POPULATION DEMOGRAPHY OF THE YELLOWSTONE NATIONAL PARK BISON HERDS by Julie Ann Fuller A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Fish and Wildlife Management MONTANA STATE UNIVERSITY Bozeman, Montana April 2006 © COPYRIGHT by Julie Ann Fuller 2006 All Rights Reserved ii Approval of a thesis submitted by Julie Ann Fuller This thesis has been read by each member of the thesis committee, and has been found to be satisfactory regarding content, English usage, format, citations, bibliographic style, and consistency, and is ready for submission to the Division of Graduate Education. Dr. Robert A. Garrott Approved for the Department of Ecology Dr. David W. Roberts Approved for the Division of Graduate Education Dr. Joseph J. Fedock iii STATEMENT OF PERMISSION TO USE In presenting this thesis in partial fulfillment of the requirements for a master’s degree at Montana State University, I agree that the Library shall make it available to borrowers under rules of the Library. If I have indicated my intention to copyright this thesis by including a copyright notice page, copying is allowable only for scholarly purposes, consistent with “fair use” as prescribed in the U.S. Copyright Law. Requests for permission for extended quotation from or reproduction of this thesis in whole or in parts may be granted only by the copyright holder. Julie Ann Fuller April 2006 iv ACKNOWLEDGEMENTS This project would not have been possible without the vision of Dr. Robert Garrott and Dr. P. J. White. I am exceedingly grateful to Drs. Garrott and White for their support when my wolf-elk research took an unfortunate turn, and thank them for their patient guidance and constructive criticism throughout this research effort. I owe many thanks to the superior instruction of Dr. Jay Rotella, and for all his assistance in helping me understand analytical methods and software code. I would also like to extend grateful acknowledgement to Keith Aune, for his time and for allowing me access to an impressive bank of data he collected with Tom Roffe, and Jack Rhyan. Phil Farnes kindly provided instrumental climatic data, and shared many ideas with me. Rick Wallen, Glenn Plumb, and the Yellowstone Center for Resources provided data and funding, and Allison Backus provided a CD library of archival documents for Yellowstone that was a wealth of interesting information. Drs. Mark Greenwood, Steve Cherry, John Borkowski, and L. Lee Eberhardt provided statistical advice. Fred Watson and Wendi Newman provided graphical support for presentations. I would also like to thank my fellow graduate students, especially M. Becker, J. Bruggeman, C. Gower, J. Grigg, J. and P. Gude, and K. Proffitt for their support, friendship, and assistance through our classes and research efforts. Kelly Proffitt deserves special thanks for her devoted and substantial efforts in reviewing and editing this manuscript. Finally, I would like to thank my dad, whose scientific mind, and capacity for reason and logic, never ceases to inspire me (even if I don’t always admit it). This research was funded by the National Park Service. v TABLE OF CONTENTS Page LIST OF TABLES ........................................................................................................... vii LIST OF FIGURES .......................................................................................................... ix ABSTRACT ........................................................................................................................x 1. A CENTURY OF DEMOGRAPHIC CHANGE IN YELLOWSTONE’S BISON HERDS ......................................................................1 Abstract ...................................................................................................................................1 Introduction....................................................................................................................2 Study Area .....................................................................................................................4 Methods..........................................................................................................................6 Data Collection Methods: Population Counts and Removals.............................6 Population Models 1902-1954............................................................................7 Population Models 1970-2000..........................................................................10 Results..........................................................................................................................15 Population Models 1902-1954..........................................................................15 Population Models 1970-2000..........................................................................16 Discussion....................................................................................................................21 2. REPRODUCTION AND SURVIVAL OF YELLOWSTONE’S BISON HERDS: AN INTEGRATED ANALYSIS ...............................................29 Abstract ..................................................................................................................................29 Introduction..................................................................................................................30 Study Area ...................................................................................................................32 Methods..................................................................................................................................33 Vital Rates.........................................................................................................33 Model Development and Evaluation ................................................................36 Structure and Parameterization of the Matrix Model .......................................43 Results..........................................................................................................................45 Response Variables and Effects of Covariates ..................................................45 Integrating Vital Rates .......................................................................................52 Discussion....................................................................................................................55 LITERATURE CITED ......................................................................................................60 vi TABLE OF CONTENTS – CONTINUED Page APPENDICES ..................................................................................................................69 APPENDIX A – Bison Counts and Removals By Herd 1902-2000 .....................70 APPENDIX B – Loge-Linear Regression of Count Data for Central Herd Bison 1970-1994 ...............................................72 APPENDIX C – Covariates used in Multiple Regression Models........................74 APPENDIX D – Regression of Northern and Central Bison Herd Population Growth Rates 1970-1981 and 1982-2000.............76 APPENDIX E – Coefficient Estimates from Pregnancy and Birth Rate Multiple Logistic and Calf-Adult Ratio Linear Regression Models..................................................................79 APPENDIX F – Calf-Adult Ratios and Covariates by Herd 1970-2005...............82 APPENDIX G – Count Data for YNP Bison Population and Loge-Linear Regression of Count Data with Time (1990-2000).................84 vii LIST OF TABLES Table Page 1. Density-dependent and density-independent candidate models for a priori hypothesis testing examining the effect of population density on population growth rate for the northern and central YNP bison herds 1970-2000...............................................................................12 2. List of a priori models examining effects of climatic effects on the annual population growth rates of the northern and central YNP bison herds 1970-2000...............................................................................14 3. Model selection results for regression factors influencing the loge count of the central bison herd in YNP 1902-1954 ......................................................16 4. Density-dependent and density-independent model selection results for the central YNP bison herds 1970-2000 .......................................................17 5. Density-dependent and density-independent model selection results for the northern YNP bison herd 1970-2000 ......................................................18 6. Warm- and cold-season covariate model selection results for the central YNP bison herd 1981-2000.....................................................................20 7. Warm- and cold-season covariate model selection results for the northern YNP bison herd 1970-2000..................................................................20 8. A priori model suite of main effects pregnancy and birth rate models for 1995-2001 YNP bison data. ..........................................................................39 9. Program MARK output analyzing YNP adult female bison survival rates over 1995-2001...........................................................................................46 10. The model selection results for pregnancy data in YNP bison 1995-2001............47 11. The model selection results for birth rate data in YNP bison 1995-2001..............48 12. Estimated birth rates for YNP bison in two age categories