The units of perception in the antiphonal calling behavior of cotton-top tamarins (Saguinus oedipus): Playback experiments with long calls

We investigated how the acoustic structure of the cotton-top tamarin monkey's (Saguinus oedipus) combination long call relates to the antiphonal calling behavior of conspecifics. Combination long calls can function as contact calls and are produced by socially isolated individuals. Often conspecifics respond to these calls with their own long calls. Structurally, these calls are always composed of one or more 'chirps' followed by two or more 'whistles'. We compared the antiphonal calling responses to playbacks of complete, naturally produced long calls versus single whistles or single chirps. Subjects responded significantly more to whole calls than to either syllable-type alone. Thus, our data suggest that, in terms of the antiphonal calling behavior of socially isolated conspecifics, the whole long call is the unit of perception.