This moth is the first known animal that can actively fend off enemies with ultrasound tones. Photo: William Conner
Reading Folders ward off bat attacks with a kind of ultrasonic clicking sound that disturbs the echosounders of these enemies. The robbers can not locate their prey with it, and most of their attacks remain unsuccessful. So far it was known that certain species of butterflies can hear the sounds of bats and react to them. However, scientists have not yet realized that they can protect themselves by actively disrupting the locating signals. Bertholdia trigona, a nocturnal butterfly of the marten family, is a favorite prey of the great brown bat Eptesicus fuscus. Both occur together in large areas of Central America up to northern Colorado in the USA. The researchers competed against butterflies and bats in a room equipped with a high-speed and infrared video camera and an ultrasound microphone. They trained four bats to catch moths tied to a string. The bats were presented both butterflies of the species Bertholdia trigona, as well as those of another species that makes no noise. If the bat had not caught the moth after one minute or five tries, the attempt was unsuccessful.

All bats caught the control moths, which made no noise, much more frequently than the butterflies of the species Bertholdia trigona, the researchers report. On the other hand, when the scientists removed the tympanic organs they needed to create the clicking sounds, the bats were able to catch all the moths. In fact, it is the clicking sounds that lead to the failure of the Great Brown Bat species to catch their prey, the researchers conclude.

Also, the question of whether the butterflies not only disturb their enemies with the noise of the bats, but also scare, the researchers examined in their studies. In this case, however, it would come to a habituation effect, but the researchers could not observe. For other types of butterflies, scientists could not prove this defense mechanism, but he seems to have proven successful for Bertholdia trigona as an effective defense.

Aaron Corcoran (Wake Forest University, Winston-Salem) et al .: Science, doi: 10.1126 / science.1174096 ddp / science.de? Stefanie shrub display

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