Validation of Stable Isotope Analysis for Determining Dietary Proportions and Trophic Dynamics in Plains Sharp-Tailed Grouse
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VALIDATION OF STABLE ISOTOPE ANALYSIS FOR DETERMINING DIETARY PROPORTIONS AND TROPHIC DYNAMICS IN PLAINS SHARP-TAILED GROUSE (TYMPANUCHUS PHASIANELLUS JAMESI) SEJER DIXON MEYHOFF Bachelor of Arts, University of New Brunswick, 2012 Renewable Resource Management Diploma, Lethbridge College, 2016 A thesis submitted in partial fulfilment of the requirements for the degree of MASTER OF SCIENCE in ENVIRONMENTAL SCIENCE Department of Geography and Environment University of Lethbridge LETHBRIDGE, ALBERTA, CANADA © Sejer Meyhoff, 2020 VALIDATION OF STABLE ISOTOPE ANALYSIS FOR DETERMINING DIETARY PROPORTIONS AND TROPHIC DYNAMICS IN PLAINS SHARP-TAILED GROUSE (TYMPANUCHUS PHASIANELLUS JAMESI) SEJER D. MEYHOFF Date of Defence: March 26, 2020 Dr. D. Johnson Professor Ph.D. Thesis Supervisor Dr. B. Ellert Research Scientist Ph.D. Thesis Examination Committee Member Dr. J. Byrne Professor Ph.D. Thesis Examination Committee Member Dr. S. Wiseman Associate Professor Ph.D. Thesis Examination Committee Member Dr. C. Coburn Professor Ph.D. Chair, Thesis Examination Committee ii ABSTRACT Stable isotopes in the tissue of a consumer organism can be used to estimate the proportional utilization of foods based on different isotopic signals and can also be used to estimate changes to diet over time. In this study, stable isotopes of nitrogen (δ15N) and carbon (δ13C) were used to examine the feeding relationships of plains sharp-tailed grouse (Tympanuchus phasianellus jamesi). Sharp-tailed grouse are known to consume mostly plant food and utilize insects and spiders as a high-protein food source when available. Food web dynamics are generally poorly understood, and emerging factors such as climate change are likely to alter bird-arthropod trophic relationships. Primary feathers from 40 plains sharp-tailed grouse were analyzed and used to estimate diet proportions of vegetation and arthropods from May to October. Results indicated that plains sharp-tailed grouse may primarily utilize nutrients obtained from insect prey, mainly grasshoppers (Orthoptera: Acrididae), for primary feather synthesis. iii ACKNOWLEDGEMENTS This project would not have been possible without the considerable contribution of time and resources from Dr. Ben Ellert and Katelyn Lutes at the Lethbridge Research Center, my supervisor Dr. Dan Johnson, and committee members Dr. James Byrne, and Dr. Steve Wiseman. Land access and significant contributions towards field collections were kindly provided by Rob and Audrey Taylor. Significant contributions towards laboratory work and field collections were provided by Philip Meyhoff, Scott Bazinet, Brian Fuller, and the generous hunters at CFB Wainwright. Contributions towards field work was also provided by the following individuals (listed alphabetically): Dr. Andy Hurley and his dog Larkin; Ben Belding; Dennis Quick; Jacey Fellman; Kelsey Cartwright; Lonnie Bilyk; Lorne Fitch and his dog Choco; Malte Nordmann; Shane Mascarin; and Wesley Boe. The following individuals provided consultation that was helpful to the development and completion of this project (listed alphabetically): Brad Downey; Dr. Brian Hayden; Dr. Brain Stock (R script); Dr. Doug Manzer; Dr. Erik Blomberg; Grant Chapman; Dr. Keith Hobson; Paul Jones; Shane Roersma; Dr. Sonja Leverkus; and Steve MacRae. Research and travel funding were provided by: the Johnson lab at the University of Lethbridge (research and travel); the University of Lethbridge School of Graduate Studies (research and travel); the Prairie Conservation and Endangered Species Conference Young Professional Stewardship Award (research); the Alberta Conservation Association Grants in Biodiversity (research); the Alberta Chapter and Canadian Section of the Wildlife Society (travel); the Society of Canadian Ornithologists (travel); and Bird Studies Canada (travel). iv TABLE OF CONTENTS Abstract ....................................................................................................... iii Acknowledgements .......................................................................................... iv List of Figures ................................................................................................ ix List of Abbreviations ......................................................................................... x Chapter 1: Introduction ......................................................................................1 Abstract .....................................................................................................1 1.1 Birds and Climate Change ............................................................................1 1.2 Sharp-tailed Grouse Ecology .........................................................................4 1.3 Grouse Conservation ..................................................................................5 1.4 Diet Studies and Trophic Dynamics .................................................................7 1.5 Stable Isotope Ecology ................................................................................9 1.6 Research Objectives and Hypotheses ............................................................ 