by ungrooved teeth and slightly tapering, bicolor tail. Nearly every
part of North America is inhabited by one or more kinds of _Peromyscus_.
The single species, _maniculatus_, which occurs in Washington, ranges
from the Atlantic to the Pacific and from the Arctic to tropical Mexico.
Osgood (1909: 17) remarks: "... it is probable that a line, or several
lines, could be drawn from Labrador to Alaska and thence to southern
Mexico throughout which not a single square mile is not inhabited by
some form of this species."
Deer mice are the most abundant mice in Washington. They occur at sea
level on the ocean beaches and above timber-line, even breeding in the
Arctic-alpine Life-zone. They occur on the islands in Puget Sound, the
lowland marshes and deciduous thickets of western Washington, the great
conifer forests, the alpine cirques and mountain parks, and the deserts
of eastern Washington. Almost everywhere they are the commonest mammal
encountered. They make their homes in city dwellings, under logs or in
hollow trees in the forest, in the burrows of larger rodents and, if
necessary, in burrows of their own construction.
Nests are usually cup-shaped masses of soft material, 4 to 8 inches in
diameter with central cavities 2 to 3 inches in diameter. Materials
utilized include dry grass, shredded bark, rope, rags, newspaper, moss,
cattail fluff, fur, wool, and feathers. One nest discovered in the attic
of an old building near Coulee City, Grant County, consisted of the
mummified body of a wood rat (_Neotoma cinerea_). The fur of the arched
body of the rat formed one side of the nest, while the fur of the far
side of the body had been plucked to form the remainder. In the
extensive marshes along Lake Washington, King County, deer mice occupy
the ball-shaped nests of tule wrens (_Telamtodytes palustris_). These
are constructed entirely of fragments of cattail leaves and cattail
fluff and are placed in the cattail rushes about four feet above the wet
ground of the marsh. Other deer mouse nests were found in an unused
typewriter, in the pocket of an old coat, in a window frame, under a
piece of tar paper on the ground, in a cavity in the ground under a
board, between a ceiling and a loose bit of roofing paper, under rocks
and logs, in hollows in logs, and in an unused nest of a wood rat. Where
plant cover is dense, nests are placed on the surface of the ground, as
under thick growths of tumbleweed (_Salsola_) in eastern Washington.
Deer mice are definitely nocturnal. Of thousands of specimens trapped
only a few were taken in the daytime. Two of these were taken in a rock
slide at Pass Creek Pass, Pend Oreille County, on the same day, and some
unusual conditions may have incited them to travel in daylight. Deer
mice are active throughout the winter and their lacy footprints are seen
on the snow in below-freezing weather. They are mainly terrestial but
one race (_oreas_) is at least partly arboreal for it is often taken in
traps set in trees for flying squirrels. One was caught in a trap set 50
feet from the ground. All are good climbers, and _oreas_ is perhaps the
best. One was watched as it climbed the rough cedar shake wall of a
cabin, ran upside-down across three feet of rough ceiling, and
descended the opposite wall head first. They are equally agile in
climbing rocks and cliffs.
The ordinary gait of the deer mouse is a steady run. When frightened it
may leap a distance of one foot or more. When surprised in its nest it
usually remains in the vicinity, hopping about in confusion, returning
time after time to the exposed nest.
The food of deer mice consists principally of vegetable material such as
seeds, nuts, berries, and the soft parts of fleshy plants. Mushrooms and
lichens are eaten. Insect remains are present in small quantities in
most stomachs examined. Flesh is also eaten and small mammals caught in
traps are often eaten by deer mice. Cannibalism appears to be common
only in captivity.
[Illustration: FIG. 107. Distribution of the deer mouse in Washington.
A. _Peromyscus maniculatus oreas._ B. _Peromyscus maniculatus
austerus._ C. _Peromyscus maniculatus hollisteri._ D. _Peromyscus
maniculatus gambelii._ E. _Peromyscus maniculatus artemisiae._]
Deer mice are often heavily parasitized by tapeworms and roundworms.
