POPULATION AND HABITAT ANALYSES FOR DALL’S SHEEP (OVIS DALLI) IN WRANGELL – ST. ELIAS NATIONAL PARK AND PRESERVE A THESIS Presented to the Faculty of the University of Alaska Fairbanks in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE By Miranda Lilian Naeser Terwilliger, B.S. Fairbanks, Alaska August 2005 iii ABSTRACT We summarized and statistically analyzed historical fixed-wing aerial surveys (1949-2002) and harvest records (1983-2002) of Dall’s sheep (Ovis dalli dalli) from Wrangell-St. Elias National Park and Preserve (WRST). Among survey units there were significant differences in observed densities, hunter- reported harvest, horn lengths of harvested rams, and horn length residuals from the regression of length on age. There was no consistent evidence of net change in WRST-wide sheep density, even though some survey units showed trends in density. Reported harvest in WRST declined linearly during 1973-2003 from 376 to 139 rams per year. We estimated the relationships among population and habitat characteristics with multiple linear regression. We standardized all variables and evaluated all 1, 2, and 3 variable models using Akaike’s Information Criterion for small sample sizes (AICc) for model selection. The best model for sheep density showed a positive correlation with median NDVI (relative vegetation greenness) and terrain ruggedness. The same model resulted from examining adult and lamb cohorts separately. Approximately 50% of horn length was explained by age. The habitat variables estimated did not explain a significant amount of the variance observed in reported harvests or horn length residuals from the regression of length on age. iv TABLE OF CONTENTS THESIS SIGNATURE PAGE…………………………………………………………...i TITLE PAGE……………………………………………………………………...……...ii ABSTRACT ..........................................................................................................iii TABLE OF CONTENTS .......................................................................................iv LIST OF FIGURES ...............................................................................................vi LIST OF TABLES ................................................................................................. x LIST OF APPENDICES.......................................................................................xii LIST OF ABBREVIATIONS ................................................................................xiii PREFACE ............................................................................................................ 1 GENERAL INTRODUCTION................................................................................ 2 CHAPTER I: DENSITY, HARVEST, AND HORN DIMENSIONS OF DALL’S SHEEP IN WRANGELL ST. ELIAS NATIONAL PARK AND PRESERVE, ALASKA ...…………………………………………………………………………...…..3 Abstract: ............................................................................................................... 3 STUDY AREA....................................................................................................... 6 METHODS............................................................................................................ 7 Aerial Survey Data ............................................................................................ 7 Harvest Data..................................................................................................... 9 RESULTS........................................................................................................... 11 Aerial Survey Data .......................................................................................... 11 Population Characteristics .............................................................................. 11 v Harvest Data................................................................................................... 12 DISCUSSION ..................................................................................................... 14 MANAGEMENT IMPLICATIONS........................................................................ 17 ACKNOWLEDGEMENTS................................................................................... 18 LITERATURE CITED ......................................................................................... 18 FIGURES............................................................................................................ 24 TABLES.............................................................................................................. 35 CHAPTER II: RELATIONSHIPS AMONG POPULATION AND HABITAT CHARACTERISTICS FOR DALL’S SHEEP IN WRANGELL ST. ELIAS NATIONAL PARK AND PRESERVE, ALASKA.................................................. 41 Abstract: ............................................................................................................. 41 STUDY AREA..................................................................................................... 45 METHODS.......................................................................................................... 47 RESULTS........................................................................................................... 53 DISCUSSION ..................................................................................................... 56 ACKNOWLEDGEMENTS................................................................................... 59 LITERATURE CITED ......................................................................................... 59 FIGURES............................................................................................................ 68 TABLES.............................................................................................................. 71 GENERAL CONCLUSIONS ............................................................................... 81 APPENDICES .................................................................................................... 83 vi LIST OF FIGURES Figure 1.1. Location of Wrangell-St. Elias National Park and Preserve, Alaska. .......................................................................................................... 24 Figure 1.2. The four mountain ranges of Wrangell-St. Elias National Park and Preserve, Alaska. ........................................................................................ ..25 Figure 1.3. Mountain sheep (Ovis dalli) and goat (Oreamnos americana) aerial survey units in Wrangell-St. Elias National Park and Preserve, Alaska ……………………………………………………………………………………….26 Figure 1.4. Total number of Dall’s sheep (Ovis dalli) fixed-wing aerial surveys conducted per survey unit in Wrangell-St. Elias National Park and Preserve, Alaska, 1949-2002……………………..………………………………………….27 Figure 1.5. Alaska Department of Fish and Game harvest units (UCUs) overlaid on aerial survey units in Wrangell-St. Elias National Park and Preserve, Alaska. .......................................................................................... 28 Figure 1.6. Relative density of adult Dall’s sheep in aerial survey units, Wrangell-St. Elias National Park and Preserve, Alaska…………….…………29 Figure 1.7. Number of hunter-reported Dall’s sheep rams harvested in Wrangell-St. Elias National Park and Preserve, Alaska, 1973-2002………...30 Figure 1.8. Relative level of hunter-reported harvest of Dall’s sheep in aerial survey units, Wrangell-St. Elias National Park and Preserve, Alaska….…....31 Figure 1.9. Horn length in relationship to age of reported rams harvested in Wrangell-St. Elias National Park and Preserve, Alaska……….……………...32 vii Figure 1.10. Relative horn length residuals from the regression of length on age in Dall’s sheep in aerial survey units, Wrangell-St. Elias National Park and Preserve, Alaska……………..……………………………………………….33 Figure 1.11. Relative hunter-reported horn lengths of Dall’s sheep in aerial survey units, Wrangell-St. Elias National Park and Preserve, Alaska…........34 Figure 2.1. Location of Dall’s sheep (Ovis dalli) and mountain goat (Oreamnos americana) survey units, Wrangell-St. Elias National Park and Preserve, Alaska…………………………………………………………………..68 Figure 2.2. Correlation between standardized NDVI (normalized difference vegetation index) and standardized non-forested but vegetated (alpine tundra) landcover in 13 Dall’s sheep survey units in Wrangell-St. Elias National Park and Preserve, Alaska ……………………………………….…...69 Figure 2.3. Correlated habitat variables estimated in Dall’s sheep aerial survey units in Wrangell-St. Elias National Park and Preserve, Alaska……..70 Figure C.1. Dall’s sheep densities in survey unit 1, Mentasta Mountains, Wrangell-St. Elias National Park and Preserve, Alaska, 1949-2002……… 105 Figure C.2. Dall’s sheep densities in survey unit 3, Jacksina, Wrangell-St. Elias National Park and Preserve, Alaska, 1949-2002……………………....106 Figure C.3. Dall’s sheep densities in survey unit 5E, East Mount Allen, Wrangell-St. Elias National Park and Preserve, Alaska, 1949-2002……….107 Figure C.4. Dall’s sheep densities in survey unit 7E, Klein Creek, Wrangell- St. Elias National Park and Preserve, Alaska, 1949-2002…………………..108 viii Figure C.5. Dall’s sheep densities in survey unit 7W, Chisiana, Wrangell-St. Elias National Park and Preserve, Alaska, 1949-2002……………...............109 Figure C.6. Dall’s sheep densities in survey unit 9, Ptarmigan Lake, Wrangell-St. Elias National Park and Preserve, Alaska, 1949-2002……….110 Figure C.7. Dall’s sheep densities in survey unit 10, Mount Drum, Wrangell- St. Elias National