referable to the race _oribasa_, of the Rocky Mountain Fauna. Instead
they are intermediate between that race and the Great Basin race,
_nevadensis_. Apparently _nevadensis_ was so dynamic and adaptable that
it actually entered the geographic ranges of surrounding races for some
distance. In view of Sumner's theory for the retention of subspecies,
one might say that the population pressure of _nevadensis_ on the
periphery of its range is stronger than the opposing pressure of some
surrounding races.
MUSTELA VISON.--Pending a review of the minks of North America, little
can be said concerning their historical distribution in the state of
Washington. From the general range of the species in western North
America, one would expect some effect of the Vashon-Wisconsin Divergence
to be apparent. There is some evidence for this. Minks from Idaho and
adjacent parts of British Columbia are distinctly less reddish than
minks from the area about Puget Sound, as noted by Davis (1939: 138).
GULO LUSCUS.--The range of the subspecies _luteus_, peculiar to the
Cascades and Sierra Nevada suggest that the wolverine may have been
forced southward in the Cascades and there isolated during Vashon Time.
The differences separating the southern race from the northern may have
been developed while the two populations were isolated. The range of the
wolverine was probably more extensive in glacial and immediate
postglacial time than at present.
LUTRA CANADENSIS.--The otter of western Washington seems to be a member
of the Pacific Coastal Fauna. Little can be said regarding the
distributional history of the species in the state, for specimens from
eastern Washington are not numerous enough to permit of a person
certainly establishing their systematic position.
SPILOGALE GRACILIS.--The western race of the civet cat (_latifrons_)
seems to be a coastal race, isolated in southwestern Washington and
western Oregon during Vashon time. The eastern race, _saxatilis_, is a
race of the Great Basin Fauna, that has entered the state from Oregon
and that will probably extend its range to the north.
MEPHITIS MEPHITIS.--Of the four subspecies of skunks occurring in
Washington, two seem to have been resident in the state during Vashon
Time. The western race, _spissigrada_, was probably isolated in
southwestern Washington and extended its range northward, in the
deglaciated area of western Washington, after the retreat of the ice.
Another race (_notata_) was probably isolated in the southeastern
Cascades and adjacent Oregon. _M. m. hudsonica_ of the Rocky Mountain
Fauna entered the northeastern part of Washington after the ice
retreated from there. A race of the Great Basin Fauna, _major_, entered
southeastern Washington from Oregon and may eventually extend its range
farther north.
It is interesting to note that both of the western races, _spissigrada_
and _notata_, both of which probably developed in Washington during
Vashon Time, occupy limited ranges in adjacent Oregon (Bailey, 1936:
308).
TAXIDEA TAXUS.--This species has probably long been resident on the
Columbian Plateau and in southeastern Washington. For the early
distributional history of the species see Hall (1944: 17). Pleistocene
remains, referable to this race, have been found in Franklin County.
VULPES FULVA.--The red fox of the Cascades was probably isolated there
during Vashon Time by glacial ice. Its range extends southward in the
Cascades to Oregon. The fox of eastern Washington is probably a member
of the Rocky Mountain Fauna that lived in the Blue Mountains of
southeastern Washington in Wisconsin Time and that emigrated to
northeastern Washington in Recent Time.
CANIS LATRANS.--The distributional history of the coyote in Washington
is not clear.
CANIS LUPUS.--The dark wolf (_fuscus_) of western Washington is probably
a coastal race. The race that may have occurred in northeastern
Washington probably was an invader from the Rocky Mountain Fauna, and
the race that possibly occurred in southeastern Washington would be
assumed to have long been a resident of the area.
FELIS CONCOLOR.--The cougar of western Washington is a coastal race,
probably developed while isolated in southwestern Washington and western
Oregon. The cougar of northeastern Washington probably entered the state
with other Rocky Mountain species, early in the Recent. The cougar of
the Blue Mountains of southeastern Washington has probably long been
resident there.
LYNX RUFUS.--The bobcat of western Washington seems to be a coastal race
that was isolated in either southwestern Washington or western Oregon by
Vashon ice. It has since extended its range into southern British
Columbia. The bobcat of eastern Washington seems to be a member of the
Great Basin Fauna that has spread to some forested areas on the
periphery of the more arid life-zones.
