Fig 1.
Two representative advertisement calls from four male Panamanian golden frogs showing qualitative differences in pulse patterns and dominant frequency distribution.
The first few pulses of a call are spaced out more than the remaining pulses and can therefore be identified in the spectrogram (arrows). Each call sound is depicted as a time waveform (top panel) and spectrogram with an accompanying spectrum (lower panel). “Level” indicates the relative change in output voltage of microphone signal. The spectrogram illustrates the spectral content over time. The adjacent spectrum was calculated over a 50-ms segment from the middle of each call and overlaid with the LPC function.
Table 1.
Raw data (mean ± stdev) for 13 individual Panamanian golden frogs belonging to two populations (A-, and S-population).
Table 2.
Mean within-male (CVw) and between-male (CVb) coefficients of variation, the CVb/CVw ratio and the results of model II ANOVAs examining between-male variability (13 males; 20 calls per male) in Panamanian golden frogs.
Fig 2.
Plot of the advertisement calls of 13 individual male Panamanian golden frogs in a two-dimensional signal space defined by the first two canonical scores with 95% confidence ellipses for each population.
The frogs belong to two populations (A and S) which differ in body size, skin coloration, and location of origin.
Fig 3.
Relationship between snout-vent-length and body mass (A), fundamental frequency (F0) (B), pulse interval (C), first (D) and second dominant frequency (E), and call duration (F).
The lines represent linear regression lines, with equations and r2 given in each case.
Fig 4.
A: Vocal activity (calls/hour) over a 13 month period between December 2019 and December 2020. Grey area indicates the 12 h dark phase. B: Periodogram analysis of the 13 month vocal activity. The red line indicates the critical value of 0.01 level. As expected, a 24 h period was significant. A 12 h period was also significant, although less prominent. The 12 h period depicts two peaks of high vocal activity, one between 0600 and 1200 and a second after 1500.
Fig 5.
Vocal activity of a Panamanian golden frog colony and climate data.
Vocal activity was measured in the colony at Maryland Zoo in Baltimore (MZIB) and averaged over two hours (A). Temperatures (B) and humidity (C) were available at MZIB and from weather stations near the natural habitat in Panama.
Fig 6.
Human presence reduces vocal activity.
A: Time waveform (top panel, level, relative change in output voltage of microphone signal) and spectrogram (bottom panel) of one hour of sound recording. Note that at about 1015 (red arrow), personnel enter the room and begin daily routines. The regular vertical patterns before 1015 depict frog calls. The broadband patterns after 1015 are generated by human activity. B: Actograms of average vocal activity during the months of November 2020, May 2021 and November 2021 with regular personnel activity between about 0900 and 1200 and between 1300 and 1600 (black). Dashed line box indicates regular personnel activity in the frog room. The paired actograms (grey) show vocal activity during a single 24 hour period in their respective months when personnel schedule was altered to 2 hours between 1400 and 1600. Note that vocal activity remained very high between 0600 and about 1400.
Table 3.
Average vocal activity (calls/hour) (mean and standard deviation averaged over 6 hours) between 0900 and 1500 and between 0100 and 0700 on regular and alternative days.