Horseshoe bats (Rhinolophus nippon) suppress clutter noise through echolocation frequency control to detect prey

Efficient information acquisition is essential for survival, and the adaptive adjustment of self-generated signals in active sensing species offers profound insights into how animals solve sensory challenges. Horseshoe bats lower the frequency of their echolocation calls during flight so that echoes remain stable at a reference frequency (f_ref) despite Doppler shifts. Here we reveal a previously unrecognized function: it not only aligns echoes with the most sensitive frequency range but also suppresses background clutter noise to enhance prey detection. Using phantom echo playbacks and on-board recordings, we show that bats compensate for the highest-frequency echoes rather than the strongest ones. This shifts clutter echoes below f_ref, leaving a "silent spectral window" above it. Furthermore, recordings during prey capture and noise playback experiments show that spectral glints from fluttering moth wings appear in this window and are exploited for prey detection, illustrating how sensory systems are shaped for reliable information extraction in cluttered environments.