The short version
- Bats flying together risk jamming each other’s sonar, and a Japanese team found they nudge their call frequencies apart to avoid it.
- The experiment recorded 11 eastern bent-winged bats flying alone while researchers played interfering sounds at them.
- A computer model built on one simple rule reproduced the shifts and showed a group spreading its frequencies, though real flocks were not tested here.
A bat hunting alone hears its own echoes. A bat in a flock hears everyone’s. A study in Proceedings of the Royal Society B, published online October 1 and written up by Phys.org on November 4, looks at how eastern bent-winged bats (Miniopterus fuliginosus) avoid jamming each other. Kazuma Hase of the University of Toyama and colleagues at Doshisha, Nagoya and Meiji universities fitted 11 bats with tiny wireless microphones. Each bat flew alone while the team played interfering sounds that varied in loudness, pitch and timing. The bats shifted their call frequencies in response.
The team then built a “leaky-integrator” model, which adds up the sounds a bat hears over time while letting older ones fade. Its key assumption is that bats react more strongly to calls lower in pitch than their own than to higher ones. Simulated flocks flying in two dimensions spread their frequencies apart, which matches earlier observations of real groups, and made fewer detection errors. “The group dynamics of echolocation frequency shifts can be explained by simple individual rules,” Hase told Phys.org. The Doshisha group also ran the mother-bat heart-rate study we covered in October.
The flock result comes from simulation, not from recordings of bats flying together, and neither the abstract nor the write-up gives the size of the frequency shifts.
