Temporal and spectral characteristics of the two-note vocalization of the male Eleutherodactylus coqui in Hawaii were investigated and measured in order to establish an average source level of the male coqui. We compared various vocalization parameters obtained from previous research in Puerto Rico with similar parameters measured in Hawaii, including note duration, inter-note interval, call repetition period, centre frequency and bandwidth. Digitized sound records of coqui vocalization were used to calculate the root-mean-square of source level for the frog referenced to a 1 m distance for the Co and Qui notes individually and combined. Additional parameters calculated for the vocalizations were difference in the source levels between Co and Qui notes, duty cycle, ratio of Qui to Co note duration and ratio of the Qui to Co centre frequencies. Most of the frog vocalization parameters were sensitive to air temperature displaying significant regressions over a 4°C temperature range (18.6–22.6°C). Surprisingly, the average ratio of Qui to Co centre frequency among n = 55 frogs was 1.81 with a strikingly low standard deviation of 0.07. The coupling of individual variation in Co and Qui centre frequencies producing such low ratio standard deviation is likely due to body mass-related scaling of laryngeal cartilages, vocal chords and muscles responsible for the vocal emission. Co and Qui centre frequency variations can reveal information about the body size of the calling frogs.
acoustic, anuran, Eleutherodactylus coqui , RAVEN, spectral, temporal