The natural food habits of free ranging grizzly bears in Yellowstone National Park, 1973-1974 by Stephen Patrick Mealey A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Fish and Wildlife Management Montana State University © Copyright by Stephen Patrick Mealey (1975) Abstract: The natural food habits of free-ranging grizzly bears in Yellowstone National Park were investigated in 1973-1974 to identify the grizzly's energy sources and trophic level(s), nutrient use and distribution. Food consumption was determined by scat analysis and field observations. Food quality and digestibility were estimated by chemical analysis. The results supported the hypothesized existence of three distinctive mixes of physiographic and biotic conditions or feeding economies: the valley/plateau economy, a grass/rodent economy where grizzlies were intensive diggers; the mountain economy, primarily a grass/springbeauty/root economy where grizzlies were casual diggers; and the lake economy, primarily a fish/grass economy where grizzlies were fishers. The feeding cycle in the valley/plateau and mountain economies appeared to follow plant phenology. Grizzlies fed primarily on meat before green-up and on succulent herbs after; meat, corns, berries and nuts became important during the post-growing season. Distribution was directly related to fertile soils and the occurrence of succulent herbs. Succulent grasses and sedges with an importance value percent of 78.5 were the most important food items consumed. Protein from animal tissue was more digestible than protein from plant tissue. In plants, storage fats were more digestible than structural fats. Food energy and digestibility were directly related. Five principal nutrient materials (listed with their percent digestibility) contributed to total energy intake: protein from succulent herbs, 42.8; protein and fat from animal material, 78.1; fat and protein from pine nuts, 73.6; starch, 78.8; and sugar from berries and fruits, digestibility undetermined. Protein from succulent herbs, with a nutritive value percent of 77.3 was the grizzly's most important energy source. Succulent, pre-flowering herbs had higher protein levels than dry, mature herbs; grizzly use of succulent herbs guaranteed them the highest source of herbaceous protein. Low protein digestibility of succulent herbs was compensated for by high intake. Grizzlies were digestively flexible and maximized use of protein from plant and animal sources. They appeared to be adapted to the most constant and abundant protein sources: succulent herbs and animal material from open, fertile grasslands. Competition among grizzlies for animal material during the pre-growing season may have regulatory consequences for the grizzly population. The Park's grizzly population level can be partially accounted for by the apparent facts that grizzlies are secondary consumers during pre-green-up periods and that they are relatively inefficient primary consumers during the growing and postgrowing seasons. Grizzlies occupied a trophic niche which included primary and secondary consumer levels and a mixture of both. The essential environmental requirement was the availability of fertile grasslands capable of maintaining artiodactyls, rodents and abundant nutritious herbs as potential food.  STATEMENT OF PERMISSION TO COPY > ■ In presenting this thesis in partial fulfillment of the requirements for an advanced degree at Montana State University, I agree that the Library shall make it freely available for inspection. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by my major professor, or, in his absence, by the Director of Libraries. It is understood that any copying or publication of this thesis for financial gain shall not be allowed without my written permission. C Signature _ Date (n THE NATURAL FOOD HABITS OF FREE RANGING GRIZZLY BEARS IN YELLOWSTONE NATIONAL PARK, 1973-1974 by STEPHEN PATRICK MEALEY A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Fish and Wildlife Management Approved: MONTANA STATE UNIVERSITY Bozeman, Montana August, 1975 iii ACKNOWLEDGMENT This study represents the efforts, sacrifices and dedication of many people other than myself. I express my deepest appreciation to the following: Dr. Richard R. Knight, National Park Service, who provided the research opportunity and aided in scat collection; Dr. Harold Picton, Montana State University, chairman of my committee, who provided advice throughout the study and aided in preparation of the manuscript; Drs. Richard J. Mackie and William R. Gould, Montana State University, who reviewed the manuscript; Dr. John H. Rumely, Montana State University, who aided in identification of plant specimens; Mr. Glen Cole, National Park Service, who was a constant source of stimulating, valuable advice and who aided in scat col­ lection; Dr. Don G. Despain, National Park Service, who aided in identification of plant specimens, interpreted the distribution of Park vegetation and aided, in scat collection; Drs. Douglas B. Houston and Margaret M. Meagher, and Mr. Gerald Mernin and Mr. Rod Schmidt, National Park Service, Mr. James M. Chester, Montana State University, and Messrs. Bill Hoskins, Dean C. Graham, Tom Haraden and Bill Smith, Interagency Grizzly Bear Study Team, who aided in scat collection; Ms. Elizabeth Kiendl, who aided in scat sample preparation; personnel of the Chemistry Station Analytical Laboratory, Montana State University, who provided exceptionally fine service; Mr. Kenneth R. Greer, Montana Fish and Game Department Laboratory Supervisor, who iv provided technical advice and excellent laboratory facilities, and Mrs. Della White, who provided valuable assistance in designing the tables and figures, and who typed the final manuscript. In addition, Chad A. Groth,. Montana State University, and Paul N. Hoskins, U. S, Forest Service, made significant contributions to the study. I am especially grateful to my parents, Mr. and Mrs. Robert H. Mealey, and my wife's parents, Mr; and Mrs. G. V. Slater, for encouragement and support throughout the study. Finally, I thank my wife, Marjorie, for her aid in the collection and preparation of plant specimens and in the preparation of scat samples, for typing the rough draft of the manuscript and for her encouragement during the research; and our children, Robert, Stephanie and Elizabeth, for their patience. Funding was provided by the National Park Service under Contract No. CX-6860.-4-0486 and by the Montana Agricultural Experiment Station. TABLE OF CONTENTS Page V I T A ........................................................... ii ACKNOWLEDGMENT . ............................................... iii TABLE OF CONTENTS . . . ...................................... . v LIST OF TABLES................... '............................ vii LIST OF F I G U R E S .............................................. xiv ABSTRACT............... xvi INTRODUCTION . . .................. I THE STUDY AREA . . .......... . . ................................... 3 . General................. . . . . . . . ... . . . . . . . . 3 Physiography ............................................ 3 METHODS ................................ .'.................... 11 Economy Concept . ......................................... 11 Quantitative Analysis: Scat Collection, Preparation, and Analysis ........................... 13 Qualitative Analysis: Food Quality, Digestibility and Nutritive Value ....................... . . . . . 18 Grizzly Bear A n a t o m y .................................... 20 R E S U L T S ......................... 21 Quantitative: Food Item Consumption, General Observations, and Summaries ...................... 21 Valley/Plateau Economy ............................. 21 Mountain Economy . . . . . . . . .......... 38 .Lake Economy................................... 54 S u m m a r i e s .............. 67 Qualitative: Food Item Quality and Digestibility, Nutrient Intake and Nutritive Values, Plant■ • Protein/Succulence-Flowering Relationship........... 75 V TABLE OF CONTENTS (Continued) Page Food Quality and Apparent Digestibility ... ........ 75 Nutrient Intake and Nutritive V a l u e s ............ '. 93 Plant Protein/Succulence-Flowering Relationships . . 105 Distribution and Physiography ........................... 105 Grizzly Bear Anatomy .........................................108 DISCUSSION ...................................... . . . . . . . 112 SUMMARY AND CONCLUSIONS............ 118 A P P E N D I X .......... "....................■ .................... 124 REFERENCES C I T E D ....................... .. . ................. 155 vi vii LIST OF TABLES 1. A SUMMARY OF GRIZZLY BEAR SCAT COLLECTION EFFORT IN YELLOWSTONE NATIONAL PARK, 1973-1974 ................. . 14 2. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - VALLEY/PLATEAU ECONOMY, 1973 . . . . . . 23 3. YELLOWSTONE.NATIONAL PARK.VALLEY/PLATEAU ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973 . . . . . . . 25 4. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - VALLEY/PLATEAU ECONOMY, 1974 .......... 26 5. YELLOWSTONE NATIONAL PARK VALLEY/PLATEAU ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1974 .......... 29 6. YELLOWSTONE NATIONAL PARK VALLEY/PLATEAU ECONOMY GRIZZLY BEAR KEY FOOD ITEM CONSUMPTION COMPARISON, 1973-1974 . . . ......................................... 30 7. YELLOWSTONE NATIONAL PARK VALLEY/PLATEAU ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973-1974 . . . . 32 8. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - MOUNTAIN ECONOMY, 1973 ................. 40 9. YELLOWSTONE NATIONAL PARK MOUNTAIN ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973 ................... 42 10. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - MOUNTAIN ECONOMY, 1974 ................. 44 11. YELLOWSTONE NATIONAL PARK MOUNTAIN ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1974 ................... 45 12. YELLOWSTONE NATIONAL PARK MOUNTAIN ECONOMY GRIZZLY BEAR KEY FOOD ITEM CONSUMPTION COMPARISON, 1973-1974 . . . . . . . . . . . . . . . . . . . . . . . 47 13. YELLOWSTONE NATIONAL PARK MOUNTAIN ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973-1974 . . . . . . . . 50 Table Page viii 14. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK LAKE ECONOMY, 1 9 7 3 ..................... 56 15. YELLOWSTONE NATIONAL PARK LAKE ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973 ..................... 59 16. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - LAKE ECONOMY, 1974 ....................... 60 17. . YELLOWSTONE NATIONAL PARK LAKE ECONOMY GRIZZLY BEAR rFOOD CONSUMPTION SUMMARY, 1974 62 18. YELLOWSTONE NATIONAL PARK LAKE ECONOMY GRIZZLY BEAR KEY FOOD ITEM CONSUMPTION COMPARISON, 1973-1974 63 19. YELLOWSTONE NATIONAL PARK LAKE ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973-1974 .................. 65 20. GRIZZLY BEAR KEY FOOD ITEM CONSUMPTION COMPARISON AMONG YELLOWSTONE NATIONAL PARK ECONOMIES, 1973-1974 . .............................................. 68 21. YELLOWSTONE NATIONAL PARK PARKWIDE GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973 71 22. YELLOWSTONE NATIONAL PARK PARKWIDE GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1974 72 23. YELLOWSTONE NATIONAL PARK PARKWIDE GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973-1974 .................. 74 24. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: GRAMINAE/CYPERACEAE . . 76 25. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY. AS INDICATED BY CHEMICAL ANALYSIS: CLAYTONIA LANCEOLATA . . 79 26. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: TRIFOLIUM REPENS . . . 81 LIST OF TABLES (Continued) Table Page Table ■ Page 27. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: SALMO CLARKI ........ 82 28. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: UMBELLIFERAE ........... 83 29. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: CERVIDAE/BOVIDAE . . . 85 30. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: PINUS ALBICAULIS . . . 86 31. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDI­ CATED BY CHEMICAL ANALYSIS: EQUISETUM ARVENSE, RUSSULA SP. . . . . . . . . . ......................... 88 32. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDI­ CATED BY CHEMICAL ANALYSIS: CIRCIUM FOLIOSUM, RODENTIA, POLYGONUM BISTORTOIDES ..................... 89 33. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: VACCINIUM SCOPARIUM . 90 34. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: HERACLEUM LANATUM . . 91 35. SUMMARY: GRIZZLY BEAR FOOD ITEM QUALITY AND DIGESTIBILITY .......................................... 92 36. PRINCIPAL GRIZZLY BEAR FOOD NUTRIENTS AND DIGESTIBILITIES.......... 94 37. 1974 SEASONAL GRIZZLY BEAR NUTRIENT INTAKE AND NUTRITIVE VALUES - VALLEY/PLATEAU ECONOMY ............. 95 38. 1974 SEASONAL GRIZZLY BEAR NUTRIENT INTAKE AND NUTRITIVE VALUES - MOUNTAIN ECONOMY.......................99 39. 1974 SEASONAL GRIZZLY BEAR NUTRIENT INTAKE AND NUTRITIVE VALUES - LAKE ECONOMY ........................ 101 ix LIST OF TABLES (Continued) XLIST OF TABLES (Continued) 40. NUTRIENT INTAKE AND NUTRITIVE VALUE COMPARISON AMONG ECONOMIES AND PARKWIDE SUMMARY - 1973-1974 . . . . . . . 102 41. PLANT PROTEIN/SUCCULENCE-FLOWERING RELATIONSHIP - 1974 ...... ..................................... .. 106 42. INTESTINAL LENGTH IN GRIZZLY AND BLACK B E A R S ........... 109 43. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: AGROPYRON SP. - 50%, POA SP. - 20%, BROMVS SP. - 10%, PHLEUM ALPINUM - . 10%, CAREX SP. - 10% . . . . ............................ ' 125 44. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: POA SP. - 50%, AGROPIRON SP. - 30%, PHLEUM ALPINUM - 10%, CAREX SP. - 1 0 % ......................................... 126 45. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: DESCHAMPSIA ATROPURPUREA - 80%, CAREX SP. - 1 0 % ...................127 Table Page 46. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: POA SP. - 100% . . . . 128 47. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: CALAMAGROSTIS INEXPANSA - 100% ............................. . 129 48. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS . INDICATED BY CHEMICAL CANALYSIS: CLAYTONIA LANCEOLATA - 100%, SAMPLE # 1 ........................... 130 49. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: CLAYTONIA LANCEOLATA - 100%, SAMPLE #2 . . . . . - . . . . ........ 131 xi . 50. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: CLAYTONIA LANCEOLATA - 100%, SAMPLE #3 . . ........................ 132 51. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: TRIFOHIM REPENS - 100%, SAMPLE # I ......................... 133 52. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: TRIFOLIUM REPENS - 100%, SAMPLE #2 ............................. 134 53. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: SALMO CLARKI - 100%, SAMPLE # 1 ........................................ 135 54. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: SALMO CLARKI - 100%, SAMPLE # 2 ............................ 136 55. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: SALMO CLARKI EGGS. - 1 0 0 % ...............................................137 56. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: LOMATIUM COUS . ROOTS - 1 0 0 % ............ 138 57. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: PERIDERIDIA GAIRDNERI ROOTS - 100% . . ............................ X 139 58. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: CERVUS CANADENSIS - 100%, SAMPLE # 1 ........................ 140 59. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: CERVUS CANADENSIS - 100%, SAMPLE # 2 ....................... - ............... 141 LIST OF TABLES (Continued) Table Page 60. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: MELICA SPECTABILIS ■ CORMS - 1 0 0 % .............................. 142 61. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: EQUISETUM ARVENSE - 1 0 0 % ....................... , .......... 143 62. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: PINUS ALBICAULIS NUTS - 100%, SAMPLE # 1 ..................... 144 63. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS:. PINUS ALBICAULIS NUTS - 100%, SAMPLE # 2 ..................... 145 64. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS: RUSSULA SP. - 1 0 0 % ............................................ . . 146 65. GRIZZLY BEAR FOOD QUALITY AS INDICATED BY CHEMICAL ANALYSIS: CIRCIUM F OLIO SUM - 1 0 0 % .......... .. 