The golden-mantled ground squirrel,
Citellus lateralis chrysodeirus Merriam, is one of the commonest
mammals in Crater Lake National Park and probably produces more
entertainment for visitors than all other types combined. This is not
only because these animals are aggregated along the rim and in the
campgrounds, where the greatest concentration of visitors takes place,
but also because the squirrels are handsome in appearance, readily
conditioned to the presence of human beings, and both appealing and
comical in their behavior.
This species is commonly present in
forested regions of Oregon from the Cascade mountains eastward and is
especially prevalent in the ponderosa pine forests of the Cascade, Blue,
and Wallowa Mountains. It is found, in these regions, from the edge of
the sagebrush up into the white-bark pines at 8000 feet altitude. At
Crater Lake these squirrels are present in all regions of the park
including both Wizard Island and, on one occasion, on the Phantom Ship.
The race occupying the Siskiyou mountains and therefore present in the
Oregon Caves National Monument is described as subspecifically distinct
and called the tawney-mantled ground squirrel, Citellus lateralis
The golden-mantled ground squirrel is a
chunky little animal with a body about seven inches long and a well
furred tail somewhat more than one-half the body length. Its legs are
rather short and its ears relatively small but held tautly erect. The
eyes are quite large for a burrowing animal and their size, combined
with the erect carriage of the ears, give these squirrels an air of
alertness and intelligence.
The flanks, the underside of the tail,
and the head and shoulders are colored a rich, reddish brown. This is
the coloring that accounts for the name golden-mantled. The back carries
a broad median gray stripe, on each side of which are narrower
contrasted stripes of black and white; two black ones with a white
stripe between them. These contrasted stripes following the curve of the
back while the squirrel sits up add greatly to its appearance.
". . . contrasted stripes following the curve of
the back . . ."
Ground squirrels are not very fast
animals and this squirrel compares unfavorably in speed with the
chipmunks that occupy the same territory and with small enemy carnivores
like the Cascade weasel, the Pacific marten, and the Cascade red fox.
There is, however, an alertness in its postures and a briskness and
energy in its movements that visitors find attractive. It seems probable
that the hurried gallop from point to point which the squirrels
alternate with a frozen pose or a brief nosing of the ground is highly
adaptive. An animal in motion is likely to be seen and had better hurry
if it moves at all. In addition, the time spent on exposed territory and
between feeding periods is reduced to a minimum. These points may not be
obvious to visitors, but they do see a hard-working little animal and
admire the display of energy.
Comedy is supplied by the fact that the
air of brisk alertness is not accompanied by any real evidence of great
intelligence. In fact
Citellus not infrequently plays the role of a busy fool; searching
industriously for peanuts in empty hands when full ones beckon, and
taking the trouble to investigate with a passing sniff any little object
which may lie in his pathway on the rim walk pavement. He easily
changes, too, from assured approach to precipitous flight with his tail
above his back at about the angle a stove lifter projects from the lid,
his broad little hams twinkling as his short hind legs spurn the dust.
"Comedy is supplied by the air of brisk
alertness . . ."
Golden-mantled ground squirrels are
said by Vernon Bailey to have but one brood a year of four to six or
more young. Grinnell found an average of five young in five females in
Yosemite National Park. The number probably increases with the age of
the mother and as fully adult females have ten functional mammae they
could easily accommodate larger broods. In 1936 a mother squirrel was
observed moving nine little ones from a burrow in the rim campground and
in 1938 the accidental death of a mother squirrel was followed by the
exit of eight hungry little squirrels which were adopted and fed by rim
campground visitors. Young are reported by Vernon Bailey to be born late
in June or early in July. This checks with observations at Crater Lake
National Park where in both 1937 and 1938 young squirrels emerged from
burrows along the rim during the first week in August. The adopted brood
mentioned in the previous paragraph seemed to be about three weeks old
on August the eighth. A small newly-emerged squirrel was seen coming out
of a burrow in the rim campground as late as September 3, 1937.
". . . searching industriously for peanuts . .
The episode mentioned above in which a
mother squirrel moved young from a burrow, part of which had been
collapsed by a car, shows that these animals share the typical mammalian
habit of moving young to less menaced positions. In August 1938 Dr. Fred
Miller, park physician, observed the moving of six young from a nest
somewhere in the Community House through the door to a refuge somewhere
outside the building. The young were carried by the body with ventral
surface toward the mother's mouth and curled around the mother's head
just as young deer mice are under similar circumstances.
