Chapter I: Part 1

MAMMALS OF WASHINGTON

BY

WALTER W. DALQUEST

University of Kansas Publications
Museum of Natural History

Vol. 2, pp. 1-444, 140 figures in text

April 9, 1948

UNIVERSITY OF KANSAS
LAWRENCE
1948

(7)

MAMMALS OF WASHINGTON

MAMMALS OF WASHINGTON

BY

WALTER W. DALQUEST
(Contribution from the Museum of Natural History, University of Kansas)

University of Kansas Publications
Museum of Natural History

Volume 2, pp. 1-444, 140 figures in text

APRIL 9, 1948

UNIVERSITY OF KANSAS
LAWRENCE
1948

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY
Editors: E. Raymond Hall and Donald F. Hoffmeister

Volume 2, pp. 1-444. 140 figures in text
April 9, 1948

UNIVERSITY OF KANSAS
Lawrence, Kansas

Printed by
Ferd Voiland Jr., State Printer
Topeka, Kansas
1948

21-1993

CONTENTS

PAGE

INTRODUCTION 13

PHYSIOGRAPHIC PROVINCES OF THE STATE 16

DISTRIBUTIONAL AREAS 20

CLIMATE AND VEGETATION 25

LIFE-ZONES AND ECOLOGY 32

GEOLOGIC HISTORY OF WASHINGTON 46

THE FAUNAS 52

SPECULATION AS TO EMIGRATIONAL HISTORY OF THE MAMMALS 54

SPECULATION AS TO THE LATER DISTRIBUTIONAL HISTORY OF THE
MAMMALS 68

EXPLANATION OF TREATMENT 110

CHECK LIST OF MAMMALS 112

ACCOUNTS OF SPECIES AND SUBSPECIES 121

ADDENDA 416

BIBLIOGRAPHY 417

INDEX 430

ILLUSTRATIONS

TOPOGRAPHY

FIGURE PAGE

Mount Rainier from Indian Henrys _frontispiece_

1. Cascade Mountains at Canadian Boundary 17

2. Columbia River one mile south of Kellers Ferry 19

4. Cascade Mountains in Chelan National Forest 21

5. Mount Rainier, Yakima Park 22

6. Columbia River in Stevens County 23

7. Blue Mountains, Washington 24

8. North Side of Mount Rainier 26

9. Mount Rainier: Cowlitz Chimneys 28

10. A "pothole" crowded by drifting sand 30

12. Arctic-Alpine Life-zone on Mount Rainier 33

13. Humid subdivision of the Transition Life-zone 34

14. Timbered, arid subdivision of the Transition Life-zone 35

15. Upper Sonoran Life-zone 37

16. Canadian Life-zone 38

18. McDowell Lake. Little Pend Oreille Wildlife Refuge 50

19. Pend Oreille River near Newport 59

20. Rocky bluff along north bank of the Columbia River 65

MAMMALS

FIGURE PAGE

21. Gibbs shrew-mole 122

23. Coast mole and Townsend mole 125

25. Coast mole 128

41. Long-eared bat: female with young 161

42. Boulder Cave: habitat of long-eared bats 162

48. Female black bear and two cubs 171

49. Black bear in "hibernation" 173

54. Fisher 187

59. Wolverine 202

60. Wolverine: dried pelt 203

62. River otter 208

66. Badger 220

69. Coyote 226

72. Cougar or mountain lion: skin 234

73. Cougar or mountain lion: pelts 235

75. Canadian lynx 238

76. Trapper's catch of nine Canadian lynx 239

78. Bobcat 241

82. Townsend chipmunk 260

87. Golden-mantled ground squirrel 282

89. Feeding station of Douglas squirrel 287

91. Northern flying squirrel 292

95. Northern pocket gopher 302

96. Giant mounds formed by pocket gophers 304

97. Food cache of northern pocket gopher 306

99. Beaver 315

100. Beaver lodge and pond 316

101. Cottonwood pole carved by beaver 317

102. Road flooded by beavers 320

106. Deer mouse 327

112. Pennsylvania meadow mouse 345

115. Runways of Townsend meadow mice 350

119. Muskrat 360

121. Mountain beaver 366

123. Big jumping mouse in hibernation 370

130. Elk 392

131. Group of elk 393

132. White-tailed deer 395

133. White-tailed deer: fawn 396

134. Left antler of white-tailed deer 397

135. Antlers of white-tailed deer 398

136. Mule deer 400

137. Black-tailed deer 401

138. Mountain goat 407

139. Group of mountain goats 408

DISTRIBUTION MAPS

3. Mammalian distributional areas 20

11. Life-zones of Washington 32

17. Extent of Vashon-Wisconsin ice 48

22. Gibbs shrew-mole 123

24. Townsend mole 127

26. Coast mole 129

27. Cinereous shrew 133

28. Merriam shrew and Trowbridge shrew 134

29. Wandering shrew 137

30. Dusky shrew 140

31. Mountain water shrew 141

32. Bendire water shrew and pigmy shrew 143

33. Big myotis 147

34. Yuma myotis 149

35. Fringe-tailed myotis and Keen myotis 150

36. Long-eared myotis 152

37. Hairy-winged myotis 155

38. California myotis 156

39. Small-footed myotis 157

40. Silver-haired bat 160

43. Long-eared bat 163

44. Western pipistrelle 164

45. Big-brown bat 166

46. Hoary bat 168

47. Pallid bat 170

50. Black bear 175

51. Grizzly bears 177

52. Raccoon 181

53. Western marten 185

55. Fisher 188

56. Ermine 192

57. Long-tailed weasel 196

58. Mink 199

61. Wolverine 204

63. River otter 209

64. Civet cat 214

65. Striped skunk 218

67. Badger 221

68. Red fox 225

70. Coyote 230

71. Wolf 232

74. Cougar 236

77. Canadian lynx 240

79. Bobcat 243

80. Least chipmunk 252

81. Yellow-pine chipmunk 256

83. Townsend chipmunk 261

84A. Marmots 266

84B. Townsend and Washington ground squirrels 268

85. Columbian and Beechey ground squirrels 274

86. Golden-mantled ground squirrels 280

88. Western gray squirrel 284

90. Red and Douglas squirrels 289

92. Northern flying squirrel 294

93. Great Basin pocket mouse 298