147 66. GRIZZLY BEAR FOOD QUALITY AS INDICATED BY CHEMICAL ANALYSIS: MICROTUS SP. - 1 0 0 % ..................... .. . 148 67. GRIZZLY BEAR FOOD QUALITY AS INDICATED BY CHEMICAL ANALYSIS: VACCINIUM SCOPARIUM BERRIES - 1 0 0 % ........ 149 68. GRIZZLY BEAR FOOD QUALITY AS INDICATED BY CHEMICAL ANALYSIS: HERACLEUM LANATUM - 100%, SAMPLE #1 ........ 150 69. GRIZZLY BEAR FOOD QUALITY AS INDICATED BY CHEMICAL ANALYSIS: . HERACLEUM LANATUM - 100%, SAMPLE #2'. . . . . 151 70. GRIZZLY BEAR FOOD QUALITY AS INDICATED BY CHEMICAL ANALYSIS: POLYGONUM BISTORTOIDES ROOTS - 100% . . . . 152 xii LIST OF TABLES (Continued) Table Page Table Page 71. GRIZZLY BEAR FOOD QUALITY'AS INDICATED BY CHEMICAL ANALYSIS: FRAGARIA VIRGINIAm FRUITS - 1 0 0 % ...........153 72. GRIZZLY BEAR FOOD QUALITY AS INDICATED BY CHEMICAL • ANALYSIS: RIBES SETOSUM BERRIES - 1 0 0 % ...............154 " xiii LIST OF TABLES (Continued) xiv LIST OF FIGURES . I. Map of the study area, Yellowstone National Park . . . . 4 2. Map showing substrates from major geologic formations and activities in Yellowstone National Park (after Keefer) .................................... 6 3. Map showing selected generalized soil, and vegetation relationships in Yellowstone National Park (after Keefer and Despain) ............................. 7 4. Map showing three generalized physiographic/ vegetative units in Yellowstone National Park '........ 10 5. Map showing centers of generalized grizzly bear distribution in three different economies in Yellowstone National P a r k ............................. 12 6. Hayden Valley and associated lodgepole pine forest: an example of a valley/plateau economy setting ........ 22 7. Grizzly bear seasonal food consumption in Yellowstone National Park - valley/plateau economy, 1973 . . . . . . 24 8. Grizzly bear seasonal food consumption in Yellowstone National Park - valley/plateau economy, 1974 . . . . . . 27 9. Yellowstone National Park valley/plateau economy grizzly bear key food item consumption comparison and summary, 1973-1974 .......... ....................... 31 10. Gallatin Mountains with Joseph Peak to the left and Electric Peak to the right: .an example of a mountain economy setting.......... .................... 3.9 11. Grizzly bear seasonal food consumption in Yellowstone National Park - mountain economy, 1973 . ............... ' 41 12. Grizzly bear seasonal food consumption in Yellowstone National Park - mountain economy, 1974 ............... .. 46 Figure Page XV LIST OF FIGURES (Continued) 13. Yellowstone National Park mountain economy grizzly bear key food item consumption comparison and summary, 1973-1974 ...................................... 48 14. Grizzly bear fishing in a tributary at the tip of the Flat Mountain Arm, Yellowstone Lake: an example of a lake economy setting.................................. 49 15. Grizzly bear seasonal food consumption in Yellowstone National Park - lake economy, 1973 ....................... 57 16. Grizzly bear seasonal food consumption in Yellowstone National Park - lake economy, 1974 ....................... 61 17. Yellowstone National. Park lake economy grizzly bear key food item consumption comparison and summary, 1973-1974 ........................................ 64 18. Grizzly bear key food item consumption comparison among Yellowstone National Park economies, 1973-1974 69 19. Yellowstone National Park, parkwide grizzly bear key food item consumption comparison and summary, 1973-1974 73 20. Seasonal nutrient importance value comparison among Yellowstone National Park grizzly bear food economies, 1974 96 - Figure Page 21.. Seasonal nutritive value comparison among Yellowstone National Park grizzly bear food economies, 1974 . . . . 97 22. Nutrient importance value and nutritive value comparisons among Yellowstone National Park grizzly bear food economies and parkwide summary, 1973-1974 . . 103 23. Map showing grizzly distribution by food economy superimposed over the Park’s physiographic/ vegetative units . 107 ABSTRACT xvi The natural food habits of free-ranging grizzly bears in Yellow­ stone National Park were investigated in 1973-1974 to identify the grizzly's energy sources and trophic level(s), nutrient use and distri­ bution. Food consumption was determined by scat analysis and field ob­ servations. Food quality and digestibility were estimated by chemical analysis. The results supported the hypothesized existence of three distinctive mixes of physiographic and biotic conditions or feeding economies: the valley/plateau economy, a grass/rodent economy where grizzlies were intensive diggers; the mountain economy, primarily a grass/springbeauty/root economy where grizzlies were casual diggers; and the lake economy, primarily a fish/grass economy where grizzlies were fishers. The feeding cycle in the valley/plateau and mountain economies appeared to follow plant phenology. Grizzlies fed primarily on meat be­ fore green-up and on succulent herbs after; meat, corns, berries and nuts became important during the post-growing season; Distribution was directly related to fertile soils and the occurrence of succulent herbs. Succulent grasses and sedges with an importance value percent of 78.5. were the most important food items consumed. Protein from animal tissue was more digestible than protein from plant tissue. In plants, storage fats were more digestible than structural fats. Food energy and di­ gestibility were directly related. Five principal nutrient materials .(listed with their percent digestibility) contributed to total energy intake: protein from succulent herbs, 42.8; protein and fat from animal material, 78.1; fat and protein from pine nuts, 73.6; starch, 78.8; and sugar from berries and fruits, digestibility undetermined. Protein from succulent herbs, with a nutritive value percent of 77.3 was the grizzly's most important energy source. Succulent, pre-flowering herbs had higher protein levels than dry, mature herbs; grizzly use of succulent herbs guaranteed them the highest source of herbaceous protein. Low protein digestibility of succulent herbs was compensated for by high intake. Grizzlies were digestively flexible and maximized use of protein from plant and animal sources. They appeared to be adapted to the most constant and abundant protein sources: succulent herbs and animal material from open, fertile grasslands. Competition among grizzlies for animal material during the pre-growing season may have regulatory conse­ quences for the grizzly population. The Park's grizzly population level can be partially accounted for by the apparent facts that grizzlies are secondary consumers during pre-green-up periods and that they are rela­ tively inefficient primary consumers during the growing and post­ growing seasons. Grizzlies occupied a trophic niche which included primary and secondary consumer levels and a mixture of both. The essential environmental requirement was the availability of fertile grasslands capable of maintaining artiodactyls, rodents and abundant nutritious herbs as potential food. INTRODUCTION A study of the natural food habits of free-ranging grizzly bears (Ursus arotos horribilis) Ord (Rausch, 1963) in Yellowstone National Park was conducted in 1973 and 1974 as part of the research effort of the Interagency Grizzly Bear Study Team in the Yellowstone ecosystem. Extensive grizzly bear use of unnatural foods (garbage and camp groceries) in Yellowstone National Park occurred from the early days of the Park until closure of the Trout Creek and West Yellowstone open-pit garbage dumps in 1971 (Skinner, 1925; Cole, 1971). After the removal of .the primary sources of unnatural foods in the Park, most grizzlies resumed free-ranging use of natural foods (Cole, 1974). Martinka (1974, 1970), Sumner and Craighead (1973), Cole (1972), Macpherson (1965), Murie (1961) and Murie (1944) have discussed grizzly bear food use. Seton (1953) reviewed the food use of all four North American species of bears. This study presents a description and analysis of the natural food use of free-ranging grizzlies in Yellowstone Park which has been absent from the literature. The overall objective of my research was to develop hypotheses about the grizzly’s: I) natural energy sources and trophic level(s); 2) quality and quantity of nutrient use; and 3) distribution. Specific research objectives were to: I) identify by season and location the type and relative quantitative importance of natural food -2- items; 2) estimate food quality, efficiency of food use, seasonal nutrient intake and nutritive values of the principal nutrient m a t e r i a l s 3) explore the relationship between distribution and the different physiographic/vegetative units of the Park; 4) describe the head and body lengths, and the stomachs and intestinal tracts of deceased grizzlies utilized as study specimens; 5) report general observations on feeding activities; and 6) develop a summary sketch of the generalized trophic niche of Yellowstone grizzly bears. THE STUDY AREA General Yellowstone National Park occupies about 8900 km.2 in the states of Wyoming, Montana and Idaho (Figure I). The Park was established March I, 1872 (17 Stat. 32), and "dedicated and set apart as a public park or pleasuring-ground for the benefit and enjoyment of the people and "for the preservation, from injury or spoliation, of all timber, mineral deposits, natural curiosities, or wonders ... and their retention in their natural condition." In contemporary terms its purpose is: "to perpetuate the natural ecosystems within the Park in as near pristine conditions as possible for their inspirational, educational, cultural and scientific values for this and future generations" (National Park Service, 1973). Accordingly, management programs, including the removal of unnatural food sources from bears, have been undertaken to minimize the impact of man on all components of the Park. In 1971, 99 percent of the Park's 899,139 ha. remained roadless and 88.4 percent of the area was found suitable for preservation as wilderness (National Park Service, 1971). Physiography The geology of the Park has been described by Keefer (1972) and Eaton et at. (1975), the climate by Lowery (1959), and the Figure I. Map of the study area, Yellowstone National Park. - 5- vegetat'ion zones by Despain (1973b). The Paleozoic and Mesozoic sediments, the Absaroka andesitic volcanics, and the Yellowstone rhyolitic volcanics are the three major types of substrate left by the Park's past geologic events (Figure 2). Disintegration in place of these substrates resulted in three unique soil types in the Park. Transported.soils from glacial, lacustrine and alluvial action represent a fourth type (Figure 2). Soils derived from Paleozoic and Mesozoic sediments are fertile and support a diverse plant community.(Despain, 1973a). The spruce- fir (Pioea engeXmann-Lt - Abies tasiooarpa) zone, dominated by spruce- fir forests, is endemic to these soils (Despain, 1973b; Figure 3). Whitebark pine (Pinus atbioaulis) is present in the zone and is, in some cases, the dominant species, especially near timberline. Numerous species of grasses, sedges and forbs are present in the zone. They predominate in herblands and subalpine meadows and on mountain slopes and ridgetops. This zone lies above 2,560 m. and generally has greater than 102 cm. of precipitation annually, most falling as snow. The growing season extends from early June to late August and reflects.the Park's short, cool summers and long, cold winters. The alpine-tundra zone also occurs on these soils above about 2,896 m. where low growing forbs are the predominant plant form. > Absaroka andesitic soils are fertile (Washington, 1917) and productive. The spruce-fir and alpine-tundra zones cover these soils -6- Paleozoic and Mesozoic Sediments Yellowstone Rhyolytic Volcanics. Hilii Absaroka Andesitic Volcanics. -BiSSi Transported Materials. Figure 2. Map showing substrates from major geologic formations and activities in Yellowstone National Park (after Keefer). -7- r. "ii# :•:•:•:•■ '■ - A - W ,-- ^ vEfxi i -:%:y -.-.-.- z\ , # . . # viIfliisP Fertile Paleozoic and Mesozoic !"! Sedimentary Soils: Spruce-Fir Zone. IIfMt Fertile Andesitic Soils: Spruce- | Fir Zone. Infertile Rhyolytic Soils: Lodgepole Pine Zone. Fertile Transported Soils: Douglas-fir and Grassland Zones. Figure 3. Map showing selected generalized soil and vegetation relationships in Yellowstone National Park (after Keefer and Despain). -8- (Despain, 1973b; Figure 3). Yellowstone rhyolitic soils are infertile and do not support the growth of many plant types (Washington, 1917; Stermitz et al. , 1974). The lodgepole pine (Finns contovta) zone is indigenous to rhyolitic soils and this species predominates as both a climax and a serai species (Despain, 1973b; Figure 3). Whitebark pine occurs in the zone and spruce and fir stands and small grasslands occur where moisture and soil conditions are favorable. This zone lies between .2,316 and 2,560 m. and receives 50-100 cm. of precipitation per year. Transported soils deposited by ice and water were derived by the erosion of all three major substrate types. Generally, transported soils are fertile (Odum, 1971). These soils in the Park have relatively thick A horizons and are generally highly productive. The Douglas-fir (Fseudotsugamenziesii) zone occurs on these soils along the Yellow­ stone and Lamar- River valleys (Despain, 1973b; Figure 3). Douglas-fir is the dominant forest, type and big sagebrush (Avtemesia tridentata) and various grasses, sedges and forbs cover the open areas. Aspen (Populus tremuloides), spruce, fir and lodgepole pine are also present. Grasses, sedges, forbs and big sagebrush grow on the transported soils of Hayden and Pelican Valleys, Cougar Creek Flat and Swan Lake Flat and other treeless areas. Precipitation and temperature vary over the areas with transported soils. Elevations range from I 8^29 m. to 2,560 m . probably accounting for the differences in vegetation among -9- areas. The growing season on these soils extends generally from late May to early September. The interactions among the Park's geologic events, climate, soils and vegetation have resulted in the three physiographic/vegetative units depicted in Figure 4. These are: I) the mountainous unit with the spruce-fir and alpine-tundra zones covering fertile soils; 2) the valley and plateau units with fertile soils covered by grasslands and the Douglas-fir zone; and 3) the plateau unit with lodgepole pine covering infertile soils. - 1 0 - wmmammmmmm . ......................... .*....... . / • ‘ ....... )■••••••see...................... ( • ••••••. ................. ... • • • • • • • • • • • • • • • • • • • • • ; I ) ) )• • • • • • • • • • • . • • • • • • • • / / / / / •••••••••••••..•••• ) )•••••••••#••..#... '' ‘ ’ ' Valley and Plateau Units: Fertile Soils; Douglas-fir and Grassland ' Zones. Mountainous Unit: Fertile Soils; Spruce Fir and Alpine-Tundra Zones. V.’