8 (pt. 1):60, 1839.
_Arvicola occidentalis_ Peale, U. S. Expl. Exped., Mammalogy, p.
45, 1848 (type from Puget Sound).
_M[icrotus]. townsendi_ Miller, N. Amer. Fauna, 12:66, July 23,
1896.
_Microtus townsendii townsendii_ Svihla and Svihla, Murrelet,
14:40, May, 1933.
_Type._--Obtained on the Columbia River (probably on or near Sauvie
Island, Multnomah County, Oregon); type in Philadelphia Academy of
Natural Sciences.
_Racial characters._--Size large; skull narrow in interorbital
region.
_Measurements._--Eight males and 5 females from Clark and Pacific
counties, southwestern Washington, average, respectively: total
length 208.0, 208.4; length of tail 65.7, 66.0; hind foot 26.5,
25.4; ear 15.0, 14.6; weight 80.8, 76.7 grams. Thirteen males and
9 females from Seattle average, respectively: 211.8, 209.0; 71.2,
68.6; 25.7, 26.0; 15.8, 15.4.
_Distribution._--The lowlands of western Washington from
Bellingham (J.M.E.) south to Puget Island (V.B.S.).
=Microtus townsendii pugeti= Dalquest
_Microtus townsendii pugeti_ Dalquest, Murrelet, 21:7, April 1,
1940.
_Type._--Obtained at Neck Point, northwest corner of Shaw Island,
San Juan County, Washington, by D. H. Johnson, on July 10, 1938;
type in Museum of Vertebrate Zoölogy.
_Racial characters._--Size small; skull wide in interorbital
region, averaging about 4.0 mm. (3.8-4.2); basi-sphenoid truncate
posteriorly; upper incisors strongly curved.
_Measurements._--Two males and 6 females average: total length
182.6; length of tail 50.3; hind foot 23.2; ear 15.0.
_Distribution._--Found only on the San Juan Islands, San Juan and
Skagit counties.
_Remarks._--The islands occupied by this race of mouse were heavily
glaciated by the last continental glacier (Vashon). Mice of the species
_townsendii_ apparently migrated to the islands early in the Recent era,
and under isolation developed the differences which now separate them
from the mainland population.
=Microtus longicaudus= (Merriam)
Long-tailed meadow mouse
_Description._--The several races of this species vary from small to
large in size. Their bodies are relatively longer and slimmer than those
of the other meadow mice that occur in Washington. Their most
distinctive feature is the long tail, only slightly shorter than the
head and body. Their fur is rather coarse. The color varies from grayish
brown to dull reddish brown with a brighter brown dorsal stripe. The
tail is bicolor; black or dark brown above, yellowish below. The
underparts are whitish gray.
[Illustration: FIG. 116. Distribution of the long-tailed meadow mouse
in Washington. A. _Microtus longicaudus macrurus._ B. _Microtus
longicaudus halli._]
Long-tailed meadow mice are widely distributed over the western United
States, Canada, and Alaska. In Washington the long-tailed meadow mouse
has been taken in many habitats. One specimen was taken along a small,
temporary stream through sagebrush in the Upper Sonoran Life-zone.
Others were found in marshes and near water in the arid subdivision of
the Transition Life-zone. In the humid subdivision of the Transition
Life-zone they are not uncommon in damp areas along the ocean coast, but
are rather rare in dry, grassy habitats. In the Canadian and Hudsonian
life-zones they are fairly common in forest-free, grassy places, being
most abundant near talus slides. Altitudinally they range from sea level
to 6,000 feet.
Long-tailed meadow mice are rather rare. Several were taken in the
daytime at Round Top Mountain, Pend Oreille County, and two others were
taken in daytime two miles south of Tenino, Thurston County. However
most of the specimens were caught at night.
Long-tailed meadow mice do not, at least ordinarily, make trails as do
other meadow mice. Specimens are usually taken unexpectedly, and
intensive trapping in the area where a specimen or two is taken rarely
yields additional individuals.