94. Ord kangaroo rat 300

98. Northern pocket gopher 308

103. Beaver 321

104. Northern grasshopper mouse 323

105. Western harvest mouse 325

107. Deer mouse 329

108. Bushy-tailed wood rat 335

109. Northern lemming mouse 337

110. Heather vole 339

111. Gapper and California red-backed mice 342

113. Pennsylvania meadow mouse 346

114. Montane and Townsend meadow mice 348

116. Long-tailed meadow mouse 352

117. Water rat 356

118. Creeping mouse 357

120. Muskrat 362

122. Mountain beaver 368

124. Big jumping mouse 372

125. Porcupine 375

126. Pika 378

127. Snowshoe rabbit 383

128. Black-tailed jack rabbit 386

129. Nuttall cottontail 388

INTRODUCTION

Mammals of Washington are of especial interest to the naturalist because many of them are recent immigrants; much of Washington was buried under thick glacial ice until relatively recently and many of the mammals, therefore, have inhabited the area only since the ice disappeared. The evolution or development of certain subspecies, in Washington, has certainly occurred within the last few thousand years. To be able thus to date such evolutionary changes as have occurred is of course a matter both of importance and interest to zoölogists. The evolutionary changes in several species are relatively great. In color, for example, the bobcat in the humid coastal area of western Washington is notable for its dark coloration, whereas in the more arid area of southeastern Washington it is remarkably pale and of a different subspecies. Within the limits of the state of Washington, elevations ranging from sea level to more than 14,000 feet occur. Since different elevations have their characteristic mammals, more kinds are found in Washington than in other areas of corresponding size that lack such topographic diversity. Expressed in terms of the life-zone concept, Washington includes faunas ranging from the Upper Sonoran Life-zone to those of the Arctic-Alpine Life-zone.

The basis for a study of the mammals of Washington was laid in 1929 by W. P. Taylor and W. T. Shaw in the "Provisional List of the Land Mammals of the state of Washington." Bailey's "Mammals and Life Zones of Oregon" and "The Recent Mammals of Idaho" by W. B. Davis deal with the habits and distribution of mammals in the areas bordering Washington on the south and east, and were very useful in the organization of the present report.

The study was first planned from the taxonomic and ecologic point of view. Such a study, of necessity, involves the classification and distribution of the forms concerned. Classification has required more work than any other part of the study and has been, in a sense, the nucleus of the study. Nevertheless, as the report began to take form it was recognized that the part dealing with classification and other purely technical aspects of the paper probably would be uninteresting to the average reader. Therefore it was felt that a greater impetus to the study of the mammals of Washington would be given by reducing the taxonomic accounts to the minimum and dealing principally with the problems of distribution.

As originally planned, the present report was to be of joint authorship by Dr. Victor B. Scheffer of the United States Fish and Wildlife Service, Seattle, and the writer. The press of other work prevented Dr. Scheffer from devoting as much time as he had planned to the project. He has, however, contributed his field notes, specimens, and photographs, and in many other ways assisted in the project.

Field work on mammals of Washington was carried out by the writer from 1936 to 1940 but a decision to prepare a complete report was not reached until 1938. Intensive field work was done between 1938 and 1940. In August, 1941, the author took up residence at Berkeley, California. Drafting of the manuscript was begun at that time as a student under Professor E. Raymond Hall. War conditions and the press of other work delayed completion. Subsequently, the manuscript was put in final form at the University of Kansas.

Many persons in addition to Dr. Scheffer have given assistance in the course of this work. Dr. E. Raymond Hall, in particular, encouraged the project and gave assistance in various ways including critical attention to the manuscript. I am indebted also to Dr. Trevor Kincaid and Mrs. Martha Flahaut of the University of Washington, Dr. Seth B. Benson and Dr. Alden H. Miller of the University of California, Dr. H. H. T. Jackson of the U. S. Fish and Wildlife Service, Dr. George E. Hudson of the Charles R. Conner Museum, Mr. Burton Lauckhart of the State of Washington Department of Game, and Mr. Ernest Booth of Walla Walla College. Mrs. Peggy B. Dalquest typed and edited the several preliminary drafts of the manuscript and aided in the laboratory and field work. Thanks are due also to many others, including game protectors, hunters and trappers, who have given assistance. The names of some of them are mentioned in the following pages.

