||The Mammals of Texas -
Texas Antelope Squirrel
Rodentia : Family Sciuridae : Ammospermophilus
Description. A small ground squirrel with
one narrow white line on each side of back from shoulder
to rump, and underside of tail grayish white, the lateral
tail hairs with three black bands; upperparts vinaceous
buff in summer and drab gray in winter; ears short,
hardly more than a rim; tail held over back in life.
External measurements average: total length, 226 mm;
tail, 74 mm; hind foot, 38 mm. Weight (males), 104
(94-121) g; (females), 104 (84-115) g.
Distribution in Texas. Known in Texas
east to Reagan, Crockett, and Val Verde counties.
Habits. These squirrels are
characteristic of desert regions in the southwest where
they live chiefly around the edges of the lower valleys
and in the low hills. They seem to prefer hard-surfaced,
gravelly washes or rocky hill slopes and are less common
or entirely absent on level, sandy terrain.
They usually live in burrows but
crevices in and among rocks may serve as den sites. They
also make use of abandoned burrows of other rodents.
Their burrows are usually situated at the side of a clump
of bushes, a boulder, or in a cut bank. There is usually
no mound of earth to mark the entrance. One burrow found
in a cut bank was excavated in friable soil under a bed
of hardpan about 1 m below the top of the ground and 50
cm above the roadbed. The main tunnel was 8.7 cm in
diameter, 3 m long, and lay parallel to and about 30 cm
back from the face of the cut. Access was by three
openings. Midway in the tunnel was the nest chamber which
measured 12.5 cm in width, 17.5 cm in length, and 10.0 cm
in height. An accessory loop back of the nest and two
blind pockets at one end of the main tunnel completed the
system. The nest was composed of rabbit fur, shredded
bark, feathers, dried grasses, and bits of cotton.
"Ammos" are fidgety, nervous
creatures and seldom are still for long. They are
nimble-footed and can run with surprising speed. Their
peculiar habit of carrying the tail arched forward over
the back, exposing to view the contrastingly colored
undersurface, is a readily usable field characteristic.
The nervous flickering of the tail when the animals are
excited and the mellow, rolling, trill-like calls further
help to identify them. They spend most of the time on the
ground but they may be seen in the tops of low bushes,
yuccas, and prickly pears where they also forage.
Available evidence indicates that at lower elevations
these ground squirrels do not hibernate.
Antelope ground squirrels are one of
the few mammals that may remain active during the hottest
parts of west Texas summer days. By occasionally
retreating to a shady spot where they lie outstretched,
with their limbs "spread eagle" and their belly
in contact with the cooler terrain, excess heat
accumulated during their activities is rapidly lost and
the squirrels are able to maintain a safe body
temperature. After such rests the squirrels once again
venture into the summer sun to conduct their business.
Their food is largely a wide variety of
seeds and fruits. They have been observed feeding on
seeds of yucca, juniper, salt grass, ripe fruits of
prickly pear and cholla cactus, seeds of mesquite, sotol,
creosote bush, and insects.
Breeding begins in February. One litter
of five to 14 young, based on embryo counts, is reared
each year, but there is evidence that a second brood may
be reared by some females. The young ones remain in the
nest until they are about one-fourth grown, at which time
they venture above ground and begin eating solid foods.
Information on other phases of reproduction appears to be
Photo credit: R.D. Porter.