Eavesdropping for food

Echolocating bats emit auditory signals with foraging that can be detected and used by other bats in the neighborhood. For example, feeding buzzes, those rapid terminal pulses emitted when prey in detected, might alert nearby bats to a potential food source. This appears to be the case in the lesser bulldog bat (Noctilio albiventris) in Panama.

Figure 1. A group of bats emerge from a cave to begin foraging. (Photo by Adam_d)


These bats live in small social units and forage over water for swarms of insects. Because lesser bulldog bats forage for only a few hours each night, and their prey is unevenly distributed over large areas, they must forage very efficiently. Dechmann and colleagues (2009) used playback experiments to demonstrate that feeding buzzes attracted other lesser bulldog bats to the area. Thus, these bats employ eavesdropping as a strategy to minimize the costs of foraging for unpredictable prey.

Because N. albiventris are social, the researchers predicted that members of the same social unit would forage together. Indeed, radio-tracking showed that female lesser bulldog bats departed the roost as a group and foraged together. Thus, group members are more likely to benefit from eavesdropping. These results suggest that passive information transfer (eavesdropping) may play an important role in social foraging mammals.


References

Dechmann, D.K.N., Heucke, S.L., Giuggioli, L., Safi, K., Voigt, C.C., and M. Wikelski. 2009. Experimental evidence for group hunting via eavesdropping in echolocating bats. Proceedings of the Royal Society B, 276, 2721-2728.