Processing of clustered sensory signals in gray treefrogs (Hyla versicolor): Behavioral responses in the laboratory and field.

Abstract

Anuran mating choruses may consist of hundreds of sympatric and conspecific males calling in addition to other biotic and abiotic noise, representing a complex auditory scene whose characteristics change with distance. Detecting and localizing individual males in the chorus poses a challenge to the female, especially at long ranges. We carried out a series of recordings and behavioral experiments that are aimed at determining the distance at which female treefrogs (Hyla versicolor) use the chorus as an acoustic cue for their orienting responses. We analyzed natural choruses recorded at distances of 1–100 m and used these to create stimuli for phonotaxis experiments evaluating how the chorus attracts and provides cues for localization by females. In addition, we performed phonotaxis tests in the field near natural choruses to compare the frog’s behavior under laboratory and field conditions. We found that females utilize acoustic cues for orientation toward choruses at a distance up to 50 m, but additional cues may be used to ensure orientation in the field at distances >50 m. Additional experiments revealed that temporal coherence of the male call, as opposed to a general reduction in stimulus intensity, was the most important factor in female phonotactic behavior.