|The Mammals of Texas -
Baird's Pocket Gopher
Rodentia : Family Geomyidae : Geomys
Description. Nearly identical in
appearance to G. bursarius
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.
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