LYNX CANADENSIS.--The lynx is an element of a northern fauna that was
probably forced southward into the Cascades and Rocky Mountains. Its
range was probably more extensive, as is indicated by the scattered
records of its occurrence in Oregon (Bailey, 1936:271).
MARMOTA MONAX.--The woodchuck invaded northeastern Washington in the
early Recent with the Rocky Mountain Fauna.
MARMOTA FLAVIVENTRIS.--The yellow-bellied marmot is a typical member of
the faunas of the Great Basin and the southern Rocky Mountains. It has
doubtless entered southeastern Washington from eastern Oregon at an
early time. In northeastern Washington, west of the Columbia River, it
occupies alpine habitat, but it does not occur farther east, where
_Marmota monax_ is found, or in the Cascades where _Marmota caligata_
lives.
The yellow-bellied marmots are great wanderers, and commonly are found
in scattered outcrops far out on the Columbian Plateau. There is even
one record for western Washington, near Bellingham, Whatcom County. This
individual must have crossed some low pass in the Cascades from the area
about Lake Chelan. There are records of eastern Washington birds
occurring in this same area, so it seems likely that the marmot was a
natural stray and not an animal that escaped from captivity.
MARMOTA CALIGATA.--The absence of the hoary marmot from the Cascades of
Oregon, and the presence there of _Marmota flaviventris_, indicates that
the species did not occur in the southern Cascades of Washington during
Vashon Time. Presumably the hoary marmot is a member of the fauna of the
northern Rocky Mountains and entered the Cascades of Washington in the
Recent, after which it spread widely and rapidly owing to lack of
competition with any established species of marmot.
MARMOTA OLYMPUS.--This species has probably lived in the Olympic
Mountains since pre-Vashon Time.
CITELLUS WASHINGTONI.--This ground squirrel has probably lived on the
Columbian Plateau since before Wisconsin Time.
CITELLUS TOWNSENDII.--The Townsend ground squirrel probably entered the
Yakima Valley area from Oregon. The differences between it and its
relatives in Oregon indicate a considerable period of isolation but one
far shorter than the period during which _washingtoni_ is presumed to
have been isolated from _townsendii_.
CITELLUS COLUMBIANUS.--The Columbian ground squirrel might have been
forced southward in the Rocky Mountain area by the Wisconsin glaciation,
might have lived in southeastern Washington since then, and might have
invaded northeastern Washington in the Recent with other species of the
Rocky Mountain Fauna.
CITELLUS BEECHEYI.--This ground squirrel is known to have entered
Washington about 1915 from Oregon.
CITELLUS SATURATUS.--The mantled ground squirrel of the Cascades
probably evolved, from the _lateralis_ stock, as a separate species
while isolated in the southern Cascades during Vashon Time. It is a
poorly differentiated species and may actually be instead a strongly
marked subspecies.
CITELLUS LATERALIS.--The golden-mantled ground squirrels of northeastern
and southeastern Washington are closely similar. It is deduced that
_connectens_ of southeastern Washington developed the differences that
characterize it while isolated, from the main stock, in the Blue
Mountains area of Washington and Oregon.
The race found in extreme northeastern Washington (_tescorum_) probably
reached that area in relatively recent times. Its range in Washington is
more restricted than that of several other members of the Rocky Mountain
Fauna; areas of suitable habitat west of the Columbia River are not
inhabited by these ground squirrels. Its range in Washington is almost
exactly that of (_Marmota monax_).
TAMIAS MINIMUS.--The least chipmunk of the Yakima Valley is the same
race (_scrutator_) as that occupying the Great Basin area of Oregon and
Nevada. It must have crossed the Columbia in relatively recent times.
Had it been resident in the isolated Yakima Valley area for any
considerable period of time, the development of distinctive racial
characters there would be expected. Perhaps, then, it has not been
resident there as long as has the Townsend ground squirrel which, though
closely related to the ground squirrel of eastern Oregon, is racially
distinct.
The least chipmunk of the Columbian Plateau is thought to be racially
distinct from its relatives in the Yakima Valley and eastern Oregon.
Probably it reached the Plateau very early in the Recent. It has
probably not been separated from the parent stock as long as has the
ground squirrel (_Citellus washingtoni_) of the plateau. The ground
squirrel is specifically rather than racially distinct.
