BELDING GROUND SQUIRREL. Citellus beldingi (Merriam)
size about that of House Rat; tail sparsely haired at sides, and short,
decidedly less than half length of head and body; ears small and round,
not pointed or tufted. (See pl. 2.) Head and body 7 to 8-1/2 inches
(180-215 mm.), tail 2-1/3 to 3 inches (60-74 mm.), hind foot about 1-3/4
inches (41-45 mm.), ear from crown 1/3 to 1/2 inch (8-13 mm); weight
7-1/4 to 10-1/4 ounces (207-294 grams). General coloration light
yellowish brown, paler on under surface of body; a broad area of bright
reddish brown down middle of back. Voice: General warning call of
5 to 8 shrill short whistles, seek, in quick succession; females
with young utter a single note, e-chert', at intervals.
Workings: Burrows in ground, surface openings about 2 inches in
resident in higher and more easterly portions of Yosemite region,
chiefly but not entirely in Hudsonian Zone. Recorded from near Porcupine
Flat and from near Merced Lake eastward to Mono Lake Post Office and to
Farrington ranch near Williams Butte. Ranges upward to 11,500 feet as on
Parsons Peak, and higher yet on Conness Mountain. Inhabits chiefly
grassland, occasionally rocky places, or floor of open forest.
The Belding Ground Squirrel is a hardy,
ground-dwelling member of the squirrel family inhabiting the meadows and
other grass-producing areas in the higher and more easterly portions of
the Yosemite section. This species is often called 'picket-pin' because
of the erect, stake-like posture which it assumes when on the lookout
for danger (pl. 2). Some persons have referred to it as "spermophile"
(seed eater). Both of these names have a measure of appropriateness not
always to be found in vernacular names. This squirrel is named for Lyman
Belding, the naturalist formerly resident in Stockton who collected the
specimen from which the species was first scientifically described.
The range of the Belding Ground Squirrel begins on
the west slope of the Sierras at about the lower margin of the Hudsonian
Zone. The western most report of its occurrence is from the upper
Yosemite Creek in a location west of Porcupine Flat and due north of the
Yosemite village. The first specimens actually obtained by our party
were collected about two miles east of Porcupine Flat. Merced Lake is
the westernmost point of record for the southern part of the section, in
the drainage of the upper Merced River. The maximum abundance of the
species is to be found on the larger high mountain meadows, such as
Tuolumne Meadows, in the heart of the Hudsonian Zone. (See pl.
18b). While one of us was traversing the meadows in Tioga Pass on
July 13, 1915, fully 100 of these squirrels were observed; and an equal
number was counted about two weeks later while we were going along the
floor of Lyell Cañon. The range of the species extends upward on
the Sierran crest to well above timber line, for example, on Conness
Mountain, Parsons Peak, and Parker Pass. On the east slope this squirrel
is found down through the Canadian Zone (Jeffrey pines) even to the
Farrington ranch near Williams Butte and to near Mono Lake Post Office,
close to the shore of Mono Lake.
Meadows constitute the preferred habitat of this
species, and by far the greater percentage of the animals are to be
found in the grassland. But this environment is not absolutely essential
to their welfare; for some of them live in rather rocky places and some
in areas which bear a moderate stand of trees. In the latter two
situations there is usually bunch grass in the neighborhood of the
places inhabited by the squirrels. The limited patches of grass about
many of the small glacial lakes often support small populations of the
Belding Ground Squirrel.
This species is as strictly terrestrial as any ground
squirrel of which we know. We have never seen one climb a tree or even a
bush. Once one was seen on the top of a boulder about 3 feet in height.
The Belding Squirrel is less given to clambering over rocks than the
'copperhead' or any of the chipmunks. Yet the present species, despite
its habit of remaining on the ground surface, spies out its enemies,
real or supposed, at fairly long distances and communicates at once with
others of its kind in a way that puts all the individuals in the
neighborhood on their guard.
When the traveler approaches a meadow and is still a
hundred yards or more from the nearest Belding Squirrel, his ear is
assailed by the alarm call of the animal, a series of shrill piping
whistles, loud enough to be heard by any living creature within a
quarter-mile radius. Usually there are 5 to 8 (rarely even 12) notes in
rapid sequence. Other squirrels take up and repeat this calling so that
on some occasions the rocky walls enclosing a meadow resound with their
notes. This warning call is responded to according to the circumstances
wherein the various individuals find themselves when the call is heard.
