Ecological and Life History Factors Influence Habitat and Tool Use in Wild Bottlenose Dolphins (Tursiops Sp.)

ECOLOGICAL AND LIFE HISTORY FACTORS INFLUENCE HABITAT AND TOOL USE IN WILD BOTTLENOSE DOLPHINS (TURSIOPS SP.) A Dissertation submitted to the Faculty of the Graduate School of Arts and Sciences of Georgetown University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biology By Eric Michael Patterson, B.S. Washington, DC December 7, 2012 Copyright 2011 by Eric Michael Patterson All Rights Reserved ii ECOLOGICAL AND LIFE HISTORY FACTORS INFLUENCE HABITAT AND TOOL USE IN WILD BOTTLENOSE DOLPHINS (TURSIOPS SP.) Eric Michael Patterson, B.S. Thesis Advisor: Janet Mann, Ph.D. ABSTRACT While it has long been known that individual animals behave quite distinctively from other conspecifics, only recently has this intraspecific behavioral variation itself been the subject of investigation rather than a nuisance in statistical analyses. As research amounts, it is becoming ever more apparent that the ecology of individuals can have real and measurable biological consequences. Previous studies have documented pronounced inter-individual variation in foraging behaviors in Shark Bay wild bottlenose dolphins, which often coincide with individual specialization. In this dissertation I examine how individuals’ phenotypic characteristics relate to their foraging behavior, habitat use, and ranging. In Chapter 1 I explore habitat and ranging for adult male and female bottlenose dolphins. Dolphins show marked intraspecific variation in both habitat use and ranging, which partially relates to foraging tactic, sex, and season. However, some variation cannot be explained by any obvious phenotypic or ecological factors, highlighting the importance of individual level analyses, especially for conservation and management. In Chapter 2 I examine the underlying basis of one foraging tactic involving tool use: sponge foraging. By mimicking dolphin sponging behavior, I found that dolphins that sponge forage (spongers) target prey that are difficult to detect with their echolocation, and dolphins have to use sponge tools to access this resource. Spongers appear to hunt an easy to catch, iii reliable food source that non-spongers cannot access, thereby minimizing feeding competition and providing them access to an empty niche. Finally, Chapter 3 explores life-long learning of the sponge foraging. Like humans, and many other animals, dolphins improve upon their skills with age, reaching a peak in sponging efficiency in midlife and declining thereafter. Dolphins also improved in their ability to locate sponges with age, and both this and efficiency likely help females meet the energetic demands of lactation. In all, this dissertation increases our knowledge concerning how a species ecology and life history relates to intraspecific behavioral variation and has implications for conservation, tool-use, innovation, social learning, culture, and ultimately fitness and evolution. iv To my friends, family, and to all the animals (both dolphin and non-dolphin alike) that made this work possible… My sincere gratitude, ERIC v ACKNOWLEDGEMENTS I would first like to thank my thesis committee. Dr. Lisa Singh, Dr. Gina Wimp, and Dr. Shweta Bansal were incredibly helpful throughout my entire PhD and my work would not have been possible without them. I would especially like to thank Dr. Wimp for being on all of my committees throughout my time at Georgetown, and for always asking the toughest questions and pushing me to be my best. Our long-term database, which all of my work greatly depends on, would not be in the shape it is today without the unending dedication of Dr. Lisa Singh. There are so many friends that not only supported me in my work, but also kept me sane during the last 5 years. While in DC, the biology graduate students were an extended family. Aaron Howard was always willing to help me with anything, from moving to various apartments to discussing the intricacies of our statistics (his being way more complicated than mine) and helping me learn R. I cannot thank Jenn Urbanksi enough for always being a friend to me and helping me when I needed it most. To all my other DC friends, both from Georgetown and beyond, I sincerely thank you for making this journey fun! I am also forever grateful to my cohort of associates while in Australia. Paul Hollick and family (Kate, Freya, Tim, and Ned) have always taken me in as one of their own, allowing me to stay at their place in Perth, buy their truck, and even park our boat in their only bay for weeks on end. Finally, to everyone that makes Shark Bay not only a great place to do research, but also an enjoyable place to be stuck, thank you. I would like to directly thank all of the researchers and organizations that supported this work, everyone in the Shark Bay Research Project (past and present), all members of the Shark Bay Ecosystem Research Project, and all of our funding sources throughout the years (noted specifically for each chapter below). In particular, I would like to thank the members of the vi Mann lab. Maggie Stanton has always been an incredible role model and is always willing to discuss methodological details. Ewa Krzyszczyk has taught me much of what I know about cetaceans and is a wonderful friend and colleague. Vivienne Foroughirad has been a oustanding assistant and research associate, and was always willing to look things over for me and help me get the data I needed. Meg Wallen brought in much needed fresh blood and a new perspective that was invaluable in helping me make my work more accessible. Finally, while I did not directly work with her, I am grateful to Dr. Brooke Sargeant for lighting the path with her work on dolphin foraging and individual specialization. The foundation that she set inspired me and made much of my work possible and to that I am indebt. To my family, what can I say, without them I wouldn’t even exist. I can never repay them for the support they have given me, not only during graduate school, but throughout my entire life. I could not ask for a more supportive mother and father. To my siblings Bryce, Andrea, and Elise, I am forever thankful for their willingness to entertain my interests, to listen to me talk about animals even when I have no idea what I am talking about, and for allowing us to watch Discovery Channel and Animal Planet, even when there may have been something better on TV. Of course I have to thank my dogs, Belle and Bella, for keeping my feet warm while I write, distracting me and pulling me out of my computer struck daze, and for always listening to me and never talking back. They are the best friends a man could ever ask for. Finally, to my amazing fiancé Katie: I am the luckiest man alive to have found her and I owe these last few years of happiness completely to Katie. Words cannot express my gratitude towards her. Of course I must thank the dolphins, for being there, for exhibiting interesting behaviors, and for allowing us strange land mammals to watch from our noisy boats. Before graduate vii school, I am not sure I had ever seen a wild dolphin, certainly never one up close, but after the first day out on the boat in Shark Bay I was hooked. Thank you to all the dolphins of Shark Bay. Finally, I have to thank Dr. Janet Mann, my advisor. Dr. Mann took me under her wing the second we met. She gave me an opportunity to prove myself as I had no previous work with cetaceans and actually only had two years of undergrad in Biology due to switching my major. I only hope I have made her proud. She has taught me virtually everything I know about dolphins, animal behavior, and then some. Throughout my studies, I have tried some new techniques, new methods, some of which worked, some of which failed miserably, but she has supported them all, to the fullest. I hope that we continue to work together so I can soak up her incredible dedication to the project and to studying dolphin behavioral ecology. Thank you everyone! viii TABLE OF CONTENTS Dissertation Introduction .................................................................................................... 1 References ....................................................................................................................... 6 Chapter I. Individual, Sex, and Seasonal Differences in Bottlenose Dolphin Habitat Use and Home Ranges in Shark Bay, Australia: Implications for Conservation and Management ...................................................................................................................... 10 Abstract .......................................................................................................................... 10 Introduction ................................................................................................................... 11 Materials and Methods .................................................................................................. 15 Study site and design .................................................................................................. 15 Habitat classification and availability ........................................................................ 16 Habitat use .................................................................................................................. 20 Home ranges ............................................................................................................... 24 Statistical Considerations ........................................................................................... 25 Results ..........................................................................................................................

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