【新译 X 世界】NO.58:大自然里的伪装者

In the animal kingdom, mimics are a dime a dozen. Stick insects pretend to be twigs. Hawkmoth caterpillars resemble venomous snakes. Edible heliconius butteflies disguise themselves with the wing patterns of noxious ones, and noxious ones copy each other to make it easier for predators to learn what not to eat.

动物王国里到处都有模仿者。竹节虫会伪装成树枝，天蛾幼虫会伪装成毒蛇，无毒袖蝶会进化出有毒袖蝶的翅膀图案伪装自己，有毒袖蝶则会代代复制身上的图案，躲避天敌的追击。

All these examples, though, are visual. Auditory mimicry is rarer. But, Danilo Russo of the University of Naples Federico II thinks he has found a novel case of it. Some bats, he believes, mimic angry bees, wasps and hornets in order to scare away owls that might otherwise eat them.

不过，所有这些例子都是视觉上的模仿。听觉上的模仿更罕见。但是，那不勒斯费德里克二世大学的达尼洛·罗索认为，他发现了一个听觉模仿的新案例。他相信，有些蝙蝠会为了吓走可能会吃掉它们的猫头鹰而模仿愤怒的蜜蜂、胡峰和大黄蜂的声音。

To test this idea, he and Leonardo Ancillotto, a colleague at Federico II, first recorded the buzzing that captured bats made when handled. Dr. Russo and Dr. Ancillotto recruited the services of 16 captive owls. All of these species are known to hunt bats.

为了测试这个想法，达尼洛·罗索和他的同事莱昂纳多·安西洛托首先记录了蝙蝠被捕捉时发出的嗡嗡声。接着，两人抓来了16只猫头鹰，这些都是会猎食蝙蝠的猫头鹰品种。

The researchers put the owls in an enclosure equipped with branches for them to perch on, and also two boxes with holes in them. The boxes resembled the sorts of cavities in trees that owls would explore in the wild for food. 

研究人员将猫头鹰放进一个房间，里面有树枝拱它们栖息，同时还有两个带洞的盒子。这些盒子是为了模拟猫头鹰在野外觅食时探寻的树洞。

They placed a loudspeaker alongside one of the boxes and, after the birds had settled in, broadcast through it five seconds of uninterrupted bat buzzing and a similar amount of insect buzzing three times in a row for each noise. As a control, they broadcast in like manner several non-buzzing sounds made by bats.

研究人员把扬声器放在其中一个盒子边，猫头鹰进入房间后，扬声器就会分别播放5秒蝙蝠的嗡嗡声和5秒黄蜂的嗡嗡声，一共播放3遍。作为对照，研究人员同样播放了几次蝙蝠发出的其他声音。

The results were unequivocal. When the owls heard both the bat buzzings and the hornet buzzings, they moved as far from the speakers as they could manage. In contrast, when the non-buzzing bat sounds were played, they crept closer.

结果非常清晰，当猫头鹰听到蝙蝠和黄蜂的嗡嗡声时，它们会尽可能地远离扬声器。相比之下，当播放蝙蝠发出的其他声音时，它们会离盒子更近。

Dr. Russo and Dr. Ancillotto believe this is the first reported case of a mammal using acoustic mimicry to scare away a predator. They strongly suspect, however, that it is not unique. Dr. Russo predicts that when other buzzes in this region are recorded and analysed, the results will show that acoustic mimicry by vertebrates of insects is far more widespread than currently realised.

罗索博士和安西洛托博士认为，这是首次报告哺乳动物使用声学模仿吓跑捕食者的案例。然而，他们强烈怀疑这并非个案。罗索博士预测，如果记录和分析该地区的其他嗡嗡声，结果将表明脊椎动物对叮咬类昆虫的声学模仿远比人们目前意识的更普遍。