(_For illustration, see page 531_)
The familiar house mouse is of Old World origin and may be
distinguished from most of our native mice by its proportionately
slenderer body, long hairless tail, and the nearly uniform color on the
upper and under parts of the body. Like the house rat, wandering an
alien from its original home in Asia, and transported by ship and by
inland commerce, it has gained permanent foothold and thrives in lands
of the most diverse climatic conditions, except those of the frigid
polar regions.
For centuries the house mouse has been parasitic about the habitations
of man, and in many places in America has spread into the surrounding
country, where it holds its own in the struggle for existence with
many of our native species. It is probable that its ability to live
in houses also infested by the fierce brown rat is due wholly to its
agility, and to the small size, which enables it to retreat through
crevices too small for the rat.
In buildings it hides its warm nests in obscure nooks and crannies,
making them of scraps of wool, cotton, or other soft fibrous material,
often cut from fabrics. Out in the fields, like any other hardy
vagabond, it adapts itself to whatever cover may be available on the
surface or in crevices and the deserted burrows of other mammals.
It has several litters of from four to nine young each year. The young
are born blind, naked, and helpless, but are soon able to run about,
often following the mother on her foraging expeditions. When a little
more than half grown they usually scatter from the home nest and seek
locations of their own.
Throughout most of its world-wide range the house mouse has the same
general appearance, but in some localities the effect of changed
environment is developing appreciable differences, which appear
destined to result in marked geographic races. The representatives of
these mice I caught in weedy fields on the coast of Chiapas, near the
border of Guatemala, have an appreciable rusty shade on the back in
place of the ordinary dull gray.
The success of both the house mouse and the house rat in establishing
themselves so successfully in all parts of the world, in the face of
the antagonism of mankind, affords marvelous examples of physical and
mental adaptability not equaled elsewhere among mammals.
From early days the domestic mouse has been a familiar member of the
household with people of all degree, and the housewife has had to match
her wits against the cunning persistence of this small marauder in
order to safeguard the family supplies of food and clothing.
Despite the antagonism excited by its destructive habits the mouse is
so small and often so amusing in its ways that it has commonly been
regarded with a half hostile, half friendly, interest. This is apparent
by frequent references to it in proverbs, nursery rhymes, fables, and
folklore, as well as in more serious literature.
Many cases of singing house mice have been recorded, their notes being
a series of continuous musical chirps, trills, and warblings, rising
and falling about an octave and slightly resembling the song of a
canary. It has been claimed that this singing is due to an affection of
the songster’s breathing organs, but this can scarcely account for its
being uttered at definite times and places and ceasing at the volition
of the performer.
In one instance the song had been heard in a china closet and an
observer sat by the open door to locate the singer. After patient
waiting “a mouse peered out from behind the plates, climbed up a little
way on the brackets, and after looking around several times, began to
sing.” This mouse continued to sing in the same place at intervals for
several weeks and became accustomed to the presence of people during
its performances; then it suddenly disappeared, probably a victim to
one of the dangers which constantly beset its kind.
=THE MOUNTAIN-BEAVER= (=Aplodontia rufa phaea= and its
relatives)
(_For illustration, see page 534_)
The first adventurous fur traders who penetrated the Oregon wilds
found the Chinook Indians provided with robes made of skins of the
mountain-beaver. From that time until recently but little accurate
information has been available concerning the habits of this curious
animal. Locally it is known by several other names, including
“Sewellel,” “mountain boomer,” “boomer,” and, in the Olympic mountains,
“chehalis.”
The genus of mountain-beavers contains only a single species with
several subspecies, all having a close superficial likeness in size
and form to a tailless muskrat, except for their coarse, harsh fur.
It is an exclusively North American type and, aside from a remote
relationship to the squirrel family, has no kin among living mammals.
It appears to be a sole survivor from some former age. As with the
pocket gophers, its mode of life has developed powerful muscles about
the head, front legs, and forepart of the body.
The distribution of the mountain-beaver in Tertiary times extended
through the Great Basin to North Dakota, but at present is closely
restricted to the humid region between the crests of the Cascades and
the Sierra Nevada and the Pacific coast, and from the lower Fraser
River, British Columbia, south to the latitude of San Francisco Bay,
California.
[Illustration: WHITE-FOOTED MOUSE (Adult and Young)
_Peromyscus leucopus_]
[Illustration: BEACH MOUSE
_Peromyscus polionotus niveiventris_]
Within this superbly forested region this animal delights in
locations that are cool and oozing with water, where, under the dense
shade of an almost tropical undergrowth of shrubs, ferns, and other
herbage, it constructs numberless tunnels and trails. These are
sometimes in flats, but much more often along canyons and mountain
slopes, among willow, alder, aspen, or other thickets, or even in the
heavy coniferous forest.
[Illustration: BIG-EARED ROCK MOUSE
_Peromyscus truei_]
[Illustration: BROWN RAT
_Rattus norvegicus_