Approximately ten thousand specimens of mammals were used. In decreasing order, according to the number of specimens studied from Washington, the following collections are to be mentioned: materials obtained principally from southern Washington in the years 1939 to 1942 as a result of the interest of Miss Annie M. Alexander and Dr. E. Raymond Hall; these materials are in the University of California Museum of Vertebrate Zoölogy. The writer's own collection which at one time numbered 2,500 specimens was the second source. The residue, the part not destroyed by fire at the writer's home in the spring of 1942, in Seattle, now is in the Museum of Vertebrate Zoölogy at the University of California and the Museum of Natural History at the University of Kansas. The other collections are those of the Biological Surveys of the United States Fish and Wildlife Service, the Washington State Museum at Seattle, the Charles R. Conner Museum at Washington State College, and the Museum of Natural History at the University of Kansas. In the latter collection are some materials obtained nearly half a century ago by the late L. L. Dyche, some recently taken specimens added by reason of the provision for work of this kind by the University of Kansas Endowment Association and, as noted above, a part of the author's original collection. Selected specimens from several other collections have been used and these are indicated in the text when particular reference is made to the specimens. Most of the specimens studied were conventional study skins with skulls. In some instances skeletons, skins alone, skulls alone, or entire animals preserved in alcohol have been used.

PHYSIOGRAPHIC PROVINCES OF THE STATE

The state of Washington was divided into seven physiographic provinces by Culver (1936). Culver points out that the physiography, though complicated in detail, is basically simple.

The state, including Puget Sound and other inland waters, is nearly rectangular in shape and is 69,127 square miles in area. Its western boundary is the Pacific Ocean. Politically, it is bounded on the north by the United States-Canadian Boundary (49° north lat.), on the east by the state of Idaho, and on the south by the state of Oregon.

The Cascade Mountain Range, or Cascade Mountains Province, runs from the northern to the southern boundary and divides the state into two sections, of which the eastern is slightly the larger. The mountain range trends approximately 10° east of north and continues uninterruptedly into British Columbia, but on the south the Columbia River separates the Washington Cascades from the Cascades of Oregon. Near the northern border of the state the range is wide, extending from the Mount Baker Range on the west to Mount Chopaka, 100 miles to the east. In the central part of the state it is more compact, being some 60 miles wide in the vicinity of Mount Rainier. Farther south it expands to approximately 100 miles.

The Cascades of Washington possess five great volcanic cones. These are Mount Baker (10,750 feet elevation) on the north, Glacier Peak (10,436 feet) in the north-central part, Mount Rainier (14,408 feet) in the central area, and Mount Adams (12,326 feet) and Mount St. Helens (9,697 feet) on the south. Excluding these volcanic peaks, the crests of the Cascades have a relatively uniform level descending from an average of 8,000 feet at the north to 5,000 feet at the south. Ranges jutting southeastwardly from the north-central Cascades parallel elongate intermontane valleys. These include the Entiat and Wenatchee mountains. The latter range reaches the Columbia River and forms an important barrier to mammalian movements.

There is an extensive area of anticlinal ridges extending from the southern Cascades to the Columbia River. This area includes the Horse Heaven and other hills. Most of it is drained by the Yakima River and is termed, in this report, the Yakima Valley Area.

The Puget Sound Trough, or Puget Sound Province, is immediately west of and parallel to the Cascade Mountains. It is part of a structural downwarp that extends southward into Oregon. Most of the area is below 1,000 feet elevation, and much of the northern part is below sea level and therefore flooded by the marine waters of Puget Sound. The most prominent feature of this area is Puget Sound. This is a glacially-carved and drowned river valley, studded with islands, peninsulas, fjords and bays that all possess a general north-south orientation resulting from the direction of ice movement. Puget Sound is connected with the Pacific Ocean by the Strait of Juan De Fuca, a wide channel separating the state of Washington and Vancouver Island.

The San Juan Islands represent the glaciated remnants of mountains that, in preglacial time, may have connected the mountains on Vancouver Island with the Cascades of Washington. The San Juan Islands lie at the junction of Puget Sound, the Strait of Georgia, and the Strait of Juan De Fuca. As a result of a boundary dispute and subsequent arbitration, the islands were apportioned, on the basis of the deepest channel separating them, between Canada and the United States. The American portion includes more than 400 islands. These vary in size from mere rocks above high tide to Orcas Island, 60 square miles in area.

The Olympic Peninsula, or Olympic Province, lies between Puget Sound and the Pacific Ocean. The Strait of Juan De Fuca separates this peninsula from Vancouver Island on the north. In the south the valley of the Chehalis River is a convenient boundary for the province. The central portion of the peninsula is occupied by the Olympic Mountain Range. This range is nearly oblong in shape, measuring some 70 miles east to west by 45 miles north to south. The mountains are extremely rough and jagged. They rise from sea level to above 6,000 feet. The highest peak, Mount Olympus, is 8,150 feet in elevation.

South of the Olympic Province and west of the Puget Sound Trough is an area of low, rough hills. Culver called it the Willapa Hills Province.

The northern third of the land east of the Cascade Mountains, or northeastern Washington, is termed the Okanogan Highland Province by Culver. Its southern boundary is set at the east-west flow of the Spokane and Columbia rivers. The outstanding physiographic feature of this area is its division into north-south trending areas of lowland with intervening highlands and mountain ranges. The rivers are, from east to west, the Clark Fork, Colville, Columbia, Kettle, San Poil and Okanogan. Not all intervening highlands are separately designated as mountains. Among these named are the Pend Oreille, Huckleberry, Kettle River, and Okanogan ranges.

