enter a vertical bank 6 to 15 inches below water line and occasionally 3
feet below it. About half the burrows excavated near Lake Washington,
King County, had a single entrance. About 40 per cent had double or
triple entrances situated 2 to 3 feet apart and converging within a yard
to a single burrow. About 10 per cent had double burrows more than 3
feet in length. Burrows were from 5 to 8 inches in diameter. Nest
chambers were from 12 to 15 inches in diameter, spherical, and from 6 to
30 feet from the burrow entrance. The nests themselves were bulky, loose
masses of cattail leaves. Embryos found in late February and early
March numbered 4 to 8.
Because it is abundant, widely spread and easy to trap, the muskrat is
one of the most important fur bearers in the state. The fur is
relatively stable in value. In recent years the average skin has brought
the trapper slightly less than a dollar. Muskrat flesh is eaten and sold
on the market in the eastern United States but has never been popular in
Washington. The muskrat does little damage to agriculture, most
complaints arising from its burrows which interfere with irrigation
ditches.
=Ondatra zibethicus osoyoosensis= (Lord)
_Fiber osoyoosensis_ Lord, Proc. Zoöl. Soc. London, p. 97, 1863.
_F[iber]. z[ibethicus]. osoyoosensis_ Hollister, Proc. Biol. Soc.
Washington, 23:1, February 2, 1910.
_Ondatra zibethica osoyoosensis_ Miller, U. S. Nat. Mus. Bull.,
79:231, December 31, 1912.
_Type._--Obtained at Osoyoose Lake, British Columbia, on British
Columbia-Washington boundary at head of Okanogan River, by J. K.
Lord, in 1861 or 1862.
_Racial characters._--Color of the upper parts rich, dark brown.
_Measurements._--Two males and a female from Seattle, King County,
average and measure respectively: total length 565, 555; length of
tail 262, 257; hind foot 80.5, 79; weight 2 pounds 13 ounces and 2
pounds 3 ounces.
_Distribution._--Eastern Washington generally and all but the
southern part of western Washington. Specimens from as far
southwest as Tenino (W.W.D.) are typical of _osoyoosensis_.
=Ondatra zibethicus occipitalis= (Elliot)
_Fiber occipitalis_ Elliot, Field Columb. Mus. Publ. 74, zoöl.
ser., 3:162, April, 1903.
_Ondatra zibethica occipitalis_ Miller, U. S. Nat. Mus. Bull.,
79:231, December 31, 1912.
_Type._--Obtained at Florence, Lane County, Oregon, by E. Heller,
in 1901; type in Chicago Natural History Museum.
_Racial characters._--Similar to _osoyoosensis_ but redder; fur
shorter and interpterygoid spaces of skull narrower.
_Measurements._--A male from Chinook, Pacific County, measures:
total length 580; length of tail 248; hind foot 78; ear 21; weight
863 grams.
_Distribution._--The southwestern corner of the state, extending
north to Aberdeen (V.B.S.) and east to Cathlamet (V.B.S.).
=Rattus rattus= (Linnaeus)
Roof rat
_Description._--Size large, total length approximately 400 mm.; tail
long, naked, comprising 50 per cent or more of total length; color sooty
black or brown; in brown phase, whitish beneath.
The roof rat became established in Central America some 350 years ago,
and entered the United States (English Colonies) late in the seventeenth
century. Subsequent to the introduction of the Norway rat the roof rat
decreased in numbers and is now found only in restricted areas.
=Rattus rattus rattus= (Linnaeus)
_[Mus] rattus_ Linnaeus, Syst. Nat., 1 (ed. 10):61, 1758.
_Rattus rattus_ Hollister, Proc. Biol. Soc. Washington, 26:126,
June 6, 1916.
_Type._--From Uppsala, Sweden.
_Remarks._--In Washington I have taken specimens of the roof rat in the
San Juan Islands and in the coniferous forests on the west slope of the
Cascades. In the latter area it seems to be widely spread and to live in
the wild.