TAMIAS AMOENUS.--The distributional picture of the yellow pine chipmunks
in Washington is complex. (Fig. 81.) Certain habits of these mammals
doubtless have modified what was probably the original postglacial
distribution of the species. Chipmunks are diurnal and natural
selective factors for color possibly operate more strongly on animals
active by day than on nocturnal animals. Yellow pine chipmunks are
neither forest nor desert inhabitants. Indeed, dense forests or open
deserts serve as barriers to their distribution. They prefer brush
lands, open woods, and other habitats where there is food and cover but
abundant sunlight. In such habitats they are almost independent of
altitude, temperature and humidity. They live in the Olympic Mountains
where rainfall is heavy and humidity high. They live and breed at
considerable altitudes in the Cascades, even in the crater of Mount
Rainier, where snow, ice and freezing conditions exist the year around.
On the other extreme, they occupy the low, open pine forests and brush
lands at the lower edge of the Arid Transition Life-zone where
temperatures, in summer, are high and rainfall scarce.
We find in the present distribution of the species in the Cascade-Sierra
Nevada chain and the Rocky Mountains, indication that the species had a
wide geographic range over western North America previous to the
Vashon-Wisconsin glacial interval. Probably the range of the species
extended in an arc, from the Rocky Mountains across northern Washington
to the Cascades, around the basaltic plateau desert in eastern
Washington and Oregon. Presumably the descent of the Vashon-Wisconsin
glaciers broke this arc into two parallel geographic ranges, the Rocky
Mountains and the Cascade-Sierra Nevada chain, with a desert area
between.
Almost every species of forest-dwelling animal had its range separated
into two parts by the southward movement of the glaciers. Most of these
forest-dwelling species were composed of relatively homogeneous stocks,
although the yellow pine chipmunk probably was not. The extensive range
of tolerance of the yellow pine chipmunk to altitude and climate and its
unique habitat requirements cause it to meet radically different natural
selective factors. The predators of the chipmunks near Wenatchee, Chelan
County, would include: rattlesnake, gopher snake, badger, striped skunk,
prairie falcon, red-tailed hawk and other predominantly desert-dwelling
species. The chipmunks at Stevens Pass, in the mountains to the west,
would have to contend with: marten, black bear, goshawk, bald eagle and
other alpine predators. At the present time, the chipmunk of the eastern
Cascades is racially distinct from that of the higher Cascades. Geologic
and botanical evidence indicates that the Columbian Plateau was a desert
in pre-Wisconsin Time. We suppose that a transition from alpine
conditions in the Cascades to desert conditions on the Columbian
Plateau existed even in pre-Wisconsin Times. We suppose also that the
chipmunk existed in this transition area and in the Cascades before
Wisconsin Time and in the southern and southeastern Cascades during
Wisconsin Time. We further suppose that the differences separating the
transition area race (_Tamias amoenus affinis_) from the mountain race
(_T. a. ludibundus_) came about through natural selection and not as a
result of geographic isolation. The principal difference between the two
is the paler color of the race in the transition area.
The descent of the Vashon-Wisconsin glaciers, then, found two races of
the yellow pine chipmunk in the Cascades. Chipmunks living north of the
Columbian Plateau, in northern Washington and British Columbia, were
probably forced southward onto the inhospitable plains of the plateau
and exterminated. Farther east, north of northeastern Washington,
chipmunks from the north were probably forced southward to compete with
resident chipmunks.
The range of _Tamias amoenus luteiventris_ in Washington, Idaho and
Montana is most unusual (See Howell, 1929; Davis, 1939). From a compact
range in Montana, two long fingers reach northward and westward. The
western finger crosses Idaho to end in the Blue Mountains of Oregon and
Washington. The northern finger crosses northern Idaho, northeastern
Washington and extends on into southern British Columbia. Between these
two fingers of the range of _luteiventris_ another race (_canicaudus_)
is found. This race occupies a more lowland area than does
_luteiventris_. The range of _luteiventris_ in the northern Rocky
Mountains is extensive. Presumably this race occupied an area farther
north in pre-Wisconsin Time and was forced southward to its present
range by the Wisconsin glaciers. The original population occupying
extreme eastern Washington and adjacent Idaho was _Tamias amoenus
canicaudus_. The pre-Wisconsin range of this race might have been more
extensive. At any rate, _luteiventris_ which was driven southward
displaced _canicaudus_, or some other race of chipmunk, from much of the
Rocky Mountains south of the glacier. The northern chipmunks were
adapted to more boreal conditions and perhaps otherwise better suited to
environmental conditions of the northern Rocky Mountains. A small
population of the older established race (_canicaudus_) persisted in
lowland areas of eastern Washington and adjacent Idaho.
