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Dipodomys desertidesert kangaroo rat

By Jonathan Pauli

Geographic Range

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).

Habitat

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).

  • Range elevation
    -60 to 1,710 m
    -196.85 to ft

Physical Description

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)

  • Sexual Dimorphism
  • male larger
  • Range mass
    83 to 148 g
    2.93 to 5.22 oz
  • Range length
    331 to 342 mm
    13.03 to 13.46 in
  • Average basal metabolic rate
    0.517 W
    AnAge

Reproduction

The mating system has not been reported. However, that the males are larger than the females suggests competition between males for mating. This type of male-male competition is usually associated with some males obtaining matings with more females than other males do. Copulatory plugs are formed after mating, and these are typically a form of post-copulatory competition between males. This suggests that females are likely to mate with multiple males. It seems likely, therefore, that the mating system is polygynadrous.

D. deserti show no definitive courtship period because of their intense aggressive behavior. However, there is a brief precopulatory period when the male and female halt their aggressive behavior. Reproductive activity begins early in January and continues through early July. Adult females will come into estrus 10-15 days post-partum and accept mating attempts by males. (Best et al., 1989) Females who have mated already typically resist further advances by males. A few hours after copulation, a copulatory plug forms in the vaginal orifice. This persists for several days, preventing or inhibiting further mating.

The gestation period ranges from 29-32 days and the number of embryos ranges from 1-6. One or two litters are produced annually. Young are born headfirst and the mother assists delivery by pulling on the fetal membrane. After parturition, the mother will kick sand on the neonates, perhaps to dry them. (Best, 1999).

Sexual maturity probably occurs around 2 months of age, as is common for other species of Dipodomys.

  • Breeding season
    Reproduction begins in January, and ends in early July.
  • Range number of offspring
    1 to 6
  • Average number of offspring
    3
    AnAge
  • Range gestation period
    29 to 32 days
  • Average weaning age
    21 days
  • Average age at sexual or reproductive maturity (female)
    2 months
  • Average age at sexual or reproductive maturity (male)
    2 months

The mass of D. deserti at birth ranges between 2.2 and 4.6 g. The neonate is approximately 52 mm in length, and is naked, with thin, pink, transparent skin. Complete pigmentation and furring appear by weaning, around 21 days of age (Best, 1999). Females nurse their young in the nest . Immediately after they are born, a female kicks sand onto her offspring. This may help to dry them off.

Lifespan/Longevity

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)

  • Typical lifespan
    Status: captivity
    5.5 to 8 years

Behavior

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).

Communication and Perception

Food Habits

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).

  • Plant Foods
  • leaves
  • seeds, grains, and nuts

Predation

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

Ecosystem Roles

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.

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

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

Economic Importance for Humans: Negative

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

Conservation Status

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.

Other Comments

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).

Contributors

Jonathan Pauli (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

herbivore

An animal that eats mainly plants or parts of plants.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

nomadic

generally wanders from place to place, usually within a well-defined range.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Best, T. 1999. Desert Kangaroo Rat: *Dipodomys deserti*. Pp. 525-527 in D Wilson, S Ruff, eds. The Smithsonian Book of North American Mammals. Washington, D.C.: Smithsonian Institution Press.

Best, T., N. Hildreth, C. Jones. 1989. *Dipodomys deserti*. Mammalian Species, 339: 1-8.

Brattstrom, B. 1959. Longevity in the Kangaroo Rat. Jounal of Mammalogy, 41: 404.

Carrasco, M. 2000. Species discrimination and Morphological Relationships of Kangaroo Rats (*Dipodomys*) Based on their Dentition. Journal of Mammalogy, 81: 107-122.

Nader, I. 1978. Kangaroo Rats: Intraspecific Variation in *Dipodomys spectabilis* Merriam and *Dipodomys deserti* Stephens. Illinois Biological Monographs, 49: 1-116.

Randall, J. 1997. Species-specific footdrumming in Kangaroo Rats: *Dipodomys ingens, D. deserti, D. spectabilis*. Animal Behavior, 54: 1167-1175.

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