Bats actively adjust the acoustic features of their sonar calls to control echo information specific to a given task and environment. A previous study investigated how bats adapted their echolocation behavior when tracking a moving target in the presence of a stationary distracter at different distances and angular offsets. The use of only one distracter, however, left open the possibility that a bat could reduce the interference of the distracter by turning its head. Here, bats tracked a moving target in the presence of one or two symmetrically placed distracters to investigate adaptive echolocation behavior in a situation where vocalizing off-axis would result in increased interference from distracter echoes. Both bats reduced bandwidth and duration but increased sweep rate in more challenging distracter conditions, and surprisingly, made more head turns in the two-distracter condition compared to one, but only when distracters were placed at large angular offsets. However, for most variables examined, subjects showed distinct strategies to reduce clutter interference, either by (1) changing spectral or temporal features of their calls, or (2) producing large numbers of sonar sound groups and consistent head-turning behavior. The results suggest that individual bats can use different strategies for target tracking in cluttered environments.
Big brown bats (Eptesicus fuscus) reveal diverse strategies for sonar target tracking in cluttera)
Portions of this work were presented in “Echolocating bats adapt their sonar calls to separate echoes from obstacles and prey,” at the 37th annual meeting of the Association for Research in Otolaryngology, San Diego, CA, February 2014.
Beatrice Mao, Murat Aytekin, Gerald S. Wilkinson, Cynthia F. Moss; Big brown bats (Eptesicus fuscus) reveal diverse strategies for sonar target tracking in clutter. J. Acoust. Soc. Am. 1 September 2016; 140 (3): 1839–1849. https://doi.org/10.1121/1.4962496
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