The communicative content of the common marmoset phee call during antiphonal calling

Abstract

Vocalizations are a dominant means of communication for numerous species, including nonhuman primates. These acoustic signals are encoded with a rich array of information available to signal receivers that can be used to guide species-typical behaviors. In this study, we examined the communicative content of common marmoset phee calls, the species-typical long distance contact call, during antiphonal calling. This call type has a relatively stereotyped acoustic structure, consisting of a series of long tonal pulses. Analyses revealed that calls could be reliably classified based on the individual identity and social group of the caller. Our analyses did not, however, correctly classify phee calls recorded under different social contexts, although differences were evident along individual acoustic parameters. Further tests of antiphonal calling interactions showed that spontaneously produced phee calls differ from antiphonal phee calls in their peak and end frequency, which may be functionally significant. Overall, this study shows that the marmoset phee call has a rich communicative content encoded in its acoustic structure available to conspecifics during antiphonal calling exchanges.

Figure 1

Spectro-temporal structure of marmoset phee calls. A. A spectrogram of a phee call. B. Temporal features measured for all phee calls. Features measured in both the first and second pulses of the phee are noted by ‘p1’ (pulse 1) and ‘p2’ (pulse 2). The mean of each feature is noted with a ‘o’, error bars mark standard deviation. C. Spectral features measured for all phee calls. Features measured in both the first and second pulses of the phee are noted by ‘p1’ (pulse 1) and ‘p2’ (pulse 2). The mean of each feature is noted with a ‘*’, error bars mark standard deviation.

Figure 2

Slopes for phee calls. Slope 1, shown to the left, plots the rising slope (Hz/s) in phee calls that occurs from the pulse onset to the peak frequency. Slope 2, shown to the right, plots the descending slope (Hz/s) from the peak frequency to the pulse onset. Pulse 1 is shown in the black line, while pulse 2 is shown by the grey line.

Figure 3

Discriminant functions for caller identity information. Plots the first and second functions from the discriminant function analysis for ‘Individual Identity’. Squares mark the group centroids for each of the 8 individuals whose calls were analyzed in the study, while colored open circles depict individual vocalizations produced by each individual.