Do Green Treefrogs (Hyla cinerea) Eavesdrop on Prey Calls?
Efficient foraging may be facilitated by attending to the signals produced by potential prey items. Such predatory eavesdropping is taxonomically widespread, yet there is currently a dearth of information for amphibians. Anuran amphibians, with their highly developed auditory system and robust phonotaxis toward advertisement calls when searching for mates, seem predisposed to use this hearing capability in other behavioral contexts such as foraging. We conducted playback experiments to test whether Green Treefrogs (Hyla cinerea) eavesdrop on sexual signals of prey (House Cricket [Achaeta domesticus] song), or whether the presentation of acoustic prey stimuli in addition to a live cricket improved prey localization. We found that frogs did not use acoustic prey signals to guide their foraging movements. Frogs were not indifferent to acoustic stimuli, however, because they moved away from the sound source in some treatments.Abstract
Responses of Green Treefrogs when presented with cricket song (Cr), noise (N), and silence (S), in the absence (left) and presence (right) of a cricket in jar. Initial (A) and final (B) orientation was never directional toward the speaker presenting treatment stimuli. Speaker position at 0°; orientation measured as angular deviation (least square means ± SE). Post hoc Tukey's honestly significant difference tests indicate that final orientation during playbacks of cricket song and silence was significantly different from each other, whereas orientation during playback of noise was intermediate and not significantly different from the behavior in response to either cricket song or silence. (C) Response time differed across treatments; response time data are inverse transformed such that higher values indicate faster speed.
Polar diagrams showing the final orientation angles in relation to the position of the speaker (at 0°; top of diagram); each dot represents one frog; treatments in which orientation angles were significantly clustered are indicated by an arrow denoting the length and direction of the mean vector. Note that frogs moved randomly in the silent treatments but oriented away from the sound source in most trials involving acoustic playback.
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