The part of eastern Washington south of the Okanogan Highland Province, save the extreme southeastern corner of the state, constitutes the Columbia Lava Province. This is an extensive, relatively level plateau that lies mainly below 2,000 feet elevation. The plateau consists of gently folded lava flows that reach a depth of 4,000 feet in some places (Russell, 1893) and slope inward from the east, north, and, in part, the west (Flint, 1938). These horizontal layers of basalt are extremely resistant to erosion by other than large rivers. Two great gashes cross the Plateau diagonally from the northeast to the southwest; these are Moses Coulee and the Grand Coulee. These old coulees are the former valleys of the Columbia River, and were formed at the time when the course of the river was successively blocked by the advance of Pleistocene ice. The Snake River crosses the southern edge of the Columbia Lava Province and separates the plateau proper from an area of similar land to the southward.

The Blue Mountains Province is an area of relatively small extent in the extreme southeastern corner of the state of Washington. There, the province concerned constitutes, as it were, a northward extension of the Blue Mountains of Oregon. The mountains rise to only 5,000 feet elevation in the Washington part of the Blue Mountains Province.

DISTRIBUTIONAL AREAS

The physiographic provinces are areas of land form. The form of the land has a considerable effect on the temperature, humidity, drainage, weathering, soil, and other non-organic features that combine to produce the various life-zones and influence the distribution of mammals. One might therefore expect a close correlation of mammalian distributional areas with physiographic provinces. Although there is a correlation, it is not exact because the distribution of mammals is influenced also by certain other factors. Among these are historical factors and isolation by geographic barriers.

The Cascade Mountains Province of Culver includes the Yakima Valley Area. This province contains two completely different mammalian distributional areas. The higher mountains possess a boreal, alpine fauna; the Cascade Range itself is called the Cascade Area in this report. The Yakima Valley Area possesses a desert fauna derived from the desert of eastern Oregon.

The land west of the Cascades is separated into three physiographic provinces, the Puget Sound, Willapa Hills, and Olympic Mountains Province. The differences between the mammalian faunas of the Puget Sound and Willapa Hills provinces are slight. The Olympic Mountains possess a few species not found in the lower areas. The similarities of the faunas of the three provinces far outnumber their differences, and it seems best to consider them subdivisions of one distributional area.

The Okanogan Highland Province extends, from a physiographic point of view, west of the Okanogan River Valley. This valley, however, is a fairly efficient barrier to mammals. Thus the part of the state east of the Okanogan Valley and north of the east-west flow of the Spokane and Columbia rivers may be called the Northeastern Washington Distributional Area.

The Columbia Lava Province includes the land both north and south of the Snake River. Since the Snake River serves as a barrier to some species, it seems better to term the area north of the Snake River the Columbian Plateau Area and that to the south the Southeastern Washington Distributional Area.

The Blue Mountains Province and the Blue Mountains Distributional Area are the same.

PHYSIOGRAPHIC PROVINCES DISTRIBUTIONAL AREAS

Cascade Mountains { Cascade Mountains
{ Yakima Valley

Puget Sound }
Willapa Hills } Western Washington
Olympic Mountains }

Okanogan Highlands Northeastern Washington

Columbia Lava { Columbian Plateau
{ Southeastern Washington

Blue Mountains Blue Mountains

CLIMATE AND VEGETATION

The life-zone theory of plant and animal distribution was proposed by Merriam (1892). Merriam's life-zones have been severely criticized by many authors, especially because an error was made in computing some of the data on temperature. However, zonation of vegetation and animals is obvious in Washington, and the life-zone concept has been employed in Washington by numerous botanists and zoölogists. Among them are: Piper (1906), Taylor and Shaw (1927), Jones (1936, 1938) and St. John (1937).

The higher parts of the Cascade Mountains are in the Arctic-alpine Life-zone. This is the area of wind-swept ridges, living glaciers, and permanent snow fields.

Trees are absent but a few shrubs are present; these include: _Juniperus sibirica_, _Salix cascadensis_, _Salix nivalis_, _Gaultheria humifusa_, _Empetrum nigrum_, and the heathers, _Phyllodoce glanduliflora_, _Cassiope mertensiana_ and _Cassiope stelleriana_. Jones (1938) lists a total of 98 species of plants from the Arctic-alpine Life-zone of Mount Rainier. Many of these plants are most abundant in the next life-zone lower, and are of but incidental occurrence in the Arctic-alpine Life-zone. No mammalian species is resident but individuals of several species regularly visit and occasionally breed there.

Below the Arctic-alpine the Hudsonian Life-zone stretches the entire length of the Cascades. Temperatures are low, especially in winter; then the thermometer does not rise above zero for weeks at a time. The average annual temperature at Paradise, 5500 feet, Mt. Rainier, is 38.6° (all temperatures given here are in degrees Fahrenheit). Snowfall is heavy. The average yearly snowfall, for four years, at Mt. Baker Lodge, at 4200 feet elevation, Whatcom County, was 478 inches; at Goat Lake, 2900 feet, Snohomish County, 261 inches; Tye, Stevens Pass, 3010 feet, King County, 398 inches; Paradise, 5500 feet, Mt. Rainier, 587 inches. The deepest snow recorded at Paradise was 27 feet, 2 inches on April 2, 1917. Following the spring thaws the mountain passes are opened to travel, usually in April or May, although nightly temperatures in April and May are still below zero. Spring precipitation is heavy, the monthly average for a twelve-year period at Paradise being 6.78 inches in April and 5.5 inches in May. Summer temperatures are high in the daytime, when the sun beats down through the rarefied atmosphere, but cool at night when accumulated heat is lost through the thin atmospheric blanket. In summer precipitation is light, averaging, at Paradise, 3.46 inches in June, .9 inches in July, and 3.44 inches in August. In the autumn the temperature, both daily and nightly, drops somewhat, and rain and cloudiness are the rule. At Paradise the average precipitation in September is 8.29 inches and in October 10.02 inches. The winter snows usually arrive by the middle of November.

