Signaling Behavior: Contributions of Different Repertoires
W. John Smith
University of Pennsylvania
The communication of dolphins and other cetaceans is clearly elaborate. Nonetheless, it remains difficult to describe the basic components of their signaling behavior in ways that reveal how this elaboration is achieved.
Because dolphins are difficult to observe, it may be useful to seek guidance from comparative research on other kinds of animals. Cetacean communication is unlikely to be unique in all ways, even though the phylogenetic lineage is markedly distinctive. Whatever features of communication are so basic as to be shared by diverse kinds of mammals, and shared even with birds and other vertebrates, also should be characteristic of dolphins.
At the most basic level, comparisons among species suggest that the diversification of signaling behavior is organized within a number of repertoires. Each repertoire is a distinct class of specializations. Only in the first repertoire can a unit be a single act of an individual performer. These signaling acts--vocalizations, postures, ways of depositing pheromones, and so on--are the basis of the formalized communication of any species. The units of the other repertoires are performed by varying and combining the basic signaling acts or by interacting in rule-bound ways--the signal units then being joint productions of the participants.
The overall richness of dolphins' or any other species' communication depends both on the extent to which each of the repertoires is diversified and on the ways the repertoires can be combined during actual interactions. In this chapter I attempt to describe the distinctive characteristics of each kind of signaling repertoire, as we are beginning to understand them through research on various species of birds and mammals. A few tentative suggestions are offered for research on the communication of dolphins.