This is Scientific American — 60-Second Science. I’m Annie Sneed.
Feathers are not just for flight. They keep birds warm, become part of their nests, and help them attract mates. And for one Australian bird, feathers even help produce an important sound—an alarm.
"People had long noticed that these birds produced these loud whistles."
Trevor Murray, a postdoctoral researcher at the Australian National University.
"My supervisor Rob Magrath in collaboration with May Hingee thought that they were used as an alarm. So they did some playbacks and they could show quite strongly that if you play back these sounds to other birds, they flee straightaway. So what I was really interested in was following up on that research and finding out how they produce the sound, whether it is actually a signal, and whether it’s a reliable signal."
The team focused their experiment on specific feathers in the crested pigeon’s wing. "We were able to target the eighth primary feather, which is unusually narrow—it’s about half the width of the surrounding feathers. And then we also removed, on different sets of birds, we also removed those neighboring feathers, the ninth primary feather and the seventh primary feather...and we were able to see...that the eighth primary feather, when it was missing, the high note had completely disappeared. So the eighth primary feather produced that high note and the ninth primary feather, it turns out, actually produced the low note."
And if the birds are fleeing from danger, they produce a louder and higher tempo whistle than they do during a normal takeoff. The study is in the journal Current Biology.
Murray and his colleagues did another experiment where they used the recordings they made to observe the reactions of other crested pigeons. "And from this experiment we were able to see that the eighth primary feather, the unusual feather, was actually crucial for signaling alarm. When that eighth primary feather was missing, they very rarely responded. They almost never fled. Whereas when the neighboring feather that produces the other part of the sound, that ninth primary, they actually fled just as much as to normal alarms. This shows us that this unusual primary feather is crucial for signaling alarm, and together that suggests that it has evolved to communicate with its flock mates."
So that birds of a feather can flee together.
Thanks for listening for Scientific American — 60-Second Science. I’m Annie Sneed.
羽毛的作用并不仅仅是飞行 。羽毛还可以让鸟类保暖、筑巢并帮助它们吸引异性 。而对于澳大利亚一种鸟类来说，羽毛甚至可以帮助它们发出一种重要的声音——警报 。
“我的导师罗布·麦葛雷斯及合作者梅·辛吉认为，鸟类将这种口哨声用作警报 。所以他们播放了这些口哨声的录音，结果清晰可见：他们将这些声音播放给其他鸟儿听的时候，这些鸟儿会立刻逃跑 。而我感兴趣的是后续研究，我想查明它们是如何发出这种声音的，那是否是一种信号，以及那是否是一种可靠的信号 。”
该研究团队将实验重点聚焦在冠鸽翅膀上的特殊羽毛上 。“我们的研究对象是第8根主翼羽，这根羽毛非常窄，宽度约为周围羽毛的一半 。随后，我们还去除了多组不同鸟类的周围羽毛，包括第9根主翼羽和第7根主翼羽，我们发现，当第8根主翼羽被去掉后，鸟儿的高音完全消失了 。所以，第8根主翼羽产生高音，而第9根主翼羽则产生低音 。”
如果鸟类正在躲避危险，那它们发出的口哨声要比正常起飞时的音量更高、节奏更快 。这项研究结果发表在《当代生物学》期刊上 。
默里和同事还做了一个实验，他们播放口哨声录音来观察其它冠鸽的反应 。“我们可以从这个实验中了解到，极不寻常的第8根主翼羽是发出警报声的关键 。当没有第8根主翼羽时，鸟儿很少做出反应 。它们几乎不会逃跑 。而缺少产生其他音调的邻近羽毛，即第9根主翼羽时，鸟儿会像听到正常警报一样逃走 。这表明，这根不同寻常的羽毛对发出警报至关重要，同时也显示它已经进化到可以与其它群体同伴进行交流了 。”
谢谢大家收听科学美国人——60秒科学 。我是安妮·斯尼德 。
1. be interested in 感兴趣的；有兴趣的；关心的；
例句：Neither Anna nor I are interested in high finance.
2. follow up on 追踪；
例句：You must be organized and proactive and follow up on everything.
3. flee from 逃离；逃避；
例句：The couple flee from a machete-wielding Jason.
4. communicate with 沟通；联系；交流；
例句：Family therapy showed us how to communicate with each other.