.V. Plateau Unit: Infertile Soils; Lodgepole Pine Zone with Spruce and ' Fir. Figure 4. Map showing three generalized physiographic/vegetative units in Yellowstone National Park. METHODS Economy Concept In the context of human culture an economy is understood to be an institutionalized process of exchange between producers and consumers (Peterson, 1971). The concept of economy as a process of exchange between producers and consumers can be applied to biologic systems including grizzly bears (consumers) interacting with their food sources (producers). In 1973 I hypothesized three unique feeding economies for grizzlies in the Park: the valley/plateau, mountain and lake economies. The basis for distinguishing these economies was the simultaneous occurrence of scats in each. After further study in 1974, each economy, in addition, seemed to represent a distinctive mix of physiographic and biotic conditions which appeared to result in a characteristic pattern of interactions between grizzlies and food items which was unique to each economy. Grizzlies in.each economy seemed to have characteristic feeding activities which allowed them to maximize food use. Figure 5 shows the hypothesized economies. Desig­ nated areas represent centers of concentrated grizzly feeding activity determined by locations of scats collected in 1973 and 1974 (the Absaroka Range was not sampled). Areas of high grizzly density determined by aerial surveys are coincident (Knight, 1974, 1975). Grizzlies in the Park appeared to be distributed by economy. - 1 2 - Mountain Economy Valley/Plateau Economy Lake Economy Figure 5. Map showing centers of generalized grizzly bear distribution in three different economies in Yellowstone National Park. -13- Quantitative Analysis: Scat Collection, Preparation, and Analysis Table I presents a summary of the scat collection effort. Travel in the roadless area of the Park was by horseback. Travel on Yellow­ stone Lake was by canoe. Grizzly bear scats and visual observations of feeding activity were used in determining the quantitative importance of food items used by grizzly bears. . Grizzly scats were usually distinguished from black bear scats on the basis of size; those with diameters 5 cm. or greater were normally considered to be grizzly (Murie, 1954). Several associations in the field between different grizzlies and their scats justified this approach. Other evidence considered in identifying scats was associated track sign, associated feeding activity sign, visual observations of bears and the general nature of the location. Scats with diameters less than 5 cm. were assumed to be those of small or immature grizzlies only if they were found in an area generally . associated with grizzly activity and some evidence of grizzly use was present. Every grizzly scat located singly was collected. When groups of 10-25 scats were located, one-half the total in each group was col­ lected. When groups of more than 25 scats were located, one-third the total in each was collected. All scats were individually identified according to location, altitude, vegetative surroundings and TABLE I. A SUMMARY OF GRIZZLY BEAR SCAT COLLECTION EFFORT IN YELLOWSTONE NATIONAL PARK, 1973-1974. 1973 1974 Valley/Plateau Economy Mountain Economy Lake Economy Valley/Plateau Economy Mountain Economv Lake Economy Scats Per- Man Per- Srats Per- Man Per- Per- Man Per- Sratfi Per- Man Per- Per- Man Scats cent Davs Per- Per- Man cent Davs Per- April 7 3.1 10 4.7 May 25* 20.8 31 14.0 40 18.6 7** 5.8 3** 8.1 8** 36.4 23 10.4 40 18.6 4** 3.0 3** 3.6 July 40 33.3 30 40.0 11 29.7 20 33-3 14 63.6 10 100.0 35 15.9 40 18.6 52 39.0 50 32.3 76 91.5 40 95.2 August 31 25.8 30 40.0 15 40.5 30 50.0 42 19.0 60 27.9 60 45.1 60 38.6 4 4.8 2 4.8 September 11 9.2 13 17.3 3 8.1 10 16.6 50 22.7 15 6.9 13 9.7 35 22.6 October 6 5.0 2 2.6 5* 13.5 32 14.5 10 4.7 4 3.0 10 6.5 Total 120 99.9 75 99.9 37 99.9 60 99.9 22 100.0 10 100.0 220 99.6 215 100.0 133 99.8 155 100.0 83 99.9 42 100.0 Percent Grand Total 67.0 52.0 20.7 41.0 12.3 7.0 50.4 52.0 30.5 38.0 19.0 10.0 Grand Total Scats - 179I IlIan Days - 145 Scats - 436 Man Days - 412 Two Year Parkwide Comparison Two Year Comparison ISy Economy Valley/Plateau Mountain Scats Per­ cent Man Days Per­ cent Scats Per- Man Days Per- Scats Per- Man Days Per- Scats Per- Man Days Per- 1973 179 29.1 145 26.0 1973 120 35.3 75 26.0 37 21.8 60 28.0 22 21.0 10 19.0 1974 436 70.9 412 74.0 1974 220 64.7 215 74-0 133 78.2 155 72.0 _S3 79.0 42 81.0 Overall Total 340 100.0 290 100.0 170 100.0 215 100.0 105 100.0 52 100.0 Total 615 100.0 557 100.0 Two Year Total 55.3 52.0 27.6 38.0 17.1 10.0 *Scats from previous year(s). **Scats collected following month. -15- approximate age. Age was estimated to the nearest month. Factors considered in age estimation were: state of scat desiccation and/or decay, presence and stage of maturity of insect eggs and/or larvae in the scat, growth status of vegetation under and around the scat and other associated and dateable evidence of grizzly activity. All scats were air dried for storage. Those scats which were extremely moist and/or infested with insect eggs and/or larvae were oven-dried at low heat to kill any organisms which could ghange the nature of scat contents. Analysis of scat contents was conducted both in the field and in the laboratory. Field analysis was advantageous because scat contents were more identifiable when fresh and plant remains in the scats were usually represented by specimens growing nearby. Materials analyzed in the field were taken to the laboratory for further study. Analysis of bear scats in the laboratory followed the techniques of Tisch (1961), Russell (1971) and Sumner and Craighead (1973). Basic steps involved: I) rehydration of fecal material to render it pliable and restore original form; 2) separation of material into homogeneous groups by use of screens (No. 10 and 20 mesh); 3) identi­ fication of contents; and 4) recording. Identification to species, through macroscopic and microscopic examination, was usually successful for all items except grass. Reference, collections of plants and seeds at the Montana Fish and Game -16- Department Wildlife Laboratory and the Montana State University Herbarium provided invaluable assistance in the identification process. The basic botanical references were Flora of Montana3 Fart I3 by Booth (1950), Flora of Montana3 Part II3 by Booth and Wright (1959), and Grasses of Montana3 by Booth (1972). Mammal remains were identified with the assistance of personnel at the Wildlife Laboratory. Basic references were A Guide to Montana Mammals3 by Hoffmann and Pattie (1968) and A Study of Identifying Charaoteristios of Mammal Hair3 by Spence (1963). The occurrence and percent composition of each identified food item was recorded as each scat was analyzed. Percent composition denotes the percent of the total scat volume.consisting of a single, food item. Visual estimates of volume were recorded under one of four categories: trace - 25%; 25-50%; 50-75%; and 75-100%. This method of determining food use by estimation of scat composition by volume under­ valued the.use of some foods, because differential digestibility among food items was established through proximate analysis techniques. Animal material was found to be more digestible than most plant material. Data were grouped and analyzed by the economy, month and year in which scats were collected. Data were also grouped in three categories which related grizzly food use and plant phehology. The latter in­ cluded: pre-growing season, April I-June I; growing season, June I- -17- September I; and post-growing season, September !-November 15. These periods approximately reflect plant growth conditions in the Park (Despain, 1974). In grouped data presentations, food items are presented in rank order according to importance value calculated as: Importance _ Frequency of Occurrence % x % of Diet Volume Value .01 where Frequency of Occurrence Percent equals the total number of times a specific food item appeared in scats of the sample group, divided by the total number of scats in the sample; and Percent of Diet Volume equals the average percent composition of an item which appeared in scats of the sample group, divided by the total number of scats in the sample. Importance value was chosen as the indicator of food item importance because it establishes relative equilibrium between items which occurred infrequently but in high volume percentages- and items which occurred frequently but In low volume percentages. Importance value is convenient in providing a single unit of expression for frequency of occurrence and percent composition. Sumner and Craighead (1973) used a similar approach. Percent Composition Per Item and Importance Value Percent were calculated. Percent compositions per item indicate the degree of selection for particular foods; values were derived by dividing the -18- average percent composition of those scats containing a given item by the total number of scats containing that food item. Importance value percents were derived by adding the importance values in the group and dividing individual values in the group by the sum. Importance value percents were calculated to facilitate comparison of food item im­ portance values between and among groups. Qualitative Analysis: Food Quality,. Digestibility and Nutritive Value To estimate food quality, efficiency of food use, seasonal nutrient intake and nutritive values of the principal nutrients, determinations were made of: I) the identities, energy values and apparent digestibilities of the principal nutrient materials of the most important foods listed in Table 23; 2) seasonal nutrient intake and nutritive value; and 3) plant protein/succulence-flowering relationship. Standard proximate analysis procedure detailed by Crampton and Harris (1969) was used in estimating the quality and apparent di­ gestibility of food items. Food items containing starch were also evaluated by a special starch analysis method (Banks et al. , 1970). Food quality is defined in terms of the amounts of protein, fat and carbohydrate present in a food item and the caloric values of these principal nutrients. Apparent digestibility is a measure of nutrient utilization and digestive efficiency. It was estimated by calculating -19- the percentage of nutrient intake not present in food item residues in scats. Determinations of food quality and apparent digestibility were subject to a minimum of four sources of possible error: I) analytic procedures could not account for all material completely assimilated; 2) in proximate analysis, nitrogen-free extract values are determined by difference; 3) feces probably contained protein and fat from non­ dietary origin (Crampton and Harris, 1969); and 4) sampling error. Food items and scats containing residues of these same items were ■ collected at the feeding site. Scat and food item samples were paired and submitted to the Chemistry Station Analytical Laboratory at Montana State University for analysis. Analytical methods for proximate analysis followed the Association of Official Agricultural Chemists Handbook (1975). The digestibilities of four principal grizzly nutrient materials . were estimated by averaging the values for individual food items. Seasonal nutrient intake was calculated from 1974 seasonal food, use data. Nutrient importance values were determined in a way similar to that presented for the determination of food item importance values. A nutritive value index of the principal nutrients was calculated to estimate each nutrient's contribution towards the grizzly's energy intake. The index was calculated according to the formula: NVI = Nutrient Intake (Importance Value %) x Digestibility % -20- Nutritive value indices were converted to percents to facilitate comparisons. The relationship between plant protein content and succulence­ flowering condition was investigated by sampling and comparing vegetation from five plots in the Park. A protein loss factor was calculated to show the change in percent protein relative to percent crude fiber as vegetation completed reproduction and underwent desic­ cation. Protein Loss Factor, (PLF) was calculated according to the ' formula: Early Late % Protein % Crude Fiber % Protein % Crude Fiber PLF Grizzly Bear Anatomy The fresh carcasses of two grizzlies were obtained for study. Head and body lengths and descriptions of stomachs and intestinal tracts are presented. Linear measurements were made with Vernier calipers and a meter stick. Head and body measurements were taken from tip of nose to the last vertebrae. Intestinal measurements were taken, with the mesentary removed, from the pyloric valve to the anus. J RESULTS Quantitative: Food Item Consumption, General Observations, and Summaries Valley/Plateau Economy- Major epicenters of the valley/plateau economy were Hayden, © (Figure 6) Pelican and Lamar Valleys, and Cougar Creek Flat. Fertile, transported soils support an abundant grassland biota which provided most of the food used in the economy. The valleys and flat were largely surrounded by plateaus with infertile soils and lodgepole pine forests. The plateau component provided cover and occasional food. Table 2 and Figure 7 show, with one exception, seasonal food item consumption in 1973. The May sample was collected between 1968 and 1973 at the rate of 4-5 scats per year. Grasses and sedges greatly exceeded all other food items in importance in all months (Table 2). Animal material and corms of melica grass (Meliaa S-Pectdbilis) were most important as foods during the pre- and post-growing seasons (Figure 7). In Table 3, the annual summary, the percent compositions per item of the six highest ranking foods are near or above fifty per­ cent indicating that these items were specifically selected. Table 4 and Figure 8 show seasonal food item consumption in 1974. They indicate that grasses and sedges were the most important foods in all months except April when artiodactyls were most important. Grass Photo by Mary Meagher Figure 6. Hayden Valley and associated lodgepole pine forest: an example of a valley/plateau economy setting. TABLE 2. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - VALLEY/PLATEAU ECONOMY, 1973.________________________ Frequency Percent Percent Importance Occurrence Composition of Diet Importance Value Sample Use Elevation Per Item Volume Value Percent May 25* Stems/Leaves 7458 72.0 58.1 41.8 30.10 64.20 Cervidae / Bovidae Cervus canadensis 80Z Odoeoileus henionus 10% Bison b ison 10% 7235 40.0 68.0 27.2 10.90 23.30 BodeatU Thcnomys ta lp o id e s 80% M ierotus 20% 7560 20.0 70.0 14.0 2.80 6.00 Me lice, s p e c ta b i l i s Corms 7850 24.0 48.3 11.6 2.80 6.00 Uebelliferae P er id e r id ia g a irdne r i 50% - Lomatium ecus 50% - Roots toot. 7200 8.0 42.5 .27 .58 Avg. 7461 98.0 46.87 100.08 7 Stems/Leaves 7467 85.7 80.0 68.6 58.8 84.4 C laytcn ia lanceo la ta 7733 42.8 30.0 12.9 5.5 7.9 Rodentia Thomomys ta lp o id e s 8000 28.6 65.0 IB. 6 5.3 7.B Avg. 7636 100.1 69.6 99.9 July 40 Stems/Leaves 7847 60.0 57.6 34.60 20.800 57.70 T n fo li ia n repens Sterns/Leaves/Heads 7311 37.5 65.3 24. SO 9.200 25.50 Circitan f o l i o sum Stems/Heads 7720 25.0 58.5 14.60 3.700 10.30 Ombelliferae P e r id e r id ia g a irdne r i 71% - Lomatium coue 29% - Roots toot. 7000 17.5 29.3 S.10 .900 2.50 Foraicidae Mature/Larvae 7460 12.5 26.0 2.30 .410 1.10 Cervidae Cervus canadensis 6967 7.5 48.3 3.60 .270 .75 Heliea s p e c ta b i l i s 7800 5.0 95.0 4.80 .240 .67 Garbage 7800 5.0 60.0 3.00 .150 .41 SquiseUan arvense 8050 5.0 47.5 2.40 .120 .33 Beracleien lanatwn Stems/Leaves 8125 5.0 37.5 1.90 .090 .25 Rodentia Thomomys ta lp o id e s 50% M icrotus 507, 7850 10.0 9.3 .93 .090 .25 Polygoniien b is to r to id e s 7800 5.0 17.5 .87 .040 .11 Vaeciniwn scopcriion Berries/Leaves 7800 2.5 10.0 .25 .006 .02 Avg. 7604 99.85 36.016 99.89 August 31 Grand, nae/Cyperaceae Graainae 80% Stems Carex sp. 20% Heads 7928 80.6 32.6 26.30 21.20 45.30 Circium f o l i o sum Stems/Heads 7613 48.4 48.7 23.60 11.40 24.40 T r ifo lium repens Stems/Heads 7850 32.3 59.5 19.20 6.20 13.30 Formicidae Mature/Larvae 8093 48.4 22.0 10.60 5.10 11.00 Rodentia M icrotus 57% Thomomys ta lp o id e s 43% 6986 22.6 26.4 S.90 1.40 2.90 Equisetum arvense 8300 12.9 40.0 5.20 .67 1.40 Polygonium b is to r to id e s 7883 19.4 16.7 3.20 .63 1.30 C laytonia lanceo la ta Melica s p e c ta b i l i s 8650 3.2 100.0 3.20 .10 .22 7900 3.2 30.0 .97 .03 .06 Cervidae Cervus canadensis 7800 3.2 20.0 .65 .02 .04 Umbelliferae Peidderid ia g a ird n e r i - Roots 7900 3.2 15.0 .48 .02 .03 Ranunculus sp. Stems/Leaves/Flowers 8200 3.2 10.0 .32 .01 .02 Avg. 7841 99.62 46.78 w n r r 11 Graminae Sterns/Leaves/Heads 7969 72.7 48.8 35.5 28.8 58.7 Pinus a lb ic a u l is Nuts 7880 45.5 40.0 18.2 8.3 17.0 T r ifo lium repens VaeeiMium scoparium Sterns/Leaves/Heads 7988 36.4 37.5 13.7 5.0 10.2 Berries/Leaves 7933 27.3 42.7 11.7 3.2 6.5 Rodentia Thomomys ta lp o id e s 7900 18.2 55.0 10.0 1.8 3.7 Melica s p e c ta b i l i s 7950 18.2 31.0 5.6 1.0 2 .0 Vespidae Mature/Larvae 7600 18.2 30.0 .5.5 1.0 2 .0 Avg. 7916 100.2 49.1 100.1 October 6 Graminae Stems/Leaves/Heads 7725 66.6 57.5 38.3 25.5 57.7 Meliea s p e c ta b i l i s 7800 50.0 50.0 25.0 12.5 28.3 Rodentia M icrotus 8100 16.6 100.0 16.6 2.8 6 .3 Pinus a lb ic a u l is 7900 16.6 50.0 8 .3 1.4 3.2 Cervidae Cervus canadensis 7900 16.6 50.0 8 .3 1.4 3.2 Total Polygoniion b is to r to id e s 7400 16.6 20.0 3 .3 .6 1.4 120 Avg. 7782 99.8 44.2 100.1Sample ♦Scats from previous years. UffOMAST-E VALUE EEtCDfT »« St St M 7Z Tt ao as a st ioo =HtUUll ^ Ciajtonia .:mcwc La M S S STAAEAMN3* u^elllfrree I C te^nae /C yper»ce«« C irc ti* - folioma , 19.2 W S V S W S S n 3 TrifcH i* r*p*m 35.3 i/Cypai 2 Trifo l it* n»p«u 3 CifSTtiei folio*!