ECOLOGY OF MERRIAM’S TURKEYS IN THE SOUTHERN BLACK HILLS, SOUTH DAKOTA BY CHAD P. LEHMAN A dissertation submitted in partial fulfillment of the requirements for the degree Doctor of Philosophy Major in Wildlife and Fisheries Sciences South Dakota State University 2005 UMI Number: 3172304 3172304 2005 UMI Microform Copyright All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, MI 48106-1346 by ProQuest Information and Learning Company. ii ECOLOGY OF MERRIAM’S TURKEYS IN THE SOUTHERN BLACK HILLS, SOUTH DAKOTA This dissertation is approved as a creditable and independent investigation by a candidate for the Doctor of Philosophy degree and is acceptable for meeting the thesis requirements for this degree. Acceptance of this dissertation does not imply that the conclusions reached by the candidate are necessarily the conclusion of the major department. Dr. Lester D. Flake Date Dissertation Advisor Dr. Charles G. Scalet Date Head, Department of Wildlife and Fisheries Sciences iii Acknowledgements Sincere thanks and appreciation are extended to a friend and mentor, Dr. Lester D. Flake, for his guidance and support throughout this study. I thank Dr. Mark A. Rumble for his advice, study suggestions, patience, and review of the manuscript. I thank Dr. Timothy Wittig, Paul Evenson, Dr. Cuirong Ren, and Rudy King for providing valuable statistical advice and assistance. Thanks to Dr. Gary Larson, Dr. Jonathan Jenks, and Dr. Daniel Hubbard for being a part of my graduate committee, and for reviewing this manuscript. A huge appreciation is extended to Dan Thompson for his hard work and dedication with this project while pursuing his Masters Degree. As a fellow turkey chaser, he provided valuable assistance trapping turkeys and collecting data. I enjoyed working with technicians Mark Rohlfing, Chad Sexton, Cory Kassube, Les Flack, Eric Maichak, and Matt May. I wish to express my thanks for the cooperation of landowners in Fall River and Custer counties, and the United States Forest Service for providing access to lands. Special thanks are extended to the families of Richard “Gene” Miller, Ned Westphal, Marty Elmore, and Doug Brown for their friendship and for providing access to lands and equipment. Most importantly, I extend my love and gratitude to my family for their support and understanding these past three years. To my wife, Michelle, I will always be grateful for your love, support, and patience throughout this project. This research project was supported by the South Dakota Department of Game, Fish and Parks, Federal Aid to Wildlife Restoration Fund, Project W-75-R-132, No. 7599, administered by the South Dakota Department of Game, Fish and Parks; South Dakota State University; McIntire-Stennis funding through the South Dakota Agricultural iv Experiment Station; USDA Forest Service, Rocky Mountain Research Station. Additional funding was provided by the National Wild Turkey Federation through their National Projects Research Grant; and the South Dakota Chapter of the National Wild Turkey Federation, South Dakota Super Fund. A sincere thanks is extended to the Fall River Chapter of the National Wild Turkey Federation for their support in the field and for supplying equipment when needed. v Abstract ECOLOGY OF MERRIAM’S TURKEYS IN THE SOUTHERN BLACK HILLS, SOUTH DAKOTA Chad P. Lehman April 2005 I investigated resource selection patterns, survival, reproduction, and recruitment of Merriam’s turkeys ( Meleagris gallopavo merriami ) in a xeric ponderosa pine ( Pinus ponderosa ) ecosystem in the southern Black Hills, South Dakota. Winter survival of female Merriam’s turkeys associated with supplemental food from livestock feeding or farmsteads was not different ( P = 0.70) from females that wintered in forest habitats. Turkeys selected for open to mid-canopy (0-70%) mature (>22.9 cm diameter at breast height [DBH]) structural stage pine stands for feeding sites. During the hunting period, gobbling activity was lower ( P = 0.001) in a hunted population than a nonhunted population, presumably due to the negative association between gobbling and subsequent disturbance of flocks by hunters. Currently, the spring hunting season starts before most females have initiated nests, and it encapsulates the second gobbling peak. Daily movements (Spider Distances) of females decreased abruptly from prelaying to laying behaviors, and movements less than 364.9 m for eastern turkeys, 115.0 m for Rio Grande turkeys, and 331.0 m for Merriam’s turkeys were indicative of a nest initiation; information on daily movements can be used to improve estimates of nesting parameters. Merriam’s turkeys had higher nesting rates and nest success estimates than most vi Merriam’s turkey populations found elsewhere in the current range. Supplemental feeding at farmsteads did not enhance nesting rates or nest success for adult females. Successful nests were on steeper slopes, had greater visual obstruction, and greater total ground level vegetation and shrub cover than unsuccessful nests. Precipitation during the incubation period was also an important variable predicting nest success. Fifty-four percent of poult mortality occurred 0-7 days posthatch and poult survival to 4 weeks posthatch averaged 33%. Females with poults selected for meadow habitats that were near the edge of pine stands and shrub patches, had greater total ground level vegetation and shrub cover, and had greater visual obstruction than random sites. Survival of poults ≤ 14 days posthatch decreased during cold periods and during or immediately following periods of rainfall. Poult survival increased when visual obstruction was greater, and when biomass of Coleoptera was higher. Although supplemental feeding at farmsteads (50-91% of the population) did not enhance survival and reproduction for adult