Virtually all of the deer mice taken on Jones Island in the San Juan
Islands had livers so infected by the eggs of a nematode worm as to be
swollen to several times their natural size, and had a yellow,
crystalline appearance. The maggots of parasitic flies often occur in
the anal and genital region of deer mice, effectively sterilizing some
individuals.
Predatory snakes, birds, and mammals doubtless kill and eat deer mice.
Strangely enough, although deer mice may be the commonest mammal in an
area, the pellets of owls collected in the same area usually contain the
remains of relatively few deer mice. The impact of owls seems to be
greatest upon mice, such as _Microtus_, which follow definite runways.
The breeding season of the deer mouse extends over most of the spring
and summer. Growth and development of the young of _Peromyscus m. oreas_
have been discussed by A. Svihla (1936A). Embryos found varied in number
from 2 to 8 with a mean of 4.5.
=Peromyscus maniculatus oreas= Bangs
_Peromyscus oreas_ Bangs, Proc. Biol. Soc. Washington, 12:84, March
24, 1898.
_Peromyscus akeleyi_ Elliot, Field Columb. Mus. Publ. 30., zoöl.
ser., 1:226. February 1, 1899 (type from Elwha River, Olympic
Mountains, Washington).
_Peromyscus maniculatus oreas_ Osgood, N. Amer. Fauna, 28:51,
April 17, 1909.
_Type._--Obtained on Church Mountain, 6,500 ft., Mt. Baker Range,
near the U. S. boundary, British Columbia, by Allan Brooks on
August 29, 1896; type in Museum of Comparative Zoölogy.
_Racial characters._--Size large; tail more than 50 per cent of
total length; color of upper parts reddish.
_Measurements._--Twenty-five males and 15 females average: total
length 202; length of tail 110; hind foot 22.6; ear 18.7.
_Distribution._--From the Cascade Mountains west to the Pacific
Ocean, save for the Puget Sound area and a narrow band extending
southward nearly to the Columbia River. Marginal localities along
the west side of Puget Sound are: Deer Park (W.W.D.), Lake Cushman
(W.W.D.), and Kelso (M.V.Z.). Marginal localities on the west side
of the Cascade Mountains are: Tomyhoi Lake (W.W.D.), Forks of
Skykomish River (W.W.D.), North Bend (W.W.D.), Mt. St. Helens
(V.B.S.) and Yacolt (M.V.Z.). Marginal localities on the east
slope of the Cascade Mountains are: Grouse Creek (W.W.D.), Lake
Wenatchee (W.W.D.), Easton (W.W.D.), Morrison Springs Ranger
Station (W.W.D.) and Wind River C.C.C. Camp (W.W.D.).
=Peromyscus maniculatus hollisteri= Osgood
Peromyscus maniculatus hollisteri Osgood, N. Amer. Fauna, 28:62,
April 17, 1909.
_Type._--Obtained at Friday Harbor, San Juan Island, San Juan
County, Washington, by N. Hollister on October 23, 1903; type in
United States National Museum.
_Racial characters._--Similar to _oreas_ but darker, less reddish,
and with much shorter tail. Length of tail about 40 per cent of
total length.
_Measurements._--Populations of deer mice on the various islands
vary slightly in average measurements. The average measurements of
10 males and 10 females from San Juan Island, 20 males and 15
females from Blakeley Island, and 20 males and 15 females from
Cypress Island, are respectively: total length 189, 183, 179;
length of tail 87, 82, 79; hind foot 22.8, 22, 19.5; ear 19.4,
18.7, 19.5; weight 33, 29, 32 grams.
_Distribution._--The San Juan Islands, San Juan and Skagit
counties, in northern Puget Sound.
=Peromyscus maniculatus austerus= (Baird)
_Hesperomys austerus_ Baird, Proc. Acad. Nat. Sci. Philadelphia,
7:336, 1855.
_Sitomys americanus austerus_ Allen, Bull. Amer. Mus. Nat. Hist.,
5:192, August 18, 1893.
_P[eromyscus]., austerus_ Bangs, Amer. Nat., 31:75, January 1,
1897.
