Effects of Off-Road Vehicles on the Nesting Activity of Loggerhead Sea Turtles in North Carolina
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EFFECTS OF OFF-ROAD VEHICLES ON THE NESTING ACTIVITY OF LOGGERHEAD SEA TURTLES IN NORTH CAROLINA By LINDSAY R. NESTER A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2006 Copyright 2006 by Lindsay R. Nester To my mom, Ruth Nester. ACKNOWLEDGMENTS I would like to thank the people working for Cape Hatteras National Seashore where my love for sea turtles was fostered. I would especially like to thank my boss, Marcia, during my time at Cape Hatteras. Special thanks go to all the employees, SCAs, and volunteers at Cape Hatteras, Cape Lookout, and Pea Island for their data collection. The following people were especially helpful: Jenn, Matthew, Jim, Jeff, Dennis, Tracy, Ruth, Gail, Michael, Elizabeth, Kenny, Les, and Shiloh. My advisor, Nat Frazer, deserves a big thanks for guiding me through the grad school process. He was also a very good sport and endured less than desirable field conditions. A committee member, Perran Ross, provided invaluable support and knowledge. He spent an inordinate amount of time and effort guiding me through the thesis process. I would also like to thank Mary Christman for giving statistical advice that was essential to the completion of this project. I am greatly appreciative of John Confer’s constructive advice, perspective, and support. Russ Scarpino and Mario Mota provided valuable technical advice. April Norem offered useful editing advice. I would like to thank Mom, Dad and Kristin, for all of their support. Battle Cat has provided unconditional love and tolerated my absences in the summers and time on the computer. I would also like to thank all of my friends from Richmond, Virginia, who have been my base of support: Meagan, Abby, Kelly, Nick, Van, and Cheryl. iv TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iv LIST OF TABLES............................................................................................................ vii LIST OF FIGURES ......................................................................................................... viii ABSTRACT.........................................................................................................................x CHAPTER 1 INTRODUCTION ........................................................................................................1 Loggerhead Status ........................................................................................................5 General Description of Loggerheads............................................................................6 Hypotheses..................................................................................................................13 False Crawl and Nesting Laying .........................................................................13 Emergence Success .............................................................................................13 Incubation............................................................................................................13 Habitat Quality ....................................................................................................13 Sand and Beach Characteristics...........................................................................13 Conclusion ..................................................................................................................14 2 METHODS.................................................................................................................15 Study Sites ..................................................................................................................15 Background Information on Cape Lookout.........................................................17 Background Information on Pea Island...............................................................19 Statistical Analysis......................................................................................................38 False Crawl and Nesting Laying .........................................................................39 Emergence Success .............................................................................................39 Incubation............................................................................................................39 Habitat Quality ....................................................................................................41 Sand and Beach Characteristics...........................................................................42 3 RESULTS...................................................................................................................43 False Crawl and Nesting Laying.................................................................................43 Emergence Success.....................................................................................................44 v Incubation ...................................................................................................................45 Habitat Quality............................................................................................................48 Sand and Beach Characteristics..................................................................................49 ORV Counts................................................................................................................51 4 DISCUSSION.............................................................................................................52 Sand and Beach Characteristics..................................................................................52 False Crawl and Nest Laying......................................................................................54 Emergence Success and Habitat Quality ....................................................................55 Length of Incubation and Possible ex Ratio Effects...................................................57 5 MANAGEMENT IMPLICATIONS ..........................................................................61 Management Requirements ........................................................................................61 Implications for Future Management .........................................................................66 Cape Hatteras..............................................................................................................67 False Crawl and Nesting Laying .........................................................................67 Incubation............................................................................................................68 Habitat Quality ....................................................................................................68 Cape Lookout..............................................................................................................70 False Crawl and Nesting Laying .........................................................................70 Incubation............................................................................................................71 Habitat Quality ....................................................................................................71 Conclusions.................................................................................................................71 LIST OF REFERENCES...................................................................................................73 BIOGRAPHICAL SKETCH .............................................................................................81 vi LIST OF TABLES Table page 2-1 Least squares model for incubation period and specified variables. The Groups 1 through 3 represent separate models involving incubation period........................40 2-2 Variables and their definitions used in my study on the effects of ORV use on loggerhead sea turtle nesting activity. ......................................................................41 3-1 Results for 2005 nesting season for nest and false crawl occurrences in logistic models with the following variables: Group 1 Sand Characteristics, Group 2 Beach Characteristics, Group 3 Light: Intensity. .....................................................45 3-2 2005 Incubation period in days displayed in least squares models for the following variables: Group 1 Sand Characteristics, Group 2 Beach Characteristics, Group 3 Date laid, Year, and Site type..........................................47 3-3 2005 Results from nesting and false crawl locations for the following variables by Site Type (ORV and non-ORV): Group 1 Sand Characteristics, Group 2 Beach Characteristics for Cape Hatteras National Seashore, Cape Lookout National Seashore, and Pea Island Wildlife Refuge, North Carolina, USA. ...........50 3-4 ORV counts during 2005 sea turtle nesting season for Cape Hatteras (Ocracoke, Hatteras, and Bodie Islands) and Cape Lookout (South Core and North Core Islands) National Seashores, North Carolina, USA. Park management at North Core and South Core Islands allow both ATV and ORV use. In contrast, staff at Ocracoke, Hatteras, and Bodie Islands allow ORV use only...................................51 vii LIST OF FIGURES Figure page 1-1 Loggerhead returning to the ocean after nesting on Bodie Island of Cape Hatteras National Seashore, North Carolina, USA in summer 2005. Photo by Jenn Snukis.................................................................................................................6