NESTING ECOLOGY AND POPULATION GENOMICS OF AMERICAN BLACK DUCKS IN NORTH CAROLINA by Daniel M. Lawson A thesis submitted to the Faculty of the University of Delaware in partial fulfillment of the requirements for the degree of Master of Science in Wildlife Ecology Winter 2020 © 2020 Daniel M. Lawson All Rights Reserved NESTING ECOLOGY AND POPULATION GENOMICS OF AMERICAN BLACK DUCKS IN NORTH CAROLINA by Daniel M. Lawson Approved: __________________________________________________________ Christopher K. Williams, Ph.D. Professor in charge of thesis on behalf of the Advisory Committee Approved: __________________________________________________________ Jacob L. Bowman, Ph.D. Chair of the Department of Entomology and Wildlife Ecology Approved: __________________________________________________________ Mark W. Rieger, Ph.D. Dean of the College of Agriculture and Natural Resources Approved: __________________________________________________________ Douglas J. Doren, Ph.D. Interim Vice Provost for Graduate and Professional Education and Dean of the Graduate College ACKNOWLEDGMENTS I thank the North Carolina Wildlife Resources Commission (NCWRC), and the University of Delaware for funding this project and providing support throughout. I further thank NCWRC staff for allowing me access to their equipment, and specifically thank Doug Howell for his solid commitment to the fruition of this project. I thank my advisor, Dr. Chris Williams, and my graduate committee, Dr. Kyle McCarthy, Dr. Greg Shriver, Doug Howell, and Joe Fuller for their advice and insights during this research. I thank the University of Delaware (UD), the College of Agriculture and Natural Resources, and the Department of Entomology and Wildlife Ecology for the opportunity to pursue my graduate degree. I am grateful for the assistance of the many UD staff and technicians who contributed to this research in some form or another including Kendal Fletcher, Alex Barnes, Glennon McCreery, Kimberly McCargo, Giovanni Pambianchi, Dennis Haggerty, and Corbin Hawkins. Most importantly, I would like to thank my family for providing the foundation to excel and for their constant prayers and reassurances. I would also like to thank Kayla Harvey for her love and support and commitment to betterment. Finally, I would like to thank all of my friends for keeping me sane through the whole process. iii TABLE OF CONTENTS LIST OF TABLES ........................................................................................................ vi LIST OF FIGURES ..................................................................................................... viii ABSTRACT .................................................................................................................. xi Chapter 1 NESTING ECOLOGY OF AMERICAN BLACK DUCKS IN COASTAL NORTH CAROLINA ......................................................................................... 1 Introduction ........................................................................................................ 1 Study area ........................................................................................................... 4 Methods .............................................................................................................. 7 Results .............................................................................................................. 13 Discussion ......................................................................................................... 23 Management Implications ................................................................................ 28 2 NESTING HABITAT SELECTION OF AMERICAN BLACK DUCKS IN COASTAL NORTH CAROLINA, WITH IMPLICATIONS IN FUTURE SEA LEVEL RISE ........................................................................................... 30 Introduction ...................................................................................................... 30 Study area ......................................................................................................... 32 Methods ............................................................................................................ 34 Results .............................................................................................................. 42 Discussion ......................................................................................................... 51 Management Implications ................................................................................ 55 3 MALLARD–BLACK DUCK HYBRIDIZATION AND POPULATION STRUCTURE IN COASTAL NORTH CAROLINA ...................................... 56 Introduction ...................................................................................................... 56 Study area ......................................................................................................... 60 Methods ............................................................................................................ 62 Results .............................................................................................................. 67 Discussion ......................................................................................................... 74 Management Implications ................................................................................ 78 REFERENCES ............................................................................................................. 79 iv Appendix SLAMM GMSLR SIMULATIONS OF VARYING INTENSITY IN COASTAL NORTH CAROLINA, USA, 2019–2100 ..................................... 96 v LIST OF TABLES Table 1 MCestimate® predictor of nest failure: abbreviation, definition, and data type of variables predicting American black duck nest success in coastal North Carolina, USA, 2017–2018. .............................................. 12 Table 2 Mean nest initiation date (Julian Day), day of first nest initiation, last nest initiation, and 25th, 50th, and 75th quartiles of black ducks in coastal North Carolina, USA, 2017–2018. .............................................. 15 Table 3 Mean initiation dates (Julian Day) and analysis of variance (ANOVA) of nesting black ducks in mainland marsh, natural island, and spoil- island habitats in coastal North Carolina, USA, 2017–2018. .................. 16 Table 4 Contributions to American black duck nest fates (i.e. successful, abandoned, nonviable eggs, unknown, destroyed) from 2017–2018 with percent contributions for each category and sub-category (i.e. natural, investigator, avian, flooding, mammal, unknown) within Hyde and Dare counties of coastal North Carolina, USA. ................................ 18 Table 5 MCestimate 12-variable nest failure model rank, name, K, AICc, delta AICc, and weight of black ducks in coastal North Carolina, USA, 2017–2018. .............................................................................................. 20 Table 6 Marsh (natural-island and mainland marsh) nesting versus spoil-island nesting black duck incubation recess chronologies and sample sizes, recess duration, recess frequencies, recess duration time per day, and incubation constancy estimates for each.in Hyde and Dare counties of coastal North Carolina, USA, 2017–2018. .............................................. 23 Table 7 SLAMM input parameters for the simulation of GMSLR for mainland Hyde and Dare Counties, North Carolina, USA, 2019–2100. Values for parameters with no specific local information were kept at the model default value. ................................................................................ 40 Table 8 Macro-habitat description of searched area (ha), black duck nests found per habitat and nest density per habitat, coastal North Carolina, USA, 2017–2018. .................................................................................... 44 vi Table 9 Spoil-island, natural island, and mainland marsh micro-habitat characteristics of nest sites (use). Group-wise ANOVA results are recorded for distance to open water (DOW), elevation, visual obstruction (VOR), vegetation height (Veg height), and ground cover relative percent composition. 2017–2018 Hyde and Dare Counties, North Carolina, USA. .............................................................................. 45 Table 10 Natural island and mainland marsh micro-habitat characteristics of nest sites (use) and randomly sampled (non-use) points. T-test results are recorded for elevation, visual obstruction, vegetation height, and ground cover relative percent composition. 2017–2018 Hyde and Dare Counties, North Carolina, USA. .............................................................. 47 Table 11 Spoil-island micro-habitat characteristics of nest sites (use) and randomly sampled (non-use) points. T-test results are recorded for elevation, visual obstruction, vegetation height, and ground cover relative percent composition. 2017–2018 Hyde and Dare Counties, North Carolina, USA. .............................................................................. 48 Table 12 Predicted change of regularly and irregularly-flooded marsh area and predicted number of black duck nests (assuming 1 nest per 122 ha in regularly-flooded marsh and 137 ha in irregularly flooded marsh) by 2100 given simulated scenarios of eustatic SLR in mainland Hyde County, mainland Dare County, and Outer Banks (made up of both Dare and Hyde Counties), North Carolina, USA. ................................... 50 Table 13 Simulation‐based indices