當飢餓的蝙蝠飛滿夜空，被牠們視為美味的大虎蛾，如果模仿難吃的近親蛾類的聲音，可以增加自己存活的機率，根據位於北卡維克福思特大學（Wake Forest University）的一份最新報告。
刊登於29日美國國家科學院院刊的研究，首次記錄動物如何利用模仿音效（acoustic mimicry）作為他們的防禦策略。該研究是由維克福思特大學生物學博士生芭爾巴（Jesse Barber）和生物教授康爾（William Conner）共同發表。
大虎蛾針對蝙蝠定位獵物使用的聲納，而製造他們自己微聲納的敲響聲（clicks）。敲響聲是由蛾的一對鼓膜（tymbals）發出來的。許多大虎蛾類使用鼓膜製造特定聲音，以警告蝙蝠他們是不好吃的那類蛾。其他種類則製造近似於那種高頻率的音效。
芭爾巴表示，「我們發現蝙蝠不會捕獵那些好吃的、但發出高頻率音效的蛾類。」她進行4年的研究當中，錄製每隻蛾發出的聲音，也包括蝙蝠的音效。
蝙蝠一吃到不可口的蛾，就會很快學到要遠離它們，並將蛾發出的警示音效與難吃連結在一起。第二次蝙蝠就會避免捕抓發出同種音效的蛾，即使這次發出音效的是好吃的蛾類。
芭爾巴表示已有證據顯示蛇、貓頭鷹和蜜蜂等動物也會利用類似的模仿音效。
In a night sky filled with hungry bats, good-tasting tiger moths increase their chances of survival by mimicking the sounds of their bad-tasting cousins, according to a new Wake Forest University study.
Published in the May 29 issue of the "Proceedings of the National Academy of Sciences," the study is the first to show how an animal species uses acoustic mimicry as a defensive strategy. The research was conducted by Jesse Barber, a doctoral student in biology at Wake Forest and the study was co-authored by William Conner, professor of biology at Wake Forest.
In response to the sonar that bats use to locate prey, the tiger moths make their own ultrasonic clicks. They broadcast the clicks from a paired set of structures called "tymbals."
Many species of tiger moth use the tymbals to make specific sounds that warn the bat of their bad taste. Other species make sounds that closely mimic those high-frequency sounds.
"We found that the bats do not eat the good-tasting moths that make the similar sounds," said Barber, who has worked on this research for four years. He recorded the sounds emitted from each moth, as well as the sounds made by the bats.
All the bats quickly learned to avoid the noxious moths first offered to them, associating the warning sounds with bad taste.
The bats then avoided a second sound-producing species of moth even though it was not noxious-tasting but only made the same warning sounds.
Barber said anecdotal observations indicate that animals such as snakes, owls and bees also use acoustic mimicry.
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