Regarding the range of _canicaudus_, surrounded by the range of
_luteiventris_ on three sides and faced by desert on the west, Davis
(1939: 220) writes, "It may be that, of these two races, _luteiventris_
has a greater range of tolerance to environmental conditions and, thus,
is able to succeed in areas to which _canicaudus_ is not adapted. This
inference is supported by the fact that _luteiventris_ occupies a large
range which is diversified geographically and climatically, whereas
_canicaudus_ seems to be limited to a much smaller, more nearly uniform
area." Seemingly _canicaudus_ now exists only in an area ideally suited
to it, and one where it can successfully compete with the generally more
adaptable and successful _luteiventris_. The maximum extent of the
glacial ice, then, found _luteiventris_ the dominant chipmunk in the
northern Rocky Mountains, with an isolated population of _canicaudus_ in
eastern Washington and adjacent Idaho.
The topography of the ground moraine exposed by the retreat of the
Vashon-Wisconsin glaciers was a barrier to many species of mammals. The
rough, rocky surface with thin soil probably first supported mosses and
grasses, then brush, and later trees. The earlier stages of plant
succession on the deglaciated ground probably presented ideal habitat
for yellow pine chipmunks. Certainly the races immediately adjacent to
the glaciers extended their ranges farther north than many species. In
eastern Washington, _T. a. luteiventris_ spread to the northeastern
corner of the state and on into British Columbia. In the northern
Cascades, _T. a. affinis_ spread northward and eastward, across the
Okanogan River, into northeastern Washington as far as the range of
_luteiventris_. The chipmunk of the higher Cascades (_ludibundus_)
likewise extended its range northward into British Columbia. In the
northwestern Cascades of northern Washington and southern British
Columbia, a richly-colored race, _T. a. felix_, now occupies a limited
geographic range. This race doubtless originated from _ludibundus_ stock
but the method of its development is unknown. Perhaps in early
postglacial time, selective factors developed in chipmunks of the
western slopes of the Cascade Mountains the rich, dark color of _felix_.
The ancestral _ludibundus_ may have given rise to a pale race,
_affinis_, in the arid eastern Cascades and a dark race, _felix_, on the
humid western slope of the Cascades. This seems improbable for there is
no trend to darker color on the western border of the range of
_ludibundus_ south of the range of _felix_, and instead, _affinis_ may
have given rise to _ludibundus_. A more appealing hypothesis is that a
local mutation in some _ludibundus_ stock so changed the range of
tolerance of a portion of the population that it was allowed to enter
the more dense habitat along the coast north of the Fraser River and,
there, isolated by habitat selection, it developed the characters of
_felix_. Population pressure later forced it eastward until the eastern
border of its range again met the range of the ancestral race,
_ludibundus_.
The chipmunks of the Olympic Mountains probably reached their present
range from the Cascades. Their probable path of emigration was westward
from Mt. Rainier, along the glacial outwash train of Nisqualli Glacier,
to the moraine and outwash apron of the Vashon Glacier and thence to the
Olympics. So similar are the chipmunks of Mt. Rainier and the Olympic
Mountains that Howell (1929) included Mt. Rainier in the range of
_caurinus_.
Briefly summarized, the probable pre-Vashon-Wisconsin distribution of
chipmunks of the species _Tamias amoenus_ in Washington was:
_ludibundus_ in the higher Cascades; _affinis_ in the eastern Cascades;
_canicaudus_ in eastern Washington and adjacent Idaho; and
_luteiventris_ in the area north of the range of _canicaudus_. The
descent of the Vashon-Wisconsin ice restricted but did not materially
alter the ranges of _ludibundus_ or _affinis_. On the east,
_luteiventris_ was forced southward to compete with _canicaudus_ and
displaced it over a large region, especially in mountainous areas.
