During the reproductive season, males seek a female by either extending their burrows to those occupied by a female, or by searching above ground for an entrance to a female burrow. Because home ranges of males do not overlap, but male home ranges overlap with those of one to four females, the breeding system is polygynous. The highly territorial behavior of desert pocket gophers decreases during the breeding season in accordance with this mating behavior.
Mating System: polygynous
Desert pocket gophers have two reproductive cycles in a year, one in spring and another in summer. The breeding season is also prolonged in the summer months, allowing for the possibility of having more than one litter per year.
The gestation period of G. arenarius is 18 to 19 days and females have 3 to 4 offspring per reproductive effort. Newborn pocket gophers are born altricial with closed eyes, ears, and cheek pouches. At about 26 days the offspring's ears and eyes open and around 39 days the cheek pouches have opened and are able to carry food. At about 100 days molting to adult pelage is half complete. Weaning occurs around 35-40 days of age; however, the young stay with their mother until about the age of 2 months, when they begin to disperse.
Breeding interval: Desert pocket gophers have two reproductive cycles a year, with a prolonged breeding season during the summer months.
Breeding season: Mating usually occurs during the spring and summer months.
Range number of offspring: 4 to 6.
Range gestation period: 18 to 19 days.
Range weaning age: 35 to 40 days.
Average time to independence: 2 months.
Range age at sexual or reproductive maturity (female): 9 to 12 months.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Not much is known about the parental care of desert pocket gophers. Newborns are atricial when born, requiring some parental care to survive. Young stay with their mother for almost a month after weaning, however the reasons for such extended care is unknown. Male parental care is either absent or unknown.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning, Protecting: Female); pre-independence (Protecting: Female)
Desert pocket gophers have small eyes and ears as an adaptation for moving through underground tunnels. They do not rely heavily on visual or acoustic perception channels. They mainly perceive their environment through the vibrissae covering their body, and through their sensitive tail, which they use as a guide when moving backwards out of a tunnel. Chemical cues are also very important.
Little is known about the communication habits of desert pocket gophers in the wild. Pocket gophers in captivity make grinding, chattering noises with their teeth, eliciting similar clicking noises from other pocket gophers nearby.
Communication Channels: tactile ; acoustic
Other Communication Modes: pheromones
Perception Channels: visual ; tactile ; acoustic ; chemical
The conservation status of Geomys arenarius is described as near threatened.
IUCN Red List of Threatened Species: near threatened
Desert pocket gophers are considered pests by humans because of the great economic loss they can cause in agricultural areas. Their burrowing and ejecta mounds can damage crops as well as lead to the depletion of grazing ranges. Some crops that are particularly damaged through desert pocket gopher activity are sweet potatoes, sugar cane, and peas. Desert pocket gophers can also cause erosion through their mounds and tunnels and are considered a nuisance by home gardeners.
Negative Impacts: crop pest
Humans benefit from desert pocket gophers through their cycling of the soil. This cycling process allows for soil aeration and blending of organic matter into the soil which in turn increases soil fertilization.
The main influence of desert pocket gophers on the ecosystems in which they live is through their continuous working of the soil. Desert pocket gophers increase the mixing and aeration of soils they inhabit, increasing soil fertility and stimulating vegetation growth. The vertical cycling of soil through desert pocket gopher activity also increases soil fertility in that it loosens and aerates the earth as well as mixes organic matter into the soil, through such things as fecal materials and vegetation stores underground. However, this continuous working of the soil can also accelerate soil erosion on overgrazed ranges.
Ecosystem Impact: soil aeration
Desert pocket gophers are strict herbivores. They are opportunistic feeders and will eat a wide variety of plants including underground roots, rhizomes, and bulbs they encounter within their burrow system. They also feed on above ground vegetation that is easily accessible from their burrows. They will eat any part of the plant including stems, roots, leaves, flowers, needles, buds and seeds. They also eat alfalfa as well as a variety of grass species. Desert pocket gophers obtain adequate amounts of water from the moisture in the vegetation they feed on. They rarely require fresh water to drink.
Plant Foods: leaves; roots and tubers; wood, bark, or stems; seeds, grains, and nuts; fruit; flowers
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Folivore )
Desert pocket gophers are found from extreme western Texas and southwest, southcentral New Mexico (USA) to extreme north Chihuahua (Mexico). This species is commonest in the narrow strip of bottom land along the upper Rio Grande Valley from Chihuahua into New Mexico.