The inherent or unconditioned behavior
of these squirrels is interesting and can be usefully compared with the
learned or conditioned responses that are in time built up by contact of
squirrels with the park visitors. Young squirrels are quite timid upon
emergence and for a few days depend upon the early morning hours for
their initial foraging, a time when few people are around. They stay
near a burrow entrance and hole up promptly if disturbed. This timidity
is typical of the behavior of all squirrels in regions where contact
with man is a rare incident. The air of easy assurance adopted by older
park squirrels is evidence of their domesticability.
". . . tail above his back about the angle a
stove lifter projects from the lid . . ."
These rodents have quite a tendency to
dig in the ground and the young ones do a good deal of random digging
before they actually tunnel a home site for themselves. In digging, the
head is lowered and the fore limbs are moved very rapidly for a brief
interval. The limbs are then held still while the head is raised for a
look around. Digging and looking alternate at rapid intervals. If partly
within a burrow a squirrel will back out to raise his head for
observation. When well into a burrow, a squirrel, observed at the rim on
July 15 1938, continued digging without kicking out the loose dirt which
soon covered him. Hidden by this the squirrel continued on into the
ground. About ten minutes later he burst out head first. The maneuver
simultaneously cleared the burrow entrance and prepared it for possible
retreat and got the squirrel clear of the entrance without embarrassing
him with the adherence of loose earth. The interval had presumably been
used to dig a length of burrow and a turn around.
Interesting comparisons can be made
between the golden-mantled ground squirrel and a rather small brown
gopher which occupies the same territory and is therefore a competitor.
Both mammals dig a tunnel system, that of the gopher being attended to
particularly during the winter so that "he, while his companion sleeps,
is toiling upward in the night." The squirrel feeds for the most part
above ground while the gopher feeds for the most part underground on
roots, there available, or on greens and grains pulled through the roof
of the tunnel or gathered in short surreptitious forays launched from a
tunnel entrance. In the latter the gopher emerges headfirst but goes to
earth tail first. This reversal of direction without turning the body
cannot be profitably employed by the squirrel for he ranges for a
distance and maneuvers his body without regard to the position of the
tunnel entrance. The squirrel always goes to earth head first. However,
if a squirrel partly emerged is alarmed, he backs down gopher-like into
for awhile, may even register their
annoyance by scolding the intruder as they hole up. But less blase,
young squirrels, if not too greatly alarmed, immediately "pop up" after
backing down, to see what is going on. This interesting example of
youthful curiosity may be employed to demonstrate another pattern of the
remarkable specificity of squirrel behavior. If in the game of pop up,
back down, the young squirrel emerges enough to get one hind foot on the
ground at the edge of the tunnel entrance he continues out, turns
rapidly and goes to earth head first. This experiment, performed with a
number of young squirrels, always produced the same result. The balance
of advantages and disadvantages of the alternative methods reaches a
critical point when one hind foot is in the air preparatory to complete
emergence. Past this point, when the hind foot is on the surface of the
earth, the advantage is presumably in favor of rapid emergence and
immediate holing up.
". . . hungry little squirrels were adopted and fed by
rim campground visitors."
"The air of easy assurance."
Squirrels can occasionally be seen
carrying dry material which they presumably use for bedding. Grass from
the previous fall which has been pressed down by the snow, dries rapidly
when the snow has melted and so provides an acceptable bedding material.
An individual squirrel, when not interfered with during the process, may
make trip after trip to the same site of supply and carry a load of dry
grass back to a tunnel each time. The route taken for the journey out
may be repeated each time but a different route is usually chosen for
the return journey and this is repeated on each return. An exception to
this was provided by a squirrel in the utilities area which made twelve
trips in carrying old bedding from one tunnel which it deposited in
another. In this moving process the squirrel took the shortest route
between the two tunnel entrances, which were only about thirty feet
apart, and the routes going and coming were therefore coincident.
A squirrel gathering bedding works
vigorously with forepaws and teeth to loosen grass which is taken
between the jaws. The squirrel then stands up and trims this load into a
neat bundle. More grass may be added and the trimming process repeated.
Thus to arrange the load between the jaws a squirrel makes rapid and
complicated movements with the forepaws. As a result he can run with his
grass sheaf without stepping on loose ends and as the bundle does not
project laterally much further than the ears the squirrel can enter a
tunnel entrance on the run without embarrassment. A squirrel running
with bedding has been seen to stop, stand up and retrim his load when a
loose end of dried grass became detached and started to drag. On one
occasion a squirrel running down the inner wall of the Sinnott Memorial
ramp, stopped at the lower turn where two visitors offered him peanuts.
