HOME RANGES AND DIVING BEHAVIOR OF NEW ZEALAND SEA LIONS ALONG THE CATLINS COAST, SOUTH ISLAND, NEW ZEALAND A Dissertation by NATHAN MARK REED Submitted to the Office of Graduate and Professional Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Chair of Committee, Randall Davis Committee Members, William Seitz Blair Sterba-Boatwright Bernd Würsig Intercollegiate Faculty Chair, Anja Schulze May 2021 Major Subject: Marine Biology Copyright 2021 Nathan Reed ABSTRACT New Zealand sea lions (Phocarctos hookeri) were extirpated from the North and South Islands of New Zealand during pre-European native hunting, and their numbers were greatly reduced on the Auckland and Campbell Islands during European commercial sealing. However, they began reoccupying South Island in 1994, and pup production remains low but steady. The home range, at-sea movements, and diving behavior of females at the breeding colony along the Catlins Coast of South Island have not been studied since its inception in 2006. The goal of the study was to: 1) evaluate the performance of home range models to identify the most accurate model(s) for a semi- aquatic distribution, 2) track movements to identify home ranges, and 3) record diving behavior of females to characterize foraging behavior and estimate energy expenditure. To accomplish this study, we attached satellite telemeters and video and data recorders to females along the Catlins Coast during austral winter of 2019. Home ranges were most accurately modeled by separating inshore and offshore habitats and applying adaptive local convex hulls (LOCOH) and fixed kernel density with plug-in bandwidth selection (PKDE), respectively. This method minimized the ranges outside of used habitat, handled boundaries to movement, and performed accurately in cross-validation evaluation. The results showed the importance of home range model selection. Total home ranges were small and restricted to coastal areas. Foraging cycles were frequent, with short times at sea and onshore. Dives were shallow, short in ii duration, and divided into three types based on variables derived from three-dimensional dive analysis. Dive characteristics indicated a benthic foraging strategy with transit periods between foraging patches. At-sea estimated metabolic rate varied by activity, with an estimated field metabolic rate lower than that of females at the Auckland Islands, possibly indicating differences in energetic expenditure among populations. It appears that females along the Catlins Coast consume nearshore, abundant prey and require less time and smaller home ranges for foraging compared to that for females in the Auckland Islands. Although reoccupation of their historic range on South Island will take decades, suitable habitat for breeding and prey availability along the southeast coast are encouraging. iii DEDICATION To the teachers, mentors, family, and friends who inspired me to ask questions and search for answers. This is for you all. iv ACKNOWLEDGEMENTS I would like to thank my committee chair, Dr. Randall Davis, for the research opportunities throughout the years. My involvement in numerous projects helped to shape me as a researcher. Thank you for the support and guidance throughout my graduate career. Thank you also to my committee members, Dr. Seitz, Dr. Sterba-Boatwright, and Dr. Würsig, for your guidance and contributions to the project over the years. Your help improved the work greatly. Numerous people contributed to the research efforts of the project, but a special thank you to my fieldwork team in the Catlins: Charles Barnett, John Burke, Tom Burns, Simon Childerhouse, Alison Clarke, Micah Jensen, and Mikaylie Wilson. Without your time and resources, the data collection and project would never have happened. Also, thank you to Amélie Augé and Bruce Robertson for your expertise and contributions to the work. A big thank you to the scientific mentors who helped shape my passions, Dr. Jacobsen and Dr. Gathany. Your examples as godly scientists inspired me to pursue my interests and contribute to this world. Thank you to the TAMUG graduate community, who constantly challenged me to keep learning and working. Your encouragement motivated me to be a better scientist, student, and friend. v Finally, I would like to thank my parents for their unwavering support over the years. Your interests in my work and encouragement throughout my education have meant more to me than you will ever know. Thank you to my wife, Lauren, for your love and support and for not letting me quit. You inspire me to be my best. vi CONTRIBUTORS AND FUNDING SOURCES Contributors This work was supervised by a dissertation committee consisting of Professors Randall Davis (advisor) and Bernd Würsig of the Department of Marine Biology, Professor William Seitz of the Department of Marine Sciences, and Professor Blair Sterba-Boatwright of the Department of Mathematics and Statistics at Texas A&M University Corpus Christi. The analyses depicted for Chapter 2 were conducted in part by Professor Sterba- Boatwright. All other work conducted for the dissertation was completed by the student independently. Funding Sources Graduate study was supported by a graduate assistantship-teaching from Texas A&M University at Galveston. This work was also made possible by Texas A&M University at Galveston Comprehensive Research Funds, Erma Lee and Luke Mooney Marine Research Endowment Student Travel Award, and Texas A&M University at Galveston Marine Biology Department Travel and Match Funds. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of Texas A&M University. vii TABLE OF CONTENTS Page ABSTRACT .......................................................................................................................ii DEDICATION .................................................................................................................. iv ACKNOWLEDGEMENTS ............................................................................................... v CONTRIBUTORS AND FUNDING SOURCES ............................................................vii TABLE OF CONTENTS ............................................................................................... viii LIST OF FIGURES ............................................................................................................ x LIST OF TABLES ...........................................................................................................xii CHAPTER I INTRODUCTION ........................................................................................ 1 Taxonomy....................................................................................................................... 1 Evolution ........................................................................................................................ 1 Abundance and Distribution........................................................................................... 2 Reproduction .................................................................................................................. 5 Foraging ......................................................................................................................... 7 Management ................................................................................................................... 9 Research ....................................................................................................................... 11 References .................................................................................................................... 13 CHAPTER II CROSS-VALIDATION HOME RANGE MODEL SELECTION FOR A SEMI-AQUATIC SPECIES ......................................................................................... 22 Introduction .................................................................................................................. 22 Methods ........................................................................................................................ 25 Animals and Instrumentation ................................................................................... 25 Location Filters ......................................................................................................... 27 Home Range Models ................................................................................................ 28 Cross-Validation Comparisons ................................................................................. 29 Results .......................................................................................................................... 30 Location Filters ......................................................................................................... 30 Total Home Range .................................................................................................... 30 Inshore and Offshore Home Ranges ........................................................................ 34 Discussion .................................................................................................................... 36 References .................................................................................................................... 48 viii CHAPTER III HOME RANGES, FORAGING BEHAVIOR, AND ENERGETICS OF NEW ZEALAND SEA LIONS ALONG THE CATLINS COAST .......................... 57 Introduction .................................................................................................................