First report of signature whistles in an oceanic common bottlenose dolphin (Tursiops truncatus) population from Revillagigedo Archipelago, Mexico

Abstract

AbstractThis study is the first baseline acoustic description of common bottlenose dolphin populations (Tursiops truncatus) from Revillagigedo Archipelago and the first identification of signature whistles (SWs) in an oceanic population of T. truncatus. A total of 85% (199/233) of the recorded whistles were classified as stereotyped whistles and subsequently (bout analysis/SIGID) categorized into one of five SW types. External observers were in perfect agreement in classifying whistles into the adopted SW categorization. SWs represented 42% (98/233) of the repertoire. Overall, most whistle types were categorized as sine (80%; SW1, SW2, SW4, and SW5) with one downsweep (20%, SW3). Roca Partida Island had the highest number of SW types. Principal component analysis explained 77% of the total SWs variance, highlighting the importance of shape/contour variables to the SWs variance. The combined mean SWs acoustic parameters from Revillagigedo Archipelago were higher than that recorded in coastal regions, which may indicate there are differences between SWs of pelagic and coastal populations. However, further acoustic and ecological studies in the Archipelago are needed to clarify and expand our findings, to identify its members (Photo ID and SW Revillagigedo Catalog), and to investigate this topic at other oceanic islands.