Mating call recognition in the barking treefrog (Hyla gratiosa): Responses to synthetic calls and comparisons with the green treefrog (Hyla cinerea)

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1. Eighty-six of 93 gravid females ofH. gratiosa responded in 471 of 566 two-choice experiments; in most experiments synthetic mating calls were used. 2. A synthetic call was as attractive as a typical natural (recorded) call only if it had a distinct pulsatile beginning (Table 1). 3. Females preferred a periodic synthetic call (500/s) over an aperiodic (filtered noise) call, but failed to show a preference between calls with periodicities of 250/s and 500/s (Table 2). 4. Although a bimodal spectrum (greatly attenuated second harmonic) is typical of the mating call ofH. gratiosa, females did not show a preference for a call of 0.50 + 2.00 kHz over one of 0.50 + 1.00 + 2.00 kHz. 5. The most effective high frequency band was about 1.00 to 2.50 kHz; the optimum low-frequency band was about 0.40 to 0.50 kHz (Tables 3, 4, and 5). 6. Females discriminated against calls in which the low-frequency peak (0.40 or 0.50 kHz) was attenuated by 12 dB relative to the high-frequency peak. They discriminated against signals with high-frequency attenuation of 18 to 20 dB only at moderate to high sound pressure levels (Table 6). 7. Results are compared with those of similar studies of the green treefrog (H. cinerea) (Table 7).