Whistle repertoire of bottlenose dolphins (Tursiops truncatus) in the Mississippi Sound

Abstract

The whistle repertoire of wild bottlenose dolphins (Tursiops truncatus) in the Mississippi Sound, part of the northern Gulf of Mexico, was investigated. There is a large population of dolphins in this area, and many dolphins that are now housed in zoos and aquariums were captured in the Mississippi Sound. This paper reports the types of whistles that are predominant in this area, and how these whistles are used in the context of concurrent surface behavior. Over the course of 1 year (April 2004–March 2005), dolphin whistles were recorded as part of an ongoing study of the effects of human activity on wild bottlenose dolphins. The surface behavior of the focal group was categorized at 1-min intervals as follows: mill, travel, mill/travel, feed, social, with boat, or with shrimp boat. Whistles were then categorized as one of the following: upsweep, downsweep, convex, concave, sine, or constant frequency. Preliminary analysis of the data suggests that both the rate of whistling and the types of whistles produced vary as a function of dolphin behavior. Further analysis of the data will reveal if different types of whistles are associated with specific surface behavior categories. [Research supported by Department of Commerce.]