Date of Award
Doctor of Philosophy
Gordon M. Burghardt
Todd M. Freeberg, Neil Greenberg, John C. Malone, Richard A. Saudargas
Turtles are little studied with respect to learning, cognition and social behavior in spite of being phylogenetically a central group. Populations of many species of these long-lived animals are declining due to commercial activities (pet trade and food), pollution, and habitat destruction. This integrative study of freshwater turtle (Emydidae) behavior investigated their sociality, individual learning and memory capabilities, and the ability of turtles to learn from others.
First, I studied turtle underwater social behavior which involved naturalistic observations and ethogram development of the underwater social behavior of (Family Emydidae) at the Chattanooga Aquarium. Turtle social behavioral repertoire and interaction sequencing while underwater were much more complex and varied than those recorded for turtle basking interactions. Turtles also formed stable dominance hierarchies.
Second, I trained and tested 9 Florida Red-bellied Cooters (Pseudemys nelsoni) in a discrimination choice task that I developed. Turtles were first trained to an instrumental response task (dislodging clear plastic bottles to obtain food pellets). These turtles not only showed rapid learning, but required minimal to no retraining after a period of 2 years. This study marks the first time that turtles have been shown to exhibit extensive long-term memory measured in years in a controlled experimental task. Olfactory and other controls were run to confirm that the turtles were responding only to visual cues.
Finally, I investigated whether turtles could learn about a visual object cue to obtain food reinforcement by observing other experienced turtles that had learned the task. All five P. nelsoni turtles tested showed evidence of social facilitation and stimulus enhancement learning i.e. they learned not only to follow another turtle to a stimulus indicating food but also to approach the correct bottle that contained food reinforcement. This is the first experimental study of social learning in turtles.
This integrative study of social behavior, learning, and cognition of turtles will hopefully spark interest in turtle behavior and cognition, help advance the field of comparative animal cognition, and aid in the development of their management in the wild.
Davis, Karen Marie, "Sociality, Cognition and Social Learning in Turtles (Emydidae). " PhD diss., University of Tennessee, 2009.