1 Environments of Colorado Mammals are a familiar and important component of understand the distribution and abundance of mammals Earth’s biodiversity. Biodiversity is the kinds of organisms and the details of their daily lives we must fi rst understand and their genetic and ecological relationships—an evolu- the resource base, the mosaic of Colorado’s environments tionary and ecological phenomenon in space and time (E. in space and time. Wilson 1992). The mammalian fauna of Colorado is a fas- cinating piece of that whole. To understand the diversity of mammals we need to have a perspective of the ecosphere more generally. Such a perspective is the purpose of this Geography chapter, with a focus on environments of Colorado. Colorado is known for its scenic beauty—from majes- From the standpoint of political geography, Colorado is tic mountain peaks and rushing white rivers tumbling simple: it is roughly rectangular (if we neglect some minor down dark canyons, to red-rock deserts and ceaselessly old surveyors’ errors and the fact that Earth is spherical), shifting sand dunes, to the expansive sweep of the short- measuring approximately 607 km by 444 km (377 by 276 grass prairie. Grandeur is wherever we stop to appreciate mi.) and encompassing some 270,000 km2 (104,000 sq. mi.). it, at every scale, from canyons carved in crystalline rocks Colorado lies between approximately 102° and 109° west 2 billion years old, to bold peaks sculpted by the glaciers longitude and 37° and 41° north latitude, and is subdi- of the last Ice Age, to last night’s furtive trail of a mouse vided into 64 counties (Map 1-1). A few of the counties are across the snow. We humans appreciate ecological patterns nearly natural, ecological units (e.g., Jackson, Grand, and and processes as beautiful or intriguing; to the rest of the Park counties encompass North, Middle, and South parks, mammalian fauna the evolving landscape represents oppor- respectively), but most are simply political artifacts with tunity, and native mammals respond accordingly. Thus, to rectilinear boundaries. 1 Contents Introduction xi CHAPTER 1—Environments of Colorado 1 CHAPTER 2—Mammals in General 31 • Geography 1 • Mammalian Origins 31 • Geology and Landforms 2 • Mammalian Characteristics 32 • Watersheds 5 Jaw-Ear Complex 32 Teeth 32 • Climates and Climate Change 5 Hair 34 • Soils 9 Mammary Glands 36 • Humans in the Landscape 10 Heart and Circulation 36 • Ecosystems of Colorado 10 Brain 36 Grasslands 14 Reproduction 37 Semidesert Shrublands 20 Development 38 Piñon-Juniper Woodland 21 Skeleton 39 Montane Shrublands 22 • The Diversity of Mammals 43 Montane Woodlands and Forests 23 • Orders of Mammals 44 Subalpine Forest 24 Alpine Tundra 26 • Key to the Orders of Mammals in Colorado 44 Riparian and Wetland Systems 27 • Biogeography: Patterns of Mammalian Distribution 28 v CONTENTS CHAPTER 3—History of Mammals and CHAPTER 7—Order Primates: Monkeys, Apes, Mammalogy in Colorado 45 and Kin 103 • Mammalian Evolution in Colorado: The Record • Family Hominidae—Humans and Kin 104 in the Rocks 47 Humankind—Homo sapiens 104 • Development of the Modern Fauna 53 • History of Coloradan Mammalogy 57 CHAPTER 8—Order