Two specimens taken in the Cascade Mountains in September were pregnant;
one contained two embryos and the other four.
=Microtus longicaudus halli= Ellerman
_Microtus mordax angustus_ Hall, Univ. California Publ. Zoöl.,
37:13, April 10, 1931 (not of Thomas, 1908).
_Microtus longicaudus angustus_ Goldman, Jour. Mamm., 19:491,
November 14, 1938.
_Microtus mordax halli_ Ellerman, Fam. and Genera of Living
Rodents, British Mus. Nat. Hist., 2:603, March 21, 1941 (new name
for _Microtus mordax angustus_ Hall).
_Type._--Obtained at Godman Springs, 5,700 ft., Blue Mountains,
Columbia County, Washington, by S. H. Lyman, on September 1, 1927;
type in Museum of Vertebrate Zoölogy.
_Racial characters._--Size small; color of sides pale grayish
brown; brown dorsal stripe conspicuous; tail relatively short.
_Measurements._--Four males and 5 females from eastern Washington
average, respectively: total length 164.8, 166.6; length of tail
55.8, 55.8; hind foot 22.0, 21.4.
_Distribution._--From the Blue Mountains of southeastern
Washington north, along the eastern edge of the state, to British
Columbia, and thence west, north of the Columbia River, to the
Cascades, and south along the eastern edge of the Cascades to the
Wenatchee Mountains. Marginal occurrences are: Pasayten River
(Taylor and Shaw, 1929: 24), Hart Lake (Taylor and Shaw, 1929:
24), Blewett Pass (W.W.D.), Boulder Cave (W.W.D.), and Satus Pass
(W.W.D.).
_Remarks._--Four specimens from Satus Pass, Klickitat County, are
somewhat intermediate between this race and _macrurus_, and indicate
that _halli_ crossed the Columbia River when an alpine meadow land
extended from the Simcoe Anticline to southeastern Washington.
One specimen from Selah, Yakima County, is colored somewhat like
_halli_, and is smaller than _macrurus_. Possibly the _halli_ type of
meadow mouse spread northward to the Yakima Valley. This specimen was
taken in the Upper Sonoran Life-zone. A specimen from the Arid
Transition Zone at Naches, Yakima County (taken in almost Canadian
Life-zone habitat), is like _macrurus-halli_ intergrades from the higher
Cascade Mountains.
=Microtus longicaudus macrurus= Merriam
_Microtus macrurus_ Merriam, Proc. Acad. Nat. Sci. Philadelphia, p.
353, October 4, 1898.
_Microtus mordax macrurus_ Dice, Murrelet, 13:49, May, 1932.
_Microtus longicaudus macrurus_ Goldman, Jour. Mamm., 19:491,
November 14, 1938.
_Type._--Obtained at Lake Cushman, Mason County, Washington, by C.
P. Streator on June 26, 1894; type in United States National
Museum.
_Racial characters._--Size large; tail relatively long, almost as
long as head and body; color of upper parts dull brown; dorsal
stripe obscure; underparts gray.
_Measurements._--Two males and 4 females from the Olympic
Mountains and the coast of Washington, average, respectively:
total length 212.5, 220.5; length of tail 82.5, 86.8; hind foot
25.5, 24.7; ear 15.0, 13.7.
_Distribution._--The Olympic Mountains, the coast region of
western Washington, and the Cascade Mountains, save in the
southeastern part. Marginal occurrences are: Sauk (Taylor and
Shaw, 1929: 24), Tye (W.W.D.), Naches River (W.W.D.), and Wind
River (W.W.D.).
_Remarks._--Specimens from the Cascade Mountains are referred to
_macrurus_ but are intermediate between that race and _halli_.
=Microtus richardsoni= (De Kay)
Water rat
_Description._--This is the largest meadow mouse found in Washington. It
is too large to be called a mouse and the term water rat, applied to it
by Merriam, suits it well. It is the only Washington microtine measuring
more than 8 inches in total length. The upper parts are dark, reddish
brown in color; the underparts are grayish brown. The tail comprises
about one-third of the total length.
