Calling louder and longer: How bats use biosonar under severe acoustic interference from other bats

Eran Amichai, Gaddi Blumrosen, Yossi Yovel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Active-sensing systems such as echolocation provide animals with distinct advantages in dark environments. For social animals, however, like many bat species, active sensing can present problems as well: when many individuals emit bio-sonar calls simultaneously, detecting and recognizing the faint echoes generated by one’s own calls amid the general cacophony of the group becomes challenging. This problem is often termed ‘jamming’ and bats have been hypothesized to solve it by shifting the spectral content of their calls to decrease the overlap with the jamming signals. We tested bats’ response in situations of extreme interference, mimicking a high density of bats. We played-back bat echolocation calls from multiple speakers, to jam flying Pipistrellus kuhlii bats, simulating a naturally occurring situation of many bats flying in proximity. We examined behavioural and echolocation parameters during search phase and target approach. Under severe interference, bats emitted calls of higher intensity and longer duration, and called more often. Slight spectral shifts were observed but they did not decrease the spectral overlap with jamming signals. We also found that pre-existing inter-individual spectral differences could allow self-call recognition. Results suggest that the bats’ response aimed to increase the signal-to-noise ratio and not to avoid spectral overlap.

Original languageEnglish
Article number20152064
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1821
StatePublished - 23 Dec 2015


  • Acoustic interference
  • Biosonar
  • Echolocation
  • Jamming-avoidance
  • Lombard effect


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