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This Caterpillar¹ Whistles While It Irks

毛虫会吹口哨？还是一种恐吓战术？

Songbirds produce a rich repertoire² of sounds: songs, of course, but also chatter³ calls, flight calls and alarm calls: like this high-pitched warning from a black-capped chickadee: < seet call >. But chickadees aren't the only ones endowed with chirping⁴ abilities. Turns out a certain type of caterpillar can, too. < caterpillar whistle > Once again, the bird, then the caterpillar. <seet call, caterpillar whistle > Sounds pretty darn similar.

鸣禽能发出各种丰富的声音：包括歌唱，交流鸣叫、飞行鸣叫和警报呼叫。比如黑顶山雀发出的高音警告。但山雀并非唯一拥有鸣叫功能的动物。事实证明，某种类型的毛虫也拥有这种能力。再听一次，先是鸟鸣，然后是毛虫发出的声音。（两种声音）听起来非常像。

\"Yeah it's pretty crazy." Jessica Lindsay is a biologist at the University of Washington. She says this species, the North American walnut⁵ sphinx caterpillar, makes the sound using tiny pairs of breathing holes, called spiracles. "They compress themselves lengthwise like an accordion⁶ and so that compression pushes air out of the spiracles, making whistling sounds."

“是的，这很疯狂。”杰西卡·琳赛是华盛顿大学的一名生物学家。她说，北美胡桃木毛虫这一物种，通过被称为“气门”的微小的呼吸孔发出此种声音。“他们像手风琴一样把自己压缩得很长，这种压缩会把空气从气门里吹出来，发出吹口哨的声音。”

A cool coincidence, for sure. But here's where it gets interesting. Lindsay then played the caterpillar whistle through a speaker near a bird feeder. And the birds—of many different species—dove for cover. "Sometimes we'd see nuthatches flicking⁷ their wings, which is a big sign of distress⁸ for them. Sometimes it would take a really long time to return to feeding, which is a big indicator⁹ that they were taking that whistling noise pretty seriously."

当然，这只是一个很酷的巧合。但有一个很有趣的现象。琳赛在一个喂鸟器近用一个扬声器播放了毛虫的口哨声。这时，黑顶山雀以及其他许多不同种类的鸟都纷纷去寻找掩护。“有时我们会看到五子雀拍打着它们的翅膀——这对它们来说表示巨大不幸的信号。有时鸟儿们需要很长时间才能恢复进食——这在很大程度上表明它们把毛虫的口哨声当真了。”

And whereas the birds were unperturbed by the song of a house finch—a control sound—they responded to the caterpillar whistles with almost the same urgency as when they heard that real alarm call <seet call> from a chickadee. Suggesting the caterpillars¹⁰… are onto something. "They're basically using bird speak to say that there's a dangerous predator¹¹ in the area and that the birds better get into cover."

然而，鸟儿们却没有受到家朱雀歌声的干扰——一种控制声音。它们听到毛虫发出的哨声做出的紧急反应，与它们听到黑顶山雀发出的真正的警报呼叫时反应几乎相同。这就说明毛虫……在表达一些信息。“基本上，它们就是在用鸟类的语言说，这里有一个危险的捕食者，鸟儿们最好赶紧找掩护。”

Lindsay presented the results at the International Symposium¹² on Acoustic¹³ Communication by Animals in Omaha.

琳赛在奥马哈举行的国际动物声学传播研讨会上展示了这一结果。

Previous work suggests the caterpillars whistle when pecked at by birds. And they sometimes squeal¹⁴, too: <caterpillar squeal> Suggesting they may have more than one scare tactic¹⁵, to worm their way out of trouble.

之前的研究表明，毛虫在被鸟儿啄食时就会发出口哨声。它们有时也会尖叫。这表明它们可能会用不止一种恐吓战术来摆脱麻烦。