* 5 Cervi Jac/B ovldac _ ; ZJZEr*1* K:i 8 IM re lU fe rae .80 Percent: -0-8 *Scats from previous years. iho I Figure 7. Grizzly bear seasonal food consumption in Yellowstone National Park - valley/plateau economy, 1973. TABLE 3. YELLOWSTONE NATIONAL PARK VALLEY/PLATEAU ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973. Food Item Use Elevation Frequency Occurrence Percent Percent Composition Per Item Percent of Diet Volume Importance Value Irpcrtance Value Percent Graminae/Cyperaceae Graminae 94Z Stems LeavesCarex sp. 6% Heads 7767 70.6 51.1 Z6.2C 25.600 71. SCOTrifolium repens Stens/Leaves/Heads 7590 24.2 59.5 14.40 3.500 S. SCOCircium feliosum Sterns/Heads 7476 20.6 52.6 11.00 2.300 6.400 Rodentia Tkomomys talpoides 52Z Micrctus >■Pa 7524 17.5 43.4 7. CC 1.300 5. 7CC Cervidae/Bcvidae Cervus canadensis 88* Odoeoileus herrionus 65. Bison bison 65 7257 12.5 59.7 7. LO .940 2.600Melica spectabilis Corns 7829 11.7 52.7 e.zo .740 2. ICC Fonnicidae Mature/Larvae 7935 16.7 23.0 s.eo .630 I. SCO Umbelliferae Perideridia gairdyicri 70% - Lomatium ecus 3C% - Rcots Roots 7130 6.3 30.5 2. so .210 .CGCEquisetum arvense Stems 8217 5.0 42.5 2.IC .110 . ZlOFolygonium bistortoides Lntire 7811 7.5 17.2 I. SC .100 .260Finus albicaulis Nuts 7880 4.2 40.0 I. TC .070 .200Claytonia lanceolata Entire 7962 3.3 47.5 I.SC .050 . 140Vaceinium scoparium Berries/Leaves 7900 3.3 34.5 1.20 .040 .110 Garbage 7800 1.6 60.0 1.00 .020 .060Heracleum lanaturr. Sterns/Leaves 8125 1.6 37.5 .CO .010 .CZO Vespidae Mature/Larvae 7600 1.6 18.2 .ZO .005 .010Ranunculus sp. Sterns/Leaves/Flowers 8200 .8 10.0 .OS .001 .003 Avg. 7683 90. IS 35.626 ICC.043 26 TABLE 4. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - VALLEY/PLATEAU ECONOMY, 1974. Frequency Percent Percent Sample Food Item Uae Elevation Occurrence Percent Composition Volume Importance Value Importance April 7 Cervidae/Bovidae Carvue oanadaneie 83.3% Bieon bieon 1 6.6% 7500 85.7 96.6 82.8 71.0 96. 70 Forb - U/I Stema/Leavee 7400 14.2 100.0 14.2 2.0 2.70 Graminae Stema/Leavea »p° 14.2 20.0 2.8 .4 .65 Avg. 7475 99.8 73.4 99.96 Mey 31 Stema/Leavee 6958 61.2 78.0 47.8 29.3 71.00 Cervidae Carvue oanadaneie 78% Odoaoilaue hamionue 22% 7122 29.0 57.0 16. SO 4.800 11.60 Rodentla Thomomye talpoidae 7188 25.8 63.0 16.20 4.200 10.20 Malioa BpaotabiHa 7117 19.3 75.0 14. SO 2.800 6.80 Umbelllferae Paridaridia gairdnari - Roots 6700 3.2 70.0 2.30 .070 .17 Forb - U/I Stema/Leavea 6700 3.2 50.0 1.60 .050 .12 Polygonium b ietorto idee 7800 6.4 10.0 .64 .040 .10 Formicidae Mature/Larvae 6800 6.4 3.5 .22 .014 .03 Avg. 7065 99.76 41.274 100.02 23 Stema/Leavee 7115 78.2 87.7 68. S 53.60 94.90 Rodentia Thomomye talpoidae 66.6% Marmota fla v iv a n tr ie 33.3% 7400 13.0 70.0 9.1 1.20 2.10 Umbelliferae Paridaridia gairdnari 50% - Roots Lomatim ooue 50% - Roots 7550 8.7 75.0 6.6 .57 1.00 Cervidae Cervue oanadaneie 8233 8.7 70.0 6.1 .53 .94 Trifo lium rapane Sterns/Leaves/Heads 7800 8.7 35.0 3.0 .26 .46 Angalioa ap. Stema/Leavea 8000 4.3 50.0 2.2 .10 .20 Chlorophyceae 6800 4.3 50.0 2.2 .10 .20 Formicidae Mature/Larvae 8000 4.3 50.0 2.2 .10 .20 Avg. 7341 99.8 56.46 100.00 July 35 Graminae/Cyperaceae Graminae 94% Sterna Carex ap. 6% Heads 7741 100.0 56.2 56.20 56.200 89. 000 Ciroium fo lioeum Stema/Heade 7720 25.7 39.4 10.10 2.600 4.100 T r i fo l im rapane Stema/Leavea/Heads 7963 17.1 57.5 9.90 1.700 2.700 Rodentla Miorotue 66.6% Thomomye talpoidae 33.3% 7759 34.3 11.2 3.80 1.300 2.000 Formicldae Mature/Larvae 7532 14.2 28.0 4.00 .600 .950 Umbelliferae Periderid ia gairdnari - Roots 74 30 8.6 65.0 S.60 .500 .800 Aetar in ta g r i f i l iu e Laavee/Stema 7800 2.9 95.0 2.70 .080 .130 Agoearie ap. Stema/Heade 7200 2.9 95.0 2.70 .080 .130 Polygonim b ietorto idee 7800 2.9 90.0 2.60 .080 .130 Equieatm arvanea 7900 2.9 75.0 2.10 .060 .100 Angalioa ap. Stema/Leavea 7800 2.9 5.0 .U .004 .006 Avg. 7730 99.84 63.204 100.046 August 42 Graminae/Cyperaceae Graminae 97% Stems Carax ap. 3% Heads 7830 80.9 59.7 48.30 39.100 83.20 C iro im fo l io em Sterna/Leaves/Heads 7887 21.4 69.2 14.80 3.200 6.80 T r i fo l im rapane Sterns/Leaves/Heads 7819 19.0 48.7 9.30 1.800 3.80 Vaooinim eaoparim Berriee/Leavea 7940 11.9 81.0 10.40 1.200 2.60 Taraxiom ap. Stema/Leavee/Heade 7960 11.9 54.0 6.40 .760 1.60 Polygonim b ieto rto idee 7810 16.6 16.4 2.70 .450 .90 Malioa epaotabilie 7823 7.1 41.6 3.00 .210 .46 Fragaria v irginiana 7846 9.5 17.5 1.70 .160 .34 Formlcidae Mature/Larvae 7861 7.1 5.0 .36 .030 .06 Ranunoulue ap. Stema/Leavea/Flowers 7870 2.4 30.0 .71 .020 .04 Veapldae Mature/Larvae 7800 4.7 10.0 .48 .020 .04 Equieetm arvenee 7870 2.3 20.0 .48 .010 .02 Rodentia Thomomye talpoidae 7800 2.3 20.0 .48 .010 .02 Umbelllferae Lomatim ooue 50% - Roots Periderid ia gairdnari 50% - Roots 7822 4.7 6.0 .29 .010 .02 Pinue a lb ioaulie 8300 2.4 10.0 .24 .006 .01 Rueeula ap. Cape/Stems 7890 2.4 10.0 .. -s< . _'006 Avg. 7848 99.88 46.992 99.97 September 50 Graminae/Cyperaceae Graminae 98% Stems Carax ap. 2% Heads 7859 56.0 79.6 44.6 25.00 76.70 Vaoainim eaoparim Berriea/Leavee 7838 26.0 60.3 16.7 4.10 12.60 T r i fo l im rapane Stema/Leavee/Heada 7986 14.0 48.5 8.8 1.00 3.10 Malioa epaotabilie Corma 7808 12.0 55.8 6.7 .80 2.60 Pinue a lb ioau lie 7800 8.0 71.2 5.7 .46 1.40 C iro im fo l io em Sterna/Heads 8025 8.0 63.7 6.1 .41 1.30 7778 6.0 76.6 4.6 .28 .90 Rueeula ap. Capa/Steme 7970 10.0 28.0 2.8 .28 .90 Smilaoina ap. 7955 4.0 75.0 3.0 .12 .40 Umbelllferae Peridaridia gairdnari - Roots 7850 4.0 65.0 2.6 .10 .30 Rodentla Miorotue 7800 4.0 17.5 .7 .03 .09 Carvue oanadaneie 7850 2.0 50.0 _ L 0 _ .06 Avg. 7873 99.3 32.60 100.26 32 Graminae Stema/Leavee/Heade 7893 43.7 53.5 23.4 10.20 39.20 Malioa epaotabilie Corma 7694 25.0 68.1 17.0 4.30 16.60 T r i fo l im repane Stema/Leavee/Heade 7906 25.0 67.5 16.9 4.20 16.10 Cervidae Cervue oanadaneie 7961 28.1 53.3 14.9 4.20 16.10 Rueeula ap. Capa/Sterna 7979 21.8 25.7 6.6 1.20 4.60 C iro im fo l io em Stema/Leavee/Haade 7920 15.6 44.0 6.8 1.10 4.20 Rodantia Thomomye talpoidae 7913 12.5 20.0 2.6 .31 1.20 Smilaoina ap. 8100 6.2 67.5 4.2 .26 1.00 Agoeerie ap. Stema/Leavee/Heade 6876 3.1 100.0 3.1 .10 .40 Formlcldaa 7800 3.1 100.0 3.1 .10 .40 Vaooinim eaoparim Berriea/Leavee 7800 3.1 50.0 1.6 .05 .20 Umbelllferae Peridaridia gairdnari - Roots 6600 3.1 20.0 .6 -M .07 SsmDla 220 Avg. 7852 99.7 26.04 99.97 100 H -2 »» «« BC T* lj?U. Percent: 3.1 Percent: 14.0 Percent: 10.4 Percent: 15.9 Percent: 19 Percent: 22.* Percent: I6-S IK> I Figure 8. Grizzly bear seasonal food consumption in Yellowstone National Park - valley/plateau economy, 1974. - 28- was most important in June and least important in October. Non-grass items.including, notably, artiodactyls and melica corms were most important during the pre- and post-growing seasons (Figure 8). Low red huckleberries (Vacoinium 'sooparium), strawberries (F^agcapia virginiana), and pine nuts (Finns 'aTbioaulis) contributed to the diet during the late growing season and post-growing season. In Table 4, the rank order of food items listed for May 1.974 is. identical with those of the May 1968-73 sample shown in Table,.2',. '%hd' - - • . ' -r . . ' v * importance value percents are comparable. ' ■ - V V| In the annual summary (Table 5), the Percent Composition Per Item- .. i, i- • ■ : column shows high selectivity for the more important foods as well as for some less important. - ■ ! ■ ; „ Table 6 and Figure 9 compare 1973 and 1974 valley/plateau, economy- data. The diets each year were similar. Grasses and sedges wereJthe most important item both years. Substantial differences'" exist-- between the years in the importance value percents of white clover (Trifolivm repens), and elk thistle (Circium foliosum). These differences exist because an area with scats containing primarily the remains of these . ' ' ' ' = / items was sampled in 1973, but not in 1974. The average elevation's of scat location are nearly identical for the two years. Table 7 and Figure 9 show two-year summaries of results. They indicate that , ' . grasses and sedges constituted 82 percent of diet importance and,, 42.9, : V-:-,/ TABLE 5. YELLOWSTONE NATIONAL PARK VALLEY/PLATEAU ECONOMY GRIZZLY BEAR FOOD CONSUMPTION __________SUMMARY, 1974.__________________________________________________________ Frequency Percent Percent Importance Occurrence Composition of Diet Importance Value Food Item Use Elevation Percent Per Item Volume Value Percent Graminae/Cyperaceae Graminae 97% Stems Leaves Carex sp. 3% Heads 7620 67.7 68.7 46. SC 31.5000 SC. OC-Clrifoliur. reperis Stens/Leaves/Heads 7906 14.1 54.3 7.70 1.1000 3.000 Cervidae/Bovidae Cerxus canadensis 89? Odocoileus kerrionus 7? Bison bison 4% 7595 12.3 65.4 8.00 .9900 2.700Ciroiun foliosur. Stems/Heads 7858 12.3 53.8 6.60 .8100 2.200Helica spectabilis Coras 7590 10.4 63.2 6.60 .6800 !.SCO Rodentia Thomomys talpoides 63.3% Miarctus 33.3%Marmota flaviventrie 3.3% 7595 13.6 32.8 4.60 .6100 1.700Vaaciniun scopariun Berries/Leaves 7863 8.6 66.8 6.60 .4900 1.300 Umbelliferae Ferideridia gairdneri 73% - Roots Lomaiium aous 27% - Roots 7458 5.0 52.5 2. CO .1300 .360Russula sp. Caps/Stems 7935 5.9 25.4 !.SC .0900 .240Polygoniun bistortoides Entire 780 7 4.5 22.5 1.00 .0500 .120 Formicidae Mature/Larvae 7554 5.4 15.5 .83 .0400 .120Taraxiaun sp. Sterns/Reads/Leaves 7960 2.3 54.0 I.ZC .0300 .080Pinus albiaaulis Nuts 7900 2.2 59.0 1.30 .0300 .080Smilacina sp. Rhizomes 8028 1.8 71.3 1.30 .0200 .060 Garbage 7778 1.3 76.6 I.OC .0100 .040Agoseris sp. Stems/Leaves/Heads 7038 .90 97.5 .66 .0060 .020 Forb - li/I Stems 7050 .90 75.0 .67 .0060 .020Prageria virginiara Fruits 7846 1.8 17.5 .31 .0050 .ClCEquisetun arvense Stems 7685 .90 47.5 .42 .0040 .010Aster integrifolius Sterns/Leaves 7800 .45 95.0 .43 .0020 .010Angelica sp. Stems/Leaves 7900 .90 27.5 .24 .0020 .010 Chlorophyceae Entire 6600 .45 50.0 .23 .0010 .003Ranunculus sp. Stecs/Leaves/Heads 7870 .45 30.0 . .14 .0006 . CC2 Vespidae Kature/Larvae 7800 .90 10.0 .09 .0008 .002 Avg. 7687 99.64 36.6074 99. 967 TABLE 6. YELLOWSTONE NATIONAL PARK VALLEY/PLATEAU ECONOMY GRIZZLY BEAR KEY FOOD ITEFi CONSUMPTION COMPARISON, 1973-1974. 1973 1974 Scat Sample - 120 Scat Sample - 220 Percent Percent• Importance Total . Average Importance Total Average Value Importance Ele- Value Importance Ele- Food Item Percent Value vation Food Item Percent Value vation Graminae/ Graminae/ Cyperaceae 71.9 Cyperaceae 86.0 TvifoZiim TrifoZivm repens 9.8 ■ repens 3.0 Ciraiim Cervidae/ foliosim 6.4 Bovidae 2.7 IUJ Rodentia 3.7 ' Ciroiim . ? Cervidae/ • foliosim 2.2 Bovidae 2.6 ■ Meliaa spectabi H s speetabiZis (Corms) 1.9 (Cprms) 2.1 Rddentia 1.7 Formicidae • 1.8 Vacciniwn 98.3 7683 seopariwn 1.3 98.8 7687 I M P O R r: W M 100 96 92 88 84 80 76 72 68 64 60 56 52 48 44 40 36 32 28 24 20 16 12 8 4 1973 Scat Sample - 120 1974 Scat Sample - 220 1973-1974 Scat Sample - 340 IO m I Melu Cervidj 'ormicidae H c a epectabilis (Corns Iervidae/ Bovidae Rodentia dircium foliosum tvifolium repens Graminae/Cype raceae I Slii-Iii-Z I CJ!-> I S i ^aecinium scoparium Rodentia ke lica sp e c ta b ilis (Conns) Eircium foliosum Cervidae/Bovidae f r i fo lium repens Graminae/Cyperaceae aaeinium scoparium Iica spectabilis (Corms) Rodentia dervidae/Bovidae Circium foliosum i'rifolium repens Graminae/Cyperaceae Figure 9. Yellowstone National Park valley/plateau economy grizzly bear key food item consumption comparison and summary, 1973-1974. TABLE 7. YELLOWSTONE NATIONAL PARK VALLEY/PLATEAU ECONOMY GRIZZLY BEAR FOOD CONSUMPTION __________ SUMMARY. 1973-1974._________________________________________________________ Frequency Percent Percent Importance Occurrence Composition of Diet Importance Value Food Item Use Elevation Percent Per Item Volume Value Percent Graminae/Cyperaceae Graminae 96” Stems Leaves Cavex sp. 4% Heads 7673 68.8 62.3 a.i: 29.5000 SC.GCCZTifoli-^r. reperB Sterns/Leaves/Heads 7753 17.6 63.0 I.9000 S.S0CCivciur rc Iioswn Stems/Heads 7674 15.3 53.2 S.1C 1.2000 3. SCC Cervidae/Bovidae Cewus canadensis 88” Odccoileus kerrionus I?. Bison bison 5% 7474 12.4 63.4 7. sc I.OOOC ZvSCC Rodentia Fhomomys talpoides 56« Micvotus 39%Mavmota flaviventvis 2' 7566 15.0 37.2 s.ec .8400 z.sccHeliaa speotakilis Corms 76 SC 10.9 59.6 e.sc .7100 Z.C0PVaoainiun scoyaviurr. Berries/Leaves 7869 6.8 61.2 4.:: .2600 .770 Formicidae Nature/Larvae 7875 9.4 20.2 I. sc .1800 .600 Umbelliferae Pevidevidia gaivdnevi 71% - Lomatiwn cous 29% - Roots Roots 7302 6.2 42.0 l a ec .1600 .440Folygoniwn bistcrtoid.es Entire 7809 5.6 20.0 I. IC .0600 .170Sussula sp. Caps/Stems 7935 3.8 25.4 .97 .0400 .100Pinue albioaulis Nuts 7890 3.0 49.5 !.SC .0400 .100Equisetwn axvense Stems 7968 2.4 43.8 !.OC .0200 .060 Garbage 7787 1.5 70.0 I. CC .0200 .040Carczicur. sp. Sterns/Leaves/Heads 7960 1.5 54.0 .SC .0100 .OZOClaytcnia lanceolate Entire 7962 1.2 47.5 .se .0070 .OZOAcosevis sp. Stems/Leaves/Heads 7038 .60 97.5 . S7 .0030 .OCS Forb - L/I Stems/Leaves 7050 .60 75.0 .44 .0030 .CCSEvagevia vivginiara Fruits 7846 1.2 . 17.5 .t! .0030 .OCS Vespidae Mature/Larvae 7700 1.2 14.1 .17 .0020 .006Sevaoleurn laratum Stems/Leaves 8125 .60 37.5 .CS .0010 .CCZAngelica sp. Stems/Leaves 7900 .60 27.5 .!6 .0010 .COZAstev iniegvifolius Stems/Leaves 7800 .30 100.0 .ZS .0009 .OOZRanunculus sp. Stens/Leaves/Flowers 8035 .60 20.0 .!Z .0007 .CCZ Chlorophyceae Entire 6800 .30 50.0 .!S .0004 .001 Avg. 7685 ss.se 35.9820 ss.ses -33- percent of diet volume. Percent composition per item for grasses and sedges is 62.3 percent suggesting that feeding was selective for these items. The general feeding cycle appeared to follow plant phenology. , During the pre-growing season, grizzlies were primarily meat eaters. They apparently congregated on ruminant wintering areas and took the animal material available. Cole (1972) has detailed this activity. In addition, corms, roots, and grass were eaten prior to and during early green-up. During the growing season, grasses, sedges, forks and rodents were used almost exclusively as food. Field observations indicated that succulent vegetation was preferred and its availa­ bility, linked with that of rodents, apparently influenced distri­ bution. Since most plants were generally succulent at this time, bear distribution appeared to be wide and open areas were feeding sites. During the post-growing season, grasses and forks remained important foods, but their use seemed to be confined' to.moist' sites usually in small forest openings and edges and stream bottoms. Seasonal foods in the lodgepole pine forests became available as grasses, sedges and forks in the valleys desiccated; nuts and berries were taken along with mushrooms (Russula sp.J and the rhizomes of smilacina (Sm1Itaovna sp.J. Field observations also indicated that predation on adult, male, breeding elk (CeyyOus canadensis nelsoni) may also have occurred. Extensive use was made of melica corms in -34- Pelican and Lamar Valleys. Distribution appeared to be concentrated in local areas throughout the economy. Intensive digging was- the characteristic feeding activity of valley/plateau economy grizzlies, especially during the growing season. The presence of pocket gophers (Thomomys talpoides) and voles (Microtus sp./ apparently motivated this activity. Field observations showed that locally concentrated excavations ranged in volume from a few hundred cm.3 ,to nearly a hundred m.3. Most were from 1-5 m.3 in volume. Large numbers of scats, were often found associated with digging sites. Contents of these scats averaged 90 percent residues of grasses' and forbs and 10 percent residues of rodents. All evidence suggests, that these grizzlies pursued meat (rodents) but settled for grasses and forbs and a small amount of meat. The small, but con­ sistent amount of success in catching rodents probably held the bears in the feeding pattern. Murie (1961) noted a similar pattern among grizzlies in M t . McKinley National Park where bears pursued rodents with marginal success for several hours, and then with resignation, finished the feeding period grazing oh grass. After resting, the . cycle was repeated. Intensive digging activity and associated evidence of grazing usually occurred in locations where xeric sites were interspersed with mesic sites. The excavations occurred on the xeric sites while grazing occurred on the. adjacent mesic sites. -35- The intensive digging pattern is illustrated by an incident which occurred in July 1974 in Hayden Valley. On July 11, near lower Alum Creek, I found an area of approximately 5,000 m.2 which had the appearance of a freshly ploughed field. ' Twenty grizzly scats con­ taining primarily the residues of grasses and sedges and a trace of rodent remains were located immediately below the site near a small watercourse. The apparent incongruity between