Trees that are characteristic of parts of the Hudsonian Life-zone include the alpine fir (_Abies lasiocarpa_), mountain hemlock (_Tsuga mertensiana_), Alaska cedar (_Chamaecyparis nootkatensis_) and white-barked pine (_Pinus albicaulis_). The following shrubs are listed by Jones (1938) as common in the Hudsonian Life-zone on Mt. Rainier: _Salix barclayi_, _Salix commutata_, _Juniperus sibirica_, _Alnus sinuata_, _Ribes howellii_, _Lutkea pectinata_, _Potentilla fruticosa_, _Sorbus occidentalis_, _Spiraea densiflora_, _Pachistima myrsinites_, _Arctostaphylos nevadensis_, _Arctostaphylos uva-ursi_, _Cassiope mertensiana_, _Cassiope stelleriana_, _Phyllodoce empetriformis_, _Rhododendron albiflorum_ and _Gaultheria ovalifolia_.

There are extensive coniferous forests in the Canadian Life-zone, still lower on the mountain slopes. This is an area of lesser temperature extremes than is the Hudsonian Life-zone. The average annual temperature at Longmire, 2761 feet, Mt. Rainier, is 43.8°. The average temperature for the winter months, however, is below freezing. In July and August the temperatures are high, especially in the daytime. The eighteen year average for Longmire during these months is 60.6°. Snow is regular but the fall is lighter than in the Hudsonian Life-zone. The annual average, over a period of nineteen years, is 184.4 inches at Longmire. Precipitation is similar to that in the Hudsonian Life-zone, averaging perhaps slightly less.

In the Cascades the typical feature of the Canadian Life-zone is the extensive coniferous forest that extends, almost without a break, the entire length of the Cascades on both sides of the main crest. In addition to Douglas fir, the following trees occur in this forest: western hemlock (_Tsuga heterophylla_), amabalis fir (_Abies amabalis_), white pine (_Pinus monticola_) and noble fir (_Abies nobilis_). Other plants include _Vaccinnium ovalifolium_, _Vaccinnium membranaceum_, _Menziesia ferruginea_, _Alnus sinuata_, _Acer circinatum_, _Sorbus cascadensis_, _Cornus canadensis_, _Clintonia uniflora_, _Stenauthium occidentale_, _Galium oreganum_, and _Prenanthes lessingii_. Saprophytes abundant in, if not confined to, this zone are listed by Jones as: _Monotropa uniflora_, _Monotropa hypopitys_, _Allotropa virguta_, _Newberrya congesta_, _Pterospora andromedea_, _Corallorrhiza maculata_, _Corallorrhiza mertensiana_ and _Corallorrhiza striata_.

West of the Canadian Life-zone in the western Cascades, the coniferous forests merge with the lowland forests of western Washington. To the east of the Canadian Life-zone in the eastern Cascades, there is a distinct change to a more arid climate and flora. At Leavenworth, 1167 feet, Chelan County, the annual average precipitation is but 19.5 inches and at Cle Elum, 1930 feet, but 23.23 inches. Temperatures are higher, the annual average of the above two localities being 47.2° and 45.4° respectively. The winter months are cold, with the average temperature in January and February below freezing. In summer the averages in July and August at Leavenworth are 68.8° and 68.0°, with the average maximum being 87.5° and 86.1°. Snowfall is heavy, the yearly average at Leavenworth being 98.5 inches and at Cle Elum 86.3 inches. The effect of this more arid climate is seen in the vegetation. The dense Douglas fir forest, is replaced by more open forests of yellow pine (_Pinus ponderosus_). Groves of oak (_Quercus garryana_) are found near streams. The open forests give way to the extensive grasslands bordering the desert. The transition of vegetation is similar to that occurring in the Yakima Valley Area.

In the Yakima Valley Area, arid conditions prevail. The average yearly precipitation at Yakima is 6.67 inches. Only in November, December and January may more than one inch of precipitation be expected monthly. Snow may be expected in the winter months and the yearly average snowfall is 22.1 inches. Winter temperatures are low, the average for December and January being but slightly above freezing. Summer temperatures are extreme; the July average is 73.1° and the average maximum for the same month is 89°. The highest temperature recorded is 111°.

The open pine forests of the eastern Cascades give way to grasslands. Grasses of several species are common but the bunchgrass (_Agropyron spicatum_) is most important. Other plants include the primrose (_Oenothera pallida_), lupines (_Lupinus_), and _Mertensia_. In ravines and near watercourses such shrubs as hawthorn (_Crataegus douglasii_), service-berry (_Amelanchier cusickii_, _Amelanchier utahensis_), aspen (_Populus tremuloides_), syringa (_Philadelphus lewisii_), snowberry (_Symphoricarpos albus_), choke-berry (_Prunus melanocarpa_) and elderberry (_Sambucus caerulae_) form thickets. Lower in the valley the vegetation is xerophytic, similar to that of the Columbian Plateau. Sagebrush (_Artemisiae tridentata_) is dominant. Other shrubs include rabbit brush (_Chrysothamnus nauseosus_, _Chrysothamnus viscidiflorus_), hop sage (_Grayia spinosa_), black sage (_Purshia tridentata_) and greasewood (_Sarcobatus vermiculatus_).