_Peromyscus maniculatus austerus_ Osgood, N. Amer. Fauna, 28:63,
April 17, 1909.
_Type._--Obtained at Old Fort Steilacoom, Pierce County,
Washington, by J. G. Suckley, probably on January 20, 1854; type in
United States National Museum.
_Racial characters._--Similar to _oreas_ but smaller with
relatively shorter tail; tail narrower at base, less sharply
bicolor; upper parts duller, browner, less reddish. In _oreas_ the
tail is usually more than 100 mm. In _austerus_ the tail is
usually less than 90 mm.
_Measurements._--Twenty-seven males and 23 females from Seattle,
King County, average: total length 180.5; length of tail 88.6;
hind foot 21; ear 18. The average weight of 15 adults is 21 grams.
_Distribution._--The Puget Sound area and south to the Columbia
River in a narrow band through the lowlands. Marginal localities
on the west side of Puget Sound are: Port Angeles (W.W.D.),
Bremerton (W.W.D.), 4 miles north of Shelton (W.W.D.), Tenino
(W.W.D.) and Mouth of Klama River (M.V.Z.). Marginal localities on
the east side of Puget Sound are: Bellingham (W.W.D.), Arlington
(W.W.D.), Everett (W.W.D.), 4 miles east of Monroe (W.W.D.), Fall
City (W.W.D.), and Vancouver (W.W.D.).
=Peromyscus maniculatus rubidus= Osgood
_Peromyscus oreas rubidus_ Osgood, Proc. Biol. Soc. Washington,
14:193, December 12, 1901.
_Peromyscus maniculatus rubidus_ Osgood, N. Amer. Fauna, 28:65,
April 17, 1909.
_Type._--Obtained at Mendocino City, California, by J. A. Loring on
November 17, 1897; type in United States National Museum.
_Racial characters._--Closely similar to _austerus_ but paler with
longer skull. Specimens from Washington are almost purplish-brown
in appearance.
_Measurements._--Six males and 2 females from Puget Island,
Wahkiakum County, average: total length 177; length of tail 89;
hind foot 21.9; ear 18.7.
_Distribution._--This is the deer mouse of the humid coastal belt
of Oregon and California. It enters Washington only at Puget
Island, Wahkiakum County, in the Columbia River.
=Peromyscus maniculatus gambelii= (Baird)
_Peromyscus gambelii_ Baird, Mamm. N. Amer., Pacific R. R. Reports,
8:464, 1857.
_Sitomys americanus gambelii_ Allen, Bull. Amer. Mus. Nat. Hist.,
5:190, August 18, 1893.
_P[eromyscus]., t[exanus]. gambelii_ Mearns, Proc. U. S. Nat.
Mus., 18:446, March 25, 1896.
_Peromyscus maniculatus gambeli_ Osgood, N. Amer. Fauna, 28:67,
April 17, 1909.
_Type._--Obtained at Monterey, Monterey County, California, by W.
P. Trowbridge; skin catalogued on January 4, 1853; type in United
States National Museum.
_Racial characters._--Size small; tail short; color pale, varying
from buffy gray to rich buff; rarely dark reddish brown.
_Measurements._--Twenty-five males and 15 females average: total
length 160; length of tail 71; hind foot 19.8; ear 17.7.
_Distribution._--The Columbian Plateau. Intergradation with
_oreas_ occurs between the Columbia River and the Cascade
Mountains. Marginal records on the west are: Chelan (W.W.D.),
Leavenworth (W.W.D.), Cle Elum (W.W.D.), Satus Pass (W.W.D.), Lyle
(V.B.S.). Marginal localities on the north are: Chelan (W.W.D.), 5
miles north of Coulee (W.W.D.), Sprague (V.B.S.) and Steptoe Butte
(M.V.Z.).
=Peromyscus maniculatus artemisiae= (Rhoads)
_Sitomys americanus artemisiae_ Rhoads, Proc. Acad. Nat. Sci.
Philadelphia, p. 260, October 23, 1894.
_Peromyscus texanus artemisiae_ Miller and Rehn, Proc. Boston Soc.