To accept these the squirrel was obliged to put down his sheaf of grass
and by running down the ramp the writer was able to prevent the squirrel
from retrieving the grass before he ran away. This grass sheaf was in
the form of an 8 which the squirrel had been holding in the center so a
loop projected on each side. The grass in this bundle held together and
could be lifted by the center or either loop without becoming
Like most rodents the golden-mantled
ground squirrel grooms himself around the head, neck, and belly with his
fore paws. Hinder parts except the tail, are worked over with the teeth.
The tail is combed by a sort of shucking motion with the fore paws and
combed with the teeth as well. Grooming is particularly important in
small mammals since a smooth coat conserves heat which radiates rapidly
from the relatively large surface of a small creature. Squirrels dust
themselves by a moderate rolling in dust piles often raised by a few
rapid paw strokes for the purpose. They frequently save time by diving
into dust like a base-runner making a head-first second. Frequently
after the dive they lie spread-eagled in the dust for a brief period and
this same position, with all limbs extended, may be used in resting. A
well nourished little squirrel thus stretched out, after an interval of
peanut gathering, has all the air of smugness carried by a lucky
investor after a hard hour of coupon clipping.
". . . edible objects are always lifted first by
the jaws and then transferred to the forepaws . . ."
Squirrels forage busily and nose over
the ground for food. They frequently forage by standing on the hind
limbs while they reach out and pull vegetation to the mouth with the
fore paws. In this manner they nibble young leaves and flower buds of
Newberry's knotweed and bleeding-heart and the seeds of wild grasses,
the heads of which they obtain by arm over arm reeling in of the stem.
It is interesting that in spite of this use of the fore limbs in a
special circumstance, that edible objects like peanuts are always lifted
first by the jaws and then transferred to the fore paws for manipulation
during husking or fragmentation prior to storage in the cheek pouches.
Occasionally a squirrel with its mouth full of food will clutch an
object on the ground and pull it toward the body but will then merely
hold it with its paw until the mouth can be used as the grasping organ.
The golden-mantled ground squirrel has
a vocabulary of at least four different sounds. There is a high- pitched
"peesk" which is quite bird-like in tone, sometimes followed by a trill
which is rather more musical than the similar trill of the western
chipping sparrow. Both single and multiple noses seem prompted by
excitement or alarm. These sounds are made while sitting, sometimes with
one foot raised. The mouth is widely opened for the first sound and the
body vibrates obviously with the trill. On August 6, 1938, the writer
stopped to investigate a singing squirrel which had gathered an audience
of a number of campers. One of them estimated that the squirrel,
presumably a female since it was occasionally followed by young, had
already sung for an hour and "sang almost every day!" There is a throaty
little growl which is uttered as a warning to interlopers and during
pursuit of them or while in the throes of combat. This sound is commonly
employed when squirrels are competing for peanuts. Rather rarely a
squirrel running from a pursuer, utters a series of high squealing notes
when pursuit is close. In general these animals are rather silent and
are usually credited with the single note first mentioned (Bailey, 193,
"It takes young squirrels a little while to
accustom themselves to eating from visitors' hands."
It takes young squirrels a little while
to accustom themselves to eating from visitor's hands. No critical test
of this has been made, but by using experience at Government
Headquarters as a criterion, it can be said that some young squirrels
accept food the second or third day it is offered. Conditioning appears
to be continuous over a long period for the biggest end presumably
oldest individuals usually show the least hesitation. Even when young
squirrels are taking food readily from the hand the bristling of the
hairs on the tail show that the situation is producing considerable
emotional disturbance. Emotionality in animals is difficult to estimate
and this pilomotor response might be used in behavior experiments.
The greatest accumulation of squirrels
in Crater Lake National Park is at the head of the Crater Wall Trail,
immediately north of the Rim Parking Area. A dozen squirrels may often
be seen here, begging, feeding, bickering with one another, or running
home with the take. On August 8, 1938, a squirrel with full pouches was
followed to its burrow which proved to be 220 yards west of the Crater
Wall Trail on the edge of the fill for the shoulder of the Rim Road. The
squirrel, which had been observed taking this route before, crossed the
road twice to get to its burrow; once to the island at the Y just at the
top of the hill and then across the south fork of the highway that leads
to the Rim Road.
After considerable observation of known
individual squirrels, the writer came to the conclusion that the
squirrels with home sites a considerable distance from the head of the
Crater Wall Trail filled their cheeks with more peanuts, before starting
on the home trip, than did the squirrels with a shorter distance to go.
