Effect of echo flow on bat behavior

Michaela Warnecke

Differences in perceived optic flow stimuli have been shown to influence flight behavior in some visual animals (e.g. Srinivasan et al., 1996). How acoustic flow may alter behaviors, on the other hand, has not been extensively studied. I am interested in how the bat perceives and processes the continuously changing acoustic information during flight. Inspired by research investigating optic flow, I built a corridor of wooden poles, each of which can be individually moved. This experimental setup allows me to construct two corridor walls that each have different spacing between the poles, and will thus return different sound profiles to the bat in flight.

In recent work with this paradigm, I manipulated the corridor walls to present the bat with two baseline (both corridor walls (1) have sparse pole spacing, (2) or dense pole spacing) and two experimental (one wall has sparse, the other wall has dense pole spacing and vice versa) conditions. Our findings show that bats center their flight path in the baseline condition and show wall-following behavior in the acoustically imbalanced conditions towards the sparsely-spaced corridor wall. We also found that bats did not adapt their flight speed or call rate across corridor conditions, and emitted mostly sonar sound groups when navigating the different corridor conditions.

While this experiment describes behavioral adaptations to different kinds of acoustic flow patterns, it does not explain whether bats make these flight path adaptations in order to balance the echo flow from the two sides of the corridor (as has been shown for the effect of optic flow in visually-guided animals), or whether they simply steer away from the more echoic side of the corridor. I have since extended this experiment to include different bat species, corridor manipulations, and neural recordings to answer that question.

References

Warnecke M, Lee W, Krishnan A and Moss CF (2016). Dynamic echo information guides flight in the big brown bat. Front. Behav. Neurosci. 10:81. doi:10.3389/fnbeh.2016.00081

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