=Rattus rattus alexandrinus= (Geoffroy)
_Mus alexandrinus_ Geoffroy, Catal. Mam. du Mus. Nat. d'Hist. Nat.
Paris, p. 192, 1803.
_R[attus]. rattus alexandrinus_ Hinton, Jour. Bombay Nat. Hist.
Soc., 26:63, December 20, 1918.
_Type._--From Alexandria, Egypt.
_Remarks._--This subspecies seems to be rare in Washington. My specimens
are all from small, isolated islands in the San Juan group. All were
taken in the vicinity of human habitations. _R. r. alexandrinus_
resembles _R. r. rattus_, differing only in brown color of upper parts.
=Rattus norvegicus norvegicus= (Erxleben)
Norway rat
_[Mus] norvegicus_ Erxleben, Syst. Regni Anim., 1:381, 1777.
_Rattus norvegicus_ Hollister, Proc. Biol. Soc. Washington,
29:126, June 6, 1916.
_Type._--From Norway.
_Description._--Larger, heavier-bodied and coarser-furred than the
black rat or roof rat with shorter, heavier tail. The tail is less
than 50 per cent of the total length. The color of the back is
dull, reddish brown, the sides are paler and the underparts are
dirty gray.
_Remarks._--The Norway rat was absent from the Pacific Coast of the
United States before 1851. It probably reached the coast slightly after
that date. It is common about all large cities in Washington. In the
western part of the state it lives along streams and marshes under feral
conditions.
=Mus musculus= Linnaeus, subsp?
House mouse
_[Mus] musculus_ Linnaeus, Syst. Nat., 1 (ed. 10):62, 1758.
_Description._--Size small; tail about 50 per cent of total length,
naked; ears small, about 12 mm. in height; upper incisors not grooved;
color of upper parts reddish or grayish brown; underparts brown or gray.
_Remarks._--The house mouse became established in North America soon
after its settlement by Europeans. It is now common throughout the state
of Washington, principally near human habitations, but often lives in
the wild.
Races of the house mouse have been dealt with by Schwartz and Schwartz
(1943: 59-72), and by Nichols (1944: 82-89), but lack of adequate
material prevents subspecific identification of house mice from
Washington at this time.
=Aplodontia rufa= (Rafinesque)
Mountain beaver
_Description._--The mountain beaver is a stout-bodied animal about 14
inches in length, with a tiny tail that is almost invisible externally.
The head is large, wide and low with small eyes, small ears and long
vibrissae. The legs are short and heavy, but the forefeet are small and
handlike; the hind feet are large and powerful. The claws of both
forefeet and hind feet are long and strong. The pelage is short, coarse
and rough. The upper parts are dark reddish brown and the underparts are
grayish brown. The feet are pink.
[Illustration: FIG. 121. Mountain beaver (_Aplodontia rufa rufa_),
Seattle, Washington, March 19, 1940. (Fish and Wildlife Service photo
by Victor B. Scheffer, No. 919.)]
Mountain beavers are confined to the Pacific Coast and range from
southern British Columbia to central California. The genus contains a
single species of which Taylor (1918) recognized nine races. The
principal habitat of the mountain beaver is clearings at the edge of
coniferous forests. The animals are most abundant near springs, streams
and damp places, although they are not aquatic. The tangled jungles of
deciduous trees and shrubs that grow in the ravines and stream valleys
of the Puget Sound area present optimum habitat. They occur also on
hillsides, on logged-off land and along roadside clearings. In the
mountains they occur in thickets and forests, always, in our experience,
near streams.