Rodentia: Rodents 107 Millennia of Subsistence 58 • Key to the Families of the Order Rodentia in The Nineteenth Century: Exploration and Colorado 109 Exploitation 59 • Family Sciuridae—Squirrels 109 Scientific Study of Coloradan Mammals 61 Academic Mammalogy 62 • Key to the Species of the Family Sciuridae in Colorado 110 Cliff Chipmunk—Neotamias dorsalis 111 CHAPTER 4—People and Wildlife: Stewardship Least Chipmunk—Neotamias minimus 113 of Wild Mammals in Colorado 65 Colorado Chipmunk—Neotamias quadrivittatus 114 • Recreational Values 66 Hopi Chipmunk—Neotamias rufus 116 Hunting and Trapping 73 Uinta Chipmunk—Neotamias umbrinus 118 • Aesthetic Values 76 Yellow-bellied Marmot—Marmota flaviventris 120 • Scientific Values 77 White-tailed Antelope Squirrel— Ammospermophilus leucurus 123 • Educational Values 77 Rock Squirrel—Otospermophilus variegatus 125 • Urban Wildlife Values 78 Golden-mantled Ground Squirrel— • Unintended Human Impacts on Wildlife 79 Callospermophilus lateralis 127 • Wildlife and Public Health 80 Thirteen-lined Ground Squirrel—Ictidomys Rabies 80 tridecemlineatus 129 Plague 81 Franklin’s Ground Squirrel—Poliocitellus Tularemia 82 franklinii* 131 Other Tick-borne Diseases 82 Spotted Ground Squirrel—Xerospermophilus spilosoma 132 Hantavirus 83 Wyoming Ground Squirrel—Urocitellus elegans 134 • Problem Mammals 83 Gunnison’s Prairie Dog—Cynomys gunnisoni 137 • Futures of Wildlife Management: The Human White-tailed Prairie Dog—Cynomys leucurus 140 Dimension 85 Black-tailed Prairie Dog—Cynomys ludovicianus 143 Conflicting Views 87 Abert’s Squirrel—Sciurus aberti 149 Wildlife Ethics 88 Fox Squirrel—Sciurus niger 152 Pine Squirrel, Chickaree, or “Red Squirrel”— CHAPTER 5—Order Didelphimorphia: Tamiasciurus hudsonicus 155 Opossums and Kin 91 Northern Flying Squirrel—Glaucomys sabrinus* 157 • Family Didelphidae—Opossums 92 • Family Castoridae—Beavers 158 Virginia Opossum—Didelphis virginiana 92 American Beaver—Castor canadensis 158 • Family Heteromyidae—Pocket Mice and Kin 162 CHAPTER 6—Order Cingulata: Armadillos 97 • Family Dasypodidae—Armadillos 98 Nine-banded Armadillo—Dasypus novemcinctus 98 * Species of possible occurrence in Colorado. vi CONTENTS • Key to the Species of the Family Heteromyidae Subfamily Neotominae: New World Rats and in Colorado 163 Mice 215 Olive-backed Pocket Mouse—Perognathus • Key to the Species of the Subfamily Neotominae fasciatus 164 Known or Expected to Occur in Colorado 215 Plains Pocket Mouse—Perognathus flavescens 166 Western Harvest Mouse—Reithrodontomys Silky Pocket Mouse—Perognathus flavus 168 megalotis 217 Great Basin Pocket Mouse—Perognathus parvus 170 Plains Harvest Mouse—Reithrodontomys Hispid Pocket Mouse—Chaetodipus hispidus 171 montanus 218 Ord’s Kangaroo Rat—Dipodomys ordii 173 Brush Mouse—Peromyscus boylii 220 Banner-tailed Kangaroo Rat— Canyon Mouse—Peromyscus crinitus 222 Dipodomys spectabilis* 176 White-footed Mouse—Peromyscus leucopus 223 Deer Mouse—Peromyscus maniculatus 225 • Family Geomyidae—Pocket Gophers 177 Northern Rock Mouse—Peromyscus nasutus 229 • Key to the Species of the Family Geomyidae in Piñon Mouse—Peromyscus truei 230 Colorado 177 Northern Grasshopper Mouse—Onychomys Botta’s