Three species of meadow mice are known to inhabit the park, and of
these, two are so similar that the positive field identification of each
is difficult in most instances. Only the Cascade meadow mouse, or water
vole, shows sufficiently distinctive characteristics to permit easy
recognition. Of the two similar species, the Oregon meadow mouse is
probably most likely to be encountered.
The Oregon meadow mouse, _Microtus oregoni oregoni_ (Bachman), is
similar in general coloration to the Olympic meadow mouse, but has
conspicuous ears, is distinctly smaller, and has been found from park
boundaries to 5,000 feet and higher.
The Olympic meadow mouse, _Microtus longicaudus macrurus_ Merriam, is
dark brown above, with slightly paler sides, and with under parts a dull
buff or whitish. The tail is distinctly bicolor, black or brown above,
white below. The ears are inconspicuous. The head and body measure about
five and one-quarter inches, the tail about three and one-half inches.
This mouse is rarely found above the 3,000 foot elevation.
The Cascade meadow mouse, _Microtus richardsonii arvicoloides_ (Rhoads),
is much larger than any of the other species found in the park. The head
and body measure about six inches, the tail a little over three inches
in a typical specimen. In general this species prefers a moister habitat
than the other meadow mice, and is usually found from 4,000 feet to
forest line (6,500 feet). It is the most abundant of the park mammals
found at high elevations, and has been recorded at Camp Muir, 10,000
feet.
_Specimens in park collection:_ Oregon meadow mouse, RNP-27, RNP-32,
RNP-51, RNP-71; Olympic meadow mouse, RNP-31; Cascade meadow mouse,
RNP-5, RNP-26, RNP-48, RNP-49, RNP-50, RNP-59, RNP-60, RNP-75, RNP-81,
RNP-109; Longmire Museum, Park Headquarters.
As the name implies, the general habitats of these rodents are the open
parks and meadows, from park boundaries to above the forest line. They
are locally abundant in many places, and are active throughout the year,
feeding upon the various green and succulent plants, burrowing along the
surface of the ground beneath the snow to find food in winter. Only the
Cascade meadow mouse shows any marked deviation in its habits, being
semi-aquatic, at least in summer, with a marked preference for marshy or
boggy meadows, taking to the water readily to escape danger, and
burrowing along the banks of small streams. In winter this mouse often
seeks the hillsides and normally dryer sites, probably in search of a
more abundant food supply, the change in habitat being encouraged by
abundant winter moisture. These hillside habitats often reveal earthen
tunnels on the ground surface as the snow melts, similar to those made
by the pocket gopher. Mounds of earth thrown up around the burrows of
the Cascade meadow mouse are also similar to the gopher mounds, but may
be distinguished from the latter by the open burrows, often left so,
rather than being closed by earthen plugs.
It is well that the meadow mice are so abundant and prolific, since they
constitute a large portion of the food supply of coyotes, foxes, and
other predators.
MOUNTAIN LEMMING MOUSE, OLYMPIC PHENACOMYS, HEATHER VOLE
_Phenacomys intermedius oramontis_ Rhoads
The lemming mouse is similar in appearance and habits to the meadow
mice; the head and body are four and one-half inches to five inches
long; the tail from one to one and one-half inches. The back is a
grizzled gray-brown, showing a yellowish tinge; the belly is gray-white;
the fur is sprinkled with black hairs. The dull color and short tail
distinguish this mouse from all others except the Oregon meadow mouse.
The latter is slightly smaller, the hair is less woolly, but field
distinction is difficult or impossible.
_Specimens in park collection:_ None.
The genus _Phenacomys_ is found in the western United States and most of
Canada, inhabiting the mountain summits and colder zones.
The Olympic phenacomys of Mount Rainier occurs only at the higher
elevations, 4,500 to 8,500 feet in the park, and its range extends into
the Olympic Mountains, as well as southward along the Cascade crest into
central Oregon.
The alpine parks and windswept slopes well above forest line are the
home of the hardy little lemming mice. One of the common names for the
animal, heather vole, is suggestive of the locality where they may be
found, finding shelter in the protection afforded by the low-growing
masses of the heather. Their range is not entirely confined to the
alpine country, however, since records have been established in the
upper forested areas, down to a low elevation of 4,000 feet.
The only conspicuous evidences of the presence of the heather vole are
the tidy, compact winter nests of dried grass, lichen, and other plant
fibers. These nests, constructed on the ground under the snow, are
apparently abandoned when the snow melts, and it is difficult to
discover other signs of the animal’s activities.
Like the meadow mice, the mountain lemming mouse is a staple item in the
diet of the predators.
CASCADE RED-BACKED MOUSE
_Clethrionomys gapperi cascadensis_ Booth
The red-backed mouse is slightly larger than a house mouse; in a typical
specimen the head and body are about four inches long, the tail slightly
less than two inches. The distinguishing characters which separate this
animal from the other mice are the broad, reddish-brown stripe over the
back from the forehead to the base of the tail (this stripe
distinguishes it from the held mice), and the inconspicuous ears and
short tail which are so different from the large ears and long tail of
the white-footed mouse.
_Specimens in park collection:_ RNP-17, RNP-62, RNP-63, RNP-65, RNP-66,
RNP-67, RNP-68, RNP-69; Longmire Museum, Park Headquarters.
The many species of red-backed mice occur generally over the wooded
sections of North America.
The Cascade red-backed mouse is found in the Cascade Mountains from
British Columbia southward into Washington, east into northern Idaho and
northeastern Oregon. In Mount Rainier National Park it occurs generally
from park boundaries to forest line.
The heavily wooded areas of the park are the preferred habitats of the
red-backs. They are usually common in such localities, but are not
locally abundant in colonies, as are the field mice.
The activities of these mice are not confined to nocturnal excursions.
They may be seen at any time of day, and the quiet observer in the deep
woods is almost certain to glimpse them if he is patient enough to watch
for a few moments.
NORTHWESTERN JUMPING MOUSE
_Zapus princeps trinotatus_ Rhoads
The Northwestern jumping mouse is a little larger than a house mouse,
head and body about four inches, tail about six inches. The back is
dark, sprinkled with buff; a broad band of buff, sprinkled with blackish
hairs, extends along the sides; the underparts are pure white. The long
tail is dull gray above, white below, and almost naked except for a tiny
tuft of dark hair at the tip. This mouse may be easily distinguished
from any other park animal by the long hind legs and tail.
_Specimens in park collection:_ RNP-6, RNP-24, RNP-25, RNP-52, RNP-53,
RNP-54, RNP-58, RNP-73, RNP-76, RNP-92; Longmire Museum, Park
Headquarters.
The jumping mice are found throughout most of the United States from
northern California and North Carolina, northward into Canada to the
Arctic Circle. The Northwestern jumping mouse occurs from northern
California through the Cascades to the coastal region of southern
British Columbia.
In Mount Rainier National Park this animal is found irregularly from
park boundaries to 6,000 feet. It is not common and is rarely seen.
The usual habitats of the jumping mice are the subalpine parks and
meadows, where they may sometimes be abundant in a restricted locality.
They hibernate from early fall until late spring, and during their
period of summer activity they rarely leave the nest during daylight
hours. The nests are on the ground, small and dome-shaped, made of dried
grasses.