_Sciurus kaibabensis_]
While at a summer camp I once saw one of these chipmunks give an
exhibition of the exquisitely keen power of scent which must be
necessary to recover scattered stores. The chipmunk had been coming
repeatedly down a wooded slope in full view for twenty-five yards or
more to the floor of the porch for food supplied by the campers. While
it was absent carrying food to its burrow I placed a few nut meats on
the flat top of a stump about fifteen feet to one side of the porch
and farther away than the point where the chipmunk was being fed bread
crumbs. On its return several minutes later, instead of going as usual
to the porch, it ran directly to the stump, climbed up it, and promptly
made off with the nuts, which it had evidently located from afar. They
sometimes climb beeches and other trees to gather nuts even to a height
of fifty or sixty feet, and are commonly seen on low limbs and in
bushes.
[Illustration: FLYING SQUIRREL
_Glaucomys volans_]
[Illustration: BLACK-FOOTED FERRET
_Mustela nigripes_]
The entrances to the burrows are usually under logs, roots, or rocks,
or the den may be in a hollow log, stump or base of a tree, or even
under a cabin in the woods. The burrows in the ground are commonly a
series of tunnels some yards in length, with an oval nest and storage
chamber two or three feet underground, and with branches from the main
passageway. The nest chamber, a foot or more in diameter, is filled
with fragments of dry leaves and other soft vegetable material. One
chamber is usually used for sanitary purposes. The used entrance hole
is commonly without a sign of dug earth about it, the loose soil from
the burrow and its chambers apparently having been thrown out at
another opening, which appears to be used for this purpose only and is
kept plugged with earth.
Throughout most of the northern half of its range these chipmunks
usually hibernate from some time in October until March. Their
hibernation is far less profound than that of the woodchuck and they
not infrequently appear above ground during periods of mild weather,
even in midwinter. The hibernating period is shorter in the southern
part of the range.
They vary much in numbers from year to year and at times appear to
increase suddenly in localities where food is plentiful, indicating a
probable food migration. The young, numbering from four to six in a
litter, are born at varying times between the last of April and late
summer, indicating the possibility of more than one litter a season.
The most characteristic note of this chipmunk is a throaty _chuck,
chuck_, which is ordinarily used as a call note, but which in spring is
uttered many times in rapid succession to express the seasonal feeling
of joy and well being, thus taking on the character of a song. Such
joyful notes may be heard on every hand in places where the little
songsters are numerous. In addition, they have a high-pitched, chirping
note and a small churring whistle when much alarmed.
=THE OREGON CHIPMUNK= (=Eutamias townsendi= and its relatives)
(_For illustration, see page 543_)
The resident species of birds and mammals in the humid coastal region
of Oregon, Washington, and southern British Columbia are strikingly
characterized by their darker and browner colors in comparison with
closely related species in more arid districts.
The Oregon chipmunk is one of the common species showing marked
response to these local climatic conditions and is the darkest of all
the many species of chipmunks in the Western States. This chipmunk is
one of several geographic races into which the species is divided by
changing environment. The species, as a whole, ranges along the west
coast from British Columbia to Lower California, and the races at the
extremes of the line differ much in color.
As befits a habitant of the humid forested region, the Oregon chipmunk
is robustly built and distinctly larger than the other chipmunks of
the Western States. It is common and generally distributed throughout
this region, occurring from among the drift logs along the ocean beach
to above timberline on the Cascade Mountains. Within these limits
it frequents almost every variety of situation. It occurs in the
midst of gloomy forests of giant spruces, cedars, and firs, but is
particularly fond of old fences and brush patches on the borders of
farm clearings in the valleys as well as the vicinity of rocky ledges,
brush piles, and fallen timber, where the low thickets offer a variety
of food-bearing plants and ready shelter.
On the mountains it is most numerous about rock slides and “burns” or
other openings in the forest. Several pairs usually haunt the vicinity
of old sawmills and of mountain cabins. Like others of their kind, they
are alert and vivacious, varying in mood from day to day, but always
interesting. At times they are excessively shy and retiring, and a
person might spend a day in their haunts without seeing or hearing one,
although it is safe to say that the intruder had been seen and every
foot of his progress noted by the chipmunks. On another day, perhaps
because the sun shines more brightly and nature is in a happier mood,
the animals appear on all sides. Their slowly repeated sociable _chuck,
chuck_, is heard from the depths of the brushy covert as well as from
the tops of stumps, logs, rocks, or other lookout points where they sit
to view their surroundings. If alarmed they utter a sharp, birdlike
chirping note as they vanish in the nearest shelter. As one moves
about in their haunts he may now and then see one appear for a moment
above the undergrowth in a tall bush, on top of a stump, and sometimes
even mounting a few yards up a tree trunk to observe the cause of the
disturbance, only to vanish quickly.
They are always skirmishing for food, and carrying it in their cheek
pouches to hidden stores. On the approach of winter this activity
becomes very marked. A surprising variety of fruits and seeds are eaten
and stored, among them the salmonberry, red elderberry, black-capped
raspberry, thimble berry, blackberry, blueberry, gooseberry, thistle
seed, dogwood seed, hazelnuts, acorns, and others. They have favorite
feeding places, such as the top of a stone or stump or the shelter of
a log where they carry nuts or other seeds. These places are always
marked by little piles of empty shells or chaff from seeds. About
ranches they raid grain fields and other crops, sometimes in numbers
sufficient to do considerable damage.