Climatic conditions in the Olympic Mountains are, in general, similar to those of the higher Cascade Mountains. There is a limited area of Arctic-alpine Life-zone on Mount Olympus. The principal life-zone is the Hudsonian. The Canadian merges with the lowland Humid-Transition and is difficult to ascertain as a separate zone. In the Hudsonian Life-zone the average temperatures are low. Winter climate is bitter and the snow lies deep. In the absence of government weather stations in the Olympics, detailed descriptions of climatic conditions can not be given. Vegetation of the Hudsonian Life-zone of the Olympic Mountains is, in general, similar to that of the same life-zone of the Cascades (see Jones, 1936, Botanical Survey of the Olympic Peninsula).

The lowlands of western Washington have a cool, humid climate. The average annual temperature of the area varies little from 50°. In winter the temperature, especially in January and February, commonly drops below the freezing point at night. Summer temperatures are moderate, rarely reaching 90°. Snowfall is light, averaging about 10 inches. The prevailing winds are from the west and are moisture-laden. They rise over the Olympic Mountains and loose heavy rains along the coastal area of the lowlands. The average annual precipitation at La Push, Clallam County, is 97.9 inches; at Clearwater, Jefferson County, 124.98 inches; at Aberdeen, Grays Harbor County, 81.58 inches; at South Bend, Pacific County, 83.35 inches. In contrast, the more inland areas receive less than half as much precipitation. The yearly average at Bellingham is 31.09 inches; at Seattle, 30.07 inches; at Tacoma, 39.53 inches; at Vancouver, Clark County, 37.24 inches.

The outstanding feature of the vegetation of western Washington is the coniferous forest. Previous to the logging activities a dense cover of Douglas fir, western hemlock and red cedar spread almost unbroken over the area. The openings in the forest and the marshy ravines and river valleys supported growths of underbrush and deciduous trees so dense and luxuriant as to compare with a tropical jungle. In the dense rain forests along the coast, mosses and lichens develop an understory vegetation many inches deep and clothe the branches of the forest trees. The mild temperature and excessive rainfall cause some species that usually are of bush or shrub size to reach the proportions of small trees. In some places one can climb twenty feet from the ground in a huckleberry tree, the trunk of which is five inches in diameter. The coniferous forest is made up of several species of trees. Most important among these are the western hemlock (_Tsuga heterophylla_), Douglas fir (_Pseudotsuga taxifolia_), and red cedar (_Thuja plicata_). Locally the western yew (_Taxus brevifolia_), lodgepole pine (_Pinus contorta_) and spruce (_Picea sitchensis_) may be common. Deciduous trees are numerous and include several willows (_Salix_ sp.), aspen (_Populus tremuloides_), hazel (_Corylus californica_), alder (_Alnus oregona_), oak (_Quercus garryana_), broadleaf maple (_Acer macrophyllum_), vine maple (_Acer circinatum_), and flowering dogwood (_Cornus nuttallii_). Mosses and ferns are abundant. The sword fern (_Polystichum munitum_) and bracken (_Pteridium aquilinum_) are especially common. Space prevents listing all but a fraction of the typical shrubs but these include huckleberry (_Vaccinium parvifolium_, _Vaccinium ovatum_), Oregon grape (_Berberis nervosa_), salal (_Gaultheria shallon_), rose (_Rosa gymnocarpa_), thimbleberry (_Rubus parviflorus_), salmonberry (_Rubus spectabilis_), blackcap raspberry (_Rubus leucodermis_) and wild blackberry (_Rubus macropetalus_).

The higher parts of some of the ranges of northeastern Washington are in the Hudsonian Life-zone, but most of the mountains are in the Canadian Life-zone. The valleys are in the Transition Life-zone. Climatic conditions are similar to those of the eastern slopes of the Cascades. Winter temperatures are low, the average for December, January and February being below freezing. Summer temperatures are high, the July average for Colville being 67.2° and the July average maximum being 87.4°. Vegetation consists principally of coniferous forests in the mountains and deciduous woods in the valleys. Among the interesting features of the vegetation are the extensive stands of almost pure larch (_Larix occidentalis_). In most respects the flora closely resembles that of the Blue Mountains.

The Blue Mountains of southeastern Washington differ from other ranges in Washington in their relative aridity. There are few streams and a single river drains the area. There are no government weather stations in the Blue Mountains. The winter temperatures are low and the snow deep and lasting. Summer temperatures are high and humidity and precipitation low. Coniferous forests of the type of arid regions form the principal tree cover. Typical plant species include the white fir (_Abies grandis_), alpine fir (_Abies lasiocarpa_), larch (_Larix occidentalis_), spruce (_Picea columbiana_), and such shrubs as fool huckleberry (_Menziesia ferruginea_), _Pachystima myrsinites_, dogwood (_Cornus canadensis_), wild current (_Ribes petiolare_), mountain mahogany (_Cercocarpus ledifolius_), spirea (_Spiraea_ sp.), lupines (_Lupinus_) of several species, maple (_Acer douglasii_), buckbrush (_Ceanothus sanguineus_), sticky brush (_Ceanothus velutinus_), and huckleberry (_Vaccinium membranaceum_).