The most conspicuous evidence of the presence of mountain beavers is
their burrows. These are large tunnels, four to eight inches in
diameter. To each set of tunnels there are numerous entrances, some
partly concealed in brush or beside logs or stumps, and some are in the
open. Those in the open are less used as entrances than as places for
receiving the loose earth which the animals excavate. A pile may contain
nearly a cubic yard of earth and stones. Many of the burrows are
shallow, and cave-ins are common. Breaks in the roof of a burrow are not
repaired, although debris is removed from the burrow itself. The burrows
seem not to be constructed according to a system, but are extended to
take in whatever brush, logs or other cover is available. They are
commonly dug through damp or muddy soil. Small streams flow through some
burrows. Such partly flooded runs seem to be favored by the animals.
The nest of a mountain beaver excavated by Scheffer (1929: 15), under
the roots of a fallen tree, was oval in shape, twenty inches high and 13
inches wide. The nest was protected from flooding by a basal chamber, or
basin, six inches beneath the nest. Two drainage tunnels lead away from
this basal chamber. The nest was composed of the leaves and stems of
bracken laced together with grass and fine twigs. Two other nests
examined by Scheffer measured 17 by 18 inches and 19 by 17 inches. Both
were about two feet beneath the surface.
Around Puget Sound the mountain beavers mate in early March. The young
number two to three, rarely four, per litter and are born in early
April.
Mountain beavers enter water readily but wade rather than swim. They are
rather noisy, splashing in water and breaking twigs or rustling leaves
on the ground. They climb bushes and saplings, clipping off branches for
food as they ascend. According to Scheffer (1929: 15) they leave the
stubs of branches attached to the trunk to facilitate their descent.
Twice a mountain beaver was found several feet up in a sapling. In both
saplings the animal had clipped the branches close to the trunk and was
desperately reaching with its hind feet for missing branches. When the
observer came near, one animal squealed, tumbled to the ground, and
scurried frantically to its burrow.
Although principally nocturnal, mountain beavers are not infrequently
active by day, especially in the fall. At this season they harvest food
and spread it on logs to dry. The cured hay is removed to their burrows
for nesting material and food. In winter mountain beavers are more
restricted in habits and are rarely seen by day. Presumably they feed on
stored food at this time but they forage somewhat. In winter they eat
such evergreen shrubs as salal (_Gaultheria shallon_) and Oregon grape
(_Berberis nervosa_). They eat also the bark of trees, especially that
of the willow (_Salix_). Under cover of snow, in the mountains, they
burrow to some extent and pack excavated earth in snow burrows. The
melting of the snow in the spring reveals the earth core, six to eight
inches in diameter and two to four feet long. Several such earth cores
were forked, showing that part of the earth had been pushed into a
branching burrow.
[Illustration: FIG. 122. Distribution of the mountain beaver in
Washington. A. _Aplodontia rufa rufa._ B. _Aplodontia rufa rainieri._]
The mountain beaver holds its food in its forefeet, squirrel-like, when
it eats. Its food consists of the leaves and bark of woody plants and
entire herbs, including roots. The mountain beaver is the only mammal so
far as known that eats the bracken fern. It feeds on the branches of
coniferous trees, including Douglas fir, red cedar, and hemlock. Such
thorny species as the blackberry, blackcap and devil's club are eaten.
The odiferous skunk cabbage and the stinging nettle are on its bill of
fare. A list of its food would include most plants found in its habitat,
and we know of no species that it refuses as food.
The mountain beaver is more of a nuisance than a pest. In most of its
range there is but little farming although where crops are raised the
mountain beaver may do some damage. It undermines roads and trails and
defiles springs and streams. Control is simple for the animals readily
enter steel traps set in their burrows.
=Aplodontia rufa rufa= (Rafinesque)
_Anisonyx? rufa_ Rafinesque, Amer. Monthly Mag., 2:45, November,
1817.
_Haplodon rufus_ True, Proc. U. S. Nat. Mus., 7 (1884):596, 1885.
_Aplodontia rufa_ Merriam, Ann. New York Acad. Sci., 3:316, May,
1886.
_Aplodontia olympica_ Merriam, Proc. Biol. Soc. Washington, 13:20,
January 31, 1899 (type from Lake Quiniault, Grays Harbor County,
Washington).
