||The Mammals of Texas -
Plains Pocket Gopher
Rodentia : Family Geomyidae : Geomys
Description. These are medium to small
sized, dark brown gophers with large, furlined cheek
pouches. The body is thick-set and appears heaviest
anteriorly, from which it gradually tapers to the tail,
widening a little at the thighs. The eyes are tiny and
beadlike, and the ears are very rudimentary, represented
only by a thickened ridge of skin at the base. Long
curved claws are present on the front feet for digging;
the claws on the hind feet are much smaller.
The dental formula is I 1/1, C 0/0, Pm
1/1, M 3/3 X 2 = 20. The upper incisors have two grooves.
External measurements average: total length, 236 mm;
tail, 65 mm; hind foot, 31 mm. Weight: males, 180-200 g;
females, 120-160 g.
Distribution in Texas. Northwestern and
north-central Texas, south to Midland and Tom Green
counties in west and to McLennan County in east. Grayson
and Dallas counties appear to be the eastern limit of
this species in Texas.
Habits. This pocket gopher
typically inhabits sandy soils where the topsoil is 10 cm
or more in depth. Clayey soils are usually avoided. These
gophers live most of their solitary lives in underground
burrows, coming to the surface only to throw out earth
removed in their tunneling and to forage for some items
of food. They seldom travel far overland. The average
diameter of 40 burrows examined in Texas was nearly 6 cm;
the average depth below the surface, 14 cm, with extremes
of 10 cm and 67.5 cm. Much of their burrowing is done in
search of food. The underground galleries attain
labyrinthine proportions in many instances because the
tunnels meander aimlessly through the feeding areas. This
is particularly noticeable under oak trees that have
dropped a good crop of acorns. Burrows have been examined
that extend well over 100 m, excluding the numerous short
side branches. Only one adult gopher normally occupies a
single burrow system.
The average mound thrown up by these
gophers is about 30 by 45 cm, about 8 cm in height, and
crescentic in outline. The opening through which the
earth is pushed is usually plugged from within. The
gopher digs with its front claws and protruding teeth,
shoves the loose earth ahead of it with its chin and
forefeet, and uses the hind feet for propulsion. The
ceaseless energy of these subterranean miners is
suggested by the size of the huge winter mounds they make
in sites that have poor underground drainage. One of
these was 2 m long, 1.5 m wide, 60 cm high, and weighed
an estimated 360 kg. The female that occupied this mound
weighed 150 g. A typical winter mound contains numerous
galleries, a nest chamber, a toilet, and food storage
These rodents feed on a variety of
plant items, chiefly roots and stems of weeds and
grasses. Most plant food is encountered and ingested
while the gopher digs, but some "grazing" of
food present along burrow walls probably also occurs. The
furlined cheek pouches are used to carry food and nesting
material but never dirt. Captive gophers have eaten white
grubs, small grasshoppers, beetle pupae, and crickets.
Earthworms and raw beef were ignored.
Breeding begins in late January or
early February in eastern Texas and continues for a
period of some 3 or 4 months. One litter a year, or two
in quick succession, appears to be the rule. The young,
usually two or three in number, are born from March to
July. The young are nearly naked, blind, and helpless at
birth. They remain with their mother until nearly
full-grown and then are evicted to lead an independent
As long as they remain in their
burrows, pocket gophers are relatively safe from
predators other than those which are specialized for
digging, such as badgers and long-tailed weasels.
However, when a gopher leaves its burrow it is highly
vulnerable, and most predation losses probably occur on
the surface. Known predators, other than those mentioned
above, include coyotes, skunks, domestic cats, hawks,
owls, and several kinds of snakes. As a result of the
protection offered by the burrow, pocket gophers are
long-lived relative to many other rodents, insectivores,
and lagomorphs, living an average of 1-2 years in the
In farming regions these rodents can be
destructive to crops and orchards. The amount of damage
is closely associated with the number of animals. The
average population density in eastern Texas is about 3.2
gophers per ha. The highest population density of record
is 17.6 per ha. These gophers can be controlled on small
areas by trapping and on large ones by placing poisoned
grain in their burrows.
Remarks. Historically, Geomys
bursarius has been considered one wide ranging, but
morphologically variable species that was distributed
over most of the Great Plains and south-central United
States, including the Texas Panhandle and eastern Texas.
However, recent studies by specialists trained in
cytological and biochemical taxonomy have revealed that
in actuality there are five species of pocket gophers
ranging over these regions of Texas (designated G.
bursarius, G. attwateri,
breviceps, G. knoxjonesi, and G. texensis).
These are considered cryptic species, meaning that they
cannot be differentiated on the basis of observed
morphological characteristics although they are
genetically distinct. Karyotypic, electrophoretic, and
mitochondrial DNA data are required to confidently
distinguish questionable specimens, although all appear
to be allopatric in range.
Photo credit: L. K. Couch.