Those out in the meadows usually at once run toward their burrows;
others closer by, within a few yards of their homes, rise straight up on
their haunches, with forelimbs pressed against the body. When an
individual squirrel has assumed this position, it, too, utters the
shrill whistled call. If its curiosity remains unsatisfied, as when its
view of the approaching person is imperfect, the squirrel rises still
farther until it is standing bolt upright on the soles of its hind feet.
The call given then is apt to be of an even more penetrating quality
than at first. If the person continues to approach, the squirrel drops
to all fours and runs to the entrance of its burrow where sometimes it
again assumes the 'picket-pin' position; but it more often remains
hunched up on all fours, with its hind feet well under its body, ready
to dart down the hole at an instant's further warning. Even when in the
upright position at the mouth of the burrow the rapidity with which a
squirrel can drop into its retreat is surprising. Once scared into the
ground it stays only a short time, then pokes its head out again, to
just below the level of its eyes.
When sitting erect and observing its surroundings a
squirrel can often be seen to twitch its nose as if sniffing and drawing
in the air. Probably it uses the sense of smell to aid its powers of
sight and hearing.
On flat open land where grass is at best very short,
the usual mode of progression for this squirrel is a heavy run, with
little up and down movement of the body, and with the tail down. In high
grass, instead of parting the stalks and running between them, the
squirrel progresses by a series of jumps; each hop carries the animal up
so that it can look about for some distance and be able to spy an
Once a Belding Squirrel was come upon in a rocky
place; the animal ran over some rocks and jumped over a creek which was
fully 2 feet wide, in its effort to escape. Another, on Mount Hoffmann,
ran along the face of a pinnacle of rock, clinging to small cracks in
The Belding Ground Squirrel subsists chiefly upon
grass and grass seeds, and depends less upon the larger seeds, nuts, and
roots such as are eaten by the California Ground Squirrel and the
chipmunks. When feeding, the animal sits in a hunched-up position, the
hind legs in entire support of the body. The forefeet, when grass is
being eaten, are used to draw the grass stalks or heads toward the mouth
where they can be cut off. Larger items are held in the forepaws, while
small pieces are nibbled off with the front (incisor) teeth and rapidly
ground up by the cheek teeth (molars). In a few instances Belding
Squirrels were captured in meat-baited traps set for carnivores. Certain
other members of the squirrel family seek flesh bait when available, but
the present species seems to be more restricted in its food preferences
to vegetable material. At the mule corral on Tuolumne Meadows in 1915
the 'picket-pins' were foraging around barley sacks, gleaning scattered
grain like rats. Several Belding Squirrels were caught in steel traps
set in the entrances to Marmot burrows, and one was captured in a
Macabee gopher trap which had been set in a gopher burrow.
Each 'picket-pin' evidently restricts itself closely
to use of its own particular burrow and does not, in time of danger,
dart into whatever retreat happens to be nearest at hand. On Lyell
Meadows one was repeatedly seen to run from the meadowland, where there
were numerous holes, to a particular burrow in the granite gravel above
the trail. Near the same place, one of our party suddenly came upon one
of these squirrels, posted at 'observation,' within one foot of an open
burrow. The squirrel, instead of darting into this nearest hole, ran to
one fully 30 feet farther away.
The burrows are usually constructed right in the
meadows which furnish the animals their food; less frequently they are
dug in the rocky soil at the margins of the meadows. Those squirrels
which live in the bunch-grass areas at or above timber line make their
burrows; of necessity, in the granite soil. A typical meadowland burrow
at Snow Flat was opened and studied by the authors on June 28, 1915.
This burrow was close to the bank of a small creek, which meandered
through the meadow, and was near a large granite boulder. The ground was
heavily matted with grass roots to a depth of 1-3/4 inches (45 mm.) and
all the tunnels had been excavated below this mat. The whole tunnel
system was remarkably level, unlike those of the California Ground
Squirrel in the lowlands; but this may have been conditioned by the
nearness of the creek and of the water table. Two short, deeper tunnels
which were found may have been prospects toward a deeper system which
would have been excavated later in the season. There was melting snow
about the meadow and the ground was quite wet on the date of our study,
especially below the level of the tunnels laid open. The presence of
this extreme amount of moisture may have acted to deter the squirrel
from going any deeper.
The total length of all the tunnels in this system
was 53.3 feet (16.25 meters) and the average tunnel diameter 2 inches
(52 mm.). The total amount of earth excavated was therefore 2010 cubic
inches8.7 gallons of earth, or nearly enough to fill two 5-gallon
oil cans. Yet there were no mounds of earth at the entrances to the
burrow. The soil had either been pushed into the creek or else washed
away by the summer rains and melting snow water.
