Bats jamming bats: Food competition through sonar interference

Science  07 Nov 2014:
Vol. 346, Issue 6210, pp. 745-747
DOI: 10.1126/science.1259512

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Competing bats jam one another's signal

Animals that live in large social colonies may benefit from many aspects of group living, but also have to contend with many of the downsides of living and foraging, with countless neighbors. Corcoran and Conner show that Mexican free-tailed bats, which live in colonies that can number in the hundreds of thousands, deal with this high level of competition for food by actively jamming competitors' echolocation. The interfering bats produce an ultrasonic signal just as the foraging bat produces its feeding call, effectively jamming the echolocation signal and causing the forager to miss its target.

Science, this issue p. 745


Communication signals are susceptible to interference (“jamming”) from conspecifics and other sources. Many active sensing animals, including bats and electric fish, alter the frequency of their emissions to avoid inadvertent jamming from conspecifics. We demonstrated that echolocating bats adaptively jam conspecifics during competitions for food. Three-dimensional flight path reconstructions and audio-video field recordings of foraging bats (Tadarida brasiliensis) revealed extended interactions in which bats emitted sinusoidal frequency-modulated ultrasonic signals that interfered with the echolocation of conspecifics attacking insect prey. Playbacks of the jamming call, but not of control sounds, caused bats to miss insect targets. This study demonstrates intraspecific food competition through active disruption of a competitor’s sensing during food acquisition.

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