digging effort and food eaten was confusing. I returned to the digging site three days ‘ later with my dog. The leashed dog's reaction was remarkable. In a frenzied state he pulled free and immediately caught three voles. The sight, sound and smell of voles were the apparent causes for the dog's reaction. The grizzly reaction to the locally high population of voles may. have been similar and resulted in a kind of "overkill" excavation effort. Ultimately, the main food taken was succulent grass. The presence of voles appeared to anchor the bear(s) to the area. .Another link between rodent activity and plant food became apparent early in October 1973 while observing two adolescent grizzlies feeding in Pelican Valley. The bears appeared to travel a random course sniffing the ground intently. They would stop occasionally and dig furiously for a few moments and then feed. Inspection of the feeding sites revealed that the bears were locating, digging out and eating the contents .of pocket gopher nests. All of these nests -36- contained caches of roots, bulbs and corns. One-half kg., dry weight, of these items remained at a nest site where a bear had fed. Field observations suggested that white clover was the most highly preferred and highly selected plant food eaten during the growing season. Where it was abundant, especially along upper Pelican Creek and in thermal areas between Mary Lake and Hayden Valley, it was used extensively. As many as 50 scats containing exclusively white clover residues were found in individual white clover patches. This item also appeared to be preferred by elk and bison (Bison bison) and was heavily used by them in September. Such use often removed white clover from grizzlies as a significant food source. The relationship between grizzly distribution and plant succu­ lence was most apparent in the Pelican Valley-Fishing Bridge area. During the early and middle portion of the growing season, vegetation was generally succulent throughout the area and bears seemed widely distributed. The only concentrated feeding activity occurred in white clover patches and in areas with high rodent, densities. During the late growing season and post-growing season, all herbaceous vegetation except that on moist.sites became desiccated and grizzly feeding was confined to the moist sites. The largest proportion of moist sites seemed to occur in small openings which were interspersed throughout the lodgepole pine forest in lower Pelican Valley and near the Fishing Bridge Campground. Grizzlies appeared to be drawn to these moist sites -37- with their remaining succulent grasses and forbs. The most dramatic evidence of this effect was observed on October 2, 1974 at the Fishing Bridge sewage lagoons. On this date, bluegrass (Poa'sp.), brome (Bromus sp.7 and other grasses remained succulent■on the lagoon dikes near the sludge. All other herbaceous vegetation in the vicinity and in the Park generally appeared brown. Intense grazing on the dikes by grizzlies was evident. Feeding was particularly intense on the banks where grass removal had exposed mineral soil. Sixty-five fresh scats were counted in the area. A different pattern of post-growing season food use was revealed" by an incident which occurred in the western extreme of Hayden Valley on October 4, 1974. During the night my camp at Mary Lake Patrol Cabin was visited by a grizzly. Tracks in the snow indicated that the bear had shared grain pellets with my tied horses. It then left the camp. Soon after daylight I followed the tracks on horseback. As it traveled, ■ the bear had fed on mushrooms and the rhizomes of smilacina. Since there was no moon, the bear probably detected the presence of these items by smell. The trail led through some thermal areas where the bear had eaten white clover. I tracked the bear to the edge of Hayden Valley where it was.unintentionally encountered at short range feeding on the putrid carcass of a bull elk. On October 10, I revisited the location and found only the broken skull and 7-point antlers of the elk. Tooth wear indicated the elk had been 7-9 years old. The -38- general appearance of the site suggested that the elk had been killed. This incident is probable evidence that some grizzlies become predatory on vulnerable ruminants, in this case probably an unwary breeding bull, during the post-growing season after herbs have dried. The result of this successful predation, the possession of an elk carcass, did not appear to have precluded other foraging activities. Most scats collected near the elk cache contained mixtures of residues of plant and elk origin. Mountain Economy The Gallatin (Figure 10) and Washburn Ranges were major centers of the mountain economy. The fertile andesitic and sedimentary derived soils of the economy supported abundant vegetation in mountain meadows and parklands and on ridgetops. These sites provided most of the food items in the economy. Table 8 and Figure 11 show seasonal food consumption in 1973. Western, springbeauty' (Claytonia' lanceolata).' was the most important food during the growing season months. Grasses ranked a distant second. Grasses and pine nuts were the most important foods during the post-growing season. Table 9, the annual summary, shows that spring- beauty and pine nuts were highly selected as indicated by their respective percent compositions per item. Photo by Jim Chester Figure 10. Gallatin Mountains with Joseph Peak to the left and Electric Peak to the right: an example of a mountain economy setting. TABLE 8. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - __________ MOUNTAIN ECONOMY. 1973.________________________________________________ Frequency Percent Percent Importance Occurrence Composition of Diet Importance Value Month Sample Food Item Use Elevation Percent Per Item Volume Value Percent June 3 Clautonic. Iaheeolata Entire 6000 66.6 80.0 £3.3 35.5 56.1 Graminae Stems/Leaves/Heads 8630 66.6 55.0 ze.e 24.4 38.6 Equisetum arvense Stems 7500 33.3 30.0 1C.0 . 3.3 5. 3 Avg. 8160 99.9 63.2 100.0 July 11 Claytonia lanceclata Entire 9000 81.8 62.8 67.70 55.40 88.6 Graminae Stems/Leaves/Heads 8700 27.3 83.3 22.70 6.20 P.8 Cervidae Cervus canadensis 9100 9.0 95.0 8.60 .77 1.2 Formicidae Mature/Larvae 8850 18.2 5.0 .91 .17 .3 Avg. 8927 99.91 62.54 100.0 August 15 Claytonia lanceolata Entire 9150 80.0 69.2 SB. 40 44.30 73.70 Graminae Stems/Leaves/Heads 8888 60.0 30.3 18.20 10.90 18. 60 Umbelliferae Lomatium cous - Roots 9500 13.3 65.0 8.70 1.20 2.10 Pinus albieaulis Nuts 9250 13.3 60.0 8.00 1.10 1.90 Russula sp. Cap/Stem 8450 13.3 30.0 4.00 .53 .90 Vaecinium seopariur. Berries/Leaves 8800 6.6 40.0 2.60 .17 .29 Formicidae Mature/Larvae 9400 20.0 4.0 .80 .16 .27 Cervidae Cervus canadensis 7600 6.6 25.0 1.65 .11 .19 Civcium foliosun Stems 9300 6.6 10.0 .66 .04 .07 A v g . 9056 100.01 58.51 100.02 September 3 Graminae S terns/Leaves/Heads 8300 66.6 52.5 35.0 23.3 44.2 Pinus albieaulis Nuts 8300 66.6 35.0 23.3 15.5 29.4 Umbelliferae Lomatium cous - Roots 9100 33.3 100.0 33.3 11.1 21.1 Cervidae Cervus canadensis 9000 33.3 25.0 8.3 2.8 5.3 A v g . 8550 99.9 52.7 100.0 October 5* Pinus albieaulis Nuts 8900 100.0 94.6 94.6 94.60 98.80 Claytonia lanceolata Entire 8600 20.0 25.0 5.0 1.00 1.00 Total Sample 37 Rodentia Microtus A v g . 8800 8843 20.0 2.0 .4 100.0 .08 95.68 . 08 99.88 *Scats from previous years. *Scats from previous year. Figure 11. Grizzly bear seasonal food consumption in Yellowstone National Park - mountain economy, 1973. TABLE 9. YELLOWSTONE NATIONAL PARK MOUNTAIN ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973. Food Item Use Elevation Frequency Occurrence Percent Percent Composition Per Item Percent of Diet Volume Importance Value Importance Value Percent Clajtonia lanceolate Entire 8975 65.0 73.4 47. CO 30.900 69.000 Graminae Stems/Leaves/Heads 8750 43.2 46.1 20. OC 8.600 18.200Pinus albicaulis Nuts 8844 24.0 73.6 18. CO 4.300 9. 600 Umbelliferae LcmatiiJK oous - Roots 9367 8.1 77.0 6.20 .500 I. ICC Cervidae Cervus canadensis 8567 8.1 48.3 4.00 .320 .710 Circiun fcliosun Stems/Heads 9300 8.1 10.0 .80 .060 .180 Fonnicidae Mature/Larvae 9125 10.8 4.5 .50 .050 .110Vaccinium sccparium Berries/Leaves 8800 2.7 40.0 1.10 .030 .070 Russula sp. Caps/Stems 8450 2.7 30.0 .81 .020 .050Equisetum arvense Stems 7500 2.7 30.0 .81 .020 .050 Rodentia Marctus 8800 Avg. 8890 2.7 2.0 .05 99.87 .00144.801 .002100.022 -43- Tables 10, 11, and Figure 12 show 1974 food consumption. Springbeauty and grasses were the most important food items in June, July and August. Springbeauty was the most important item in July and was of nearly equal importance with grasses in August. In September,, grasses and sedges were most important. Scats containing the remains of these items were found at an average elevation of 8330 feet (2539 m.). Pine nuts ranked second and scats containing pine nut residues were found at an average elevation close to that of scats containing grass/sedge residues. Percent compositions per item of these two foods indicate that they were taken in combination with other items (Table 10). Most scats containing pine nut residues also contained grass residues. In October, pine nuts were the.most important item and scats containing pine nut residues were found at an average elevation of 9200 feet (2804 m.). This item was ex­ clusively selected (Table 10). Table 12 and Figure 13 compare 1973 and 1974 mountain economy data. The most important food items consumed each year were identical, their contributions to total diet importance were, nearly identical and their rank orders are similar. Springbeauty ranked first, and grasses and sedges ranked second each year. Large differences in importance values for the different food items exist between years. These differences are the probable result of incomplete and sporadic sampling in 1973 as compared with that of 1974. The average TABLE 10. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - ___________ MOUNTAIN ECONOMY. 1974.________________________________________________ Frequency Percent Percent Importance Occurrence Composition of Diet Importance Value Month Sample Food Item Use Elevation Percent Per Item Volume Value Percent June 4 Graminae Stems/Leaves 8853 75.0 46.6 34.9 26.2 61.5 Equisetum arvenss Stems 8200 25.0 100.0 25.0 6.3 14.8 Umbelliferae Perideridia gairdneri - Roots 8360 25.0 60.0 15.0 3.8 8.9 Trifoliian repens Stems/Leaves 8800 25.0 50.0 12.5 3.1 7.3 Cervidae Cervus canadensis 9400 25.0 30.0 7.5 1.9 4.5 Rodentia Thomomys talpoides 8360 25.0 20.0 s.o 1.3 3.1 Avg. 8710 99.9 42.6 100.1 July 52 Claytonia lanceolata Entire 9456 59.6 83.5 49.30 29.70 61.80 Graminae Sterns/Leaves 9210 48.0 63.0 30.30 14.50 30.20 Umbelliferae Lomatium cous 71% - Roots Perideridia gairdneri 29% - Roots 9286 27.0 49.6 13.40 3.60 7.50 Rodentia Thonomys talpoides 9450 3.8 52.5 2.00 .08 .17 Formicidae Mature/Larvae 9380 9.6 7.2 .69 .06 .13 Chlorophyceae Entire 8000 1.9 100.0 1.90 .04 .08 Equisetun arvense Stems 8400 1.9 100.0 1.90 .04 .08 Avg. 9311 99.99 48.02 99.96 August 60 Graminae/Cyperaceae Graminae 79% Stems Leaves Carex sp. 21% Heads 8666 71.6 43.0 30.80 22.000 47.300 Claytonia lanceolata Entire 9590 50.0 87.6 43.80 21.900 47.000 Umbelliferae Lomatium cous 82% - Roots Perideridia gairdneri 18% - Roots 9141 18.3 35.4 6.50 1.200 2.600 Heracleum lanatum Sterns/Leaves 8500 11.6 44.0 5.10 .600 1.300 Formicidae Mature/Larvae 8981 13.3 22.7 3.00 .400 .860 Circium foliosum Stems/Leaves/Heads 8975 6.6 50.0 3.30 .220 .470 Trifoliian repens Stems/Leaves/Heads 7750 6.6 22.5 1.50 .100 .220 Mertensia eiliata Stems/Leaves 9325 3.3 50.0 1.60 .050 .100 Pinus albicaulis Nuts 8200 5.0 13.3 .67 .030 .060 .Equisetum arvense Stems 8000 1.6 90.0 1.40 .020 .040 Ranunculus sp. Stems/Leaves/Flowers 7600 1.6 50.0 .80 .010 .020 Pastinaca sativa Stems/Leaves 8900 1.6 50.0 .80 .010 .020 Rodentia Thomomys talpoides 9000 1.6 25.0 .40 .006 .010 Frageria virginiana Fruits 8500 1.6 20.0 .32 .005 .010 Russula sp. Caps/Stems 8000 1.6 10.0 .16 .002 .004 Avg., 8849 100.15 46.553 100.014 September 13 Graminae/Cyperaceae Graminae 86% Stems Carex sp. 14% Heads 8330 53.8 49.9 26.9 14.40 42.4 Pinus albicaulis Nuts 8405 46.1 35.8 16.5 7.60 22.4 Claytonia lanceolata Entire 8175 30.7 63.7 19.6 6.00 17.7 Ribes setosum Berries/Leaves 8600 15.3 100.0 15.3 2.30 6.8 Rodentia Thomomus talpoides 8420 15.3 65.0 10.0 1.50 4.4 Frageria virginiana Fruits 8300 23.0 23.3 5.4 1.20 3.5 Umbelliferae Lomatium cous - Roots 8120 15.3 40.0 6.1 .93 2.7 Avg. 8336 99.7 33.93 99.9 October 4 Pinus albicaulis Nuts 9200 74.0 100.0 75.0 55.5 89.6 Umbelliferae Lomatium cous - Roots 9233 25.0 100.0 21.0 6.3 10.2 Total Sample 133 Avg. 9208 100.0 61.8 100.0 TABLE 11. YELLOWSTONE NATIONAL PARK MOUNTAIN ECONOMY GRIZZLY BEAR FOOD CONSUMPTION ___________ SUMMARY, 1974._____________________________________________________________ Food Item Use Elevation Frequency Occurrence Percent Percent Composition Per Item Percent of Diet Volume Importance Value Importance Value Percent ClayUmia lanceolata Gramlnae/Cyperaceae Entire Graminae 87% Stems Leaves 9439 48.9 84.2 41.20 20.100 50.500 Umbelliferae Carex sp. 13% Heads Lomatium eous 76% - Roots 8817 58.6 48.0 28.10 16.500 41.SCO Perideridia gairdneri 24% - Roots 9117 21.8 45.6 9.90 2.200 5.500Pinus albicaulis Nuts 8553 9.0 46.2 4.20 .380 .950 Formicidae Mature/Larvae 9134 9.8 16.7 1.60 .160 .400Heracleum lanatum S terns/Leaves 8500 5.3 51.4 2.70 .140 .350 Rodentia Thomomys talpoides 8850 4.5 46.7 2.10 .090 .220Equisetum aruense Stems 8200 2.2 96.6 2.20 .050 .130Circium foliosum Stems/heads 8975 3.0 50.0 I.SO .050 .130Trifolium repens Stems/Leaves/Heads 7960 3.8 28.0 1.00 .040 .100Ribes setosum Berries/Leaves 8600 1.5 100.0 1.50 .020 .050Progeria virginiana Fruits 8350 3.0 22.5 .68 .020 .050Mertensia ciliata Stems/Leaves 9325 1.5 50.0 .75 .010 .020 Chlorophyceae Entire 8000 .75 100.0 .75 .006 .015Pastinaca sativa Stems/Leaves 8900 .75 50.0 .38 .003 .010Ranunculus sp. Stems/Leaves/Flowers 7600 .75 50.0 .38 .003 .010 Cervidae Cerous canadensis 9400 Avg. 8988 .75 30.0 .2399.17 .00239.774 .00599.940 12 2# J0 It 12 I4 Tnfsliun repeno immiwwwiiuiiiiiiiunmwiimin 6.3 Uabel 11 ferae Figure 12. Grizzly bear seasonal food consumption mountain economy, 1974. in Yellowstone National Park - TABLE 12. YELLOWSTONE NATIONAL PARK MOUNTAIN EQONOMY GRIZZLY BEAR KEY FOOD ITEM CONSUMPTION COMPARISON, 1973 -1974. 1973 Scat Sample - 37 1974 Scat Sample -■ 133 Food Item Percent importance Total Value Importance Percent Value Average Ele­ vation Food Item Importance Value Percent Percent Total Importance Value Average Ele­ vation Claytonia lanoeolata 69.0 Claytonia lanoeolata. 50.50 Graminae/ Cyperaceae ' 19.2 Graminae/ Cyperaceae 41.50 Pinus albioaulis 9.6 Umbelliferae (Roots) ' 5.50 i Umbelliferae (Roots) 1.1 Pinus albioaulis .95 4>* I . 98.9 8890 .98.45 . 8988 e o z i c n t I 100 96 92 88 84 80 76 72 68 64 60 56 52 48 44 40 36 32 28 24 20 16 12 8 4 1973 Scat Sample -. 37 1974 Scat Sample - 133 1973-1974 Scat Sample - 170 IS I I O :i mbelliferae (Roots) inus albicaulis GraminaeClaytonia lanceolata s 5 O 0 ' T O Umbel ■ ■ ES Eg Bi Bi B :i nus a lb icau lis liferae (Roots) draminae/Cyperaceae blaytonia lanceolata : J Il T O Umbel Hnus a lb icau lis liferae (Roots) draminae/Cyperaceae blaytonia lanceolata I4N OO I Figure 13 Yellowstone National Park mountain economy grizzly bear key food item consumption comparison and summary, 1973-1974. -49- elevations of scat location are comparable. Table 13.and Figure 13, containing two-year summaries of results, show that springbeauty ranked first in food consumption importance with a value of 55.5 percent. Scats containing residues of this item were located at an average elevation of 9314 feet (2839 m.). Springbeauty was highly selected as indicated by the 81.3 percent composition per item. Grasses and sedges ranked second. These items were, taken at an average elevation of 8806 feet (2684 m.). They were eaten in combination with other foods. The roots of Umbelliferae ranked third and were taken in combination with other items. Pine nuts ranked fourth. In September, they were taken below 2743 m. and eaten in combination with grass. In October, they were exclusively selected at elevations above 2743 m. The general feeding cycle appeared to follow plant phenology as seemed to be the case for the valley/plateau economy. Elk and moose (Aloes aloes shlrasi-) wintering areas existed in the economy and use of ruminant material probably occurred during the pre-growing season although it was not sampled. During the growing season springbeauty and grasses and sedges were the most important foods. Field ob­ servations indicated that springbeauty was taken primarily in ridge- top herblands while grasses and sedges were taken in meadows and parklands. Feeding activities and distribution in relation to these foods appeared to be influenced by plant succulence. Feeding began TABLE 13. YELLOWSTONE NATIONAL PARK MOUNTAIN ECONOMY GRIZZLY BEAR FOOD CONSUMPTION SUMMARY, 1973-1974. ___________________________________________________________ Frequency Percent Percent Inportance Occurrence Composition of Diet Importance Value Food Item Cse_________________________Elevation Percent_____ Per Item. ___Volume_____Value______ Percent Claytcnia lanceolata Entire 9314 Graminae/Cyperaceae Graminae 69% Stems Leaves Ccrex sp. 11% Heads 8806 Umbelliferae Lomatium cous 78% - RootsPerideridia gairdneri 22% - Roots 9140 Pinus albicaulis Nuts 8678 Fonnicidae Mature/Larvae 9132 Heracleum lanatum Stems/Leaves 8550 Rodentia Tkomomys talpoides 86%Miarctus 14% 8843 Ciraium foliosum Stems/Heads 9114Equisetum arvense Stems 8025Trifolium repens Stems/Leaves/Heads 7960 Cervidae Cervus canadensis 8775Ribes setosum Berries/Leaves 8600 Frageria virginiana Fruits 8350 Mertensia ailiata Stems/Leaves 9325 Chlorophyceae Entire 8000 Pastinaea sativa Stems/Leaves 8900Ranunculus sp. Sterns/Leaves/Flowers 7600Vaacinium saoparium Berries/Leaves 8800 Russula sp. Caps/Stems 8450 52.0 81.3 41.60 22.200 88. SCO 55.3 47.7 26. 