|The Mammals of Texas -
Texas Pocket Gopher
Rodentia : Family Geomyidae : Geomys
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
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
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
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
Photo credit: John L. Tveten.