The Columbian Plateau and southeastern Washington present desert conditions. At Odessa, 1590 feet, Lincoln County, the average annual precipitation is only 9.38 inches, and only in the winter may more than one inch of precipitation per month be expected. The average temperature is 48.5°. In the winter the average is below freezing but in July it is 71.3°. The average maximum for July is 90° and an extreme of 111° is recorded. Walla Walla, 991 feet, has a higher annual precipitation (16.66 inches) but higher temperature (yearly average 53.5°, July average 75.0°, average July maximum 88.6°, extreme 113°). Winter temperatures on the Columbian Plateau are low. The January average at Odessa is 25.3° and at Walla Walla 32.4° The average yearly snowfall at Odessa is 19.4 inches and at Walla Walla 23.5 inches. Vegetation of the Columbian Plateau and southeastern Washington is of the desert type. A few pines and junipers grow in favored places. Along streams the cottonwood (_Populus hastata_) and willow (_Salix_) of several species are common. Most typical are grasses and shrubs such as the bunch grass (_Agropyron inerme_, _Agropyron spictatum_), foxtail (_Alopecurus aequalis_), cheat grass (_Bromus tectorum_), saltbrush (_Atriplex truncata_), greasewood (_Sarcobatus vermiculatus_) mustard (_Arabis_ sp., _Brassica_ sp.), sagebrush (_Artemisia rigida_, _Artemisia tridentata_), rabbit brush (_Chrysothamnus nauseosus_, _Chrysothamnus viscidiflorus_) and cactus (_Opuntia polyacantha_). The arid climate of the Columbian Plateau affects, to some extent, surrounding areas. Thus the Yakima Valley Area, the Columbia Valley, where it borders the Plateau, and the Okanogan Valley possess vegetation typical of the Columbia Plateau.

LIFE-ZONES AND ECOLOGY

The Transition Life-zone is the principal life-zone in Washington. It is divisible into three subdivisions: Humid, Arid-timbered and Arid-grasslands (Fig. 11) subdivisions. The Humid and Arid-timbered subdivisions of the Transition life-zone are closely related in some respects but different in others. They are separated by the Cascade Mountains. All of the Transition Life-zone west of the Cascades belongs to the Humid subdivision and the timbered Transition Life-zone east of the Cascades belongs to the Arid-timbered subdivision.

The Arid-grasslands are of minor geographic extent. Although this subdivision is relatively distinct as concerns the distribution of plants, insects and birds, it is of little importance as concerns the distribution of mammals. For the most part, the mammals occupying it are more representative of surrounding areas. Large parts of the Arid-grasslands have been taken over for agriculture, especially wheat raising. Perhaps the greatest extent of the Arid-grasslands existing in a natural state is along the eastern Cascade Mountains and along the eastern side of the Columbian Plateau. These are truly transition areas, situated where the arid pine forests are replaced by open, sagebrush desert.

The Upper Sonoran Life-zone includes the desert areas of Washington (figure 11 D). Its principal extent is the central Columbian Plateau. From the central Columbian Plateau, fingerlike projections of desert extend along the principal valleys.

The Arctic-alpine Life-zone occurs in the high Olympic Mountains and on the higher peaks of the Cascades. This is shown on the life-zone map, Fig. 11, as white, unshaded areas.

The mammalian faunas of the Hudsonian and Canadian life-zones resemble each other closely. The boundary between them is too complex to permit separating them on a small-scale map. Consequently they are mapped together on Fig. 11 as A.

THE HUMID SUBDIVISION OF THE TRANSITION LIFE-ZONE

This subdivision is remarkably uniform in composition over western Washington. The greatest difference is in precipitation. Rainfall along the coast is heavier than that in the interior. Consequently vegetation is more dense and luxuriant along the coast.

Four habitats may be distinguished in the Humid subdivision and further subdivision is possible. The dominant and most extensive habitat is the forest. Dominant mammalian species include: _Peromyscus maniculatus_, _Sorex trowbridgii_, _Sorex obscurus_, _Tamiasciurus douglasii_, _Clethrionomys californicus_, _Aplodontia rufa_, _Glaucomys sabrinus_ and _Odocoileus hemionus_. Mammals are scarce and nocturnal forms prevail. As a rule, a line of mouse traps set in a forest habitat will take principally _Peromyscus maniculatus_ with a few _Sorex trowbridgii_ and _Sorex obscurus_ and rarely a _Clethrionomys californicus_. In some places, especially where the moss is deep, a line of mouse traps will catch only shrews.

A second important habitat is the deciduous jungle. This differs from the forest habitat in that the dominant trees are of the deciduous type and in that understory vegetation, such as shrubs and annuals, is dense. The jungle habitat occurs in ravines and in valleys of streams and rivers and, in general, covers the lower, poorly drained portions of the Humid subdivision of the Transition Life-zone. Mammals are abundant and varied in the jungle habitat. The deer mouse (_Peromyscus maniculatus_) is the most common mammal but a line of mouse traps might also catch: _Neurotrichus gibbsii_, _Scapanus orarius_, _Sorex vagrans_, _Microtus oregoni_, or _Zapus p. trinotatus_. The mountain beaver, snowshoe rabbit, and Townsend chipmunk also occur there.

The prairies form a third habitat. These areas of native grasslands are of minor extent but are the principal home of several races of gophers and the Townsend mole (_Scapanus townsendii_). Deer and elk also browse on the prairies.