4C 14.700 36.800 18.8 48.5 9. IC 1.700 4.2CC 12.4 57.9 7.2C .900 2.20. 10.0 13.8 1.40 .140 .360 4.1 51.4 2.10 .090 .220 4.1 40.3 1.70 .070 .17 C 4.1 32.8 1.60 .050 .120 2.3 79.9 I. PC .040 .ICC 2.9 28.0 .82 .020 .080 2.3 43.7 I.CC .020 .060 1.2 100.0 1.20 .010 .020 2.3 22.5 .S3 .010 .020 1.2 50.0 .88 .007 .CIS .58 100.0 .88 .008 .008 .58 50.0 .28 .002 .006 .58 50.0 .29 .002 .006 .58 40.0 .23 .001 .003 .58 30.0 .17 .001 . C0399.39 39.966 89.842Avg. 8969 -51- in snow-free locations and followed snow-melt and green-up to the highest elevations in late July and August (Table 10). After desiccation of plants on the highest ridgetops in late August, feeding occurred at lower elevations where plants remained green. Such sites were stream bottoms, springs and herblands associated with persistent snowbanks. These sites were also attractive to elk and received intense grazing pressure from them. During the early post­ growing season, feeding activities apparently continued to be influ­ enced primarily by succulent vegetation associated with moist sites. Pine nuts and gooseberries (Ribes sefosum) appeared to be eaten incidentally. In October following the desiccation of most herbs, feeding activity seemed to be concentrated on ridges generally above 2743 m. where pine nuts, Umbelliferae roots and springbeauty corms were taken exclusively. Early post-growing season foraging of mountain economy grizzlies appeared similar to that of valley/plateau grizzlies in that both seemed to concentrate on moist sites with succulent herbs and use seasonal foods incidentally. Late post-growing season foraging appeared different in the two economies because mountain economy grizzlies ate.nuts, roots and corms on high ridges while valley/ plateau grizzlies fed on grasses, forbs, nuts, mushrooms, rhizomes, and ruminants in the lodgepole pine forest. -52- Casual digging was the characteristic feeding activity of mountain economy grizzlies. Field observations indicated that this digging was usually shallow and typically resulted in excavations •having a volume of a few cm.3. The presence of springbeauty corns and biscuitroot (Lomat-ium oous) roots apparently motivated casual digging. A recount of the feeding activity of a large grizzly sow and yearling cub observed on August 25, 1974 at Fawn Pass in the Gallatin Range illustrated this activity. The bears were feeding in an open, rolling herbland .of approximately 15 ha. They traveled slowly across the opening in an ambling gait which was interrupted by frequent stops to sniff and dig. The stops appeared to be random. No intense sniffing occurred until after the bears had stopped. After sniffing the ground, the bears overturned soil and plants with strong, purposeful scooping motions. Sometimes the animals appeared to feed on overturned material and at other times they seemed to ignore the dig and move on. In­ spection of the dig sites revealed the remains of roots of biscuitroot and cbrms of springbeauty. Random digging in sites undisturbed by the bears yielded abundant amounts of these items. The above-ground portions of these plants were dried up and to me, scarcely recog­ nizable. Earlier in the growing season, such casual digging probably would have been preceded by grazing on the above-ground parts of springbeauty. -53- Another observation of grizzly feeding activity one km. south of Big Horn Pass in the Gallatin Range on July 20, 1974 illustrates a variation of the casual digging pattern. The site was a rocky,. alpine ridgetop. The bear was casually overturning rocks and earth with one paw. Each digging effort was followed by sniffing and eating. Inspection, of the digs revealed that the bear was eating ants and roots of biscuitroot. General inspection of the entire 2 ha. feeding area revealed that it was literally terraced by past and present over­ turning of rocks and soil. Another site with an appearance similar to this one was located later, on Quadrant Mountain. Grizzlies appeared to eat whitebark pine nuts in two distinct use stages: I) incidental, and 2) exclusive. The incidental use stage occurred in late August and September when the mature cones remained in the trees. Mature cones in trees were unavailable to most grizzlies since all but the very young are unable to climb (Herrero, 1972)1 The only cones available during the incidental use stage were those on the ground as a result of squirrel (Tamiasoiicpus hudsonicus) cuts and wind throw. Since no direct link between grizzlies and cones existed during this stage, the primary foods were succulent forbs and grasses; pine nuts were eaten incidentally. This contrasted with black bear use during the same time. Black bears are adept climbers and I observed them ascending whitebark pine trees, breaking off cone-bearing limbs and descending to feed. Black bears separated the nuts from the cone -54- scales by holding the cone with the paws and tearing with the teeth. Only the nuts were ingested. The exclusive use stage occurred in October and probably November after cone disintegration and/or abscission. After abscission, nuts and cones became abundant on the ground and grizzlies were linked directly to them. A move to higher, elevation ridges where whitebark pine is most abundant may have been a response to cone disintegration and abscission. , Grazing on grasses and sedges appeared to be concentrated in dense stands of succulent forage at least 8 cm. tall. Grizzlies usually grazed with a sideways motion of the head which placed the muzzle perpendicular to the vegetation. The food appeared to be grasped with the molars and plucked. Such feeding activity was per­ formed rapidly and for long, uninterrupted periods. Lake Economy The primary components of the lake economy were spawning cutthroat trout (SaVno clccrki), used as food by grizzlies, and the tributaries to Yellowstone Lake supporting spawning cutthroat trout (Figure 14). The economy functioned in the South, Southeast and Flat Mountain Arms of the Lake. Table 14 and Figure 15 show growing season food consumption in 1973. Grass was the most important food in June and cutthroat trout was the most important food in July (Table 14). Other foods with - 55- Photo by Dean Graham Figure 14. Grizzly bear fishing in a tributary at the tip of the Flat Mountain Arm, Yellowstone Lake: an example of a lake economy setting. TABLE 14. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - ___________ LAKE ECONOMY, 1973. ■__________ Month Sample Food Item. Use Elevation Frequency Occurrence. Percent Percent Composition Per Item Percent of Diet Volume Importance Value Importance Value Percent June 8 Gramihae Stems/Leaves/Heads 7800 87.5 76.4 66.9 ' 58.5 89.90Equisetum arvense Stems 7800 25.0 77.5 19.4 4.9 7.50Bepaoleum lanatum Sterns/Leaves 7800 12.5 100.0 • 12.5 1.6 2.40 Cervidae Cervus canadensis 7800 12.5 10.0 1.3 1.6 .24 Avg. 7800 100.1 66.6 100.04 July 14 Salmo olarki Entire 7800 50.0 ■ 67.9 33.9 17.00 45.0 Graminae S terns/Leaves/Heads 7800 50.0 54.3 27.1 13.60 36.0Cipoium fo liosum Stems/Heads 7800 21.4 63.3 13.6 2.90 7.7Eevaoteum Zanatum Stems/Leaves/Heads 7800 21.4 40.0 6.6 1.80 4.9 ,Equisetum arvense Stems 7800 14.3 75.0 10.7 1.50 4.1 C Cervidae Cervus canadensis 7800 14.3 42.5 6.1 .87 2.3 Avg. 7800 100.0 37.67 100.0 Total Sample 22 IOi I Figure 15 Grizzly bear seasonal food consumption in Yellowstone National Park - lake economy, 1973. -58— relatively high importance value percents were horsetail (Equ-Lsetim avvense) in June and elk thistle in July. For the year, grass was the most important food; percent composition per item of grass, cutthroat trout and horsetail indicate high levels of selection for these items (Table 15). Table 16 and Figure 16 show food item consumption in 1974. They indicate that nearly.92 percent of the year's sample is listed for July. Cutthroat trout was the most important food with an importance value percent of 43.5. Grasses and sedges, elk thistle and horsetail ranked respectively below trout in the diet. In the annual summary (Table 17), data listed under Percent Composition Per Item show that while trout was the most highly selected food of the top ranking items, all foods were taken in combination with others. Table 18 and Figure 17 compare the 1973 and 1974 annual lake economy summaries. The food items contributing to the diet were similar each year, but the rank orders and importance value percents are very different. The probable reason for the disparities is sampling differences between 1973 and 1974, which are apparent in Table I. The two-year summaries (Table 19, Figure 17) indicate that grass and cutthroat trout were nearly equal in importance. The percent composition per item of trout indicates that this was the most highly selected of the most important food items. TABLE 15. YELLOWSTONE NATIONAL PARK LAKE ECONOMY GRIZZLY BEAR FOOD CONSUMPTION ___________ SUMMARY, 1973.__________ Food. Item Use Elevation Frequency Occurrence Percent Percent Composition Per Item Percent of Diet .Volume Importance Value Importance Value Percent Graroiiiae Stems/Leaves/Heads 7800 63.6 65.4 41.6 26.50 67.1 Sdlmo alaaeki Entire 7800 31.8 . 67.9 21.6 6.90 17.5 Equisetwn arvense Stems 7800 18.2 76.3 13.9 ' 2.50 6.3 Eeracleim Ianatwn Stems 7800 18.2 55.0 10.0 ■ 1.80 4.6 Cireiwn folioswn Stems/Heads 7800 13.6 63; 3 8.6 1.20 3.0 Cervidae ■ Cervus eanadensis Avg. 7800 7800 13.6 31.7 4.3 100.0 .58. 39.48 1.5 100.0 -59 TABLE 16. GRIZZLY BEAR SEASONAL FOOD CONSUMPTION IN YELLOWSTONE NATIONAL PARK - ___________ LAKE ECONOMY, 1974.____________________________________________________ Frequency Percent Percent Importance Occurrence Composition of Diet Importance Value Month Sample Food Item Use Elevation Percent Per Item Volume Value Percent June 3 Salmo clarki Entire 7800 66.6 75.0 SC. C 32.3 SO.O Graminae Stems/Leaves 7800 66.6 75.0 so.o 33.3 50.0 A v g . 7800 10C.0 66.6 100.0 July 76 Salmo clarki Entire 7797 60.5 56.8 Z4.40 20.800 43.500 Graminae/Cyperaceae Graminae 90% Stems Carex 10% Leaves 7810 66.0 29.9 19. 70 13.000 27.200 Circium foliosum Stems/Heads 7821 50.0 44.0 22.00 11.000 23. 000 Equisetum arvense Stems 7800 21.0 38.4 8.10 1.700 3.600 Umbelliferae Ferideridia gairdneri - Roots 7807 18.4 25.3 4.70 .860 i.eoc Heracleum lanatum Stems/Leaves 7767 8.0 40.0 3.2C .260 .540 Vaacinium scoparium Berries/Leaves 7800 2.6 100.0 2.60 .070 .140 I Trifolium repe>is Stems/Leaves/Heads 7800 2.6 87.5 2. SO .060 .ISO Rodentia Thomomys talpoides 7800 2.6 35.0 .92 .020 .050 Formicidae Mature/Larvae 7800 6.6 4.4 .29 .020 .040 Frageria virginiana Fruits 7750 2.6 12.5 .33 .008 .020 Ruppia pectinate Stems/Leaves 7700 2.6 12.5 .33 .008 .020 Agoseris sp. Stems/Leaves/Heads 7800 1.3 35.0 .46 .006 .010 Cervidae Cervus canadensis 7800 1.3 25.0 .33 .004 .008 Anaeharis sp. Stems/Leaves 7800 1.3 20.0 .26 .003 .006 Polygonium bistortoides Entire 7800 1.3 10.0 .IS .002 .004 Avg. 7804 100.05 47.821 100.068 August 4 Graminae Stems/Leaves/Heads 7800 75.0 61.6 46.2 34.7 59.4 Equisetum arvense Stems 7800 50.0 42.5 21.2 10.6 18.2 Salmo a larki Entire 7800 50.0 40.0 2C.0 10.0 17.1 Total Trifolium repens Stems/Leaves/Heads 7800 25.0 50.0 12.S 3.1 5.S Sample 83 Avg. 7800 99.9 58.4 100.0 Pncnrr Hi deMs lH:•■, #■iH.UfOM, lf:•, i,.M,OU A Sf■i:, 100 SR M »» »* K) T t T? M E» 60 5 t 52 » * 40 3 t 32 2B 2* ZQ I t 12 B ■» Q ________________________ Q ■. « 12 I t 20 2" 2» 32 3 t 40 »■» RB 52 St 60 t t t t 72 7 t go «8 It i t 100___________^ s„ , I POOD ITEMS MAT ^ I hifTiI in j ty y f tf r n m tt in tortrimt.TU v>A -ifi' > ■ ■: " I Sacxci ~ larki I ^ iitimTiTrlm iA ^ '.tl11iIN i' JtME Percent: 3.6 14. t w . - y ' i i iVmirtHi i 22.0 e i e i e i e i e i e 1 Salm dark’. 2 Gramlnae/Cypereceee 3 Ciraium folioam 4 Squiaetwi arvenee i e i e i e i e m i e 23.0 - E , V Percent: 91.5 20'° 2 Squise tun arvetwe 3 SaZw clarki 4 Tnfolium repene a g K H E H E a v . i 18 ' 2 Sce ts 4 m'jfH 5.3 Percent: 4.8 SEPTEMBER , , ‘ i i S I SdZw clarki 3 Ctreium folioam 4 Equisetm arvenee 5 Uebelllferse 6 Heraclem lanatm r , \ - ‘ I ‘ 5 Figure 16 Grizzly bear seasonal lake economy, 1974. food consumption in Yellowstone National Park - TABLE 17. YELLOWSTONE NATIONAL PARK LAKE ECONOMY GRIZZLY BEAR FOOD CONSUMPTION ___________ SUMMARY, 1974. ________________________________________________________ Food Item Use Elevation Frequency Occurrence Percent Percent Composition Per Item Percent of Diet Volume Importance Value Importance Value Percent Salmo clarki Entire 7797 60.2 56.4 32.90 20.400 43.000 Graminae Stems/Leaves/Heads 7810 66.3 34.0 22. SO 14.900 31.400Circiian foliosum S terns/Heads 7821 45.8 44.0 20.10 9.200 19.400Equisetum arvense Stems 7800 21.7 38.9 8.40 1.800 3.800 Umbelliferae Perideridia gairdneri - Roots 7807 16.9 25.3 4.30 .730 I. SCOHeraeleian lanatian Stems 7767 7.2 40.0 2.90 .210 .440Trifolium repens Stems/Leaves/Heads 7800 3.6 75.0 2.70 .100 .210Vaaciniian scopariian Berries/Leaves 7800 2.4 100.0 2.40 .060 . ISO . Rodentia Thomomys talpoides 7800 2.4 35.0 .84 .020 .040 c\ Formicidae Mature/Larvae 7800 6.0 4.4 .27 .020 .040 YFrageria virginiana Fruits 7750 2.4 12.5 .30 .007 .020Huppia pectinate Entire 7700 2.4 12.5 .30 .007 .020Agoseris sp. Stems/Leaves 7800 1.2 35.0 .42 .005 .010 Cervidae Cervus canadensis 7800 1.2 25.0 .30 .004 .008Anaaharis sp. Stems/Leaves 7800 1.2 20.0 .24 .003 .006Polygoniian bistortoides Entire 7800 Avg. 7804 1.2 10.0 .1299.99 .00147.467 .002100.026 TABLE 18. YELLOWSTONE .NATIONAL PARK LAKE ECONOMY GRIZZLY BEAR KEY FOOD ITEM CONSUMPTION COMPARISON , 1973-1974. 1973 Scat Sample - 22 1974 Scat Sample - 83 Food Item Importance Value Percent Percent Total Importance Value Average Ele­ vation Food Item Importance Value Percent Percent Total Importance Value Average Ele­ vation Graminae . 67.1 SaZmo oZavki • 43.0 Salmo clarki 17.5 Graminae 31.4 Equisetvm capvense 6.3 Civoivm foZiosvm 19.4 EevaoZevm Zanatvm 4.6 Equisetvm awense 3.8 Civoivm foZiosvm- 3.0 98.5 7800 Umbelliferae (roots) 1.5 99.1 7804 IM PO R' : t I 100 96 92 88 84 80 76 72 68 64 60 56 52 48 44 40 36 32 28 24 20 16 12 8 4 1973 Scat Sample - 22 IijL i_ _ _ _ _ _ I Cervidae Circium foliosum Heraeleum lanatum Equisetum arvense Ctalmo elarki 1974 Scat Sample - I mtF Equiset 1973-1974 Scat Sample - 105 Jeraeleum lanatum elliferae (Roots) )quisetum arvense dircium foliosum Graminae halmo elarki IG\ -P> I I " ' a Il I Heracleum lanatum Umbelliferae (Roots) Equisetum arvense tireium foliosum Salmo elarki Graminae Figure 17. Yellowstone National Park lake economy grizzly bear key food item consumption comparison and summary, 1973-1974. TABLE 19. YELLOWSTONE NATIONAL PARK LAKE ECONOMY GRIZZLY BEAR FOOD CONSUMPTION ___________ SUMMARY. 1973-1974.____________________________________________________ Food Item Use Elevation Frequency Occurrence Percent Percent Composition Per Item Percent of Diet Volume Importance Value Importance Value Percent Graminae Stems/Leaves/Heads 7808 65.7 40.4 26.50 17.4000 59.200Salmo olaxki Entire 7797 54.3 57.8 . 