Following the retreat of the ice, _luteiventris_, _affinis_, and
_ludibundus_ extended their ranges northward over the deglaciated
territory. A stock of _ludibundus_ that moved westward from Mt. Rainier
became isolated and gave rise to _caurinus_. In some less obvious
development, _ludibundus_ stock gave rise to _felix_ north of the Fraser
River in the Cascades.
TAMIAS RUFICAUDUS.--Until a better understanding of the range of this
chipmunk and its relation to other _Tamias_ is gained, uncertainty will
remain concerning its distribution in the past.
TAMIAS TOWNSENDII.--This is a typical coastal species that ranges
southward, along the coast, to California. The lowland race of western
Oregon and Washington (_townsendii_) probably occurred no farther north
than southwestern Washington when the Vashon Glacier was in place.
Chipmunks of this species in the Cascades and in the southern Olympic
Mountains probably developed independently the slightly paler color that
separates _cooperi_ from _townsendii_. The tendency for species of the
Pacific Coastal Fauna of the Cascades and the Olympic Mountains to be
paler than their lowland relatives is widespread.
After the retreat of the ice, both races probably moved northward.
Perhaps because of its alpine adaptations, _cooperi_ has moved farther
than _townsendii_. Also, _townsendii_, in the lowlands, ranges to the
Fraser River, a barrier not encountered by _cooperi_.
SCIURUS GRISEUS.--This species of the Pacific Coastal Fauna probably
entered Washington from Oregon since the retreat of the Vashon Glacier.
It has probably entered the state in relatively recent times.
TAMIASCIURUS HUDSONICUS.--The two species of red squirrels, _T.
hudsonicus_ and _T. douglasii_, are specifically distinct and probably
became differentiated in the Pleistocene when southward moving glaciers
cut in two the range of the ancestral stock. The morphological
differences are too great, comparatively, to have occurred during the
Vashon-Wisconsin Divergence. _T. hudsonicus_ probably occupied a range
in pre-Wisconsin Time that included the Rocky Mountains and areas to the
north. Glacial ice probably restricted the range of _hudsonicus_ in
Wisconsin Time but after the retreat of the ice _hudsonicus_ moved
northward to reoccupy its former range. It also moved westward across
northern Washington to the Cascades, where it met the range of
_douglasii_. Farther north, it moved westward to the Pacific, thus
occupying an area that, in pre-Vashon time, probably was occupied by
_douglasii_.
TAMIASCIURUS DOUGLASII.--The Douglas squirrel probably occupied the
coastal region of Oregon, Washington and British Columbia in pre-Vashon
Time. The descent of the ice restricted its range to southwestern
Washington and areas to the south. After the retreat of the ice it moved
northward somewhat but, like other coastal species, the movement was
slow. Meanwhile _hudsonicus_ from the Rocky Mountain Fauna, had spread
to the coast of British Columbia.
GLAUCOMYS SABRINUS.--This flying squirrel is a plastic species. It
inhabits all of the forested parts of Washington. The distributional
picture presented by the 5 races (Fig. 92) which occur in Washington is
complicated. The ranges of 3 of these lie principally outside the state
of Washington.
The race _oregonensis_ occupies Washington and Oregon west of the
Cascades; _fuliginosus_ occupies the Cascades of Washington, Oregon and
southern British Columbia; _columbiensis_ occupies the interior valleys
of British Columbia and adjoining Washington; _latipes_ occupies the
northern Rocky Mountains of British Columbia, northern Idaho and extreme
northeastern Washington; and _bangsi_ occupies the Blue Mountains of
Washington and Oregon and a wide range in Idaho and eastward.
The differences separating the race _oregonensis_ from other subspecies
found in Washington are relatively great. This lowland race is smaller
and richer in color. The other races exhibit slight but relatively
constant differences. The relatively great difference between
_oregonensis_ and the other races indicates that _oregonensis_ was
isolated from the remainder of the species for a considerable time.
Presumably _oregonensis_ was a strongly differentiated coastal race in
pre-Vashon Time and occupied most of western Washington and Oregon. The
descent of the Vashon ice restricted the range of _oregonensis_ to
southwestern Washington and western Oregon. The descent of the ice
forced a northern race, _fuliginosus_, southward into the range of
_oregonensis_. The northern race, adapted to boreal conditions, was able
to compete successfully with the established _oregonensis_ only in
mountainous areas. In the Cascade Mountains, _fuliginosus_ extended its
range southward to southern Oregon.