Desert Pocket Gopher
Order Rodentia : Family Geomyidae : Geomys arenarius Merriam

Description. A dull, pale-brown pocket gopher, with two longitudinal grooves on outer face of each incisor; feet and underparts white. External measurements average: (males) total length, 262 mm; tail, 79 mm; hind foot, 33 mm; (females) 243-74-32 mm. Weight; males, 198-254 g; females, 165-207 g. Dental formula as in G. bursarius.

Distribution in Texas. Restricted in Texas to the Trans-Pecos, where it has been taken at several localities in the cottonwood-willow association along the Rio Grande in El Paso and Hudspeth counties.

Habits. Near El Paso, these gophers are especially common along irrigation ditches in the sandy river-bottom area. They seemingly cannot tolerate clayey or gravelly soils, a characteristic common to all species of Geomys. Their mounds are large and conspicuous, and often one animal will throw up 20 to 30 of them in a relatively short time.

Their underground habits are not well-known. Seth Benson reports finding flowers and cut stems of a composite (Baileya) in their burrows. Doubtless, these were being eaten. Other than this plant and cultivated alfalfa, their food preferences have not been recorded.

Raymond Lee captured two gravid females near El Paso on June 28 and one on August 8. Numbers of embryos were six, four, and four, respectively. Young individuals have been captured in late June, July, and August. These data indicate a prolonged breeding season and suggest that adult females bear more than one litter a year.

Where concentrated in numbers in farming areas, they may do considerable damage. Elsewhere, their burrowing activities are largely beneficial. Frank Blair observed that the bunch grass Andropogon in New Mexico was intimately associated with the mounds of this pocket gopher. The grass appeared to grow more successfully on old gopher mounds than on the valley floor. The excrement of the gophers helped to fertilize the mounds.

Remarks. Using karyotypic and electrophoretic analyses, David Hafner and Kenneth Geluso found shared genetic characters in G. arenarius and G. knoxjonesi, then considered a subspecies of G. bursarius. These similarities were not sufficient to combine G. arenarius with G. bursarius; however, when Robert Baker et al. recently elevated G. knoxjonesi to full specific status, based on mitochondrial DNA analysis, the taxonomic status of G. arenarius was left in question. At this time it is uncertain whether Jones’ pocket gopher and the desert pocket gopher indeed represent separate species, or if further detailed study of these taxa will show that combining the two as a single species will be warranted. It is distinctly possible that in the future G. arenarius will be shown to be merely an isolated population of the similar G. knoxjonesi.