_Aplodontia rufa grisea_ Taylor, Univ. California Publ. Zoöl.,
12:497, May 6, 1916 (type from Renton, King County, Washington).
_Aplodontia rufa rufa_ Taylor, Univ. California Publ. Zoöl.,
12:497, May 6, 1916.
_Type._--None. Based on a description by Lewis and Clark. Taylor
(1918: 455) regarded as typical specimens collected at "Marmot,
Clackamas County, Oregon (western slope of Mount Hood, not far from
the Columbia River)."
_Racial characters._--Size small; skull small.
_Measurements._--Eight males and 7 females, from the area about
Puget Sound, average, respectively: total length 343, 338; length
of tail 37.5, 33.5; hind foot 57.8, 56; ear 25, 24.5; weight 1342,
1300 grams.
_Distribution._--Western Washington, between Puget Sound and the
Cascade Mountains and southward. Marginal localities are:
Bellingham (U.S.N.M.), Sauk (U.S.N.M.), Forks of Skykomish River
(W.W.D.), North Bend (U.S.N.M.), and mouth of Klama River
(M.V.Z.).
_Remarks._--Individual variation in mountain beavers is considerable.
Two weakly defined races are recognized in Washington.
=Aplodontia rufa rainieri= Merriam
_Aplodontia major rainieri_ Merriam, Proc. Biol. Soc. Washington,
13:21, January 31, 1899.
_[Haplodontia rufa] raineri_ Elliot, Field Columb. Mus. Publ. 45,
zoöl. ser., 2:112, 1901.
_[Aplodontia rufa] raineri_ Trouessart, Catal. Mamm., viv. foss.,
suppl. p. 348, 1904.
_Aplodontia rufa columbiana_ Taylor, Univ. California Publ. Zoöl.,
12:499, 1916 (type from Hope, British Columbia).
_Type._--Obtained at Paradise Creek, 5, 200 ft., Mount Rainier,
Pierce County, Washington, by V. Bailey on August 6, 1897; type in
United States National Museum.
_Racial characters._--Similar to _rufa_ but larger with larger
skull.
_Measurements._--Three males and a female from Tye, King County,
average and measure respectively: total length 352, 340; length of
tail 35, 40; hind foot 60, 59; ear 24, 19.
_Distribution._--The higher Cascade Mountains from the Columbia
River northward to the Canadian boundary. Marginal localities are:
Canyon Creek (U.S.N.M.), Cascade Pass (U.S.N.M.), Tye (W.W.D.),
Mt. Rainier (U.S.N.M.), Mt. St. Helens (U.S.N.M.), and Yacolt
(M.V.Z.).
_Remarks._--Intergradation between _rufa_ and _raineri_ is seen in
specimens from the area between Stevens Pass and Skykomish, King County.
=Zapus princeps= Allen
Big jumping mouse
[Illustration: FIG. 123. Big jumping mouse (_Zapus princeps
trinotatus_) in hibernation. Puyallup, Washington, January 30, 1939.
(Fish and Wildlife Service photo by Victor B. Scheffer, No. 576.)]
_Description._--The big jumping mouse is a medium-sized mouse, slightly
larger than the house mouse, with an exceptionally long, tapering tail.
Head and body measure about 4 inches and the tail about 5 inches. The
body is slender with a small head, small eyes and small, naked ears. The
forefeet are small and handlike but the hind feet are large with long,
powerful legs. The long, naked tail is smoothly tapering to a narrow
point. The fur is short, posteriorly directed, stiff and bristlelike.
The dorsal area is dusky, the sides are orange or yellow, and the
underparts are creamy white. Each upper incisor tooth has a groove on
its anterior face.