female Merriam’s turkeys in the southern Black Hills, I expect populations to benefit from the continued existence of livestock feeding operations. Perhaps the greatest benefit of livestock feeding operations is the expansion of available winter habitats through provision of emergency food sources. Forest management for open to mid-canopy, mature structural stage, mast-producing pine stands will ensure the availability of winter habitat in the southern Black Hills. Monitoring rainfall and temperature data during May and June may provide an index of annual nest success and poult recruitment. Resource managers should maintain 1170 kg/ha of herbaceous biomass for brood habitat through 1 August. vii Table of Contents Page Acknowledgements............................................................................................................ iii Abstract ................................................................................................................................v List of Tables ....................................................................................................................xv List of Figures ................................................................................................................. xxi List of Appendices ........................................................................................................ xxiii CHAPTER 1. INTRODUCTION .......................................................................................1 CHAPTER 2. SURVIVAL AND CAUSE-SPECIFIC MORTALITY OF MERRIAM’S TURKEYS IN THE SOUTHERN BLACK HILLS.....................................6 A. Abstract ...................................................................................................6 B. Introduction .............................................................................................7 C. Study Area ...............................................................................................8 D. Methods .................................................................................................10 1. Capture and Radiotelemetry .............................................................10 2. Survival and Cause-specific Mortality ..............................................11 E. Results ....................................................................................................12 1. Survival .............................................................................................12 2. Cause-specific Mortality ...................................................................13 F. Discussion ..............................................................................................19 viii Table of Contents CHAPTER 3. WINTER FARMSTEAD DEPENDENCE AND HABITAT USE OF MERRIAM’S TURKEY FEMALES IN THE SOUTHERN BLACK HILLS, SOUTH DAKOTA .......................................................................24 A. Abstract .................................................................................................24 B. Introduction ...........................................................................................25 C. Study Area .............................................................................................27 D. Methods .................................................................................................28 1. Capture and Radiotelemetry .............................................................28 2. Physical Characteristics ....................................................................28 3. Forage Quality ..................................................................................29 4. Weather .............................................................................................29 5. Farmstead Use ...................................................................................29 6. Winter Home Range and Habitat Use ...............................................30 7. Statistical Analyses ...........................................................................35 a. General Analysis ..........................................................................35 b. Macrohabitat Analysis .................................................................35 c. Microhabitat Analysis ..................................................................36 d. A Priori Model Approach in Analysis of Feeding Sites and Farmstead Use ..............................................................................37 E. Results ....................................................................................................40 1. Capture and Radiotelemetry .............................................................40 ix Table of Contents 2. Physical Characteristics .....................................................................40 3. Forage Quality ...................................................................................41 4. Weather ..............................................................................................41 5. Farmstead Use....................................................................................45 6. Winter Home Range and Habitat Use................................................52 a. Home Range .................................................................................52 b. Habitat Use at Feeding Sites ........................................................52 c. Information Theoretic Modeling—Winter Feeding Sites ............55 d. Relative Variable Importance—Winter Feeding Sites ................57 e. Habitat Use at Escape Cover and Loafing Sites ...........................59 f. Information Theoretic Modeling—Escape Cover and Loafing Sites ...............................................................................................59 g. Relative Variable