Biogeographic Regions: nearctic (Native )
Desert pocket gophers are fossorial mammals which prefer sandy and disturbed soils that are excessively drained and easily penetrated. They occupy desert scrub as well as many man-made habitats. They are common along the lowlands of rivers as well as along irrigation ditches. Their use of claws for digging, as opposed to incisors, restricts this species to sandy soils that are less than 30% clay and greater than 40% sand. Desert pocket gophers spend most of their time about 100-200 mm below the surface in underground burrows that exceed 30 meters long. The burrows are made up of many side chambers and associated mounds of earth above ground, as well as a central chamber where all of the passages converge. One observed central chamber was 280mm long, 230 mm wide, and 200 mm deep.
Range elevation: 1220 to 1520 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; scrub forest
Other Habitat Features: agricultural ; riparian
There is no information about the lifespan of desert pocket gophers; however, a study conducted on a closely related species, T. talpoides, provides some data about the longevity of pocket gophers. In a five year field study that was conducted on a population of T. talpoides, the oldest female collected was 4 years and 9 months old, and the oldest male was 3 years of age. The mean lifespan for the population of interest was found to be about 13.6 months for males and 18.3 months for females. Ninety-six percent of the pocket gophers where 2 years old or less when last trapped.
Desert pocket gophers are heavily built, medium-sized gophers with relatively long, nearly naked tails and pale coloration. Their pelage is drab-brown dorsally, with thinly spread black-tipped hairs. This coloration continues until the abdomen where it may begin to blend with white hairs on the abdomen, chest, and feet.
Desert pocket gophers have massive forelimbs with large olecranon and epicondylar processes and large claws with flexible digits. They are adapted for a strong and powerful mode of digging. They have reduced eyes and pinnae, which enable them to better travel underground and through tunnels. They also have large, external, fur-lined cheek pouches which reach from the side of the mouth back to their shoulders.
Desert pocket gophers can be easily distinguished from other pocket gophers by the lack of sagittal crest, prominent knob over the middle of the jugal on the end of the squamosal arm of the zygoma, and also by checking to see that the rostrum does not exceed the length of the basioccipital. The zygoma of the desert pocket gopher are also unique among pocket gophers in that they has parallel sides in contrast to sides that converge posteriorly. The dental formula is 1/1, c 0/0, p 1/1, m 3/3, and their upper incisors are bisulcate.
There is pronounced sexual dimorphism in desert pocket gophers. Mean external and cranial measurements, excluding interorbital breadth, were all found to be greater in males. Body weights of desert pocket gophers ranged from 198 to 254 g in males, and from 165 to 207 g in females.
Range mass: 165 to 254 g.
Range length: 218 to 302 mm.
Average length: 254 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
The effect of vertebrate predators on desert pocket gophers is not well understood. This is because they are fossorial mammals and only subject to predation when above the ground. It appears that avian predators are the greatest threat to desert pocket gophers, however Canis, Mustela and Crotalus appear to have some effectiveness as predators as well.
Anti-predator Adaptations: cryptic
Geomys arenarius is a medium sized rodent, with a relatively long and hairy tail, and pale coloration. Like other gophers, their bodies are thicker than other rodents, eyes are reduced, and they are equipped with large, strong-clawed forelimbs allowing them to be fossorial. Their fur is a dull brown along their backs, with scattered black tipped hairs. The dull brown coloration continues dorsally and laterally until it reaches the chest, abdomen and feet, where it sometimes blends with the white hair of these areas.
The desert pocket gopher is in the genus Geomys , within the family Geomyidae within the order Rodentia. The evolutionary history of Geomys arenarius has been studied by several different parties, but the exact phylogeny is still being decided. While there was evidence to give the Geomys arenarius its own taxon based on genetic and morphological uniqueness, some researchers believe it is actually a subspecies of Geomys bursarius because of the similarities between the two rodents. No solid argument has been made to dispute the status of Geomys arenarius as its own species, but many researchers report that it is a subspecies, it has merely been separated by allopatric speciation.
Desert pocket gophers mostly inhabit a narrow strip of land following the Upper Rio Grande Valley from Chihuahua, Mexico, then proceeding north and west into parts of New Mexico and Texas in the United States. Due to their restricted home range size, they are isolated from other members of Geomys.
Desert pocket gophers prefer areas of well traveled, loose soil, or sandy riverbanks; places that are easy to tunnel into and make a burrow. They are commonly found near open water like rivers, ponds, or irrigation canals. The areas they inhabit are usually skirted by rocky plains or desert. Their preferred climate is one that is arid and moisture deficient, where summers are long and hot and winters are short and moderate in temperature.
In comparison to other gopher species, the desert pocket gopher-depending on the properties of the soil-can have a significant effect on the soils in the habitats it dwells in because it causes more disturbance from its digging than other species do.