Jumping mice are boreal mammals occurring in wooded regions ranging from
the Arctic region southward to North Carolina, New Mexico and
California. Jumping mice are of rather general distribution in
Washington, being only locally common. They are partial to damp, boggy
areas but avoid true swamps. They occur in clearings in the forests in
the Puget Sound area and in meadows in river bottoms and in jungles in
ravines. They reach their greatest abundance in the boggy meadows and
glacial cirques of the mountains and spread out from such areas to
seemingly less favored habitat on dryer slopes and heather meadows.
Unlike many species, they do not seem to inhabit talus slides. They are
entirely absent from the eastern Washington desert.
Sometimes the jumping mouse walks on all four feet but the ordinary
means of progression is by short hops on the hind feet alone. When
startled they travel in great bounds, covering six feet or more at a
jump. When jumping they make considerable noise, swishing or rustling
through the grass and landing with an audible thud. The long tail serves
as a balancing organ. A specimen whose tail had been lost was reported
by Svihla and Svihla (1933: 133) to turn somersaults in the air and
invariably to land on its back rather than its feet.
Jumping mice become very fat and hibernate in middle summer or early
fall. In the lowlands they disappear by late July but in the mountains
they remain active until the middle of September. They spend the winter
in nests of grass several feet beneath the surface. A hibernating
individual figured by Flahaut (1939: 17) was curled in a ball, head down
with the tail wrapped completely around the greatest circumference of
the ball.
Near Seattle the principal food of the jumping mouse was the velvet
grass (_Holchus lanatus_), and the seeds of grasses and the broad-leaved
dock. The fruit of the blackberry (_Rubus macropetalus_) is eaten and
occasional individuals are seen with the chin stained a deep purple from
the juice.
The new-born young of the jumping mouse were reported by Svihla and
Svihla (1933: 132) to average 0.8 grams in weight. They are pink,
hairless, lacking even the facial vibrissae, with eyes closed and ears
folded.
=Zapus princeps trinotatus= Rhoads
_Zapus trinotatus_ Rhoads, Proc. Acad. Nat. Sci. Philadelphia,
1894, p. 421, January 15, 1895.
_Zapus imperator_ Elliot, Field Columb. Mus. Publ. 30, zoöl. ser.,
1:228, February 1, 1899 (type from Sieg's Ranch, Elwha River,
Olympic Mountains, Clallam County, Washington).
_Type._--Obtained on Lulu Island, mouth of Fraser River, British
Columbia, by S. N. Rhoads on May 31, 1892; type in Philadelphia
Academy of Natural Sciences.
_Racial characters._--Similar to _oregonus_ but brighter; sides
orange; underparts creamy white; buffy area often present on chest.
_Measurements._--Twenty males and 15 females from western
Washington average, respectively: total length 230, 233; length of
tail 140, 140; hind foot 33, 32.8; ear 14.9, 16.3; weight 23.7,
25.7 grams.
_Distribution._--Western Washington and the Cascade Mountains,
east in the northern Cascades at least to Tomyhoi Lake (W.W.D.).
_Remarks._--Actual intergrades between _trinotatus_ and _kootenayensis_
have not been examined but the differences separating the two forms are
of the degree that usually distinguish subspecies. Since _trinotatus_
occurs in the high Cascades as far east as Mount Baker, at least, and
_kootenayensis_ probably occurs in the northeastern Cascades, the two
forms doubtless come together in the rugged, inaccessible area between
these two localities. Further collecting will probably show a narrow
zone of intergradation in extreme western Okanogan County.
[Illustration: FIG. 124. Distribution of the big jumping mouse in
Washington. A. _Zapus princeps oregonus._ B. _Zapus princeps
idahoensis._ C. _Zapus princeps kootenayensis._ D. _Zapus princeps
trinotatus._]
=Zapus princeps kootenayensis= Anderson
_Zapus princeps kootenayensis_ Anderson, Ann. Rept. Nat. Mus.
Canada for 1931, p. 108, November 24. 1932.
_Type._--Obtained on Green Mountain, 6,000 ft., 10 miles north of
Rossland, West Kootenay District, British Columbia, by R. M.