Importance—Escape Cover and Loafing Sites ..............................................................................................62 F. Discussion ...............................................................................................62 G. Management Implications ......................................................................66 CHAPTER 4. GOBBLING OF MERRIAM’S TURKEYS IN RELATION TO NESTING AND OCCURRENCE OF HUNTING IN THE BLACK HILLS, SOUTH DAKOTA....................................................................................................67 A. Abstract ..................................................................................................67 B. Introduction ............................................................................................68 x Table of Contents C. Study Area ..............................................................................................69 D. Methods ..................................................................................................69 1. Capture and Monitoring ....................................................................69 2. Gobbling Activity .............................................................................70 3. Female Nesting Chronology .............................................................71 4. Statistical Analysis ............................................................................71 5. Factors Influencing Gobbling ...........................................................72 E. Results ....................................................................................................73 1. Gobbling Activity .............................................................................73 a. Gobbling Activity in Relation to Nesting Chronology .................73 b. Gobbling Activity and Occurrence of Hunting.............................75 2. Nesting Chronology ..........................................................................75 3. Factors Influencing Gobbling ...........................................................78 F. Discussion ..............................................................................................78 G. Management Implications ......................................................................80 CHAPTER 5. PREINCUBATION MOVEMENTS OF FEMALE WILD TURKEYS RELATIVE TO NEST INITIATION IN SOUTH DAKOTA ...................81 A. Abstract .................................................................................................81 B. Introduction ...........................................................................................82 C. Study Area .............................................................................................83 D. Methods .................................................................................................84 xi Table of Contents 1. Capture and Radiotelemetry .............................................................84 2. Localized Movements .......................................................................85 E. Results ....................................................................................................87 1. Capture and Radiotelemetry .............................................................87 2. Localized Movements .......................................................................89 F. Discussion ..............................................................................................94 G. Management Implications .....................................................................96 CHAPTER 6. REPRODUCTION OF MERRIAM’S TURKEY FEMALES: A NEST SUCCESS MODEL FOR THE SOUTHERN BLACK HILLS, SOUTH DAKOTA....................................................................................................97 A. Abstract .................................................................................................97 B. Introduction ...........................................................................................98 C. Study Area ...........................................................................................100 D. Methods ...............................................................................................101 1. Capture and Radiotelemetry ...........................................................101 2. Reproduction ...................................................................................101 3. Predator Indices and Nest Depredation ...........................................102 4. Precipitation and Nest Success ........................................................103 5. Nesting Habitat ...............................................................................103 6. Statistical Analyses .........................................................................106 a. Reproduction Analysis ...............................................................106 xii Table of Contents b. Macrohabitat Analysis ...............................................................107 c. Microhabitat Analysis ................................................................108 d. A Priori Model Approach in Analysis of Nest Sites...................109 E. Results .................................................................................................113 1. Reproduction ...................................................................................113 2. Predator Monitoring and Nest Depredation ....................................116 3. Nesting Habitat ...............................................................................117 a. Comparison of Microhabitat Variables Between Nest and Random Sites ............................................................................................120 b. Comparison of Microhabitat Variables Between Successful