Nat. Hist., 30:84, December, 1901.
_Peromyscus maniculatus artemisiae_ Osgood, N. Amer. Fauna, 28:58,
April 17, 1909.
_Type._--Obtained at Ashcroft, British Columbia, by S. N. Rhoads on
July 5, 1892; type in Philadelphia Academy of Sciences.
_Racial characters._--Similar to _gambelii_ but darker, more
reddish; often with longer tail.
_Measurements._--Ten males and 10 females from northeastern
Washington average: total length 167; length of tail 80; hind foot
20; ear 17.8.
_Distribution._--Northeastern Washington and the Blue Mountains of
southeastern Washington, extending west, in northeastern
Washington, to Conconully (W.W.D.) and south to Duly Lake
(W.W.D.).
=Neotoma cinerea= Ord
Bushy-tailed wood rat
_Description._--The bushy-tailed wood rat is slightly larger than the
common Norway or brown rat. The head and body measure about 12-1/2
inches and the tail about 3-1/2 inches. It resembles the deer mouse in
general proportions. The ears are large and naked and the black eyes are
large and protruding. The tail is bushy, squirrel-like. The feet are
small and have furry soles. The fur is soft and silky. Adults are
brownish gray above with white underparts and a gray tail. Young
individuals have blue-gray upper-parts.
Wood rats range over most of North America. They exhibit great
variation, especially in the southwestern United States. The
bushy-tailed species occurs in the western United States and Canada.
Wood rats are notorious for invading buildings in the mountains and in
the desert. However, their natural habitat is broken rock or talus. This
habitat preference accounts for their distribution in Washington, for
talus is common except in the humid subdivision of the Transition
Life-zone. Wood rats are probably most abundant in the talus slides of
the Columbian Plateau, especially in the canyon of the Columbia River
and in Moses and Grand coulees. They are common in all the mountainous
areas in the state where high altitudes and steep slopes result in the
accumulation of talus. Wood rats range from sea level to 10,000 feet
elevation on Mount Rainier and from the Upper Sonoran to the
Arctic-alpine life-zones. Great horned owls and probably all of the
carnivores that share the range of the wood rat prey on it to some
extent. Sperry (1941: 15) lists _Neotoma_ in four per cent of 8,339
coyote stomachs gathered throughout the United States.
Wood rats in Washington are definitely nocturnal and are rarely seen in
daylight. On January 10, 1939, however, near Colville, Stevens County, a
companion and I were sitting on the porch of a deserted shack eating
lunch. Suddenly a wood rat darted out of the open door into the full
sunlight and tugged at a can, containing a few drops of tomato juice,
which one of us was holding in his hand. When the rat looked up and saw
the human, it hastily retreated. The wood rat has a habit of flattening
its body tightly against the ground when observed and also of "drumming"
with its feet when excited. This habit is shared by the snowshoe rabbit
and the spotted skunk. A captive specimen "drummed" by lifting its back
feet, alternately, about one-half inch from the surface of a piece of
wood and striking downward with surprising power. The agility of the
wood rat was demonstrated near Wallula where we watched a specimen by
the light of a flashlight as it climbed an almost vertical rock wall,
taking advantage of small fractures for toe-holds.
Wood rats are far from noiseless in their nocturnal activities. Near
Moses Coulee, Douglas County, wood rats were heard from a distance of 50
feet as they scampered back and forth through a concrete culvert under
the highway.
Many species of wood rats build complicated stick houses in which they
live. In Washington, elaborate stick houses are sometimes built but are
usually not occupied. In the attic of an old building near Pend Oreille
Lakes, Stevens County, two large and complicated houses were discovered.
