||The Mammals of Texas -
Rodentia : Family Sciuridae : Spermophilus
Description. A large, moderately
bushy-tailed ground squirrel; upperparts mottled grayish
brown, the hind back and rump more brownish (head or head
and upper back blackish in some parts of the state); tail
mixed buff and brown, edged with white; underparts buffy
white or pinkish buff. External measurements average:
total length, 468 mm; tail, 210 mm; hind foot, 57 mm.
Weight of adults, 600-800 g.
Distribution in Texas. Known from the
Trans-Pecos and central regions of the state.
Habits. Rock squirrels are
nearly always found in rocky areas cliffs, canyon
walls, talus slopes, boulder piles, fills along highways,
and so forth where they seek refuge and have their
dens. In the Pecos River Canyon in western Texas, where
the walls are a series of alternating, nearly vertical
precipices and narrow horizontal shelves, these squirrels
are very much at home. They scale the steep, smooth walls
with speed and assurance and never hesitate at what
appear at a distance to be perfectly smooth surfaces.
Closer inspection usually reveals that cracks and
fissures in the rocks offer them adequate footing.
Although typical ground squirrels in
most respects, they can climb trees nearly as well as
tree squirrels. In the Guadalupe Mountains of western
Texas, they have been observed 5 or 6 m up in the
flowering stalks of agaves feeding on the flowers and
buds. They also climb to the tops of junipers to forage
on the berries and in mesquites to feed on the buds or
beans. Occasionally, they den in tree hollows 5 or 6 m
from the ground. The usual den, however, is a burrow dug
under a rock; others are in crevices in rock masonry
along railroads and highways, cavities in piles of
boulders, or small caves and crevices in rocky outcrops.
They are diurnal and most active in early morning and
late afternoon, but they are rather shy and difficult to
observe at close range. Their call is usually a repeated
sharp, clear whistle.
They feed on a variety of plant
materials depending on availability. Known items include
acorns, pine nuts, walnuts, seeds of mesquite, cactus,
saltbush, agave, wild gourd, cherries, sumac, spurge,
serviceberry, berries of currant and juniper, and all
sorts of cultivated fruits and vegetables. Insects also
contribute importantly to their diet, especially
grasshoppers, crickets, and caterpillars. They are fond
of flesh and are known to catch and eat small wild
turkeys and other birds.
They store quantities of food for
winter use which, coupled with the fact that they are
seen occasionally in winter on mild days, suggests that
they either do not hibernate or that hibernation is
incomplete and only for short periods. At lower
elevations in the Big Bend region of Texas they are
active all year.
Mating activities begin in March and
continue into July, which suggests that two litters may
be produced each year. Litter size ranges from two to
five. Gravid females have been collected in June. Young
squirrels first appear above ground at 6-8 weeks of age,
and young about quarter-grown have been captured as early
as June and as late as September 20. Little is known
about the birth and early life of the young squirrels.
Photo courtesy of Texas Parks and Wildlife.