and Unsuccessful Nests ....................................................................120 4. A Priori Models Predicting Nest Site Selection .............................124 a. Models of Nest Site Selection ....................................................124 b. Relative Variable Importance .....................................................124 5. A Priori Models Predicting Nest Success .......................................124 a. Models of Nest Success .............................................................124 b. Relative Variable Importance .....................................................127 6. A Priori Models Evaluating Unsuccessful Nests ............................127 a. Evaluating Models of Unsuccessful Nests .................................127 b. Relative Variable Importance .....................................................129 F. Discussion .............................................................................................129 xiii Table of Contents G. Management Implications ...................................................................135 CHAPTER 7. SURVIVAL AND HABITAT USE OF MERRIAM’S TURKEY POULTS IN THE SOUTHERN BLACK HILLS, SOUTH DAKOTA..................................................................................................136 A. Abstract ...............................................................................................136 B. Introduction .........................................................................................137 C. Study Area ...........................................................................................138 D. Methods ...............................................................................................139 1. Capture and Radiotelemetry ...........................................................139 2. Poult Survival .................................................................................139 3. Invertebrate Use at Brood Sites ......................................................140 4. Weather Exposure During Poult-rearing .........................................141 5. Poult-rearing Habitat .......................................................................142 6. Statistical Analyses .........................................................................145 a. Poult Survival .............................................................................145 b. Invertebrates ...............................................................................145 c. Macrohabitat Analysis ...............................................................146 d. Microhabitat Analysis ................................................................147 e. A Priori Model Approach in Analysis of Poult Survival ............148 E. Results ..................................................................................................150 1. Poult Survival ..................................................................................150 xiv Table of Contents 2. Invertebrate Use at Brood Sites ......................................................151 a. Invertebrate Biomass Among Vegetation Structural Stages ......151 b. Invertebrate Biomass at Feeding Sites .......................................151 3. Weather Exposure During Poult-rearing ........................................158 4. Poult-rearing Habitat........................................................................158 a. Macrohabitat ...............................................................................158 b. Microhabitat Variables—Poult-rearing and Random Sites (All Habitat Categories) .....................................................................161 c. Microhabitat Variables—Poult-rearing and Random Meadow Sites.............................................................................................161 5. A Priori Models Predicting Poult Survival .....................................165 a. Poult Survival Model Evaluation 0-2 Weeks Posthatch ............165 b. Relative Variable Importance 0-2 Weeks Posthatch ..................165 F. Discussion.............................................................................................167 G. Management Implications ....................................................................173 CHAPTER 8. CONCLUSIONS AND FUTURE CONSIDERATIONS ........................174 Literature Cited ................................................................................................................180 xv List of Tables Table Page 1. Estimates for female Merriam’s turkeys for the southern Black Hills, South Dakota, 2001-04. Kaplan-Meier winter (1 Dec-31 Mar) seasonal survival estimates Ŝ ( t ) and survival comparison between females wintering in farmsteads and females wintering in forest ...........................................................14 2. Seasonal Kaplan-Meier survival estimates Ŝ ( t ) for adult female Merriam’s turkeys in the southern Black Hills, South Dakota, 2001-04.................................16 3. Seasonal Kaplan-Meier survival estimates Ŝ ( t ) for yearling female Merriam’s turkeys in the southern Black Hills, South Dakota, 2001-03.................................17 4. Seasonal Kaplan-Meier cause-specific mortality rates (SE) and deaths ( n ) for female Merriam’s turkeys in the southern Black Hills, South Dakota, 2001-04...20 5. Availability of various vegetation structural stage categories for female turkeys during winter (1 Dec-31 Mar) within the southern Black Hills study area, 2001-04..........................................................................................................32 6. Means in ml displacement (percentage of turkey crop by volume) and standard errors (SE) of food contents found in both females wintering in association with farmsteads