51.40- 17.1000 58.500Civciim foliosim Stems/Heads 7819 39.0 45.4 17.70 6.9000 15.500 Equisetim arvense Stems 7800 21.0 45.7 9.60 . 2.0000 4.500 Umbelliferae Perideridia gairdneri - Roots 7807. 13.3 25.3 '5.40 .4500 1.000Eeraeleum lanatim Stems/Leaves 7780 9.5 46.0 4.40 .4200 .950Xrifoliim repens Stems/Leaves/Heads 7800 2.8 75.0 2.10 .0600 .140 Cervidae Cervus canadensis 7800 3.8 30.0 1.10 . .0400 .090Vacoiniim soopccniion Berries/Leaves 7800 1.9 100.0 1.90 .0400 .090 c Eodentia Xhomomys talpoides 7800 1.9 35.0 .66 .0100 .020 I Formicidae Mature/Larvae 7800 4.7 4.4 .21 .0100 .020Frageria virginiana Fruits 7750 1.9 12.5 .24 .0040 .009Ruppia peetinata Entire 7700 ■ 1.9 12.5 .24 .0040 .009Agoseris sp. Stems/Leaves 7800 .95 35.0 .55 .0030 .007Anaeharis sp. Stems/Leaves 7800 .95 20.0 .19 .0020 .005Polygonium bistortoides Entire 7800 Avg. 7803 .95 10.0 .09100.06 .000944.4439 .002100.042 -66- Field observations indicated that the feeding cycle was apparently directly related to the presence of spawning cutthroat trout in tributaries. This presence extended generally from late June to early August. Variation existed among individual tributaries in the actual time of occurrence of spawning trout (Knight, 1975). Feeding activity in the economy is illustrated by observations made along a tributary at the tip of Flat Mountain Arm during the last half of July 1974. Estimated flow in the stream was .13/m3s and estimated peak fish density was six fish per linear meter within 0.8 km. of the mouth. Cutthroat trout caught personally in this seg­ ment averaged 38 cm. in length and 0.6 kg in weight. Eleven different grizzlies were sighted in the vicinity between July 16 and July 18, 1974 (Knight, 1975). Bears moved in the stream and along the banks looking for vulnerable fish. ■ Fish were often trapped against the bank and subse­ quently caught and eaten. Figure 14 shows this activity and the worn appearance of the stream bank. Cubs-of-the-year appeared to fish with an efficiency equal to or greater than that of adult bears (Graham,\ ' • 1975j. Grass, horsetail and elk thistle were heavily grazed in the area. Grizzly feeding activity appeared to be related to fish density in the tributary. On August 2, peak fish density was estimated to be 0.5 fish per linear meter and no fresh evidence of grizzly feeding was apparent. —67— Summaries Table 20 and Figure 18 show comparisons among the two-year summaries of food items consumed in each of the economies. For the valley/plateau economy data, seven items contribute 98.47 percent of total importance value. Grasses and sedges are by far the most important item with an importance value percent of 82. Average ele­ vation of scat location is 7647 feet (2331 m.). For the mountain economy data, four items contribute 98.7 percent of total importance value. Western springbeauty is the most' important item with an importance value percent of 55.5. Average, elevation of scat location is 8969 feet (2734 m.). For the lake economy data, six items contribute 99.65 percent of total importance value. Grass and cut­ throat trout are the most important items with importance values of 39.2 and 38.5, respectively. Average elevation of scat location is 7803 feet (2378 m.). Of the 13 food items listed in Table 20, only three are listed under more than one economy. Grass and sedge occurs in the data of all three, elk thistle occurs in the valley/plateau and lake economy data and Umbelliferae roots appear in the.mountain and lake economy data. The data indicate substantial differences in diet compositions among economies. The valley/plateau economy apparently was grass- rodent oriented, the mountain economy springbeauty-grass-root oriented. TABLE 20. GRIZZLY BEAR KEY FOOD ITEM CONSUMPTION COMPARISON AMONG YELLOWSTONE NATIONAL ___________ PARK ECONOMIES. 19 7 S-1 9 7 4:__________________ Valley/Plateau Sample - 340 Mountain Sample - 170 Lake Sample - 105 Percent Importance Total Average Importance Percent Total Average Importance Percent Total Average Value Importance . Ele- Value Importance Ele- Value Importance EIe- Food Item Percent ‘ Value vation Food Item Percent Value vation Food Item Percent Value vation Graminae/Cyperaceae 82.00 Claytonia lanceolata 55:5 Graminae 39.20 TrifoViian repens 5.30 Graminae/Cyperaceae 36.8 Salmo olarki 38.50 Ciroiian foliosian 3.30 Umbelliderae (Roots) 4.2 Ciroium foliosim 15.50 Cervidae/Bovidae 2.80 Pinus albicaulis -2.2 Equisetian arvense 4.50 Rodentia 2.30 98.7 8969 Umbelliferae (Roots) 1.00 Melioa speotabilis Heraaleian lanaiian .95 (Corns) 2.00 Vaooiniian soopariion .77 98.47 7647 ‘ IM PO R ' VALLEY/PLATEAU MOUNTAIN LAKE ECONOMY ECONOMY ECONOMY Scat Sample - 340_________ Scat Sample - 170 Scat Sample - 105 100 96 92 88 84 80 76 72 68 64 60 56 52 48 44 40 36 32 28 24 20 16 12 8 4 0 S ! ■ I I SS m ot O r~~ m s a 'raccinium scopariwn e^lica spectdbilis (Corms) lodentia dervidae/Bovidae Circium foliosum frrifolium repens draminae/Cyperaceae inus albicaulis Ambelliferae (Roots) Araminae/Cyperaceae ^laytonia lanceolata Jeracleum lanatum Imbelliferae (Roots) isetum arvense Circium foliosum Salmo clarki Craminae IONv£) I Figure 18. Grizzly bear key food item consumption comparison among Yellowstone National Park economies, 1973-1974. -70- and the lake economy grass-trout oriented. Tables 21 and 22 present parkwide food consumption summaries for 1973 and 1974, respectively. Figure 19 shows a graphic comparison of these data. The diet each year was fairly constant. The most important items in 1973 were similar to those in 1974. Six items are common to the ranking of each year's eight top foods. Grasses and sedges, and western springbeauty rank first and second, respectively, in each year's data with comparable importance value percents. Cut­ throat trout has a significantly higher importance value percent for 1974 because of increased sampling in the lake economy. High selection for springbeauty is shown both years. Table 23 and Figure 19 show two-year parkwide summaries. Eight food items constituted 97.3 percent of the diet. Grasses and sedges were the ranking foods with an importance value percent of 78.5. Of the eight ranking food items, five were plant forms and represent 93.1 percent of total importance value. The remaining three items were fish and mammals and represent 4.3 percent of total importance value. Western springbeauty was the most highly selected of the major foods. TABLE 21. YELLOWSTONE NATIONAL PARK PARKWIDE GRIZZLY BEAR SUMMARY. 1973. FOOD CONSUMPTION Food Item • Use Elevation Frequency Occurrence Percent Percent Composition Per Item Percent of Diet Volume Importance Value Importance Value Percent Graminae/Cyperaceae Graminae 96% Stems Leaves Carex sp. 4% Heads 7908 64.2 53:0 34.00 21-8000 73.600 Claytonia lanceolata Trifolium repens Cireium foliosum Entire 8830 15.6 69.8 11.00 1.7000 5.800 S terns / Leaves / Heads 7590 16.2 63.5 10.30 1.7000 5.600 Sterns/Heads 7684 17.3 52.0 9.00 1.6000 5.400 ' Cervidae/Bovidae Cervus canadensis 90% Odoeoileus hemionus 5% Bison bison 5% 7522 11.7 54.1 ' 6.40 .7500 2.500 Rodentia Thomomys talpoides 50% Mierotus 50% 7582 12.2 45.0 5.10 .6200 2.100Pinus albieaulis Nuts 8500 7.8 61.6 4.80 .3700 1.300Melioa speetdbilis Conns 7829 7.8 53.7 . 4.20 .3300 1.100 Umbelliferae Perideridia gairdneri 54% - Roots Lomatium aous 46% - Roots ' 7646 7.3 41.2 3.00 .2200 .740 -LEquisetum arvense Stems 8000 6.1 53.6 3.30 .2000 . 670 H Salmo elarki Entire 7800 4.0 67.9 2.70 .1100 .370 1 Formicidae Mature/Larvae 8133 13.4 3.9 .53 .0700 .230Heraaleum lanatum S terns/Leaves 7908 3.3 49.2 1.70 .0600 .200Polygonium bistortoides Vaeoinium sooparium Entire 7811 5.0 17.2 .90 .0500 .170 Berries/Leaves 8080 2.8 35.6 ' 1.00 .0300 .100 Garbage 7800 1.1' ' 60.0 .67 .0070 .020 Vespidae Mature/Leaves 7600 1.1 18.2 .20 .0020 .007Russula sp. Caps/Stems 8450 .56 30.0 ■ .17 .0010 .003Ranunculus sp. S terns/Leaves/Flowers 8200 .56 10.0 .05 .0003 .00199.02 29.6203 99.911 TABLE 22. YELLOWSTONE NATIONAL PAEK PARKWIDE GRIZZLY BEAR FOOD CONSUMPTION ........ SUMMARY, 1974.____________________ __________________ Frequency Percent Percent Importance Occurrence Composition of Diet Importance Value Food Item________________________ Use________________________ Elevation Percent_____Per Item Volume_____Value_______Percent Graminae/Cyperaceae Graminae 95% Stems Leaves Carex sp. 5% Heads 7988 64.7 56.2 36.40 23.6000 79.2000 Claytonia lanaeolata Entire 9439 14.9 84.2 12.60 1.9000 6.3000Circium foliosum Stems/Heads 7902 15.8 - 48.2 7.60 1.2000 4.0000Salmo elarki Dmbelliferae Entire Perideridia gairdneri 54% - Roots 7794 11.5 56.4 6.50.' .7500 2.4000 Lomatitm aous 46% - Roots 8439 12.4 41.7 5.20 ' .6400 2.2000 Trifolium repens Rodentia Stems/Leaves/Heads Thomomys talpoides 71% Miorotus 26% 7905 ' 8.9 ■ 52.5 4.70 .4200 I.4000 Cervidae/Bovidae Marmota flaoiventris 3% Cervus canadensis 90% Odocoileus hemionus 7% 7804 8.7 35.1 3.10 .2700 .9000 Bison bison 3% 7664 6.7 58:3 3.90 .2600 .8600Melioa epeotdbilis Corms 7590 5.3 63.2 3.30 .1700' .5600 Vaooinium saoparium Berries/Leaves 7857 4.8 70.0 3.40 .1600 .5400Equisetum arvense Stems 7860 5.5 47.2 2.50 .1400 .4600Pinus albioaulis ‘ Nuts " 8361 3.9' 50.0 2.00 .0800 . 2600 Formicidae Mature/Larvae 8280 6.9 14.2 1.00 .0700 .2400 Eeraoleum lanatum Stems/Leaves 8162 3.0 46.1 1.40 .0400 .1300Russula sp. Caps/Stems 7935 3.0 25.4 . .76 .0200 .0700 Frageria virginiana Fruits 8028 2.3 18.4 .42 .0100 .0300Polygonium bistortoides Entire 7806 2.5 21.4 ' .54 .0100 .3400Taraxioum sp. Stems/Leaves/Heads 7960 1.2 54.0 .62 .0070 .0200Smilaoina sp. Rhizomes 8028 9.2 71.3 . 65 .0060 .0200 Garbage 7778 .68 76.6 .53 .0040 .0100Agroseris sp. Stems / Leaves / Heads 7292 .68 76.6 .53 .0040 .0100Ribes setosum Berries 8600 .46 100.0 .46 .0020 .0070 Ctilorophyceae Entire 7400 .46 75.0 .34 ' .0020 .0070 Forb - D/I Stems/Leaves 7050 .46 75.0 .34 .0020 .0070Mertensia oiliata Stems/Leaves 9325 .46 50.0 .23 .0010 . 0030Ranunculus sp. Stems/Leaves/Flowers 7735 .46, 40.0 .18 .0008 .0030Angelica sp. Stems/Leaves 7900 .46 27.5 .13 .0006 .0020 Vespidae Mature/Larvae 7800 .46 30.0 .14 .0006 .0020Aster integrifolius Stems/Leaves 7800 .23 95.0 .21 .0005 .0020Pastinaoa sativa Stems/Leaves 8900 .23 50.0 .11 .0003 .0010Ruppia peotinata Stems/Leaves 7700 .46 - 12.5 .06 .0003 .0010Anaoharis sp. Entire 7800 ' • .23 20.0 .0599.90 .000129.7712 .000399.9853 PARKWIDE 1973 Scat Sample - 179 PARKWIDE 1974 Scat Sample - 436 PARKWIDE 1973-1974 Scat Sample - 615 100 96 92 88 84 80 *2 76 72 I S 68 I 64 E £ E S 60 E W 56 E E M 52 E ^ 48 F> i S " " F P 40 E £ O 36 I I M 32 = 28 E 24 E 20 E 16 - 12 E 8 - 4 0 I Iff m ! j Pinua Rodenti I Iica spectabili8(.Corms) albicaulis •dent a 6ervidae/Bovidae fcireium foliosum lPrifolium repens dlaytonia lanoeolata Sraminae/Cyperaceae *3* 1 Whole Food Material Corresponding Scat Material Principal Proximate Nutrient- Content • Calculated Gross Kcals Apparent Concen- Digested tration Kcals Factor Apparent Digestibility Percent Item: Claytonia lanoeolata- 100% Economy: Mountain Condition: Pre-flowering, ;Succulent, Entire Protein 30.0 168.0 112.0 0 67.0 Ether- Extract 2.8 26.0 Unknown 2.0 Unknown Nitrogen-free Extract Starch* 11.3 ■ 48.6 45.2 0 93.0 Non-Starch 36.9 158.7 Unknown Unknown(I.005) Unknown Total 401.3 •157.2 Per Gram 4.0 1.6 40.0 Item: Claytonia lanceolata- 100% Economy: Mountain Condition: Pre-flowering, Succulent, Above Ground Protein 39.0 218.4 . 150.6 0 69.0 Ether Extract 3.6 33.5 Unknown 1.9 Unknown Nitrogen-free Extract 38.1 163.8 Unknown Unknown(1.1) Unknown Total 415.7 150.6 Per Gram 4.2 1.5 . 35.7 Item: Claytonia lanceolata- 100% Economy: Mountain Condition: Flowering, Succulent, Above Ground Protein 20.7 115.9 57.1 0 49.3 Ether Extract 5.4 50.2 Unknown 1.2 Unknown Nitrogen-free Extract 50.8 218.4 Unknown(49.4)** 0 Unknown(22.6) Total 384.5 57.1(106.5) Per Gram 3.8 .6(1.1) . 15.8(28.9) . Averaged Values Protein 29.9 167.4 106.6 0 61.8 Ether Extract 3.9 36.6 Unknown 1.7 Unknown Nitrogen-free Extract Starch 3.8 16.2 15.i 0 93.0 Non-Starch 41.9 ■ 180.3 Unknown(16.4) 0 Unknown ( 7.5) Total 400.5 121.6(138.0) Per Gram 4.0 1.2(1.4) 30.5(35.0) *Starch values determined by direct, starch-specific analysis. ♦^Nitrogen-free extract values are determined by difference and are subject to possible error. Results in this category are recorded as Unknown. Numerical values are shown -in this, category and elsewhere in parentheses to show the result if the values are accepted. -80- digestibility per gram of gross energy of the three samples are comparable. This suggests an additional example of digestive flexi­ bility providing constant energy intake regardless of changes in diet nutrient levels. Table 26 shows white clover food quality and digestibility. None • I of the nutrients studied which were present in the whole food concen­ trated in the scats. This suggests that these nutrients were all probably readily digestible. Calculated energy averaged 3.6 kcals/gram and apparent digestibility per gram of gross energy averaged 13.9 per­ cent (21.9 percent if nitrogen-free extract values are accepted). Table 27 presents cutthroat trout food quality and digestibility. Averaged values for protein and ether extract content and digestibility are substantially higher than those recorded for succulent herbs (Tables 24-26). Ether extract of fish appears to.consist primarily of triacylglycerols which are the major components of storage fats in plant and animal cells; ether extract of the aerial portions of succulent herbs probably is made up primarily of phospholipids from cell membranes serving primarily as structural elements (Lehninger, 1973). Storage fats are more digestible than the waxy structural elements. Table 28 shows the food quality and digestibility of Umbelliferae roots, melica grass conns and western springbeauty corms. The roots of biscuitroot, yampa (.Pevideridia gairdneri) and the corms of melica TABLE 26. GRIZZLY BEAR FOOD QUALITY AMD DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS. Item: TxyLfoliim repens Consumption Rank: 4 Importance Value Percent: 2.4 Whole Food Material Corresponding Scat Material Calculated Apparent Concen- Apparent Principal Proximate Gross Digested tration Digestibility Nutrient Content Reals Reals Factor Percent Item: Trifoliimrepens-- 100% Economy: Valley/Plateau Condition: Flowering, Succulent Protein 22.0 123.2 45.9 0 37.3 Ether Extract 3.0 27.9 11.2 ■ 0 40.1 Nitrogen-free Extract 47.5 204.3 Unknown(14.7)* 0 Unknown(7.2) Total 355.4 57.1(71.8) Per Gram 3.6 • 57(. 72) 15.8(20.0) Item: Trifoliim repens -■ 100% Economy: Valley/Plateau Condition: Flowering, Succulent Protein. 