Pocket gopher

“ In North and Central America the Pocket-gophers form a curious group of small rodents with cheek-pouches opening on the outside. They spend their entire existence underground, and are said to use their incisor teeth as picks to open the hard earth in their tunnels. They push the loosened soil out by pressing it with their chests and fore feet. When a gopher has eaten enough to satisfy the immediate calls of hunger, it stores all spare food away in the large cheek-pouches. ”

“ Their food consists of vegetable matter such as roots, bulbs, tubers and surface foliage and green vegetation.
The pocket gopher is rather small in size, about eight inches long, including a tail of a little over two inches, and is light brown in color. The tail is only sparsely haired and the front feet are large and built for digging. The Uinta ground squirrel or picket-pin is frequently referred to by some people as a gopher, but it should not be confused with the true gopher and is seldom seen above the ground. ”

“ The habit of burrowing at different levels probably was one factor which permitted the two kinds of pocket gophers to live in the same area. The average weight of these gophers was 86 grams in males and 74 grams in females, or only an eighth as much as in Cratogeomys.
Cratogeomys gymnurus imparilis (Goldman)
Plains Pocket Gopher; Spanish, Tuza Llanera; Tarascan, Cúmu (Cŏmŏ)
Platygeomys gymnurus imparilis, Goldman, Jour. ”

“ If he does, he is immediately pounced upon by the angry owner, and is usually driven clear out of the burrow. These animals are undoubtedly far the most versatile and intelligent rodents in the world.
A most unusual miner and underground dweller is the pocket gopher of North and Central America. He is a rat-like animal, and is most plentiful on the plains of the Mississippi region. He is unusual in appearance, dressed in brown and grey fur, with tiny white feet, small eyes and ears, and a short stubby tail. His feet are wonderfully strong, and his fore-paws are armed with strong, curved claws. ”

“ Desert mountains with their thin rocky soils, elevated passes, perpendicular rocky cliffs, and stands of oaks and conifers at higher elevations present impassable barriers for pocket gophers of this species. The Río Grande, bordering Coahuila to the north, in many places flowing [594] through steep-walled cañons, also seems to be a barrier that this fossorial rodent does not cross; distinct subspecies occur on the two sides of the river directly opposite each other (also see Nelson and Goldman, op. cit.: 143) . ”

“ Therefore, the results of comparisons with only that subspecies are here reported upon. T. u. tolucae to the eastward is for one thing a much larger animal and has slightly less procumbent upper incisors. So far as we know, Thomomys umbrinus has not heretofore been reported from Michoacán. Of our seventeen skins, eight are brown, six are black and two are intermediate in color.
Most of these pocket gophers lived where there was a good growth of pine trees in the same areas where large pocket gophers of the species Cratogeomys gymnurus occurred. ”

“ Remarks.--Cratogeomys castanops consitus is a small pocket gopher (see tables 1 and 2) ; the largest adult available to us is much smaller than the smallest adult of any adjacent subspecies. Specimens from Coahuila assigned to consitus compare favorably with topotypes although those from the vicinity of Jaco are smaller, paler and have a narrower rostrum and smaller maxillary teeth. An immature male trapped three miles northeast of Sierra Mojada is tentatively assigned to consitus. This subspecies seems to be rare in northwestern Coahuila and small colonies are widely scattered. ”

“ Earth excavated during the winter months is firmly packed in tunnels which the gopher makes on the surface of the ground beneath the snow. These winding ridges of earth are revealed by the melting snow as further evidences of pocket gopher activity. ”

“ Another member of our field party (E. R. Hall) when removing from its burrow a trapped Thomomys that was caught only by the hind leg, dug around the animal whose burrow was approximately six inches underground and in doing so he also broke through the roof of a burrow of Cratogeomys. The burrow of Cratogeomys was approximately sixteen inches below the ground. Nowhere else, except 3 to 5 miles south of Pátzcuaro, have the authors found two kinds of pocket gophers living together. ”

“ The term gopher, however, belongs properly to a very different group of animals, to which it should be restricted, namely, the pocket gophers, which have external cheek pouches, and resemble the moles in living under ground and throwing up little mounds along the courses of their subterranean tunnels. Ground squirrel is a less objectionable name, because these animals really are ground squirrels ”

“ Map showing the geographic distribution of the five subspecies of the Missipi Valley pocket gopher, Geomys bursarius, in Kansas, with insert showing range of the species.
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In connection with this study each of the authors acknowledges assistance from the John Simon Guggenheim Memorial Foundation and one of us (Villa) is grateful for assistance also to Drs. Isaac Ochoterena and Roberto Llamas of the Biological Institute of Mexico. For the loan of specimens we are grateful to Dr. William B. Davis, of the Agricultural and Mechanical College of Texas; Dr. G. C. Rinker, of Hamilton, Kansas ”

“ The gopher digs long tunnels under ground, making storerooms here and there in these passages, which he fills with grass, roots, and seeds. In each cheek he has a pouch, or pocket, large enough to hold nearly a handful of grain, so the little rascal carries his stores very easily. The traps and poison by which the farmer is always trying to make way with him, he is sly enough to let alone. His greatest foe is the cat, which watches patiently at the hole where the destructive little fellow is digging and usually catches him. ”

“ Among the Pappogeomys collected by Alcorn were three specimens from the high Sierra del Tigre, an isolated range not previously sampled for pocket gophers. The Sierra del Tigre is situated in southern Jalisco and western Michoacán, and, like most of the mountainous terrain in this region of México, is volcanic in origin. To the south the Sierra del Tigre descends abruptly to lower elevations of the arid coastal plains, uninhabited by gophers of this genus. ”