and females wintering in forested habitats in the southern Black Hills, South Dakota, 2002-03 .......................................................42 7. Dry matter basis mean percentages and standard errors (SE) for crop contents found in Merriam’s females ( n = 34). Nonparametric two-sample median tests compared percentages between females wintering in association with farmsteads and females wintering in forest in the southern Black Hills, South Dakota, 2002-03.....................................................................................................43 8. Winter site selection (farmstead or forest), fidelity to previous wintering site, and winter habitat switching between years in wild turkeys in the southern Black Hills, South Dakota, 2001-04 ......................................................................46 xvi 9. Pine seed availability per m 2 (mean ± SE) at wild turkey feeding sites and random sites in the southern Black Hills, South Dakota, 2001-04. Categories are based on macrohabitat designations.................................................................47 10. Best set of a priori farmstead use prediction models based on radiolocations of radiomarked female turkeys. Relative importance of explanatory variables based upon Akaike model weights ( w i ) summed over all models within candidate set that contained variables in the southern Black Hills, South Dakota, 2001-04.....................................................................................................51 11. Radiomarked Merriam’s females ( n females), mean number of relocations ( n relocations) per polygon, mean (SE) fixed kernel home range and core area (FK 90%, FK 50%), and mean (SE) minimum convex polygon (MCP) home range (ha) for both birds wintering in association to farmsteads and birds wintering in forest in the southern Black Hills, South Dakota, 2002-03...............53 12. Winter (1 Dec-31 Mar) habitat utilization at macrohabitat level by radiomarked Merriam’s females of categories described by dominant species, structural stage, and overstory canopy cover of vegetation in the southern Black Hills, South Dakota, 2001-04 ......................................................................54 13. Winter habitat utilization at the microhabitat level for Merriam’s females in the southern Black Hills, South Dakota (2001-04) including explanatory variables that differed (*) between feeding sites and random sites within macrohabitat structural stage categories ................................................................56 14. Best set of a priori models predicting winter feeding site selection. Relative importance of explanatory variables based upon Akaike model weights ( w i ) summed over all models within candidate models that contained variables in the southern Black Hills, South Dakota, 2001-04..................................................58 15. Means and standard errors (SE) for microhabitat variables collected at loafing/escape cover and random sites during winter (1 Dec-31 Mar) in the southern Black Hills, South Dakota, 2001-04 .......................................................60 16. Best set of a priori models predicting winter loafing/escape cover site selection. Relative importance of explanatory variables based upon Akaike model weights ( w i ) summed over all models within candidate models that contained variables in the southern Black Hills, South Dakota, 2001-04 .............61 xvii 17. Nesting chronology of female Merriam’s turkeys in the southern Black Hills, South Dakota, 2001-03. Year, number of females radiomarked (N), mean number of days from 1 April to incubation (Days-Inc ± SE), and median dates for nest initiation, nest incubation, and nest hatch........................................77 18. Mean and standard error (SE) for the amount of time (hrs) between successive relocations (first nests and renests combined). Statistical values of t -ratios, degrees of freedom ( df ), and probabilities ( P -value) represent the comparisons made between time periods (prelaying and laying) for eastern, Rio Grande, and Merriam’s subspecies of wild turkey females in South Dakota, 1996-2003.................................................................................................90 19. Number of distances calculated (N), means, and standard error (SE) of preincubation movement distances (m) calculated using the SPIDER DISTANCE command. Statistical values of t -ratios, degrees of freedom ( df ), and probabilities ( P -value) comparing prelaying and laying time periods of first nests and renests for eastern, Rio Grande, and Merriam’s subspecies of wild turkey females in South Dakota, 1996-2003 .................................................91 20. Distance models for each subspecies, accuracy of prediction models using two methods, and the number of additional nests (mean ± SE) estimated using decreased movements. Number of additional nests estimated with SPIDER DISTANCES that can be used to more accurately calculate nest rates, nesting success, and renesting rates for eastern, Rio Grande, and Merriam’s subspecies in South Dakota, 1996-2003 ..............................................93 21. Availability of various vegetation structural stage categories for nesting female turkeys within the southern Black Hills study area, 2001-04 ..................105 22. Number of females ( n ), number of nests (Nests), nest rates (NR), nest success (NS), female success (FS), renest rates (RR), mean clutch size (CS) (Standard Errors), and hatching rates (HR) for adult Merriam’s females that previously wintered in farmsteads, females that previously wintered in ponderosa pine forests, and both groups combined. Reproductive parameters collected from the southern Black Hills, South Dakota, 