These were built of sticks, paper and other debris and measured more
than three feet in diameter. Three small, cup-shaped nests resembling
those of a bird, made of soft grasses, moss, and shredded paper were
found on the attic floor ten feet or more from the stick houses. These
nests gave every indication of being used, while the piles of sticks
contained no nests and seemed never to have been occupied. Near Moses
Lake, Grant County, a wood rat house built in the rafters of an old shed
was constructed entirely of tumbleweeds (_Salsola pestifer_). This house
was spherical in shape and measured more than five feet in diameter. It
appeared to be unoccupied and a wood rat, probably its builder, was
living under the floor of the shed. Most wood rat houses consist of a
half-dozen sticks arranged in a crevice in a rock pile or a cave. Wood
rats were placing fresh material on a house in the Wenatchee National
Forest on January 17, 1939, when there was two feet of snow on the
ground and the temperature was hovering around zero. The house measured
about one cubic yard and consisted of _Ceanothus_ leaves and steins,
with some twigs of fir (_Abies_). It was built under a bunk in a
broken-down cabin left by deer hunters.
The collecting habit of the wood rat has gained it the name "pack-rat."
Taylor (1920A: 91) lists the following materials from a wood rat nest on
Mt. Rainier: _Nesting material_: rags, leaves, paper, thumb of a glove,
string, thongs, oakum; _Food_: apple core, onion peel, bacon rind,
raisins, 10 bars of chocolate, figs, puff balls, bread crust, meat
scraps, cantaloupe rind, potatoes, dried apricots, lemons, mushrooms,
beans, peanuts, banana, 15 lumps of sugar; _Miscellaneous_: dime, coffee
can cover, paraffin from jelly glass, bones, 19 pieces of candles and
several cakes of soap.
As a rule only one or two wood rats are trapped at a given locality,
indicating that the species is not gregarious. The presence of wood rats
in a building, cave, mine tunnel, or talus slide can be detected in
several ways. The white, mineral-like incrustation formed by the urine
of many generations of wood rats is usually conspicuous on rocks near
their homes. A strong musky odor pervades the atmosphere in every
habitat occupied by wood rats. Wood rat feces, consisting of hard, black
cylinders one-half inch long and three-sixteenths of an inch in
diameter, are invariably found scattered on stones or exposed areas of
ground.
[Illustration: FIG. 108. Distribution of the bushy-tailed wood rat in
Washington. A. _Neotoma cinerea occidentalis._ B. _Neotoma cinerea
alticola._]
The food of the bushy-tailed wood rat is varied and includes insects and
vegetation. A captive specimen that escaped in the University of
Washington Zoölogical Laboratories killed and ate a number of lizards.
Embryos found from April 18 to June 14 varied in number from 3 to 5.
=Neotoma cinerea occidentalis= Baird
_Neotoma occidentalis_ Baird, Proc. Acad. Nat. Sci. Philadelphia,
p. 335, 1855.
_Neotoma cinerea occidentalis_ Merriam, N. Amer. Fauna, 5:58, July
30, 1891.
_Type._--Obtained at Shoalwater Bay (Willapa Bay), Pacific County,
Washington, by J. G. Cooper, in June, 1854; type in United States
National Museum.
_Racial characters._--Size large; color of upper parts cinnamon
brown.
_Measurements._--A male and a female from Glade Creek, 1/2 mile
north of the Columbia River, Benton County, measure, respectively:
total length 425, 395; length of tail 181, 176; hind foot 50, 44;
ear 32, 31; weight 532.5, 330.0 grams.
_Distribution._--Throughout the state except in the Blue
Mountains.
_Remarks._--Specimens from the Olympic Mountains and western Washington
are slightly duller-colored than specimens from eastern Washington and
young from western Washington are more bluish, less gray, than young
individuals from the Columbian Plateau. The specimens from the Columbian
Plateau show some resemblance to _alticola_. Specimens from northeastern
Washington are more like typical _occidentalis_.
=Neotoma cinerea alticola= Hooper
_Neotoma cinerca alticola_ Hooper, Univ. California Publ. Zoöl.,
42:409, May 17, 1940.
_Type._--Obtained at Parker Creek, 5,500 ft., Warner Mountains,
Modoc County, California, by N. B. Stern on June 22, 1916; type in
Museum of Vertebrate Zoölogy.
_Racial characters._--Similar to _Neotoma c. occidentalis_ but
slightly paler, with paler hind feet and narrower sphenopalatine
vacuities.
