为了骗雌鸟和自己交配，雄鸟竟会表演“狼来了”｜科学60秒
听那燕语莺啼，轻柔悦耳、鸣啭成韵，仿佛都在颂唱着春天的到来。但是你可曾想过鸟儿究竟在谈论什么？也许在说一整个冬天离别后的家长里短，或者是在说：“起开，这是我的地盘。”又或者是在警告同类小心附近的危险，即使啥事也没有。
好吧，如果你认为一只鸟会说“狼来了”听起来很蠢，那一项新的研究可能会让你大跌眼镜：在澳大利亚，某些雄性琴鸟会使用这个技巧来让它们想要追求的雌性再多呆一会儿。结果发表在《当代生物学》（Current Biology）杂志上。
华丽琴鸟以其卓越的声音模仿能力而远近闻名，从鵙（jú）鹟（wēng）优美流畅的旋律，到笑翠鸟那独特的狂笑般的叫声，都能轻松拿下。
雄性华丽琴鸟会将这些令人愉悦的听觉元素编入它们用来吸引配偶的歌曲中。
“黎明到来前它们会一直待在树顶上唱歌，繁殖季甚至会一直唱到黄昏。而它们的独唱会曲目多半是在进行模仿，雄性会轮着模仿不同种类的森林鸟类，循环往复，每一次的模仿又都独树一帜。”伍伦贡大学（University of Wollongong）的博士后阿纳斯塔西娅·达尔齐尔（Anastasia Dalziell）说道，她和同事计划对这个奇特的声学现象进行研究。
“但我们很快就意识到，雄性琴鸟偶尔还会模仿一些完全不同的其他声音。”这种特殊的交替式例行程序出现在雄性琴鸟精心制作的歌舞表演结尾，有点近似一种嗡嗡声，甚至有点烦人，而它完美地再现了鸟群发现捕食者时所发出的警报声。
“这些警报在视觉上很显眼，在声学上也很显著，是环境中存在捕食者的可靠信源。”对人类而言也是如此。“我会利用这些警报、这些鸟群，在实地考察时尽量避免踩到蛇。”
一只雄性琴鸟，就可以模仿出整个事件。“这真是太神奇了，雄鸟甚至能模仿多只小型鸟类的声音，也就是小鸟们飞过或扑向捕食者时翅膀拍打的声音，而且非常逼真。”
那么它们希望通过这种行为来达到什么目的呢？ 达尔齐尔说，这得看它们选择这样做的时机。“我们发现，当真正有捕食者在附近时，雄鸟不会模仿这种鸟群声，根本不会。它们模仿这种危险警报声的唯一情形是在求偶期间，特别是在求偶的关键时刻。”
第一种情形是：雄鸟发自肺腑地表演、用它精心准备的歌曲去取悦雌性，但对方却对它嗤之以鼻时。“当雌鸟走下舞台，也就是雄鸟唱跳求偶的一片圆形森林区域点，当雌鸟准备离开，从舞台上走下来的那一刻，雄鸟就会开始它的危险警报声模仿。”一种暗示附近有捕食者的声音，然而实际上并没有。
“我们认为这可能是雄鸟在说：‘宝，外面很危险……[查看全文]
Male Lyrebirds Lie to Get Sex
The melodious sounds of trills and tweets, whistles and warbles are a harbinger of spring. But do you ever wonder what birds are actually talking about? Maybe they’re catching up after a winter away. Or maybe they’re saying, “Step off, this twig is my territory.” Or maybe they’re signaling that there’s a predator about—even when there isn’t.
Well, if a bird crying wolf sounds silly, a new study shows that in Australia, certain male songbirds use this trick to get females they wish to woo to stick around a little longer. The results appear in the journal Current Biology.
The superb lyrebird, spelled l-y-r-e, is famous for its ability to imitate sounds in its local environment. From the fluid melody of a shrike thrush ... [CLIP: Shrike thrush sound] ... to the distinctive laugh of a laughing kookaburra. [CLIP: Kookaburra sound]
The males weave these aural entertainments into songs they sing to attract mates.
"They sing from the tops of the trees before dawn throughout the day—and even into dusk during the breeding season. And this recital song, most of it is mimicry. The male just reels through imitations of lots of species of forest birds. And they just cycle through them. Each new imitation is different from the rest." Anastasia Dalziell, a postdoctoral fellow at the University of Wollongong. She and her colleagues were planning on studying this impressive acoustical exhibition.
"But we soon realized that, every now and then, the male lyre bird was producing a completely different kind of mimicry." This alternate routine is trotted out at the very end of the male’s elaborate song-and-dance display. It’s sort of buzzy—even somewhat annoying—and it perfectly reproduces the alarm calls made by a mobbing flock of birds that has spotted a predator.
"They’re visually conspicuous. They’re acoustically conspicuous. And they are a very reliable cue of the presence of a predator in the environment." Even for humans. "I use them, mobbing flocks, to try and avoid stepping on snakes while I’m dong my fieldwork in Australia."
And a single male lyrebird can reproduce the whole shebang. "It’s really impressive. The males even manage to imitate the sounds of small birds—the wingbeats of small birds as they fly over or at the predator. It’s very very convincing."
And what do they hope to achieve with this performance? The clue, Dalziell says, came from determining when they choose to do it. "So we found that males didn’t produce this mobbing flock mimicry when a real predator was around—not at all. The only context in which they produced it, the mobbing flock mimicry, was during courtship and particularly at key moments."
The first is when the male has sung his little heart out, entertaining a female with his elaborate and lyrical ballad, but his potential paramour turns up her nose. "And it’s the moment she steps off his display platform, his sort of round circular spot on the forest floor where he does all his song and dances. The moment she attempts to leave, steps off that dancing platform, is when the male switches to his mobbing flock mimicry." A sound that suggests there’s a predator nearby—when really there isn’t.
"So we think this might be a way of the males saying, “Baby, it’s dangerous outside...[full transcript]
扫码关注“领研网”微信公众号
订阅最新“科学60秒”英语新闻
不再漏掉任何一次新知 plus 练耳的机会~