Baird's Pocket Gopher
Order Rodentia : Family Geomyidae : Geomys breviceps Baird

Description. Nearly identical in appearance to G. bursarius and G. attwateri. Morphologically, this species may be distinguished from G. bursarius by cranial characters described in the account for G. attwateri, but is not readily distinguishable from G. attwateri without genetic testing.

The most important feature for identifying this gopher is its karyotype, which has a diploid number of 74 and a fundamental number of 72. G. breviceps has four more biarmed elements in the autosomal complement than does G. attwateri. Compared to G. bursarius, G. breviceps has two more chromosomes.

G. breviceps is smaller than both G. attwateri and G. bursarius. External measurements average: total length, 208 mm; tail, 61 mm; hind foot, 26 mm. Dental formula as in G. bursarius.

Distribution in Texas. This pocket gopher is found in the eastern portion of Texas. The westward limits of its range in the state are from Falls County north to Fannin County, and southeastward along the Brazos River to Brazoria County.

Habits. The habits of G. breviceps are essentially the same as those described for G. bursarius.

These pocket gophers are polygamous, but breeding is restricted to immediate neighbors. The annual reproductive cycle in eastern Texas shows seven consecutive months of breeding activity, from February until August. A peak in production occurs in June and July, and a lesser peak in April; no young are produced from September through January. Litter size is from one to six, with an average of two or three. Females may produce two broods annually. The gestation period is 4-5 weeks and lactation lasts 5-6 weeks, after which the young leave the parental burrow. Young females may reach sexual maturity and produce a litter before the end of the breeding season.

Cellulose-digesting bacteria are known from the caecum and large intestine of G. breviceps, which may allow winter feeding on stored, underground rhizomes. Also, these pocket gophers re-ingest fecal pellets, which apparently increases the efficiency of food utilization.