Fast-moving bat ears create informative Doppler shifts

Abstract

Significance Many animal species are known for unparalleled abilities to encode sensory information that supports fast, reliable action in complex environments, but the mechanisms remain often unclear. Here, we present a nonlinear principle for sensory information encoding in bats. Through fast ear motions, bats can encode information on target direction into time-frequency Doppler signatures. These species were thought to be evolutionarily tuned to Doppler shifts generated by a prey’s wing beat. Self-generated Doppler shifts from the bat’s own flight motion were, for the most part, considered a nuisance that the bats compensate for. Our findings indicate that these Doppler-based biosonar systems may be more complicated than previously thought because the animals can actively inject Doppler shifts into their input signals.