Texas Pocket Gopher
Order Rodentia : Family Geomyidae : Geomys personatus True

Description. A large, pale-drab or grayish-drab species with relatively long, scant-haired tail, the distal half nearly naked; upper incisors with two grooves; underparts marbled white and dusky. External measurements average: (males) total length, 321 mm; tail, 110 mm; hind foot, 41 mm; (females) 303-103-39 mm. Weight, up to 400 g. Dental formula as in G. bursarius.

Distribution in Texas. South Texas as far north as Val Verde County on the west and San Patricio County on the east.

Habits. This species occurs in deep, sandy soils. It is entirely absent from the silt loams of the flood plains of the Rio Grande and also from gravelly, stony, or clayey soils scattered throughout its general range.

Numerous burrows of these gophers occur in the deep drift sands on Mustang and Padre Islands where the sand is moist enough to permit packing. Sometimes the tunnels are at the water table and the runways soppy with seepage, but most often they are about halfway between the surface and the water table 50 cm below. Excavated burrows average about 10 cm in horizontal diameter, 12.5 cm in vertical diameter, and 25 cm beneath the surface. In places where the sand was drier, yet still moist enough to maintain a burrow, the tunnels are about 12 to 15 cm in diameter. In the soils near Robstown, Texas, the burrows ranged from 6 to 8 cm in diameter.

One partially excavated burrow system on Padre Island was more than 30 m long. There were numerous short side branches, but no food cache nor a chamber for fecal pellets, as is usual in burrows of Geomys, was found. Another burrow excavated on the mainland contained a food cache of Bermuda grass. The average mounds are large; a typical one might measure 45 by 60 cm in horizontal diameter and 12 cm in height. It could contain almost 6 kg of sand.

These gophers are ferocious isolationists; they resent molestation. When angry they emit a wheezy call at frequent intervals and gnash their teeth.

Their food consists largely of vegetation. Known items include roots of grasses (Paspalum, Cynodon, and Cenchrus) and the roots, stems, and leaves of a composite (Helianthus). Most of their foraging is done underground; the plants often are seized from below and pulled into the burrow. Their feces are capsule-shaped and about 19 mm in length and 7 mm in diameter. Individuals of this species, as well as other Geomys, have the interesting habit of ingesting their own fecal pellets. A fecal pellet is taken in the incisors directly from the anus, examined and manipulated with the aid of the forefeet, and then either discarded or thoroughly chewed and swallowed. Usually two to four pellets are produced at a time with only one or two being eaten, often none. There appears to be no pattern as to which pellet or pellets are eaten. Production of fecal pellets often occurs in the nest, in which case the rejected pellets are simply pushed out into the adjoining tunnel. Pocket gophers may also stop their travels through the burrow system to defecate, again either discarding or eating the pellets after examining each one carefully. Captive individuals have been seen to interrupt a meal of grass, potatoes, or other food to defecate and then consume one or more fecal pellets. This behavior is well-documented for many species of rabbits and rodents, and may serve to extract maximum sustenance from ingested plant foods.

Their breeding habits are not well known. Pregnant females have been captured in all months except April, June, August, and September, suggesting that breeding may occur year round. Young gophers about one-fourth grown were trapped in early April. Litter size ranges from one to five, averaging three. Probably no more than two litters are reared yearly.

In southern Texas, these gophers have little economic importance except in cultivated fields or where they become established along the highways. In the latter case, they may undermine the shoulders and initiate erosion.

Photo credit: John L. Tveten.