Identifying and Characterizing Signature Whistles Using Photo-Identification of Free-Ranging Bottlenose Dolphins (Tursiops truncatus) in Tampa Bay, Florida

Abstract

The common bottlenose dolphin (Tursiops truncatus) uses vocal learning and acoustic signals within their highly social, fission-fusion lifestyle. When communicating with other individuals, they often use individually distinctive vocalizations called “signature whistles” that function in conspecific recognition. The objective of this study was to identify signature whistles in a population of bottlenose dolphins in Tampa Bay and use photographic identification to link potential individuals with specific sig-nature whistles. Acoustic recordings from 2009 to 2023 were manually analyzed using the SIGnature IDentification (SIGID) method. Thirty-three unique signature whistles were identified. Whistles were categorized based on their frequency contour, duration, and maximum frequency ranges. A minimally invasive method was used to align dolphin identifications with signature whistles. Using concurrent acoustic and dorsal fin photo-identification data, we potentially attributed signature whistles to two resident dolphins. In addition, group size was tested as a predictor variable for total signature whistle and unique signature whistle presence, which were both found to decrease as group size increased. This study helps us to understand the acoustic communication of this highly resident population of bottlenose dolphins, and it further highlights the importance of acoustic communication for this population in an increasingly urbanized and noisy environment.