15 Chapter 2: Fall Diet of Plains Sharp-tailed Grouse Assessed Using Esophageal Crop Contents .. 16 Abstract ................................................................................................... 16 2.1 Introduction .......................................................................................... 16 2.2 Study Area ............................................................................................ 19 2.3 Materials and Methods .............................................................................. 21 2.4 Results and Discussion .............................................................................. 23 Chapter 3: Estimating Feeding Relationships of Sharp-tailed Grouse In Mixsiar Using Stable Isotopes δ15N, δ13C, and Concentration Dependence ............................................................. 35 Abstract ................................................................................................... 35 3.1 Introduction .......................................................................................... 36 v 3.2 Study Area ............................................................................................ 41 3.3 Methods ............................................................................................... 41 3.3.1 Feather Sampling and Preparation .......................................................... 41 3.3.2 Baseline Sampling and Preparation.......................................................... 43 3.3.3 Stable Isotope Analysis ........................................................................ 45 3.3.4 Statistical Analysis ............................................................................. 46 3.3.5 Model Structure ................................................................................ 53 3.4 Results ................................................................................................ 56 3.5 Discussion ............................................................................................ 70 3.5.1 Conclusion ...................................................................................... 75 3.5.2 Recommendations for Further Study ........................................................ 76 Chapter 4: Sharp-Tailed Grouse Food Web Dynamics and Climate Change ......................... 78 Abstract ................................................................................................... 78 4.1 Food Web Theory .................................................................................... 79 4.2 Climate Change and Trophic Dynamics .......................................................... 83 References ................................................................................................... 86 Appendix 1: Vegetation Surveys .......................................................................... 98 Appendix 2: Primary Feather Measurements ........................................................... 106 Appendix 3.1: Resampling Replicate Feather Samples ............................................... 112 Appendix 3.2: Opposite Wing Replicate Feather Samples ........................................... 115 Appendix 3.3: Resampling Replicate Plant and Arthropod Samples ................................ 118 Appendix 4: Arthropod Relative Abundance and Relative Biomass ................................. 121 Appendix 5.1: Isotope Values and Elemental Concentrations for Sampled Arthropods .......... 125 vi Appendix 5.2: Non-Weighted Average Isotope Values for Arthropod Orders ...................... 131 Appendix 5.3: Average Relative Biomass of Arthropods .............................................. 132 Appendix 6: Lipid Correction ............................................................................. 133 Appendix 7: Standards Used to Calibrate and Normalize Isotope Data ............................ 137 Appendix 8: Isotope Values and Elemental Concentrations for Sampled Plant Material ......... 138 Appendix 9.1: Plant Isotope and Elemental Concentration Comparison ........................... 142 Appendix 9.2: Arthropod Isotope Value Comparison .................................................. 145 Appendix 9.3: Grouse Class Comparison ................................................................ 147 Appendix 9.4: Source t-Tests ...........................................................................