Anderson, on July 18, 1929; type in National Museum of Canada.
_Racial characters._--Similar to _oregonus_ but paler; yellow more
faded.
_Measurements._--Twenty females, including 15 topotypes, average
(Anderson, 1932: 109): total length 245; length of tail 140; hind
foot 30.5.
_Distribution._--Northeastern Washington. Specimens from Sullivan
Lake (E.S.B.) have been examined.
=Zapus princeps idahoensis= Davis
_Zapus princeps idahoensis_ Davis, Jour. Mamm., 15:221, August 10,
1934.
_Type._--Obtained 5 miles east of Warm Lake, 7,000 feet elevation,
Valley County, Idaho, by W. B. Davis; type in Museum of Vertebrate
Zoölogy.
_Racial characters._--Similar to _kootenayensis_ but brighter in
color, more ochraceous. Similar to _oregonus_ but paler, more
yellowish.
_Measurements._--Davis (1939:339) gives the measurements of six
adult topotypes as: total length 240; length of tail 144; hind
foot 31.
_Distribution._--A single specimen in the Charles R. Conner Museum
from Kamiak Butte, Whitman County, is referable to this race.
=Zapus princeps oregonus= Preble
_Zapus princeps oregonus_ Preble, N. Amer. Fauna. 15:24, August 8,
1899.
_Type._--Obtained at Elgin, Union County, Oregon, by E. A. Preble,
on May 29, 1896; type in United States National Museum.
_Racial characters._--Small size, pale color.
_Measurements._--Three males and 3 females from the Blue Mountains
average, respectively: total length 233, 234; length of tail 138,
139; hind foot 31.8, 31.8; ear 16, 16; weight 29, 33 grams.
_Distribution._--The Blue Mountains of southeastern Washington.
=Erethizon dorsatum= (Linnaeus)
Porcupine
_Description._--The porcupine is one of the largest rodents found in
Washington, being exceeded in size only by the beaver. Its body is heavy
and stocky, its legs short, its tail long and thick and its eyes small.
It is best known for the modified hairs, or quills, of its tail and
dorsal area. These vary in greatest diameter from one-sixteenth to
three-sixteenths of an inch and from three-quarters of an inch to five
inches in length. They are ivory-white with black tips. In addition to
quills, the porcupine possesses wooly, black underfur and long, banded
guard hair. The bands of the guard hairs are black and yellow, varying
in width. Commonly they are of a single color, black, yellow or brown.
Porcupines range over virtually all wooded parts of North America north
of Mexico, in and above the Transition Life-zone. The Canadian
porcupines have been studied by Anderson and Rand (1943A) and
intergradation between the eastern _dorsatum_ and the western
_epixanthum_ has been shown.
The porcupines are commonly considered to be forest animals. However,
they are rather rare in the denser coniferous forests. In the more open
areas on the Cascade Mountains, especially on the eastern slopes, they
are not uncommon. They are rather common in the coniferous forests of
northeastern Washington and the Blue Mountains. They seem to be rather
common also in desert areas at the southern edge of the Columbian
Plateau.
The huge incisors of the porcupine are adapted to feeding on bark. They
do feed on bark to a certain extent in Washington, but it is my
observation that more herbs and bushes are eaten than bark. In areas
where porcupines are common, trees are commonly girdled, usually close
to the top. Trees girdled in this manner in the Kettle River Mountains
included western larch, ponderosa pine, and grand fir. The tops of some
trees were killed.
The ordinary walking gait of the porcupine is a slow deliberate walk in
which he appears to waddle somewhat. They can increase their speed to a
slow trot. They are slow, deliberate climbers, ascending and descending
trees with head upward. They are able also to climb rocks and cliffs,
sometimes being seen on the tops of large boulders.
Despite their large size, porcupines are not commonly seen. They are
mainly nocturnal and, in the daytime, find concealment high in the
branches of some conifer or a cave between the rocks in a talus slide.