Am. Nat. 2007. Vol. 169, pp. 409-415. © 2007 by The University of Chicago.
Natural History Miscellany
Cues for Eavesdroppers: Do Frog Calls Indicate Prey Density and Quality?
Ximena E. Bernal,1* Rachel A. Page,1, A. Stanley Rand,2, and Michael J. Ryan1,§
1. Section of Integrative Biology, University of Texas, Austin, Texas 78712;
2. Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Panama
Submitted May 1, 2006; Accepted August 17, 2006; Electronically published
January 11, 2007
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ABSTRACT: Predators and parasites that eavesdrop on the mating signals of
their prey often preferentially select individuals within a prey/host species
that produce specific cues. Mechanisms driving such signal preferences are
poorly understood. In the túngara frog Physalaemus pustulosus, conspecific
females, frog-eating bats, and blood-sucking flies all prefer complex to simple
mating calls. In this study we assess the natural signal variation in choruses
in the wild and test two hypotheses for why eavesdroppers prefer complex calls:
(1) prey quality: complex calls indicate better quality of prey/host, and (2)
prey density: complex calls indicate higher prey/host density. Call complexity
is not correlated with frog length, mass, or body condition, but it does signal
higher abundance of prey/host. Thus, increased effectiveness of attack may have
played a role favoring the preference for complex calls in eavesdropping
heterospecifics.
Keywords: audience, call preferences, communication network, prey
preferences.
* E-mail:
E-mail:
Stan Rand died on November 14, 2005.
§ E-mail:
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