This species of meadow mouse ranges from Canada south to Colorado in the
Rocky Mountains and in the Cascades south into Oregon. The water rats
are strictly alpine animals, occurring about streams, marshes and damp
meadows. In the Cascade Mountains they are most common in the glacial
cirques where tiny streams flow through grassy meadows to plunge over
the lip of the cirque on a rocky course of cascades to the valley below.
Here their broad trails occur along the stream banks, commonly entering
the water where it is swift. These trails are well-worn roads, usually
about four inches wide but often wider. The burrows of the water rat are
about three inches in diameter and are constructed with no effort at
concealment; large mounds of earth mark their entrances. Freshly dug
burrows are so abundant that it seems likely more are dug than are
actually inhabited. Burrows are often dug beneath rocks.
The water rat is mainly nocturnal but not uncommonly is seen in the
daytime. Twice I cornered a water rat away from its burrow and each time
it escaped by swimming. The rats swam with great speed but with much
splashing. One dived under the surface of a small pool and disappeared.
Stones along the bank were pulled out until the rat was captured in a
small chamber at the end of a burrow. The burrow entered the bank at the
base of a large stone six inches beneath the surface. This burrow
resembled a miniature muskrat burrow and apparently had been dug when
the rat was under water.
Like _Phenacomys_, the water rat constructs sub-snow nests on the
surface of the ground. These are recognizable by their large size and by
piles of ovoid droppings a quarter of an inch in length. These nests are
loosely built and fall apart soon after the snow melts.
The water rat is sometimes a pest to the mammal collector for they
spring mouse traps set for other mammals without becoming caught. At
times the greater part of an entire trap line was thus rendered
ineffective by these mammals. Fully adult animals are uncommon in
collections for a rat trap or steel trap is needed to take them and
these items, when packed on back up mountains to water-rat habitat, are
usually set for still larger animals. Racey (Racey and Cowan, 1935: H27)
recounting his difficulty in securing specimens when no suitable traps
were at hand, writes: "Killed one with my hands, shot another, and a
third was stunned by a mouse trap."
Taylor and Shaw (1927: 76) list food eaten by the water rat on Mount
Rainier as the avalanche lily, dogtooth violet, _Ligusticum purpureum_,
_Valeriana sitchensis_, _Polygonum bistortoides_, _Petasites frigida_,
_Phyllodoce empetriformis_, _Potentilla flabellifolia_, _Aster_ sp.,
grass, wild clover, conifer seeds, two kinds of blueberry (_Vacinnium_)
and _Xerophyllum tenax_. Racey and Cowan (1935) list foods eaten in the
Cascades of southern British Columbia as _Lupinus polyphyllus_, _Senecio
balsamitae_, _Pedicularis bractiosa_ and _Arnica alpinus_.
A female from Dewey Lake, Yakima County, contained 4 embryos on
September 1, 1940. One from Tye, King County, had 2 embryos on September
8, 1940.
=Microtus richardsoni arvicoloides= (Rhoads)
_Aulacomys arvicoloides_ Rhoads, Amer. Nat., 28:182, February,
1894.
_Microtus richardsoni arvicoloides_ Bailey, N. Amer. Fauna, 17:62,
June 6, 1900.
_Type._--Obtained at Lake Keechelus, Kittitas County, Washington,
by A. Rupert in September, 1893. Rhoads gives the altitude as 8,000
ft. This apparently is an error, for the elevation of the lake is
2,458 ft. and the summit of Snoqualmie Pass, to the west, is 3,100
ft. Probably 3,000 ft. was intended; type in Philadelphia Academy
of Natural Sciences.
_Racial characters._--Size large; color of upper parts dark
reddish brown; underparts paler.
[Illustration: FIG. 117. Distribution of the water rat in Washington.
A. _Microtus richardsoni arvicoloides._ B. _Microtus richardsoni
macropus._]
_Measurements._--A female from Tomyhoi Lake, Whatcom County,
measured: total length 242; length of tail 68; hind foot 27; ear
17. A female from Tye, King County, measured: 257; 83; 26; 17.
_Distribution._--The Cascade Mountains, from Tomyhoi Lake (W.W.D.)
south to Potato Hill (Taylor and Shaw, 1929: 25).
