Can the elongated hindwing tails of fluttering moths serve as false sonar targets to divert bat attacks?

It has long been postulated that the elongated hindwing tails of many saturniid moths have evolved to create false sonar targets to divert the attack of echolocation-guided bat predators. However, rigorous echo-acoustic evidence to support this hypothesis has been lacking. In this study, fluttering...

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Bibliographic Details
Published in:The Journal of the Acoustical Society of America 2016-05, Vol.139 (5), p.2579-2588
Main Authors: Lee, Wu-Jung, Moss, Cynthia F.
Format: Article
Language:English
Subjects:
Acoustic Stimulation
Acoustics
Animals
Auditory Perception
Chiroptera - physiology
Echolocation
Feeding Behavior
Moths - anatomy & histology
Moths - physiology
Predatory Behavior
Signal Processing, Computer-Assisted
Sound
Sound Spectrography
Tail - anatomy & histology
Tail - physiology
Wings, Animal - anatomy & histology
Wings, Animal - physiology
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Summary:It has long been postulated that the elongated hindwing tails of many saturniid moths have evolved to create false sonar targets to divert the attack of echolocation-guided bat predators. However, rigorous echo-acoustic evidence to support this hypothesis has been lacking. In this study, fluttering luna moths (Actias luna), a species with elongated hindwing tails, were ensonified with frequency modulated chirp signals from all angles of orientation and across the wingbeat cycle. High-speed stereo videography was combined with pulse compression sonar processing to characterize the echo information available to foraging bats. Contrary to previous suggestions, the results show that the tail echoes are weak and do not dominate the sonar returns, compared to the large, planar wings and the moth body. However, the distinctive twisted morphology of the tails create persistent echoes across all angles of orientation, which may induce erroneous sonar target localization and disrupt accurate tracking by echolocating bats. These findings thus suggest a refinement of the false target hypothesis to emphasize sonar localization errors induced by the twisted tails, and highlight the importance of physics-based approaches to study the sensory information involved in the evolutionary arms race between moths and their bat predators.
ISSN:0001-4966
1520-8524
DOI:10.1121/1.4947423