The assumption that rodents acted as though they were conversant with
the axiom, that you must have a paying load for a long haul, greatly
interested park visitors although some said they would like to believe
it but just couldn't. Dr. Kenneth Gordan of Oregon State College, basing
his observation on marked squirrels seen daily, came independently to
this same conclusion: the squirrel with the longer route home takes the
". . . filled their cheeks with more peanuts . .
Young of the year or yearling squirrels
early in the season, not infrequently dig a small hole, after they have
gone a short distance from a feeding area, and put their peanuts into
it. The hole is then carefully covered with earth pushed into it and the
site may be camouflaged by loose dirt dusted over it with brushing
motions of the forepaws. Older squirrels dig these caches much more
infrequently presumably because they have well established the routine
of taking their food home. Late in the season of 1938 a squirrel was
observed digging such a hole in the level ground just east of the
Community House. This individual deposited some peanuts and had almost
completed the earth cover when it was interrupted by the advent of
another squirrel which started a territorial squabble. The two animals
engaged in a running fight which took them as far as the west end of the
Community House and must have occupied fifteen or twenty seconds. To the
astonishment of the writer, one of the two, and presumably the one which
had been engaged in covering its little hoard, returned to the site and
completed the covering process including the refinement of brushing
loose dirt over the site.
Not the least educative of these
rodents' reactions is the series of maneuvers gone through by a timid
squirrel upon being offered food in hand, since this traces, in physical
outline, the mental shuttling which is so often a prelude to making up
one's mind. Happy approach may take place until proximity to the large
food- bearing animal lays on the paralysing hand of fear. Approach is
checked and turned into precipitous flight. At a safer distance the
possibility of food-getting again becomes the commanding stimulus and
the squirrel will return and this time accept the proffered material. As
soon as food is being taken into the mouth a squirrel is much "tamer"
and may often be lifted by the fore paws as soon as it has placed these
on the donor's hand to obtain support while reaching for the food with
its mouth. Squirrels will frequently sit contentedly on an outstretched
hand or even climb about on visitors who remain still but are not
patient with attempts at petting and they will struggle and bite
vigorously if they are seized by the body or tail.
"Squirrels will frequently sit contentedly on an
outstretched hand . . ."
A certain number are captured and kept
successfully as pets, often living for several years according to the
testimony of Park visitors who have kept them. This is presumably due to
their being able to thrive on the diet usual for the commoner domestic
pets and to stand overfeeding. They hibernate in captivity even in the
relatively warm Willamette Valley. During the winter of 1937-38
Professor Milne, of Oregon State College, kept two female squirrels in a
nest box in his yard at Corvallis. Both squirrels hibernated, "rolled in
a ball" with their heads between their fore limbs. They were cold to the
touch and promptly resumed the hibernating posture if forcibly unrolled.
They could be gradually aroused if put out in the sun and would attempt
to bite if they were touched during this interval. During the warmth of
the day they would remain active but would resume hibernation again that
night and remain asleep unless again disturbed. Quite contrary to what
is usually assumed, the smaller, thinner squirrel remained in
hibernation two or three weeks after her bigger sister had emerged.
Neither squirrel appeared to have lost weight during the hibernating
period. Squirrels emerging from winter quarters at Crater Lake in 1937
and 1938 were all in good condition also.
Three burrows were dug out in August
1937 to study the plan of construction. Two were empty (abandoned?) and
one, herewith reproduced, contained a squirrel. He hung around awhile
during the excavating process and regarded the operation with some
The burrow which has been reproduced
was the shortest and simplest of the three, being rather less than
thirty feet in length. The longest tunnel was more than a hundred feet
in total length, tortuous and containing cross connections. The third
burrow was forty feet in length. Tunnels were usually about six inches
below the surface, the greatest depth being reached in a cul-de-sac ten
inches deep, either a nest chamber or sink. No tunnel contained nesting
material. Diameters varied from two to four inches. Turn-arounds and
nesting sites or sinks were from five to seven inches in diameter. All
tunnels contained more than one open entrance, with one or more blocked
Tunnels went under rocks and the roots
of bushes when these were encountered but entrances were not necessarily
hidden. In general one might say that the tunnels were like the
squirrel, rather simple and direct.
Bailey, Vernon. 1936. Mammals and Life
Zones of Oregon. North American Fauna No. 55. U.S.D.A. Bureau of
Gordon, K. 1943. The Natural History
and Behavior of the Western Chipmunk and Mantled Ground Squirrel, Oregon
State Monograph Studies in Zoology No. 5.
Grinnell, J. and T. I. Storer. 1924.
Animal Life in the Yosemite, California University Museum Vertebrate
Zoology Contribution, California University Publications of Zoology.