Pocket Gopher—Thomomys bottae 178 leucogaster 232 Northern Pocket Gopher—Thomomys talpoides 180 Western White-throated Woodrat— Plains Pocket Gopher—Geomys bursarius 183 Neotoma albigula 234 Bushy-tailed Woodrat—Neotoma cinerea 236 Yellow-faced Pocket Gopher—Cratogeomys Eastern Woodrat—Neotoma floridana 239 castanops 186 Desert Woodrat—Neotoma lepida 241 • Family Dipodidae—Jumping Mice and Kin 187 Eastern White-throated Woodrat— • Key to the Species of the Family Dipodidae in Neotoma leucodon 243 Colorado 188 Mexican Woodrat—Neotoma mexicana 244 Meadow Jumping Mouse—Zapus hudsonius 188 Southern Plains Woodrat—Neotoma micropus 246 Western Jumping Mouse—Zapus princeps 191 Stephens’ Woodrat—Neotoma stephensi* 248 • Family Cricetidae—Native Rats, Mice, and Voles 193 Subfamily Sigmodontinae 248 • Key to Subfamilies of Cricetidae in Colorado 194 Hispid Cotton Rat—Sigmodon hispidus 249 Subfamily Arvicolinae: Voles, Meadow Mice, • Family Muridae—Old World Rats and Mice 251 and Muskrat 194 • Key to the Species of the Subfamily Murinae • Key to the Species of the Subfamily Arvicolinae Known or Expected to Occur in Colorado 251 in Colorado 195 Norway Rat—Rattus norvegicus 251 Southern Red-backed Vole—Myodes gapperi 195 House Mouse—Mus musculus 253 Western Heather Vole—Phenacomys intermedius 198 • Family Erethizontidae—New World Porcupines 254 Long-tailed Vole—Microtus longicaudus 200 North American Porcupine—Erethizon dorsatum 255 Mogollon Vole—Microtus mogollonensis 201 Montane Vole—Microtus montanus 203 CHAPTER 9—Order Lagomorpha: Pikas, Prairie Vole—Microtus ochrogaster 206 Rabbits, and Hares 259 Meadow Vole—Microtus pennsylvanicus 208 Sagebrush Vole—Lemmiscus curtatus 210 • Key to the Families of the Order Lagomorpha Common Muskrat—Ondatra zibethicus 212 in Colorado 260 Southern Bog Lemming—Synaptomys • Family Ochotonidae—Pikas 260 cooperi* 214 American Pika—Ochotona princeps 260 • Family Leporidae—Rabbits and Hares 263 * Species of possible occurrence in Colorado. vii CONTENTS • Key to the Species of the Family Leporidae in • Key to the Species of the Family Vespertilionidae Colorado 264 Known or Expected to Occur in Colorado 312 Desert Cottontail—Sylvilagus audubonii 264 California Myotis—Myotis californicus 314 Eastern Cottontail—Sylvilagus floridanus 266 Western Small-footed Myotis—Myotis Mountain, or Nuttall’s, Cottontail—Sylvilagus ciliolabrum 315 nuttallii 268 Long-eared Myotis—Myotis evotis 317 Snowshoe Hare—Lepus americanus 271 Little Brown Myotis—Myotis lucifugus* 318 Black-tailed Jackrabbit—Lepus californicus 274 Fringed Myotis—Myotis thysanodes 321 White-tailed Jackrabbit—Lepus townsendii 276 Cave Myotis—Myotis velifer* 323 Long-legged Myotis—Myotis volans 323 CHAPTER 10—Order Soricomorpha: Shrews, Yuma Myotis—Myotis yumanensis 325 Moles, and Kin 279 Eastern Red Bat—Lasiurus borealis 327 Hoary Bat—Lasiurus cinereus 328 • Key to the Families of the Order Soricomorpha in Colorado 280 Silver-haired Bat—Lasionycteris noctivagans 330 Western Pipistrelle, or Canyon Bat— • Family Soricidae—Shrews 280 Parastrellus hesperus 332 • Key to the Species of the Family Soricidae in Eastern Pipistrelle, or Tricolored Bat— Colorado 281 Perimyotis subflavus