Title

Possible Maternal Influences on the Ontogeny of Echolocation in Bottlenose Dolphins (Tursiops truncatus)

Date of Award

2006

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

Stan Kuczaj

Advisor Department

Psychology

Abstract

In recent years, evidence has emerged to suggest that vocalizations involved in human speech, birdsong, primate calls, and dolphin whistles pass through various developmental stages before becoming functional (Marler, 1970; McCowan & Reiss, 1995; Oller, 1980; Seyfarth & Cheney, 1997). However, little is known about the ontogeny of dolphin echolocation. The sounds produced when dolphins echolocate are thought to serve a variety of functions including communication, navigation, and foraging. Infant dolphins may begin life with a predisposition to echolocate that develops by learning from the mother and/or through practice. However, it is also possible that dolphin calves possess an innate ability to produce functional sonar clicks immediately postpartum. This study investigated the ontogeny of dolphin echolocation and calf sonar characteristics by analyzing the overlapping click trains of seven bottlenose dolphin mother/calf pairs from 2 months until 6 months of age (recorded from June 2000 to June 2003). Overlapping click trains are those trains in which a click train from the mother and a click train from the calf overlap one another. Recorded train duration, click count, train density, interclick interval, and initiation of train were examined for trends of development and indications of maturation and vocal learning influences. Comparisons between mother and calf click trains were also done on these variables in an effort to find further evidence of vocal learning.