A fourth habitat is the marsh. In it there is here included the sphagnum bogs and marshy shores of lakes and streams. This habitat is characterized by damp ground, standing water, and dense vegetation. Typical mammalian species include the water shrew (_Sorex bendirii_), Townsend meadow mouse, muskrat and mink.

Other habitats, such as aerial for the bats and aquatic for the beaver and otter, might be listed.

THE ARID TIMBERED SUBDIVISION OF THE TRANSITION LIFE-ZONE

In Washington the Arid timbered subdivision of the Transition Life-zone is the open, pine forest. Because of the aridity of this habitat, marshes and streamside thickets are uncommon, but where habitats of this kind do occur they have a fauna distinct from that of other habitats.

The pine forest habitat includes many diurnal species, such as the red squirrel, yellow-pine chipmunk, and Columbian ground squirrel. The white-tailed deer occurs here and, for most of the year, the mule deer. Snowshoe rabbits are usually present. Near rocks the bushy-tailed wood rat is common. Mice are scarce, probably because of the open nature of the surface of the ground. A night's trapping usually yields only a few _Peromyscus maniculatus_.

The mammalian fauna of the marshes and streamside thickets is similar. Shrews including _Sorex vagrans_ and _Sorex obscurus_ are uncommon. Meadow mice, including _Microtus pennsylvanicus_, _Microtus longicaudus_, and more rarely _Microtus montanus_, are taken.

THE ARID GRASSLANDS SUBDIVISION OF THE TRANSITION LIFE-ZONE

This subdivision is so much utilized by man where it occupies any considerable areas, and is of such a transitional nature elsewhere, that it is important for only a few native wild mammals. The sagebrush vole (_Lagurus curtatus_) seems to be confined to the arid grasslands. The white-tailed jack rabbit is now found principally in the arid grasslands, but its confinement there has resulted probably from competition with the black-tailed jack rabbit. The montane meadow mouse (_Microtus montanus_) is the only common, representative species. Many species from the Upper Sonoran Life-zone extend into the arid grasslands where conditions are suitable. These include _Reithrodontomys megalotis_, _Perognathus parvus_, _Citellus washingtoni_ and _Marmota flaviventris_. A few species more typical of the Arid timbered subdivision of the Transition Life-zone stray onto the arid grasslands. _Citellus columbianus_ and _Microtus longicaudus_ may be included here.

THE UPPER SONORAN LIFE-ZONE

The sagebrush desert in Washington is relatively uniform in nature. Several different habitats may be distinguished, such as sandy areas, open sage, dense sage, stony ground, and talus. Qualitatively, however, the mammalian fauna of these areas is surprisingly similar. Quantitatively, there are great differences. For example, the grasshopper mouse is rare in the open sage areas with hard, claylike soil but common on drifted sand. The harvest mouse is common in dense sage but rare in open sage or in open, sandy areas. Mammals are abundant on the sagebrush desert and typical species include: the black-tailed jack rabbit, Nuttall cottontail, Ord kangaroo rat, Great Basin pocket mouse, Townsend ground squirrel, Washington ground squirrel.

Marshes are not uncommon on the Columbian Plateau and elsewhere in the Upper Sonoran Life-zone in Washington. They do not possess a fauna that is strictly Upper Sonoran but instead contain species more typical of the Arid-timbered subdivision of the Transition Life-zone. Meadow mice found in desert marshes include _Microtus montanus_ and _Microtus pennsylvanicus_. The only shrew we have found is _Sorex vagrans_. The harvest mouse (_Reithrodontomys megalotis_) is often abundant in marshes.

THE CANADIAN LIFE-ZONE

The Canadian Life-zone is a relatively uniform area in which the forest habitat is most important. Talus and swift, cold streams bring some typical mammalian species into the Canadian Life-zone from the Hudsonian. Mammals are usually common; they are abundant only in the upper portion of the Life-zone. Arboreal species and forms adapted to life beneath the forest cover are dominant. The Douglas squirrel, red squirrel, northern flying squirrel and Townsend chipmunk are typical arboreal species. Traps set beneath the trees might catch _Peromyscus maniculatus_, _Clethrionomys gapperi_, _Neotoma cinerea_, _Sorex obscurus_, or _Sorex trowbridgii_.

THE HUDSONIAN LIFE-ZONE

In Washington the Hudsonian Life-zone is of greater diversity than any other. Frost and steep slopes have formed great masses of talus and, in this talus, certain species of mammals, such as _Ochotona princeps_, _Marmota caligata_ and _Marmota olympus_ are found. Other species, such as the golden-mantled ground squirrels, mountain chipmunk, bushy-tailed wood rat, red-backed mouse and long-tailed meadow mouse find the talus an ideal home. Glacial action has produced, in the Hudsonian Life-zone, numerous level or concave areas that contain small lakes and slow-moving streams. Dense, herbaceous vegetation is abundant nearby. Small mammals abound and a line of mouse traps will almost certainly catch a few such typical species as: _Sorex palustris_, _Sorex obscurus_, _Microtus oregoni_, _Microtus richardsoni_, _Microtus longicaudus_ and _Zapus princeps_ as well as the ever present _Peromyscus maniculatus_. The shrew-mole or heather vole might also be taken, though the latter is more apt to be found in nearby heather meadows.

TABLE 1. Distribution of mammals in Washington by Life-Zones. _A._ Abundant. _C._ Common. _R._ Rare.

Column headers:

A: Humid Transition
B: Arid-timbered Transition
C: Arid-grasslands Transition
D: Upper Sonoran
E: Canadian
F: Hudsonian