POPULATION ECOLOGY OF THE EASTERN BOX TURTLE (TERRAPENE CAROLINA CAROLINA) IN A FRAGMENTED LANDSCAPE by Nathan H. Nazdrowicz A thesis submitted to the Faculty of the University of Delaware in partial fulfillment of the requirements for the degree of Masters of Science in Entomology and Applied Ecology Summer 2003 Copyright © 2003 Nathan H. Nazdrowicz All Rights Reserved POPULATION ECOLOGY OF THE EASTERN BOX TURTLE (TERRAPENE CAROLINA CAROLINA) IN A FRAGMENTED LANDSCAPE by Nathan H. Nazdrowicz Approved: ___________________________________________________________ Jacob L. Bowman, Ph.D. Professor in charge of thesis on behalf of the Advisory Committee Approved: ___________________________________________________________ Douglas W. Tallamy, Ph.D. Chair of the Department of Entomology and Wildlife Ecology Approved: ___________________________________________________________ Robin W. Morgan, Ph.D. Dean of the College of Agriculture and Natural Resources Approved: ___________________________________________________________ Conrado M. Gempesaw II, Ph.D. Vice Provost for Academic and International Programs ii ACKNOWLEDGMENTS I express my sincere appreciation to my major professor, Dr. J. L. Bowman, and my other committee members, A. Doolittle, Dr. D. C. Forester, Dr. R. R. Roth, and Dr. D. W. Tallamy for their knowledge and guidance. I thank all those who helped with radio-telemetry and capture of turtles, in particular R. Baity, S. Bussells, J. Doughty, C. Howey, R. Kipp, R. Iglay, J. Johnston, J. Judy, I. Lajoie, and A. Porter. I also thank J. Longcore, Dr. E. P. Catts, Dr. R. R. Roth and their many graduate students and research assistants who kept detailed capture records of box turtles in the University of Delaware Woodlot since 1965. I would like to express my sincere gratitude to M. Frederick and the Frederick family for their interest in conservation and for allowing us to use the Turkey Run property. I thank the Delaware Division of Parks and Recreation and White Clay Creek State Park for allowing us access to the property and for waiving the park entrance fee. I thank J. White for taking photographs and for encouraging and spurring my interest in box turtles and herpetology many years ago. Additionally, I would like to thank Dr. J. W. Gibbons for review of my methods. I also gratefully acknowledge the MacIntire-Stennis Forestry Research Program, which provided funding for this project. Finally, I thank my parents, Debbie and Hank Nazdrowicz, whose love, support, encouragement, and understanding has contributed greatly to my success. iii TABLE OF CONTENTS LIST OF TABLES . vi LIST OF FIGURES . x ABSTRACT . xi Chapter 1 INTRODUCTION . 1 Population Abundance . 2 Population Density . 5 Sex Ratios . 8 Age Structure and Distribution . 12 Mortality and Survival Rates . 15 Summary . 18 2 STUDY SITES . 20 The Woodlot . 20 Webb Farm . 24 Turkey Run . 28 White Clay Creek . 31 3 METHODS . 33 Turtle Handling . 33 Transmitter Attachment and Radio Tracking . 36 Intensive Searches . 38 Mortalities . 38 Analyses . 39 Catch Per Unit Effort . 39 Mortalities and Survival . 40 Sex Ratio . 40 Aging Technique . 41 Age Structure . 41 Population Abundance and Density . 41 Long-term Data . 43 iv 4 RESULTS . 47 Catch Per Unit Effort . 55 Survival . 55 Immigration/Emigration . 61 Sex Ratio . 62 Aging Technique . 65 Age Structure . 65 Population Abundance Estimates . 68 Population Density Estimates . 73 Long-term Data . 76 The Woodlot (1965-2002) . 76 Turkey Run (1994-2002) . 83 5 DISCUSSION . 88 Immigration/Emigration . 88 Mortalities and Survival . 89 Aging Technique. 91 Age Structure . 91 Sex Ratio . 93 Populations Abundance . 95 Study Site Effects . 97 Management Recommendations . 99 LITERATURE CITED . 102 v LIST OF TABLES Table 1. Summary of reported population densities of eastern box turtles (Terrapene carolina). .7 Table 2. Summary of adult sex ratios reported in population studies of eastern box turtles (Terrapene carolina). 13 Table 3. Percentage of juveniles reported in population studies of eastern box turtles (Terrapene carolina). 16 Table 4. Definitions for the Jolly-Seber general and reduced models used to estimate population abundance of eastern box turtles from all captures and intensive searches at the University of Delaware Woodlot, University of Delaware Webb Farm, Turkey Run, and White Clay Creek study sites. Survival rate, capture rate, population growth rate, and population size either varied by sex and time, time, sex, remained constant, or were fixed to an estimated value. .44 Table 5. Number of individual eastern box turtles captured and capture events from incidental finds and intensive searches during 2001, 2002, and over the course of the study (2001-02) for University of Delaware Woodlot, University of Delaware Webb Farm, Turkey Run, and White Clay Creek study sites. 48 Table 6. Number of individual eastern box turtles captured and capture events from intensive searches during 2001, 2002, and over the course of the study (2001-02) for the University of Delaware Woodlot, University of Delaware Webb Farm, Turkey Run, and White Clay Creek study sites. .49 Table 7. Frequency of capture for male, female, and juvenile eastern box turtles for 2001, 2002, and over the course of the study (2001-02) captured during incidental finds and intensive searches for University of Delaware Woodlot, University of Delaware Webb Farm, Turkey Run, and White Clay Creek study sites. 51 vi Table 8. Capture frequency of all adult eastern box turtles, radio-tagged box turtles, and adult box turtles without transmitters captured over the course of the study (2001- 02) during intensive searches and incidental finds for University of Delaware Woodlot, University of Delaware Webb Farm, Turkey Run, and White Clay Creek study sites. Juveniles were excluded due to differences in capture probability. .. .53 Table 9. Number of individual eastern box turtles captured on the study sites only in 2001, captured on the study sites for the first time in 2002, and captured on the study sites in both 2002 and 2001 by incidental finds and intensive searches for University of Delaware Woodlot, University of Delaware Webb Farm, Turkey Run, and White Clay Creek study sites. .54 Table 10. Catch-per-unit-effort (CPUE) for adult and all eastern box turtles captured over 6 seasons in 2001 and 2002 at the University of Delaware Woodlot, University of Delaware Webb Farm, Turkey Run, and White Clay Creek study sites. .. 56 Table 11. Summary of eastern box turtle mortalities recorded at University of Delaware Woodlot (WL), University of Delaware Webb Farm (WF), Turkey Run (TR), and White Clay Creek (WC) study sites and associated areas in 2001 and 2002. 57 Table 12. Sex ratio of eastern box turtles in 2001and 2002 for all captures and intensive searches at the University of Delaware Woodlot, University of Delaware Webb Farm, Turkey Run, and White Clay Creek study sites. 63 Table 13. Sex ratio of eastern box turtles from all captures and intensive searches over the course of the study (2001-02) for University of Delaware Woodlot, University of Delaware Webb Farm, Turkey Run, and White Clay Creek study sites. .64 Table 14. Mean annuli added after 1 year for eastern box turtles at the University of Delaware Woodlot, University of Delaware Webb Farm, Turkey Run and White Clay Creek study sites. Shaded.