This burrow system contained no well constructed
nest; but in one place there was some grassy material, either the
remains of an old nest or, more likely, the beginning of a new one. The
inhabitant of this burrow was a female which would have given birth to
young, within two weeks probably.
One burrow of this species was noted at the base of a
lodgepole pine. In this case there was a mound of earth at the
The young of the Belding Ground Squirrel are born
about the first of July, there being, so far as all our evidence shows,
but one brood per year. Yet a pair was seen in what looked like a mating
pursuit as late as July 13. The number of young was ascertained
definitely in only one case, that of the female containing 5 embryos, at
Snow Flat, June 28. A female obtained July 2 east of Porcupine Flat had
evidently just given birth to 6 young. In females taken on July 8 and
21, 1915, the mammary glands were functional. The young, when they first
appear above ground, are scarcely more than one-third grown. The first
young were noted in 1915 on July 25. But near Williams Butte three young
only a third grown were seen on June 28 (1916). At the end of July
(27-31) in 1915, in Lyell Cañon and on Tuolumne Meadows, young
were out at the mouths of burrows in numbers, usually in groups of five
and six. At Tenaya Lake on July 29 the young animals seen were larger
than those at the higher stations. It is therefore probable that the
young are born earlier at the lower altitudes than at the higher levels.
The record at Williams Butte goes to substantiate this belief. Full size
is not attained for some weeks; young weighing scarcely more than half
as much as adults were taken at Merced Lake August 31 and in Tioga Pass
September 25, 1915.
As early as July 26 small new burrows with mounds of
earth at the entrances were beginning to appear on Tuolumne Meadows.
These were evidently made by young which had been turned out of the
parental burrows to shift for themselves.
When the young first go above ground they frisk about
the entrance to the burrow under the watchful eye of the female parent.
In Lyell Cañon on July 25, 1915, one of us came upon a single
young animal running in and about some rock crevices adjacent to the
burrow at the side of the meadow. The mother was standing guard,
uttering her note, e-chert', every few seconds. The observer
'squeaked,' whereupon the parent squirrel at once rose upon her hind
feet in the picket-pin position and uttered the shrill piping warning
call of the species; the youngster promptly ran into the burrow. The
adult remained standing on her hind feet for 48 seconds, then sank down
on her haunches.
A day or two later, another family group consisting
of a female and 2 half-grown young, on Tuolumne Meadows, was studied at
close range for some time.14 At first the youngsters did not
venture very far out of the hole; and when they did they remained on the
far side of their mother. Later, they gained courage and came more into
view, one being more venturesome than the other. The mother stood much
of the time in the picket-pin position giving the e-chert' call.
At each utterance her body was shrugged up, the head and shoulders
thrown forward and the tail given an upward flip; much effort seemed to
be put into the production of this note. In cases where families of 5 or
6 young were seen, they all sat close about the entrance of the burrow
and when frightened all attempted to crowd into the hole at the same
instant. One youngster, bewildered by some horses, ran directly at one
of our party and then escaped into a shallow hole some distance from its
14This was done by the
method of direct approach. The observer garbed in dull brown-colored
outing clothes, started about 100 feet away and advanced slowly in a
direct line toward the squirrels. As he came closer his movements were
made slower and slower so as not to startle the animals. Sidewise
movement was avoided in every possible way. The squirrel, using
monocular vision, was thus less able to appreciate his approach. This
method is very useful in getting close to birds or mammals in order to
study or photograph them.
The Belding Ground Squirrel escapes the rigors of the
Sierran winterwhen the temperature falls low and all the
grasslands are blanketed in snowby hibernating. The exact duration
of the hibernation period is not known. At the Farrington ranch, near
Williams Butte, one of these squirrels was obtained on April 29, 1916.
In many localities individuals are out before all the snow has
disappeared, and in places they have been seen to run over snow banks.
At the end of September many of the animals were still abroad in Tioga
Pass and on Tuolumne Meadows, even after a slight snowfall. Our latest
record is of an individual out at Ten Lakes on October 6, 1915.
The only direct evidence of enemies is a note that at
Tuolumne Meadows a Mountain Weasel was seen killing one of these
squirrels. The weasel had the squirrel by the back of the neck. The
larger high-mountain carnivores probably also levy toll on the Belding
Ground Squirrel whenever opportunity offers.