_Measurements._--A female from Stay-a-while Spring, Columbia
County, measures: total length 387; length of tail 171; hind foot
43; ear 33; weight 330 grams.
_Distribution._--Southeastern Washington, south of the Snake
River.
_Remarks._--The only adult specimen available from the Blue Mountains
shows well the characters attributed to _alticola_.
=Synaptomys borealis wrangeli= Merriam
Northern lemming mouse
_Synaptomys (Mictomys) wrangeli_ Merriam, Proc. Biol. Soc.
Washington, 10:63, March 19, 1896.
_Synaptomys (Mictomys) truei_ Merriam, Proc. Biol. Soc.
Washington, 10:62, March 19, 1896 (type from Skagit Valley, Skagit
County, Washington).
_Synaptomys borealis wrangeli_ Howell, N. Amer. Fauna, 50:26, June
30, 1927.
_Type._--Obtained at Wrangel, Alexander Archipelago, Alaska, by C.
P. Streator on September 6, 1895; type in United States National
Museum.
_Racial character._--Dark color.
_Distribution._--The northwestern Cascades, from Mt. Baker
northward.
_Remarks._--The relationship of this race to _artemisiae_ remains
to be worked out.
[Illustration: FIG. 109. Distribution of the northern lemming mouse in
Washington. A. _Synaptomys borealis wrangeli._ B. Possible range of
_Synaptomys borealis artemisiae_.]
_Description._--Lemming mice may be recognized by their short, thick
bodies, slightly larger than the bodies of the common house mouse
(_Mus_); short tails, which are less than 20 per cent of their total
length; small, inconspicuous ears; and grooved upper incisors.
Mice of the genus _Synaptomys_ range over much of boreal North America.
Two species and eleven races are recognized by Howell (1927B: 9).
_Synaptomys borealis_ ranges westward across Canada from Labrador to the
Pacific Coast and from Alaska south to Washington. The lemming mice are
terrestrial and inhabit runways similar to those of meadow mice
(_Microtus_). They are alpine in distribution. Shaw (1930: 7-10) found
them among typical annual herbs in a cold, boggy mountain valley. Other
than this, nothing is known of the species in Washington. Indeed little
is known of the life history of any member of the genus.
The lemming mouse possesses four pairs of mammae, two pectoral and two
inguinal. It is the most primitive of the microtines. It seems to be of
boreal origin but is not known from the Old World. It was evidently
forced southward by the Pleistocene glaciers into Washington and is now
retreating northward in the wake of the ice. The only specimens recorded
from Washington are from the northern border of the state.
=Phenacomys intermedius= Merriam
Heather vole
_Description._--Heather voles are heavy-bodied, short-legged mice,
closely similar in general appearance to other microtines that occur in
Washington. Their dull, brownish upper parts, lacking a distinct reddish
dorsal stripe, separate them from the red-backed mice (_Clethrionomys_)
and the lack of grooves on their upper incisors separates them from
_Synaptomys_. Their relatively short tail (30 per cent or less of their
total length) separates them from most meadow mice (_Microtus_). There
are no external characters which serve to separate them from all species
of _Microtus_ and the teeth must be examined certainly to identify
_Phenacomys_. In _Microtus_ the angles between the cusps of the inner
and outer sides of the lower molars are of approximately equal depth,
but in _Phenacomys_ the angles on the inner side of the lower molars are
at least twice as deep as those of the outer side of the jaw. In
addition the molars of _Phenacomys_ are rooted while those of _Microtus_
are not.
The heather voles and their relatives are primitive microtines that
range through boreal North America including the higher parts of the
Rocky Mountains and the cool area along the Pacific Coast. Several
species are included in the genus: an arctic form (_ungava_), a lowland
Pacific Coastal species (_albipes_), two tree-inhabiting species
(_longicaudus_ and _silvicola_) and a mountain species (_intermedius_).
Thus far only _intermedius_ has been found in Washington but further
search may reveal that one or more of the arboreal species and possibly
_albipes_ are also present.