Next Species
Previous Species

Home Page

Copyright Information

  The Mammals of Texas - Online Edition

Texas Antelope Squirrel
Order Rodentia : Family Sciuridae : Ammospermophilus interpres (Merriam)

Texas Antelope Squirrel (Ammospermophilus interpres).  Photo by R.D. Porter.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.

Species distribution mapDistribution 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 lacking.

Photo credit: R.D. Porter.