=Microtus richardsoni macropus= (Merriam)
_Arvicola (Mynomes) macropus_ Merriam, N. Amer. Fauna, 5:60, July
30, 1891.
_Microtus richardsoni macropus_ Bailey, N. Amer. Fauna, 17:61,
June 6, 1900.
_Microtus richardsonii macropus_ Taylor and Shaw, Occ. Pap. Chas.
R. Conner Mus., no. 2:25, December, 1929.
_Type._--Obtained in the Pashimeroi Mountains, 9,700 ft., Custer
County, Idaho, by C. H. Merriam and V. Bailey in 1890; type in
United States National Museum.
_Racial characters._--Similar to _arvicoloides_ but slightly
smaller and redder.
_Measurements._--A female from Stay-a-while Spring, Columbia
County, measures: total length 228; length of tail 73; hind foot
25; ear 14.
_Distribution._--The Blue Mountains of southeastern Washington.
=Microtus oregoni oregoni= (Bachman)
Creeping mouse
_Arvicola oregoni_ Bachman, Jour. Acad. Nat. Sci. Philadelphia,
8:60, 1839.
_Microtus oregoni_ Miller, N. Amer. Fauna, 12:9, July 23, 1896.
_Microtus morosus_ Elliot, Field Columb. Mus. Publ. 30, zoöl.
ser., 1:227, February 1, 1899 (type from Boulder Lake, 5,000 ft.,
Clallam County, Washington).
_Microtus oregoni oregoni_ Miller, U. S. Nat. Mus. Bull., 79:227,
December 31, 1912.
_Microtus oregoni cantwelli_ Taylor, Jour. Mamm., 1:180, August
24, 1920 (type from Glacier Basin, 5,935 ft., Mt. Rainier, Pierce
County, Washington).
[Illustration: FIG. 118. Distribution of the creeping mouse, _Microtus
oregoni oregoni_, in Washington.]
_Type._--Obtained at Astoria, Clatsop County, Oregon, by J. K.
Townsend in 1836; type in Philadelphia Academy of Natural Sciences.
_Measurements._--Ten males and 10 females from southwestern
Washington, average, respectively: total length 133, 126; length
of tail 35, 32; hind foot 16.9, 16.7; ear 9.8, 9.7; weight 19.3,
19.1 grams.
_Distribution._--The Cascade Mountains, the Olympic Mountains, and
the lowlands of western Washington.
_Remarks._--A large series of topotypes of _Microtus o. oregoni_ in the
California Museum of Vertebrate Zoölogy, and the rather large series
from Cowlitz County, Washington, show a wide range of variation in
color, size, and cranial characters. Specimens from the Cascade and
Olympic Mountains seem to average a bit paler than topotypes of
_oregoni_, but are not worthy of recognition as distinct races. Too few
topotypes of _Microtus o. serpens_ from British Columbia are available
to judge the status of that race with any certainty, but specimens from
northwestern Washington are certainly _oregoni_.
_Description._--The creeping mouse is a small species of general
microtine form. The head and body measure about 4 inches and the tail
about 1-1/2 inches. The ears are small and the eyes tiny, nearly buried
in the fur. The fur is short and rather rough. It does not lie back
smoothly, thereby giving a woolly appearance. The upper parts are
reddish or grayish brown and the underparts are grayish white. The
nondescript appearance suggests a young rather than adult mouse.
The creeping mouse (subgenus _Chilotus_) is restricted to the Pacific
Coast and ranges from British Columbia to California. In Washington it
occupies almost every conceivable "mouse" habitat in its range,
including wet marshes, damp ravines, dry forest, damp, mossy forest,
meadows, alpine meadows and fields of short grass. It is rare in all but
the latter habitat. In fields of short or dry grass it is often
abundant. In the Cascade Mountains it was in relatively dry places along
streams or rock slides. Altitudinally it ranges from sea level to at
least 6,000 feet, and from the Humid Transition well into the Hudsonian
life-zones.