In sheltered spots they make underground burrows with nest chamber
and store-rooms excavated along the passages. They usually retire
to these dens to hibernate during the last of September or first of
October, and appear again about March or April, often long before the
snow disappears. During fall and early winter they are sometimes seen
running about over newly fallen snow. One which was dug from its winter
quarters in British Columbia the last of November would move about
slowly and sleepily if teased, but when left undisturbed would curl
up and go to sleep again. This indicates the difference between the
light and often broken hibernation of chipmunks and the deep lethargy
which possesses ground squirrels in the North at this time. Toward
the southern end of their ranges neither chipmunk nor ground squirrel
hibernates. They mate soon after they awake from their winter sleep,
and the young, two to five or six in number, are born from April to
June. Whether more than one litter is born during a season, is, like
many other details concerning the lives of these attractive animals,
still to be learned.
=THE PAINTED CHIPMUNK= (=Eutamias minimus pictus= and its
relatives)
(_For illustration, see page 543_)
The preceding sketch tells how the Oregon chipmunk, living under a
cool, humid climate, in a region of great forests, has responded to
its environment by developing dark colors and a robust physique. The
painted chipmunk of the Great Basin has given an equally perfect
response to entirely different conditions. It is one of the geographic
races of a species peculiar to the sagebrush-covered plains and hills
from the Dakotas across the Rocky Mountains and the Great Basin region
to the east slope of the Cascades and the Sierra Nevada. Its home is on
treeless plains, in a climate characterized by brilliant sunshine and
clear, dry air. In this environment the painted chipmunk has developed
a smaller and slenderer body than the Oregon species, and strikingly
paler colors.
These differences in physique are accompanied by equal differences in
mental and physical expression. These little animals are exceedingly
alert and agile, darting through dense growths of bushes with all
the easy grace of weasels. When running they hold the tail stiffly
erect. When alarmed they utter a shrill chippering cry, especially
when darting into shelter. They also have a chucking call, uttered at
intervals, which may be used merely as a note of sociability or to put
their neighbors on the alert.
Although one of the most distinctive animals of the sagebrush plains,
this chipmunk also ranges into the borders of open forests on the
mountain sides. It is most numerous on flats and foothill slopes among
heavy growths of sage and rabbit brush. When its territory is invaded
by settlers it does not hesitate to gather about the borders of fields
and even to raid barns in search of grain and other food. Its burrows
are dug under large sagebrush and other bushes and under rocks and
similar shelter.
As with others of their kind, painted chipmunks habitually gather
seeds of many plants and carry them in their cheek pouches to their
underground dens. In addition to seeds and green vegetation, they eat
any fruits growing in their haunts, and also many insects, especially
grasshoppers and larvae. In one locality in Nevada during June and July
more than half their food consisted of a web worm and its chrysalids
with which the sage bushes swarmed. The chipmunks climbed into the
bushes and pulled the larvæ from the webs. As half the bushes were
infested, the work of the many chipmunks had a material effect in
reducing the numbers of this pest. The vegetable food eaten includes
the seeds of _Ribes_, _Kuntzia_, _Sarcobatus_, pigweed, and many other
weeds, serviceberry, various grasses, oats, wheat, and the seeds of
small cactuses. They regularly climb into the tops of large sage and
other bushes for their seeds and the ground beneath is often covered
with the small sections of twigs cut by them. They climb readily and
often travel from bush to bush through tall thickets like squirrels in
tree-tops. On warm mornings after frosty nights they may be seen in the
tops of the bushes basking in the sun.
Throughout most of their range they begin hibernation in September or
October, and reappear early in spring. The young appear a month or more
later, and litters containing from two to six may be born throughout
the summer, indicating the possibility that several litters may be born
to the same pair in a season.
So alert and shy are they that even a person in their haunts day
after day will see but few of them. Their hearing is extremely acute,
and even at a great distance the footsteps of an intruder sets them
all on the alert. On every side they run swiftly to cover before the
observer has opportunity to see them. In such places a large setting
of baited traps will reveal their presence in surprising numbers. In
one locality, during a brief visit, traps set among the brush for other
small mammals yielded more than forty chipmunks.
On stormy and cloudy days, especially if the weather is cool, painted
chipmunks remain in their dens, but on mild sunny days they frisk about
with amazingly quick darting movements. A horseman riding along a road
leading through a sagebrush flat will frequently see them racing across
the road often several hundred yards away, the sound of the horse’s
footfalls having alarmed the chipmunks over a wide area. Here and there
one may be seen climbing hastily to the top of a tall bush to take a
look at the cause of alarm before finally seeking concealment. When
pursued among the bushes they often run considerable distances before
taking refuge in a burrow. When hard pressed they will enter the first
opening encountered, but if it is not its own home the fugitive soon
comes out and scampers away, apparently fearful of the return of the
owner or perhaps owing to his presence.
[Illustration: