ABSTRACT
The frequency-modulated (FM) whistles of dolphins have received considerable attention from field and laboratory researchers over the last several decades. A large variety of FM patterns has been documented among dolphins (Dreher & Evans, 1964; Caldwell & Caldwell, 1979), and this between-subject variability has led to the conjecture that the whistles are a major component in a system of intraspecies communication. While there is no dispute that the whistles serve in some communicative capacity, the sophistication of that system remains an open question. The variety and relative frequencies of whistles recorded from multiple animals engaged in navigation, play and foraging led Dreher and Evens (1964) to suggest a complex system with some similarities to human language, but the test of such a hypothesis requires the identification of the individual producing the sounds and the order in which they are produced (Wood, 1973). Presently, new technology is being applied with success to the sorting of sounds made by individual animals (Tyack, 1986) and to analysis of the ontogeny of the whistle production (Sayigh, Tyack, Wells, & Scott, 1990).
