Dipodomys deserti
desert kangaroo rat

Desert kangaroo rats inhabit dunes in the most arid regions of southwestern North America. They occur at elevations ranging from 60 meters below sea level in Death Valley, California, to 1,710 meters in Huntoon Valley, Nevada (Best et al., 1989).

Dipodomys deserti is adapted to live in the lowest, hottest, and most arid regions of North America (Nader, 1978). D. deserti is associated with areas that have substantial accumulations of wind driven sand. The number of sand dunes may limit the distribution of D. deserti, but they may be present in arid regions that have silty ground and are also known to occur at one locality in central Arizona where the soil is gravelly (Best et al., 1989).

In contrast to larger members of the genus, desert kangaroo rats occur in areas that receive little precipitation. To compensate for the extreme and prolonged aridity of the region, they are restricted to sand dunes, which harbor richer food sources.

D. deserti uses mainly un-vegetated mounds for burrow sites. Burrows are typically made in areas which are not highly ephemeral. On the surface, the burrow is lumpy, uneven and has many sloping entrances that lead down into the maze of passages. Some of these may be plugged with dirt. Underground chambers consist of multiple storerooms and a central nest. Within these chambers, D. deserti stores large amounts of mesquite pods and other plant seeds.

Desert kangaroo rats may form widely spaced colonies with clusters of 6-12 large burrows in each colony. However, these colonies rarely last for long periods of time and will be moved when food is scarce (Best et al., 1989).

All of the members of the genus Dipodomys have fur-lined cheek pouches that are used to transport seeds. D. deserti has four toes on each hind foot, and all of the feet are covered with long hairs. The upper parts of the body are pale brown to grayish (depending on the subspecies), and the underside is white. D. deserti has indistinct white spots over the eyes, behind the ears (which extends across the shoulder to the white underbelly), and an indistinct white band across the hips. There is also a darker spot of pelage at the base of facial vibrissae (Best, 1999).

Males average 342 mm in length and females average 331 mm in total length. The tail is usually 201 mm long in males and 195 mm in females, which accounts for more than ½ of the total length. In both sexes, the tail has long, white-tipped guard hairs along the top. D deserti has the thickest hair in their genus. Juvenile pelage resembles that of the adult, but is typically shorter and less dense.

Desert kangaroo rats are one of the most sexually dimorphic species of kangaroo rats, with males being about 2.5% larger than females. Males weigh between 91 and 148 g, whereas females weigh from 83 to 141 g

D. deserti posses huge auditory bullae (which frequently meet in the center of the dorsal surface of the skull, completely hiding the interparietal and supraoccipital bones). The tooth enamel is thick. The sides of the teeth lack grooves, and they have flatter skulls than any other member of the genus Dipodomys.

Populations do not exhibit much geographic variation, possibly because D. deserti inhabit a region that has relatively homogenous terrain and no permanent geographic barriers separating populations (Best 1989). (Best, 1999)

Although little has been reported on the longevity of wild D. deserti, lifespan in captive individuals has ranged between 5.5 years to 8 years (Brattsrom, 1959; Nader, 1979)

Although principally nocturnal, D. deserti often ventures out of the burrow during daylight. Much of this time is spent modifying burrows: plugging entrances, opening new entrances and digging new tunnels. Desert kangaroo rats are extremely solitary, and except when a female has a litter, no burrow has more that one occupant. Individuals are highly aggressive and actively drive conspecifics out of their territory (Best, 1999).

Desert kangaroo rats will frequently traverse open areas at high speeds in search of large clumps of seeds. In a single night, an individual may forage in a radius of up to 100 m. When an unknown object is encountered these kangaroo rats are is known to kick sand at the object to determine whether it is alive and if it is a threat. Desert kangaroo rats have been reported to kick enough sand onto traps they encounter to either spring them or bury them. D. deserti also dust bathe in the sand to keep their pelage clean and free from grease.

D. deserti has been observed caching seeds in captivity, but little is known of its wild food caching habits.

Desert kangaroo rats are excellent swimmers and, like all other kangaroo rats, do not hibernate (Best et al., 1989).

Desert kangaroo rats do not generally eat succulent plants. They prefer a diet of dried plant matter from the previous year, particularly leaves of sage, and seeds of the creosote bush and will also eat seeds. D. deserti will drink water when it is available, but can survive long periods of time without water, subsisting on their dry diet (Best et al., 1989).

Desert kangaroo rats serve as prey to snakes, hawks, owls, bobcats, spotted skunks, coyotes and foxes (Best, 1999).

Although the ecosystem roles of this species have not specifically be reported, they are prey to a large number of carnivores, and so the availability of these rodents is likely to affect predator populations. Also, through their seed caching behavior, they disperse seeds.

There are no reported negative effects of this species on humans.

There are no reported positive effects of this species on humans.

This species has no special conservation status, but has been reported to suffer from automobile traffic. However, there is a positive impact on this species from agriculture, which may outweigh the negative effect of auto traffic.

Although D. deserti is not a species at risk, some interactions with humans can be detrimental. Vehicles on southeastern California highways are reported to have severely impacted populations of desert kangaroo rats, resulting in near elimination of the species along a wide area on both sides of the road (Best et al., 1989).

Conversely, it appears that cultivation favorably alters the habitat for desert kangaroo rats. Cultivation removes vegetative cover, allowing the winds to pile up large quantities of sand and form dunes. Although desert kangaroo rats won’t inhabit areas under immediate cultivation, they quickly colonize a region once farming has ceased.

Dipodomys is a member of one of the most diverse Hetromyid subfamilies, the Dipodomyinae, which contains 9 genera, more than 60 species and has a rich fossil history dating back 20 million years (Carrasco, 2000). However, no fossils of D. deserti have been discovered. Most likely, D. deserti originated in the early part of the Pleistocene in southeastern regions of California and the lower Colorado desert (Nader, 1978).