2001-2003............................................114 xviii 23. Number of females ( n ), number of nests (Nests), nest rates (NR), nest success (NS), female success (FS), renest rates (RR), mean clutch size (CS) (Standard Errors), and hatching rates (HR) for yearling Merriam’s females. Reproductive parameters collected from the southern Black Hills, South Dakota, 2001-2003...............................................................................................115 24. Nest site habitat selection at the macrohabitat scale for radiomarked Merriam’s females of categories described by vegetation type, structural stage, and overstory canopy cover in the southern Black Hills, South Dakota, 2001-04 ................................................................................................................119 25. Comparison (ANOVA and chi-square) of nest sites and stratified random site variables at the microhabitat level in the southern Black Hills, South Dakota, 2001-04 ................................................................................................................121 26. Comparison (multiple-response permutation and chi-square procedures) of successful and unsuccessful nest site variables at the microhabitat level in the southern Black Hills, South Dakota, 2001-03 .....................................................123 27. Best set of a priori models predicting nest site selection (Candidate Set 1) for Merriam’s turkey females. Relative importance of explanatory variables based upon Akaike model weights ( w i ) summed over all models within candidate models that contained variables in the southern Black Hills, South Dakota, 2001-04...................................................................................................125 28. Best set of a priori models predicting successful nest sites (Candidate Set 2) for Merriam’s turkey females. Relative importance of explanatory variables based upon Akaike model weights ( w i ) summed over all models within candidate models that contained variables in the southern Black Hills, South Dakota, 2001-03...................................................................................................126 29. Information-theoretic models predicting unsuccessful nests (Candidate Set 3) for Merriam’s turkey females. Relative importance of explanatory variables was based upon Akaike model weights ( w i ) summed over all models in the southern Black Hills, South Dakota, 2001-03 .....................................................128 30. Availability of various vegetation structural stage categories for females with poults within the southern Black Hills study area, 2001-04 ................................143 31. Poult survival Ŝ ( t ) at 1, 2, and 4 week posthatch intervals from visual observations of Merriam’s broods raised by adult females in the southern Black Hills, South Dakota, 2001-2003 ................................................................152 xix 32. Average dry weight (g) ± SE of invertebrates collected at random sites using sweep nets. Vegetation structural stage categories included trees < 22.9 cm diameter at breast height (DBH) and overstory canopy cover (OCC) 0-40%, trees < 22.9 cm DBH and OCC 41-70%, trees < 22.9 cm DBH and OCC >70%, trees > 22.9 cm DBH and OCC 0-40%, trees > 22.9 cm DBH and OCC 41-70%, and trees > 22.9 cm DBH and OCC >70%, meadow, and meadow edge. Data collected in the southern Black Hills, South Dakota, 2002-2003 ............................................................................................................153 33. Average number ( n ± SE) and average biomass (g) (± SE) of available invertebrates collected at poult feeding sites using sweep nets in the southern Black Hills, South Dakota, 2001-2003 ................................................................154 34. Proportion of crop contents found within samples of varying poult age classes (1-21 days, 22-49 days, and 50-84 days posthatch). Age class crop contents were compared using multiple-response permutation procedures. Crops of poults raised from unmarked females were collected in the southern Black Hills, South Dakota, 2001-2003 ..........................................................................156 35. Proportions of different size classes of Orthoptera invertebrates found within poult crops of varying ages (1-21 days [ n = 28]), 22-49 days [ n = 15]), and 50-84 days [ n = 9]) posthatch). Comparisons of different size classes between poults hatched from first nests and poults hatched from renests using multiple-response permutation procedures. Crops of poults raised from unmarked females were collected in the southern Black Hills, South Dakota, 2002-2003 ............................................................................................................157 36. Annual exposure of Merriam’s turkey poults to weather conditions 0-14 days posthatch in the southern Black Hills, South Dakota, 2001-2003 .......................159 37. Poult-rearing habitat selection at the macrohabitat scale for radiomarked Merriam’s females with poults of categories described by vegetation type, structural stage, and overstory canopy cover in the southern Black Hills, South Dakota, 2001-04 ........................................................................................160 38. Comparison of poult feeding sites and stratified random sites at the microhabitat level for all macrohabitat categories combined in the southern Black Hills, South Dakota, 2001-04 ....................................................................162 39. Comparison of poult-rearing and random sites within the meadow macrohabitat category at the microhabitat level in the southern Black Hills, South Dakota, 2001-04 ........................................................................................164