Creeping mice construct tiny tunnels among the grass roots and seldom
venture out of them. In suitable habitat the surface of the ground
beneath the grass is a maze of these tunnels, which cross, intersect,
and divide in a complex network. An observer standing in a field
occupied by creeping mice can scarcely conceive of the extent and
perfection of the tiny tunnel system at his feet.
Creeping mice lived but a day or two in captivity. Save for the bits of
grass blades left in their runways, little is known of their food or
other life habits. Their nests are round balls of dry grasses placed in
cavities under logs. None of the many examined possessed a lining of
softer materials. Embryos found in pregnant females from April 10 to May
18 numbered from 2 to 4.
=Lagurus curtatus pauperrimus= (Cooper)
Sagebrush vole
_Arvicola pauperrima_ Cooper, Amer. Nat., 2:535, December, 1868.
_Arvicola pauperrimus_ Merriam, N. Amer. Fauna, 5:64, July 30,
1891.
_L[agurus]. pauperrimus_ Thomas, Ann. and Mag. Nat. Hist., ser. 8,
9:401, April, 1912.
_Microtus pauperrimus_ Bailey, N. Amer. Fauna, 55:214, August 29,
1936.
_Lemmiscus pauperrimus_ Davis, Recent Mamm. Idaho, Caxton
Printers, p. 327, April 5, 1939.
_Lemmiscus curtatus pauperrimus_ Goldman, Proc. Biol. Soc.
Washington, 54:70, July 31, 1941.
_Type._--Obtained on the "Plains of the Columbia" near the Snake
River, southwestern Washington by J. G. Cooper on October 9, 1860.
Probably from the Bunchgrass Hills near Wallula (Old Fort Walla
Walla), Walla Walla County: type in United States National Museum.
_Measurements._--Bailey (1900: 69) gives the average of 3 adults
from the vicinity of Antelope, Oregon, as: total length 115;
length of tail 20; hind foot 16.
_Distribution._--Known in Washington only from the type and a
specimen from Badger Mountains, 8 miles southwest of Waterville
(Taylor and Shaw, 1929: 25).
_Remarks._--This rare vole is the smallest microtine rodent in
Washington. The head and body measure about 4 inches and the tail about
1 inch. The upper parts are grayish or yellowish brown and the
underparts grayish. The upper incisors are not grooved and the inner and
outer angles of the molars are about equal in length.
Mice of the genus _Lagurus_ occur in Siberia and in prairie areas of the
northwestern United States and Canada. The sagebrush vole inhabits the
Upper Sonoran Life-zone. It prefers upland areas of low sagebrush with
sparse grass. Poorly formed runways and small piles of feces indicate
its presence. The type of _Lagurus pauperrimus_ was obtained in
southwestern Washington 80 years ago, and a single additional record has
since been obtained. Nothing is known of its habits in Washington. The
life history of related forms has been reported on by Hall (1928:
201-204) from Nevada and Moore (1943: 188-191) from Oregon.
Davis (1939: 326) raised the subgenus _Lemmiscus_ Thomas (for American
forms) to generic rank and Goldman (1941: 69) accepted this usage.
Comparison of the Siberian and American species reveals but three
impressive differences: the dorsal stripe of the Siberian mice, the
greater development of prisms in the molars of the American species, and
the presence of cement in the angles of the molars of the Siberian
specimens and its lack in the American. These differences seem to be of
no more than subgeneric value. Goldman (1941: 69) showed that all
American _Lagurus_ belong to a single species.
=Ondatra zibethicus= (Linnaeus)
Muskrat
_Description._--The muskrat is a large aquatic rodent. Head and body
measure about 14 inches; the tail about 10 inches. The body is plump and
the head small. Eyes and ears are relatively small. The forefeet are
small and handlike with furred wrists. The hind feet are large with
webbed toes and naked wrists. The tail is narrow, constricted at the
base and flattened vertically. It is scaled and possesses scattered,
stiff hairs. The underfur is dense and soft. The guard hair is stiff and
shiny. The upper parts are rich, dark brown. The underparts are gray
washed with cinnamon.
