Echolocating bats can adjust sensory acquisition based on internal cues

Arjan Boonman,Aya Goldshtein,Eran Amichai,Stefan Greif,Itai Rieger,Yossi Yovel,Ofri Eitan

doi:10.1186/s12915-020-00904-2

Abstract

BackgroundSensory systems acquire both external and internal information to guide behavior. Adjustments based on external input are much better documented and understood than internal-based sensory adaptations. When external input is not available, idiothetic—internal—cues become crucial for guiding behavior. Here, we take advantage of the rapid sensory adjustments exhibited by bats in order to study how animals rely on internal cues in the absence of external input. Constant frequency echolocating bats are renowned for their Doppler shift compensation response used to adjust their emission frequency in order to optimize sensing. Previous studies documented the importance of external echoes for this response.ResultsWe show that the Doppler compensation system works even without external feedback. Bats experiencing accelerations in an echo-free environment exhibited an intact compensation response. Moreover, using on-board GPS tags on free-flying bats in the wild, we demonstrate that the ability to perform Doppler shift compensation response based on internal cues might be essential in real-life when echo feedback is not available.ConclusionsWe thus show an ecological need for using internal cues as well as an ability to do so. Our results illustrate the robustness of one particular sensory behavior; however, we suggest this ability to rely on different streams of information (i.e., internal or external) is probably relevant for many sensory behaviors.

Highlights

Sensory systems acquire both external and internal information to guide behavior
Doppler shift compensation in bats is a prime example of a sensory adjustment [4]
Three of the four bats flew for a few minutes (117 ± 69 s,) more than 40 m above ground, which should disable any echo reception (Fig. 1a, b). This finding shows that R. ferrumequinum bats find themselves deprived of echoes almost on a nightly basis

Summary

Introduction

Sensory systems acquire both external and internal information to guide behavior. Adjustments based on external input are much better documented and understood than internal-based sensory adaptations. Constant frequency echolocating bats are renowned for their Doppler shift compensation response used to adjust their emission frequency in order to optimize sensing. Sensory systems must constantly adjust according to the information they receive to improve sensory acquisition How they do so have mostly been studied in the context of external input. It was reported in Rhinolophus ferrumequinum that if the temporal overlap between signal emission and echo reception is smaller than about 50%, bats will not Doppler compensate. This suggests that these bats compare the frequencies of the emitted signal and the received echo, depending on echoic feedback for proper sensing [11]

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Conclusion