23.1 129.4 39.2 0 30.3 Ether Extract 2.8 26.0 3.7 0 14.2 Nitrogen-free Extract 47.2 202.9 Unknown(43.8) 0 Unknown(2I.6) Total 358.3 42.9(86.7) Per Gram 3.6 .43(.87) 11.9(24.4) Averaged Values Protein 22.5 126.3 42.6 0 33.8 Ether Extract 2.9 26.9 7.5 0 27.1 Nitrogen-free Extract 47.4 203.6 Unknown(29.3) 0 Unknown(I4.4) Total 356.8 50.0(79.3) Per Gram 3.6 .50(.79) 13.9(21.9) *Nitrogen-free extract values are determined by difference and are subject to possible error. Results in this category are recorded as Unknown. Numerical values are shown in this category and elsewhere in parentheses to show the result if the values are accepted. -82- sPYwM R!a yV.AAbr k-BVaTpp": #^Bb.vr Bx" ".y-fv.k.b.vr Bf .x".IBv-" kr IF-E.IBb BxBbrf.fa Item: Salmo clapki Consumption Rank: 5 Importance Value Percent: 1.7 Whole Food Material Corresponding Scat Material Calculated Apparent Concen- Apparent Principal Proximate Gross Digested tration Digestibility Nutrient Content Reals Reals Factor Percent Item: Salmo clarki -100% Economy: .Lake Condition; Without Eggs Protein 78.6 440.2 352.3 0 80.0 Ether Extract 8.2 76.3 63.3 0 82.9 Nitrogen-free Extract 0 Total 516.5 415.6 Per Gram 5.2 4.2 80.8 Item: Salmo olarki -100% Economy: Lake Condition: With Eggs Protein 69.7 390.3 233.5 0 59.8 Ether Extract 23.0 213.9 199.0 0 93.0 Nitrogen-free Extract ■ 1.0 4.3 . Unknown 6.3 Unknown Total 608.5 432.5 .Per Gram 6.1 4.3 ' 70.5 Item: Salmo olarki - Eggs Economy: Lake . Condition: Eggs Ripe Protein 68.5 383.6 279.4 0 72.8 Ether Extract 14.6 135.8 108.9 0 80.2 Nitrogen-free Extract 12.0 51.6 Unknown(12.5)A 0 Unknown C24.2) Total - 571.0 388.3(400.8) Per Gram 5.7 3.9(4.0) ' 68.4(70.3) Averaged Values Protein 72.3 404.7 288.4 0 70.8 Ether Extract 15.3 142.0 123.7 0 85.3 Nitrogen-free Extract 4.3 18.5 Unknown(4.2) 2.1 Unknown(8.I) Total 565.2 412.1(416.3) Per Gram 5.7 4.1(4.2) 73.2(73.7) *Nitrogen-free extract values are determined by difference and are subject to possible error. Results in this category are recorded as Unknown. Numerical values.are shown in this category and elsewhere in parentheses to show the result if the values are accepted. - 83- TAflLE 28. GRIZZLY BEAR FOOD QUALITY AMD DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS. Item; Umbelliferae (with other starch sources for comparison) Consumption Rank; 6 Importance Value Percent; 1.7___________________________________ Whole Food Material Corresponding Scat Material Calculated Apparent Concen- Apparent Principal Proximate Gross ' Digested tration Digestibility Nutrient Content Reals Reals Factor Percent Item; Lomatium aous (Umbelliferae) - Roots - 100% Economy; Mountain Condition; Flowering Protein 6.0 33.6 11.8 0 35.0 Ether Extract 1.4 13.0 5.6 0 43.0 Nitrogen-free Extract Starch* 34.3 147.5- 143.6 0 97.4 Non-Starch 43.3 186.2 Unknown(77.0)** 0 Unknown(41.5) Total 380.3 161.0(238.0) Per Gram •3.8 I.6(2.4) 42.1(63.1) Item; Perideridia gairdneri (Umbelliferae) - Roots - 100% Economy: Mountain Condition; Flowering Protein 4.8 26.9 4.5 0 16.7 Ether Extract .5 4.7 Unknown 2.0 Unknown Nitrogen-free Extract Starch 40.1 172.4 99.3 0 57.6 Non-Starch 47.5 • 204.3 Unknown(21.I) 0 Unknown(10.3) Total 408.3 103.8(124.9) Per Gram 4.1 I.0(1.2) 24.4(29.3) Item: Melica epectabilis - Corms - 100% Economy: Valley/Plateau Condition: Flowering Protein 6.1 '34.2 13.5 0 39.5 Ether Extract .4 3.7 1.8 0 .48.6 Nitrogen-free Extract Starch 10.4 ■ 44.7 30.1 0 67.3 Non-Starch 78.3 336.7 UnknownQQ. I) 0 Unknown(8.9) Total 419.3 45.4(75.5) Per Gram 4.2 •45(.76) 10.7(18.1) Item: Claytonia lanoeolata - Corms - 100% Economy; Mountain Condition: Pre-flowering , Succulent Protein 12.1 67.8 . Unknown Unknown Unknown Ether Extract 1.6 14.9 Unknown Unknown Unknown Nitrogen-free Extract Starch 11.3 48.6 45.2 0 93.0 Non-Starch 55.4 238.2 Unknown Unknown Unknown Total 369.5 Unknown Per Gram 3.7 Unknown Unknown Averaged Values . Protein 7.3 40.6 9.9 0 . 30.4 Ether Extract 1.0 9.1 2.5 0 30.5 Nitrogen-free Extract Starch 24.0 103.3 79.6 0 78.8 Non-Starch 56.1 274.2 Unknown(42.7) 0 Unknown(20.2) Total 394.4 103.4(146.1) Per Gram 3.9 I.0(1.5) 25.7(36.8) *Starch values determined by direct, starch-specific analysis. ^Nitrogen-free extract values are determined by.difference and are subject to possible error. Results in this category are recorded as Unknown. Numerical values are shown in this category and elsewhere in parentheses to show the result if the values are accepted. -84- grass were collected at about the same stage of maturity. Starch content of the corms was much lower than that of the roots; digesti­ bility of starch in corms was comparable with that in roots. The lower starch content of melica corms is reflected in the 10.7 percent digestibility per gram of gross energy. This compares with 42.1 per­ cent for biscuitroot and 24.4 percent for yampa. Two other indicators identified melica corms as having lower food value than biscuitroot and yampa: I) after having been ground in a Wiley Mill, melica corms retained a course, granulated appearance while both biscuitroot and yampa, after the same treatment, had the appearance of very fine flour; 2) melica corms in scats appeared nearly intact, while roots of biscuit root and yampa in scats were greatly altered. The data show that western springbeauty corns are low (11.3 percent) in starch in pre­ flowering condition. After flowering, springbeauty corms are full, fleshy and starch levels are probably much higher than 11.3 percent due to replenishment of carbohydrate stores depleted during growth initiation (Klein, 1965). Food quality and digestibility of elk tissue and pine nuts are presented respectively in Tables 29 and 30. The high digestibility of elk protein and storage fat is apparent in Table 29. In Table 30, the high energy and digestibility of storage fats in pine nuts are apparent. Item: Cervidae/Bovidae Consumption Rank: 8 ___________ Importance Value Percent: 1.3________ '_________ _______________ TABLE 29. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS. Whole- Food Material ______Corresponding Scat Material Calculated Apparent Concen- Apparent Principal Proximate Gross Digested tration Digestibility Nutrient Content Kcals Kcals Factor Percent Item: Cervus canadensis Economy: Valley/Plateau Condition: Lean Tissue - 100% Protein 88.20 493.90 414.4 0 83.9 Ether Extract 6.70 62.30 54.4 0 87.3 Nitrogen-free Extract .11 .47 Unknown 161.8 Unknown Total 556.70 468.8 Per Gram 5.6 4.7 83.9 Item: Cervus canadensis Economy: Valley/Plateau Condition: Lean Tissue Protein 88.20 493.90 404.8 0 81.9 . Ether Extract 6.70 62.30 39.0 0 62.6 Nitrogen-free Extract .11 .47 Unknown 111.8 Unknown Total 556.70 443.8 Per Gram 5.6 4.4 78.6 Averaged Values Protein 88.20 493.90 409.6 0 82.9 Ether Extract 6.70 62.30 46.7 0 74.9 Nitrogen-free Extract .11 .47 Unknown 136.8 Unknown Total 556.70 456.3 ' Per Gram 5.6 4.6 81.3 Item: Pinus attri-caulis Consumption Rank: 11 _____Importance Value Percent: .48 ____ TABLE 30. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS. Whole Food Material Corresponding Scat Material Calculated Apparent Concen- Apparent Principal Proximate Gross Digested tration Digestibility Nutrient Content Kcals Reals Factor Percent Item: Finns albicaulis - Nuts - 100% Economy: Mountain Condition: Mature Protein. 11.9 66.6 29.0 0. 42.0 Ether Extract 21.8 202.8 193.5 0 ■ 95.4 Nitrogen-free Extract 27.2 116.9 Unknown(14.1)* 0 Unknown(I2.I) Total 386.3 221.5(235.6) Per Gram 3.9 2.2(2.4) 56.4(61.5) Item: Finns albicaulis - Nuts - 100% Economy: Mountain Condition: Mature Protein 11.9 66.6 34.1 0 ' 51.2 Ether Extract 21.8 202.8 126.5 0 62.4 Nitrogen-free Extract 27.2 116.9 Unknown(6.8) 0 Unknown(5.8) Total 386.3 160.6(167.4) Per Gram 3.9 1.6(1.7) 41.0(43.5) Averaged Values — - ----------------- n Protein 11.9 66; 6 31.1 0 46.6 Ether Extract 21.8 202.8 160.0 0 78.9 Nitrogen-free Extract 27.2 116.9 Unknown(10.5) 0 Unknown(9.0) Total 386.3 191.1(201.5) Per Gram . 3.9 I.9(2.I) 48.7(52.5) *Nitrogen-free extract values are determined by difference and are subject to possible error. Results in this category are recorded as Unknown. Numerical values are shown in this category and elsewhere in parentheses to show the result if the values are accepted. -87- Table 31 presents, the food quality and digestibility of horse­ tail and mushroom. Mushroom, ranking 16th out of 32 food items con­ sumed,. was 23.3 percent protein and contained 3.9 kcals/gram of calculated energy. Protein was 66.5 percent digestible. Ether extract, primarily storage fat (Jackson, 1975) was 46.5 percent digestible. The food quality of seven additional foods is shown in Tables 32-34. Food quality of ripe berries and fruits is shown in Table 33. Individual items averaged 8.9 percent protein, 6.2 percent ether extract and 66.0 percent nitrogen-free extract. . Calculated energy averaged 3.9 kcals/gram. In Table 34 the average value for protein content of cowparsnip (Heraeleum lanatum) is 5.7 percent. Klein (1965) reported protein values of 36.1 and 20.6,percent for the same species in southeast Alaska. Table 35 provides a summary of grizzly bear food quality and digestibility. Items are ranked by their digestibility. Animal material has the highest digestibility and the highest calculated energy content. A direct relationship between food energy and digestibility is apparent: the higher the energy of the food, the greater its digestibility. Differential digestibility of.plant and animal foods is also apparent. TABLE 31. GRIZZLY BEAR FOOD QUALITY AND DIGESTIBILITY AS INDICATED BY CHEMICAL ANALYSIS. Whole Food Material Corresponding Scat Material Calculated Apparent ' Concen- Apparent Principal Proximate Gross Digested tration Digestibility Nutrient Content Reals Reals Factor Percent Item: Equisetum arvense Consumption Rank: 10 Importance Value Percent: 51 Item: Equisetum arvense Economy: Lake Condition: Sterile Shoots Protein 15.0 84.0 26.3 .0 31.3 Ether Extract 3.7 34.4 10.2 0 29.6 Nitrogen-free Extract 40.6 174.6 Unknown 1.1 Unknown Total 293.0 36.5 Per Gram 2.9 .37 12.8 Item: Russula sp. - Consumption Rank: 16 Importance Value Percent: 03 Item: Russula sp. Economy: Valley/Plateau Condition: Mature ■ Protein 23.3 130.5 86.8 0 66.5 Ether Extract 2.8 26.0 ■ 12.1 0 46.5 Nitrogen-free Extract 53.7 230.9 Unknown(31.4)* 0 Unknown(I3.6) Total 387.4 98.9(130.3) . Per Gram 3.9 .98(1.3) 25.0(33.0) *Nitrogen-free extract values are determined by difference and are subject to possible error. Results in this category are recorded as Unknown. Numerical values are shown in this category and elsewhere in parentheses to show the result if the values are accepted. -89- TABLE 32. GRIZZLY BEAR FOOD QUALITY AS INDICATED BY CHEMICAL ANALYSIS. Whole Food Material Calculated Principal Proximate Gross Nutrient Content Reals Item: Ciraium foliosum Consumption Rank: 3 Importance Value Percent: 4 .4 Species: . Ciraium foliosum - 100% Economy: Valley/PlateaiLI Condition: Pre-flowering, Succulent Protein 9.0 50.4 Ether Extract 1.8 16.7 Nitrogen-free Extract 52.3 224.9 Total 292.0 Per Gram 2.9 Item.: Rodentia Consumption Rank: 7 Importance Value Percent : 1.3 Species: Miorotus sp. - 100% Economy: Valley/Plateau Condition: Mature Protein 69.8 39.0.9 Ether Extract 8.7 80.9 Nitrogen-free Extract 3.7 15.9 Total 487.7 Per Gram 4.9 Item: Polygonum bistortoides Consumption Rank: . 15 Importance Value Percent: .07 Species: Polygonum bistortoides, Roots - 100% Economy: Mountain Condition: Flowering, Succulent Protein • 11.0 61.6 Ether Extract 1.2 11.2 Nitrogen-free Extract 71.4 307.0 Total 379.8 Per Gram 3.8 -90- TABLE 33. GRIZZLY BEAR FOOD QUALITY AS INDICATED BY CHEMICAL ANALYSIS. Item: Vaeotni-Uin saoparium (with other sugar sources for comparison) Consumption Rank: 12 Importance Value Percent: .37 Whole Food Material Principal Nutrient Proximate Content Calculated Gross Reals Species: Vaacinium seoparium - 100% Economy: Valley/Plateau Condition: Ripe Berries Protein 9.7 54.3 Ether Extract 6.1 56.7 Nitrogen-free Extract 67.8 291.5 Total 402.5 Per Gram 4.0 Species: Ribes setosum - Economy: Mountain 100% Condition: Ripe Berries Protein ' 7.2 40.3 ' Ether Extract 5.2 48.4 Nitrogen-free Extract 66.7 286.8 Total 375.5 Per Gram 3.8 Species : Fvagaxia vivginiana - 100% Economy: Valley/Plateau Condition: Ripe Fruits Protein 9.8 54.9 Ether Extract 7.5 69.8 Nitrogen-free Extract 63.6 273,5 Total 398.2 Per Gram . 4.0 Averaged Values Protein 8.9 49.8 Ether Extract 6.2 57.7 Nitrogen-free Extract 66.0 283.8 Total 391.3 Per Gram 3.9 -91- TABLE 34. GRIZZLY BEAR FOOD QUALITY AS INDICATED BY CHEMICAL ANALYSIS. Item: Eerdoleum lanatvm Composition Rank: 14 Importance Value,Percent: .14' Whole Food Material Calculated Principal Proximate Gross Nutrient Content Kcals Species: Heraotevm lanatvm - 100% Economy: Valley/Plateau Condition: Pre-flowering , Succulent Protein , 7.3 40.9 Ether Extract 2.2 20.5 Nitrogen-free Extract 44.5 191.4 Total 252.8 Per Gram 2.5 Species: Heraolevm lanatvm - 100% Economy:■ Valley/Plateau Condition: Post-flowering, Succulent Protein 4.1 23.0 Ether Extract 1.5 14.0 Nitrogen-free Extract 43.5 187.1 Total 224.1 Per Gram 2.2 Averaged Values Protein 5.7 31.9 Ether Extract 1.9 17.7 Nitrogen-free Extract 44.0 189.7 .Total 239.3 Per Gram 2.4 TABLE 35. SUMMARY: GRIZZLY BEAR FOOD ITEM QUALITY AND DIGESTIBILITY. Food Item Apparent Digested Reals/Gram Apparent Digestibility Percent Calculated Reals/Gram Whole Food Consumptive Use Rank Cervidae/Bovidae 4.6 81. f 5.6 8 Salmo clarki 4.1 (4.2)* 73.-2: (73.7 . 5.7 5 Sinus albioaulis (Nuts.) 1.9 (2.1) 48.? (52.5) 3.9 11 Claytonia lanoeolata 1.2 (1.4) 30.5 (35.0) 4.0 2 Umbelliferae (Roots) plus corns of Melioa speotabilis and Claytonia lanoeolata 1.0 (1.5) 25.7 (36.8) 3.9 6 Russula sp. .98 (1.3) 25.0 (33.0) 3.9 16 Graminae/Cyperaceae .52 (.73) 15.8 (21.5) 3.3 I Trifolium repens .50 (.79) 13.9 (21.9) 3.6 4 Equisetum'arvense .37 ' 12.8 2.9 10 *Results in parentheses include nitrogen-free extract values. 93- Nutrient Intake and Nutritive Values The five principal nutrient materials contributing to total grizzly energy intake are listed in Table 36 with their sources and estimated digestibilities. These data were derived from data in Tables 24-34. Protein from succulent herbs is estimated to be 42.8 percent digestible, protein and fat from animal material is estimated to be 78.1 percent digestible, fat and protein from whitebark pine nuts is estimated to be 73.6 percent digestible, starch from herbs is estimated to be 78.8 percent digestible, and the digestibility of sugar from berries and fruits of shrubs and herbs is undetermined. Table 37 and Figures 20 and 21 present 1974 seasonal grizzly nutrient intake and nutritive values for the valley/plateau economy. Figure 20 shows nutrient importance values which equate to quanti­ tative nutrient intake, Figure 21 shows nutritive value percents which are nutrient importance values modified by their respective digesti­ bilities. Nutritive value percents represent estimates of each nutrient's contribution towards the grizzly's energy intake. All data show that animal protein and fat were the principal nutrients during much of the pre-growing season. They were replaced as the primary nutrients by protein from succulent herbs towards the end of the pre­ growing season. Protein from succulent herbs remained the most im- . portant nutrient throughout the rest of the year, but declined somewhat -94- TABLE 36. PRINCIPAL GRIZZLY BEAR FOOD NUTRIENTS AND DIGESTIBILITIES. Principal Nutrient Source* Apparent Digestibility Percent** Protein Succulent Herbs 42.8 Protein, Fat Animal 78.1 Fat, Protein Pinus albioaulis 73.6 Starch Herbs 78.8 Sugar Shrubs, Herbs Undetermined *Succulent Herbs: Graminae, Cyperaceae, Claytonia Ianceolata3 Ciraiwn foliosim3 Trifoliwn repens3 Equisetwn arvense3 etc. ■ Animal: Cervidae, Bovidae, Salmo Clarki3 Rodentia, Formicidae, Vespidae. Herbs - starch: Perideridia gairdneri3 Lomatiwn cous3 Claytonia Ianaeolata3 Polygonum bistortoides3 Melioa Speaiabilis3 Smilaaina sp. Shrubs and Herbs - sugar: Vaocinium Saoparium3 Ribes Setosum3 - Frag aria virginiana. **Values are weighted averages. TABLE 37. 1974 SEASONAL GRIZZLY BEAR NUTRIENT INTAKE AND NUTRITIVE VALUES - VALLEY/PLATEAU ECONOMY. Month Scat Sample Principal Nutrients Source Frequency of Occurrence Percent Percent of Diet Volume Importance Value Importance Value Percent Apparent, Digestibility Percent Nutritive Value Index Percent April 7 .Protein Succulent Herbs 28.5 17.0 ‘ 4.8 6.3 42.8 2.7 3.6 Protein, Fat Animal 85.7 82.8 70.9 93.6 78.1 73.1 96.4 • Total 99.8 75.7 - 99.9 75.8 100.0 May 31 Protein Succulent Herbs 67.7 49.9 33.7 57.4 42.8 24.6 42.6 Protein, Fat Animal 61.2 32.9 20.1 34.3 78.1 26.7 46.2 Starch Herbs 29.0 16.9 4.9 8.3 78.8 6.5 11.3 Total 99.7. 58.7 99.9 57.8 100.1 June ' 23 Protein Succulent Herbs 95.6 75.9 72.50 93.50 42.8 40.0 88.7 Protein,-Fat Animal 26.0 17.4 4.50 1 5.80 78.1 4.5 10.0 Starch Herbs 8.7 6.5 .56 .72 78.8 .6 1.3 Total 99.8 77.56 100.02 45.1 100.0 July 35 Protein Succulent Herbs 97.1 86.1 69.5 93.90 42.8 40.20 89.4 Protein, Fat Animal 48.6 7.8 3.8 5.10 78.-1 4.00 8.9. Starch Herbs 11.4 6.1 .7 .95 78.8 .75 1.7 Total 100.0 74.0 99.95 44.95 100.0 August 42 Protein Succulent Herbs 88.1 82.30 72.500 94.900 42.8 40.600 96.90 Protein,- Fat Animal 14.3 1.30 .180 .230 78.1 .200 .50 Fat,- Protein Pinus albicaulis . 2.4 -.24 .006 .007 73.6 .005 .01 Starch Herbs 28.6 3.90 1.100 1.400 78:8" 1.100 2.60 Sugar Shrubs, Herbs 21.4 12.10 2.600 3.400 Unknown ——— — Total 99.84 76.386 99.937 41.905 100.01 September 50 Protein Succulent Herbs 80.0 59.3 47.40 86.90 42.8 37.20 89.50 Protein, Fat Animal 6.0 1.7 .10 .18 78.1 .14 .34 Fat, Protein Pinus albicaulis 8.0 5.7 .46 .84 73.6 .62 1.50 Starch * Herbs 20,0 12.3 2.50 4.60 78.8 3.62 8.71 Sugar Shrubs, Herbs 26.0 15.7 4.10 7.50 Unknown — —— Total 94.7 54.56 100.02 41.58 100.05 October 32 Protein Succulent Herbs 78.1 55.8 43.60 ' 72.60 42.8 31.1 59.1 Protein, Fat Animal 43.7 20.5 8.90 14.80 78.1 11.6 22.1 Starch Herbs 34.4 21.8 7.50. 12.50 78.8 9.9 18.8 Sugar Shrubs, Herbs 3.1 1.6 .05 .08 Unknown Total 99.7 60.05 99.98 52.6 100.0 Annual Summary Protein Succulent Herbs 80.0 67.3 53.80 88.10 42.8 . 37.70 81.7 Protein, Fat Animal 32.3 13.4 4.30 7.00 78.1 5.50 11.9 Fat, Protein Pinus albicaulis 2.2 1.3 .03 .05 73.6 .04 • i . Starch Herbs 21.8 10.7 2.30 3.70 78.8 2.90 6.3 Sugar Shrubs, Herbs 10.5 6.1 98.8 . 64 61.07 1.10 99.95 Unknown 46.14 100.0Total - 96- — hO _