“ They drag leaves and any manageable portion of plants into their burrows, and much of the material so taken down into the ground decays and enriches the ground to a depth of several inches. The pocket gopher has done much to furnish a surface layer of loose, mellow, easily cultivated and highly productive soil. Like the earth worm, the gopher for century after century has been bringing up to the surface fine material, to the amount of several tons annually to the acre, avoiding necessarily the pebbles, cobbles and coarser constituents. ”

“ Geomys quinni was widespread and common throughout the central Great Plains from the late Pliocene (Rexroad fauna) through the early Pleistocene (Nebraskan and Aftonian deposits) .
Hibbard (1956:179) referred the pocket gopher remains taken from the Saunders local fauna in Meade County, Kansas, to Geomys tobinensis, a small species having continuous enamel bands around the lower premolar in younger specimens. The Saunders local fauna was deposited in the late Aftonian and is younger than the Deer Park local fauna discussed above. ”

“ As the dirt accumulates in its rear the animal turns in its burrow and, bringing its wrists together under its chin, with the palms of its hands held up, forces itself along by its hind feet, pushing the earth outward. All the pocket gophers have external cheek pouches, which are used for carrying food. They are great hoarders, and fill their storehouses with vastly more than they consume. The cheek pouches reach back as far as the shoulder. A captured animal filling its pouches after a meal made motions so rapid that they were hard to observe. ”

“ Although some question as to the exact age of the Curtis Ranch local fauna still seems to exist, most authorities on the Pleistocene agree that the age is not Pliocene and that it is older than Rancholabrean. Gidley (1922:122) described the pocket gopher found in the Curtis Ranch beds as Geomys parvidens, which is preoccupied by Geomys parvidens Brown (1908:194) , a name proposed for the pocket gopher from the Conard Fissure of Arkansas; therefore, Hay (1927:136) proposed the name Geomys persimilis for the Curtis Ranch species to replace Geomys parvidens Gidley. ”

“ This divides Coahuila into a more humid and less elevated northeastern area which is an inland extension westward of the Coastal Plain and a more arid and higher western and southern area which is a part of the "Mesa del Norte" of the Mexican Plateau. In the extreme southeast the still higher elevated plains and intermontane valleys within the Sierra Madre Oriental afford a third habitat for populations of this species. The subspecies of these pocket gophers found in any one of these three habitats show greater affinity to each other than they do to any subspecies found in the other habitats. ”

“ During the mating season in spring pocket gophers run about clumsily from one burrow to another and may often be seen on the surface by the light of the rising sun. Most of their short trips above ground are made at night, when they sometimes swarm out and wander over a limited territory. Their night wanderings are proved in California by the many bodies which the morning light often reveals in the sticky crude oil on newly oiled roads which the gophers have tried to cross. ”

“ Little evidence of pocket gophers was found on unusually rocky slopes, steep slopes, or in stands of [Pg 48] pinyon and juniper or in relatively pure stands of oak-brush. In addition to workability of the soil, the presence of herbaceous plants, many of them weedy annuals, is probably the most important factor governing the success of pocket gophers in a local area. No female was recorded to have contained embryos, but two had enlarged uteri or placental scars. This fact and the capture of nine half-grown individuals indicate breeding prior to late August when most specimens were trapped. ”

“ The isolation of soils with textures suitable to this animal has resulted in the isolation of gopher populations. The distribution is similar to that of species occurring on islands. In this instance, however, the populations of gophers are separated by soils of heavy texture which render burrowing difficult or impossible for gophers. ”

“ T. H. Scheffer (1938B: 220-224) found the gestation period of the pocket gopher to be approximately 28 days. No second brood is raised in Washington. Near Kennewick, Yakima County, the young are born from February to April. The average number of embryos found in 76 female gophers was 6.3. Near Olympia, Thurston County, the young are born from March to June. The average number of embryos from 312 females was 5.0.
Thomomys talpoides devexus Hall and Dalquest
Thomomys talpoides devexus Hall and Dalquest, Murrelet, 20:3, April 30, 1939. ”

“ When trapping, it is possible to predict what species will be taken by the types of burrows and soil. Gophers of the bottae group have their burrows in the areas of the deepest soil and heaviest vegetation, whereas the areas of shallow, rocky soil covered with sparse vegetation are the habitat of talpoides. Above 6,000 feet the only gopher encountered is talpoides. Along Settlement Creek on the west side of the Oquirrh Mountains, which is the type locality of oquirrhensis, bottae and talpoides have essentially [Pg 13] the same vertical distribution as in Rose Canyon. ”

“ Thus, it was possible when comparing different kinds of pocket gophers to use only one age class of one season of one sex.
Age was estimated to some extent by size of animal and nature of its pelage. The immature pelage is grayer and the hair is more crinkled than in adults. A more certain guide to age, however, is furnished by the skull. With increasing age some sutures disappear, the rostrum increases in length and the ridges marking the limits of the temporal muscles come to fuse and eventually, in males, form a high sagittal crest. ”

“ Pocket gophers feed almost exclusively upon the roots and bulbs exposed by their burrowing activities, although at rare intervals they may move a short distance from the burrow to gather surface food. ”

“ The genus of mountain-beavers contains only a single species with several subspecies, all having a close superficial likeness in size and form to a tailless muskrat, except for their coarse, harsh fur. It is an exclusively North American type and, aside from a remote relationship to the squirrel family, has no kin among living mammals. It appears to be a sole survivor from some former age. As with the pocket gophers, its mode of life has developed powerful muscles about the head, front legs, and forepart of the body. ”

“ With the exception of the moles no other extensive group of American land mammals is so highly specialized for a peculiarly restricted mode of life as the pocket gophers. They form a strongly marked family, the Geomyidæ, which includes various genera and many species, all very similar in external form, but varying from the size of a large mouse to a massively formed animal equalling a large house rat in weight. ”