Brigham Young University BYU ScholarsArchive Theses and Dissertations 2010-04-19 Diet Reconstruction of Bighorn Sheep (Ovis canadensis) Using Stable Isotopes Joshua M. Whitaker Brigham Young University - Provo Follow this and additional works at: https://scholarsarchive.byu.edu/etd Part of the Animal Sciences Commons BYU ScholarsArchive Citation Whitaker, Joshua M., "Diet Reconstruction of Bighorn Sheep (Ovis canadensis) Using Stable Isotopes" (2010). Theses and Dissertations. 2328. https://scholarsarchive.byu.edu/etd/2328 This Thesis is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Diet Reconstruction of Bighorn Sheep (Ovis canadensis) Using Stable Isotopes Joshua M. Whitaker A thesis submitted to the faculty of Brigham Young University in partial fulfillment of the requirements for the degree of Master of Science Todd F. Robinson Steven L. Petersen Tom Smith Department of Plant and Wildlife Sciences Brigham Young University August 2010 Copyright © 2010 Joshua Whitaker All Rights Reserved ABSTRACT Diet Reconstruction of Bighorn Sheep (Ovis canadensis) Using Stable Isotopes Joshua M. Whitaker Department of Plant and Animal Sciences Master of Science We determined the diet contributions of grasses, forbs and shrubs for three herds of bighorn sheep along the Wasatch Front, Utah using stable isotope techniques and determined the electivity values for different forage species for four herds. Forbs were generally the most common forage eaten across all herds while shrubs were the least used forage resource. The Provo Peak and Mount Nebo herds used grasses, forbs and shrubs at proportions similar to other bighorn sheep populations across the west, while the Antelope Island herd used forbs at higher levels than any other local herd. Additionally, the herd on Antelope Island was analyzed to compare differential use by rams and ewes. Our results indicate that there was no significant difference in diet between sexes on Antelope Island. Bluebunch wheatgrass (Pseudoroegneria spicata) was a common species across all sites and was an important forage for all populations. Managers may consider these proportions when seeding in bighorn habitat improvement projects. Key words: bighorn sheep, stable isotopes, habitat improvement ACKNOWLEDGEMENTS I wish to thank those who have made this project possible. First, my gratitude to my lovely wife, Jessica, and my three sons, Caleb, Travis, and Derek. Also, my parents and other family, who have been supportive of my schooling. Secondly, to Dr. Todd F. Robinson for helping me to accomplish this work. I am grateful to Jericho Whiting, the Utah Division of Wildlife Resources and many friends and colleagues who have worked and advised on this project. I appreciate the faculty and staff of Brigham Young University for the courses and outside help they provide to students and for the work they have provided so that I could complete my education. iii TABLE OF CONTENTS Diet Reconstruction of Bighorn Sheep (Ovis canadensis) Using Stable Isotopes..............................i ABSTRACT.........................................................................................................................................ii ACKNOWLEDGEMENTS...................................................................................................................iii LIST OF TABLES................................................................................................................................vi LIST OF FIGURES.............................................................................................................................vii LITERATURE REVIEW....................................................................................................................... 8 INTRODUCTION............................................................................................................................... 8 Habitat......................................................................................................................................... 9 Diets........................................................................................................................................... 10 Habitat Use................................................................................................................................ 13 Reintroduction Efforts in Utah .................................................................................................. 14 Electivity Indices ........................................................................................................................ 17 Isotope Techniques ................................................................................................................... 17 C3 and C4 plants........................................................................................................................ 18 Diet reconstruction.................................................................................................................... 19 CONCLUSION................................................................................................................................. 20 LITERATURE CITED .................................................................................................................... 21 INTRODUCTION............................................................................................................................. 26 MATERIALS AND METHODS ......................................................................................................... 27 Location ..................................................................................................................................... 27 Field Procedures........................................................................................................................ 28 Mass Spectrometry Procedures ................................................................................................ 29 Diet Reconstruction................................................................................................................... 29 Electivity Indices ........................................................................................................................ 30 RESULTS......................................................................................................................................... 31 Study Areas................................................................................................................................ 31 Antelope Island..........................................................................................................................33 Provo Peak................................................................................................................................. 36 Mount Nebo .............................................................................................................................. 37 Mount Timpanogos ................................................................................................................... 39 DISCUSSION................................................................................................................................... 40 iv Antelope Island..........................................................................................................................41 Provo Peak................................................................................................................................. 42 Mount Nebo .............................................................................................................................. 43 Mount Timpanogos ................................................................................................................... 44 CONCLUSION................................................................................................................................. 46 LITERATURE CITED ........................................................................................................................ 48 v LIST OF TABLES Table 1. Mean δ13C values for plant species, plant families and fecal samples from each site. Table 2. Mean and standard deviation of plant family contribution to overall diet for rams and ewes on Antelope Island. Table 3. Mean and standard deviation of plant taxa contribution to Antelope Island ram diets. Table 4. Mean and standard deviation of plant taxa contribution to the Provo Peak herd’s overall diet. Table 5. Mean and standard deviation of plant taxa contribution to the Mount Nebo herd. vi LIST OF FIGURES Figure 1. Location of study sites in Utah. Figure 2. A comparison of C3 and C4 plants types found in the diet of bighorn sheep on Antelope Island, Utah from 2005 to 2006. Figure 3. Comparison and reconstruction of diets from Antelope Island, 2006. Figure 4. Comparison and reconstruction of diets by forage type from Antelope Island. Figure 5. Electivity indices for Antelope Island herd. Figure 6. Provo Peak herd diet reconstruction by species. Figure 7. Provo Peak herd diet reconstruction by forage type. Figure 8. Electivity indices for the Provo Peak herd. Figure 9. Mount Nebo herd diet reconstructionby species. Figure 10. Mount Nebo herd diet reconstruction by forage type. Figure 11. Electivity indices for