫声，以及这对我们学习其他语言有何蚁nVZo#.Mm&QzKs*。
谢谢大家收听科学美国人——60秒科学UaoE|xJ]6NK|E3K=p。我是杰森·古德曼UO6UhrG(!8gO。

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重点讲解

重点讲解：
1. show up 出现；露面；
It was getting late when she finally showed up.
天色已晚，她终于赶到了]Z9vWF=NKIdH4f8,Ft。
2. prefer to do sth. 更喜欢；偏好；
It is commonly asserted that older people prefer to receive care from family members.
人们普遍确认，老年人更愿意由家人照顾ayur~[fH,wb@n[[SN。
3. eavesdrop on 偷听；窃听；
I don't like eavesdropping on people talking on the phone.
我不喜欢偷听人家打电话Ng;cuEgKMf6=(f。
4. rely on 依赖；依靠；
Many animals rely on concealment for protection.
许多动物靠藏匿自己来避害jHa0WR99#[wU!5。