Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 12-2009 Effects of Coyote Removal on Pronghorn and Mule Deer Populations in Wyoming Dylan Earl Brown Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Other Animal Sciences Commons Recommended Citation Brown, Dylan Earl, "Effects of Coyote Removal on Pronghorn and Mule Deer Populations in Wyoming" (2009). All Graduate Theses and Dissertations. 498. https://digitalcommons.usu.edu/etd/498 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. EFFECTS OF COYOTE REMOVAL ON PRONGHORN AND MULE DEER POPULATIONS IN WYOMING by Dylan E. Brown A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Wildlife Biology Approved: _____________________ _____________________ Michael R. Conover Terry A. Messmer Major Professor Committee Member _____________________ _____________________ John A. Shivik Byron R. Burnham Committee Member Dean of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2009 ii ABSTRACT Effects of Coyote Removal on Pronghorn and Mule Deer Populations in Wyoming by Dylan E. Brown, Master of Science Utah State University, 2009 Major Professor: Dr. Michael R. Conover Department: Wildland Resources I studied the relationship between coyote (Canis latrans) removal and pronghorn (Antilocapra americana) and mule deer (Odocoileus hemionus) density and fawn:doe ratios in southwest Wyoming and northeast Utah in 2007 and 2008. Coyote removal variables studied included the number of coyotes removed, ground hours worked, total hours worked, coyotes removed/aerial gunning hour, coyotes removed/ground work hour, and coyotes removed/total effort hour. None of the variables explained changes observed in fawn:doe ratios of pronghorn or mule deer. The number of coyotes removed, ground hours worked, total hours worked, and coyotes removed/aerial gunning hour were positively correlated with pronghorn density. However, none of the coyote removal variables were correlated with mule deer density. Coyote removal conducted in the winter and spring explained more variation and had a stronger positive correlation with fawn survival and ungulate density than removal conducted in the summer or fall. My results suggest that coyote removal conducted over large areas may increase density of iii pronghorn. However, coyote removal did not appear to increase mule deer fawn survival or density. (64 pages) iv ACKNOWLEDGMENTS Funding was provided by the Predator Management Districts of Lincoln and Sweetwater counties of Wyoming. I thank my advisor, Dr. Michael Conover, for this opportunity and advice given throughout my graduate career, and my committee members, Dr. Terry Messmer and Dr. John Shivik, for their support and feedback. I would like to thank all the graduate students in the Conover and Messmer labs, in particular Josh Vest, for his help in editing and his input on many aspects of the project. Thanks go to all Wyoming Game and Fish employees who helped with the project, especially Mark Zornes and Tim Woolley. I thank USDA Wildlife Services for providing coyote removal data, in particular Rod Merrell as well as the National Wildlife Research Center and Dr. John Shivik for the use of a camp trailer and pickup during the second year of the project. This project would not have been a success without the help of Joe Barnett, who assisted with ungulate and scat counts. Vic Dana helped me learn the country during my first field season and provided a place to stay. Finally, I thank Jody McLeod for supporting me throughout the process. Dylan Earl Brown v CONTENTS Page ABSRACT………………………………………………………………………...ii ACKNOWLEDGMENTS………………………………………………………..iv LIST OF TABLES....…………………………………………………………….vii LIST OF FIGURES………………………………………………………………ix INTRODUCTION ...................................................................................................1 Effects of Predation on Ungulates ......................................................................2 STUDY AREA ........................................................................................................7 METHODS ............................................................................................................10 Coyote Removal.................................................................................................10 Ungulate Counts.................................................................................................11 Coyote Density Index ........................................................................................12 Statistical Analysis .............................................................................................13 RESULTS ..............................................................................................................16 Coyote Removal Indices ....................................................................................16 Effects of Coyote Removal on Coyote Density .................................................16 Pronghorn Density Estimates .............................................................................17 Mule Deer Density Estimates ............................................................................18 Relationship of Coyote Removal to Pronghorn Fawn:Doe Ratios and Density Indices ............................................................................................20 Relationship of Coyote Removal to Mule Deer Fawn:Doe Ratios and Density Indices ............................................................................................23 Effects of Timing on Efficacy of Coyote Removal ...........................................25 DISCUSSION ........................................................................................................28 Impact of Coyote Removal on Coyote Density .................................................28 Impact of Coyote Removal on Pronghorn Populations .....................................29 Impact of Coyote Removal on Mule Deer Populations .....................................31 Impact of Timing on Efficacy of Coyote Removal ...........................................32 MANAGEMENT IMPLICATIONS .....................................................................34 vi LITERATURE CITED ..........................................................................................35 APPENDICES .......................................................................................................41 APPENDIX A. COMBINED COYOTE REMOVAL DATA ..........................42 Total Coyotes Removed By Wildlife Services and Private Contractors .......42 Total Hours Spent Removing Coyotes ..........................................................43 Ground Hours Spent Removing Coyotes .......................................................44 Aerial Hours Spent Removing Coyotes .........................................................45 APPENDIX B. WILDLIFE SERVICES COYOTE REMOVAL DATA .........46 Coyotes Removed by Wildlife Services ........................................................46 Total Hours Worked by Wildlife Services.....................................................47 Ground Hours Worked by Wildlife Services .................................................48 Aerial Hours Worked by Wildlife Services ...................................................49 APPENDIX C. PRIVATE CONTRACTOR COYOTE REMOVAL DATA ...50 Coyotes Removed by Private Contractors .....................................................50 Total Hours Worked by Private Contractors .................................................51 Ground Hours Worked by Private Contractors ..............................................52 Aerial Hours Worked by Private Contractors ................................................53 APPENDIX D. UNGULATE SURVEY DATA ...............................................54 Pronghorn Dependent Variables ....................................................................54 Mule Deer Dependent Variables ....................................................................55 vii LIST OF TABLES Table Page 1 Effect of management type (coyote removal vs. non-removal) on change in number of does per km, fawns per km, total pronghorn per km, and fawns per 100 does between 2007 (pre-treatment year) and 2008 (treatment year), Wyoming Coyote Predation Study, 2008..… 20 2 Effect of management type (coyote removal vs. non-removal) on number of pronghorn does per km, pronghorn fawns per km, total pronghorn per km, and pronghorn fawns per 100 does for 2007 (pre-treatment year), Wyoming Coyote Predation Study, 2008.……….. 21 3 Effect of management type (coyote removal vs. non-removal) on number of pronghorn does per km, pronghorn fawns per km, total pronghorn per km, and pronghorn fawns per 100 does for 2008 (treatment year), Wyoming Coyote Predation Study, 2008….………….21 4 Correlations between variables monitoring the intensity of coyote removal with number of pronghorn does observed per km of transect and pronghorn fawns observed per km during 2007 and 2008 at the 10 sites where pronghorn occurred, Wyoming Coyote Predation Study, 2008………………………………........................….. 22 5 Correlations between variables monitoring the intensity of coyote removal with total