Patterns of echolocation in a group of captive bottlenose dolphins in Roatan, Honduras

Abstract

Patterns of echolocation in a group of bottlenose dolphins (Tursiops truncates) at the Institute for Marine Sciences in Roatan, Honduras were examined. While much is known about echolocation, the role of echolocation in the context of dolphin social or communicatory behavior has been, for the most part, speculative (Xitco, 1996). Two females and two males were paired and presented a variety of novel targets in the water. Approximately equal numbers of each pair combination were conducted over 22 sessions consisting of a 5-min no-target trial followed by a 5-min target trial. Data were obtained via an underwater video camera and by an underwater observer. Number of click trains, silent passes, passes by both dolphins, passes by a clicking dolphin, and times a dolphin approach and click on the target first were analyzed. Clearly, dolphins paid attention to the targets. The number of trains and passes significantly increased during target trials. Females clicked more often during target trials and were first to approach and click at the target. Target type had no effect on echolocation behavior. This study should be repeated at other facilities and with other dolphins to determine whether gender differences are real or due to small sample sizes.