Diet Analysis of Wintering Waterfowl in the Southeastern United States in Relation to Ecoregion, Habitat, and Guild By Justin Andrew Walley David A. Aborn Mark S. Schorr Associate Professor of Biology, Professor of Biology, Geology, and Environmental Sciences Geology, and Environmental Sciences (Committee Chair) (Committee Member) Thomas P. Wilson Jennifer N. Boyd Associate Professor of Biology, Associate Professor of Biology, Geology, and Environmental Sciences Geology, and Environmental Sciences (Committee Member) (Committee Member) Diet Analysis of Wintering Waterfowl in the Southeastern United States in Relation to Ecoregion, Habitat, and Guild By Justin Andrew Walley A Thesis Submitted to the Faculty of the University of Tennessee at Chattanooga in Partial Fulfillment of the Requirements of the Degree of Master of Science: Environmental Science The University of Tennessee at Chattanooga Chattanooga, Tennessee August 2016 ii Copyright © 2016 By Justin Andrew Walley All Rights Reserved iii ABSTRACT Wintering waterfowl diet has been studied across North America to gain a better understanding of their foraging habits and feeding ecology. There is a need for a better understanding of waterfowl foraging based on ecoregion, guild, and habitats of wintering waterfowl, especially within the Mississippi Flyway. This study investigated the stomach content of wintering waterfowl in the Southeast United States, within the Mississippi Flyway region. The esophagus, proventriculus, and gizzard of each specimen were removed, dried, and sorted for statistical analysis. Multiple two-way ANOVAs were run to test the effects of ecoregion, habitat, and guild on total mass and diet mass in waterfowl. A difference between years was determined so separate analyses were conducted for each year. My results suggest that there was a significant difference in 2014 data for ecoregion by habitat within the Ridge and Valley ecoregion. Total diet composition results suggest that waterfowl consume different food components in each ecoregion. When analyzing guild diet composition, the results suggest that each guild consumes different types of food products, with the dabblers consuming the most agricultural products, divers consuming the most varied diet, and geese consuming the most grasses. iv ACKNOWLEDGMENTS I would like to thank Dr. David Aborn for advising me during my undergraduate tenure at the University of Tennessee at Chattanooga and also accepting me as a graduate student, giving me the guidance, assistance when I needed help, and being a mentor throughout my bachelor’s and master’s degrees. I would also like to thank Dr. Thomas P. Wilson for his advice and being a mentor to me not only with my research, but on other projects as well. I would also like to thank Dr. Mark S. Schorr for his help with statistical analysis and suggestions for the project. For writing advice and suggestions throughout my research I owe thanks to Dr. Jennifer N. Boyd. I would like to thank the multiple hunters who donated their waterfowl for this study. I also thank the many graduate students who helped process specimens in the lab as well as my undergraduate assistants for their work in the lab. I owe thanks to the University of Tennessee of Chattanooga and the department of Biology, Geology and Environmental Science for giving me the educational foundation and opportunity to further my knowledge in the sciences. The faculty and staff at UTC have been great mentors throughout my tenure and have given great advice. Lastly, I would like to thank my family and friends for their continuous support throughout this process. v TABLE OF CONTENTS ABSTRACT ....................................................................................................................... iv ACKNOWLEDGMENTS ...................................................................................................v LIST OF FIGURES .......................................................................................................... vii LIST OF ABBREVIATIONS ............................................................................................ ix CHAPTER I. INTRODUCTION .........................................................................................................1 1.1 Mississippi Flyway ............................................................................................1 1.2 Wintering Waterfowl Habitat ............................................................................2 1.3 Waterfowl Foraging and Feeding Ecology ........................................................4 1.4 Waterfowl Diet Analysis....................................................................................6 1.5 Expansion on Research ......................................................................................7 1.6 Research Questions ............................................................................................7 II. STUDY AREA AND METHODS ...............................................................................9 2.1 Study Area .........................................................................................................9 2.2 Data Collection ................................................................................................11 2.3 Dissection .........................................................................................................12 2.4 Data Analyses ..................................................................................................13 III. RESULTS .................................................................................................................15 3.1 2013 and 2014 Year Comparison ....................................................................15 3.2 Ecoregion by Habitat ......................................................................................17 3.3 Ecoregion by Guild ..........................................................................................19 3.4 2013 and 2014 Combined Years Guild by Habitat ..........................................20 3.5 Total Diet Composition by Ecoregion .............................................................21 3.5.1 Ridge and Valley Ecoregion Total Diet Composition ......................21 3.5.2 Southwestern Appalachians Ecoregion Total Diet Composition ......23 3.5.3 Mississippi Alluvial Plain Ecoregion Total Diet Composition.........24 vi 3.6 2014 Total Diet Composition by Guild ...........................................................26 3.6.1 Dabblers ............................................................................................26 3.6.2 Divers ................................................................................................27 3.6.3 Geese .................................................................................................28 IV. DISCUSSION ............................................................................................................30 4.1 Interpretation of Statistical Results ..................................................................30 4.1.1 Year Differences ...............................................................................30 4.1.2 Comparison with Other Studies ........................................................30 4.2 Diet Composition Comparisons .......................................................................31 4.2.1 Ecoregion, Habitat, and Guild ..........................................................32 4.3 Interpretation of Waterfowl Diet Composition by Ecoregion .........................33 4.4 Interpretation of Waterfowl Diet Composition by Guild .................................34 4.4.1 Geese .................................................................................................34 4.4.2 Dabblers ............................................................................................35 4.4.3 Divers ................................................................................................36 4.5 Acknowledgement of Potential Biases… ........................................................37 4.6 Management Implications ................................................................................38 V. CONCLUSION ..........................................................................................................41 5.1 Future Work .....................................................................................................41 REFERENCES ..................................................................................................................43 VITA ..................................................................................................................................46 vi LIST OF FIGURES 1 Sampling locations (counties) for this study. Samples in North Carolina and Kansas were later removed from the study because they fell outside the Mississippi Flyway (yellow area) ...............................................................................................9 2 The ecoregions occupied by the study area and the study sites (counties) within different ecoregions: Ridge and Valley (67), Interior Plateau (71), Southwestern Appalachians (68), Mississippi Alluvial Plain (73), and Mississippi Loess Plains (74) ................................................................................10 3 Mean digestive mass (+SE) of total mass and diet mass for three ecoregions in 2013 ..16 4 Mean digestive mass (+SE) of total mass and diet mass for two ecoregions in 2014 ....17 5 Mean digestive mass (+SE)