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  The Mammals of Texas - Online Edition

Mexican Ground Squirrel
Order Rodentia : Family Sciuridae : Spermophilus mexicanus (Erxleben)

Mexican Ground Squirrel (Spermophilus mexicanus).  Photo by John L. Tveten.Description. A rather small ground squirrel with usually nine rows of squarish white spots on back; tail about two-fifths of total length, moderately bushy; ears short and rounded; upperparts wood brown or buffy brown with rows of conspicuous white spots; sides and underparts whitish or pinkish buff. External measurements average: total length, 301 mm; tail, 118 mm; hind foot, 41 mm. Weight, (males) 227-330 g; (females), 137-198 g.

Species distribution mapDistribution in Texas. Occurs throughout much of southern and western Texas (west to Culberson, Jeff Davis, and Presidio counties in the Trans-Pecos), north almost to the Red River just east of the Panhandle.

Habits. Mexican ground squirrels inhabit brushy or grassy areas. In southern Texas, they are frequently associated with mesquite and cactus flats. In Kerr County, they are most common in pastures and along the highways; in Trans-Pecos Texas, they are frequently found in areas dominated by creosote-bush (Larrea).

They live in burrows, the openings to which are usually unmarked by a mound of earth. Sandy or gravelly soils are preferred, but the squirrels are by no means restricted to them. One squirrel may utilize several burrows, one of which is the homesite; the others are temporary refuges. The burrows are typically from 6 to 8 cm in diameter, enter the ground at a 30 to 50 degree angle, and range from 30 to 125 cm below the surface. The brood chamber is usually at the deepest part in a side tunnel. There are often two openings to the burrow system, possibly to facilitate escape. They also utilize burrows of pocket gophers. Although somewhat colonial, they are rather unsocial and drive away other squirrels that intrude upon their privacy. Their home range is about 45 m in radius.

Near Midland, most of the squirrels are in hibernation by November 20, although there is some activity throughout the winter. Likewise, in the Trans-Pecos they are seldom seen in winter, but in South Texas they remain active throughout the year.

Their food in early spring is chiefly green vegetation. They are known to feed on mesquite leaves and beans, agarita leaves and berries, Shasta lily, Johnson grass, pin clover, and cultivated grains. Insects also contribute importantly to their diet. In early summer about half of their diet is insects. They are fond of meat and frequently can be seen feeding upon small animals killed on the highways. In captivity they exhibit a cannibalistic tendency and kill and eat their cage mates, particularly if a strange squirrel is placed with them. Occasionally they climb into low bushes to forage, but most of their food is gathered on the ground.

Breeding begins in late March or early April and lasts for a week or two. The gestation period is probably not more than 30 days. The young, about five per litter, are born blind and almost naked and weigh from 3 to 5 g.

Photo credit: John L. Tveten.