[Illustration: FIG. 119. Muskrat (_Ondatra zibethicus osoyoosensis_),
male, Lake Washington, Seattle, October 13, 1939; weight 906 grams on
November 4, 1939. (Fish and Wildlife Service photo by Victor B.
Scheffer, No. 736.)]
Muskrats are found in Canada and the United States. They are lowland
animals, rarely ranging into the Canadian Life-zone. Their aquatic
habitat makes them relatively independent of temperature, and
consequently they occur in both the Transition and Upper Sonoran
life-zones.
The muskrat is well adapted to aquatic life. The toes of the large hind
feet are webbed at the base, the hind feet are turned slightly outward,
a fringe of stiff bristles at the rear edge of each foot furnishes
additional aid in swimming, and the laterally compressed tail makes it
an efficient rudder. In the water the surface of the fur flattens down
to entrap air in the dense underfur, keeping the body dry.
The typical habitat of the muskrat is slow-moving water or still water,
such as in lakes, ponds, marshes and sluggish rivers and streams.
Muskrats occur commonly, though not in large numbers, in more swiftly
moving streams. In Puget Sound and the San Juan Islands they occupy a
marine habitat.
In the extensive marshes along Lake Washington, King County, muskrats
are abundant. They occupy sluggish water, often water polluted by
garbage and sewage. In these marshes, banks suitable for the
construction of burrows are absent and houses are made of cattail stalks
and leaves. The food of these marsh-living muskrats consists principally
of cattail and other marsh vegetation.
In contrast to the marsh-occupying muskrats, muskrats along the open,
marsh-free shores of the lake live in deep clear water where waves lap
the shore. These muskrats live exclusively in burrows dug in the banks
and feed upon fresh-water mussels.
In still greater contrast were muskrats living 20 miles away, near
Cottage Lake, King County. Here we found them in small clear streams, 4
to 10 feet wide. Depth of the water varied from a few inches to three
feet. The streams flowed through meadows, pastures and junglelike,
deciduous woods. Muskrats were slightly more common along wooded
stretches than in open areas. Some were trapped where the streams flowed
at high velocity over shallow, gravel bottoms. The animals lived in
burrows and fed upon fresh-water mussels and a variety of plants.
Near Richmond Beach, Snohomish County, muskrats took up residence in a
small tidal pool along Puget Sound. The nearest fresh water stream large
enough to support a muskrat was two miles away. Two muskrats were
trapped here. Investigation of a tidal pool a mile to the north
disclosed unmistakable muskrat signs. Traps set in the culvert
connecting the pool with Puget Sound at high tide took several
specimens. Study showed that the muskrats were not living in the pool
but among the large boulders forming the breakwater for the Great
Northern Railroad, along the sound itself. They were feeding on marine
mussels (_Mytilus_). These mussels lived in the salt water of the sound,
not in the tidal pool.
At Peavine Pass, Blakely Island, in the San Juan Islands, muskrats were
living in the swift tidal current and deep, marine waters. Several were
seen in late afternoon. All were swimming parallel to the shore about 50
feet out. Here also they fed on _Mytilus_, but their homes were not
discovered. Certainly they were not living in the tidal pool at Flat
Point, a half-mile away.
In the interior of Blakely Island a colony of muskrats was discovered
living in a marsh of about one acre. In the rainy season the ground of
the marsh was covered with less than one inch of water. Residents said
that in the dry season springs kept the ground moist. Muskrats were
living in burrows whose entrances descended at a 45-degree angle and
were filled with water. The ground about some occupied burrows was dry,
the only water visible being in the burrow itself. A variety of marsh
vegetation provided food.
[Illustration: FIG. 120. Distribution of the muskrat in Washington.
A. _Ondatra zibethicus osoyoosensis._ B. _Ondatra zibethicus
occipitalis._]