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Dipodomys ingensgiant kangaroo rat

By Nathan Fostey

Geographic Range

The giant kangaroo rat has an extremely small range limited to the west-central region of the U.S. state of California. Specifically, it is currently found only as far north and west as Fresno County and as far east and south as San Luis Obispo and Bakersfield Counties

Habitat

Scrub desert and piedmont are the basic habitats of giant kangaroo rats. They prefer relatively flat homogenous terrain with shrubs and rocks being almost totally absent. Typical habitat is stretches of easily excavated sandy loam covered with annual grasses and herbs.

Physical Description

The giant kangaroo rat is the largest of all kangaroo rats and has a body length ranging from 15 to 20 cm and a tail length of 18 to 21.5 cm. Unlike many other kangaroo rats, D. ingens possesses five toes on each hind foot, a white stripe running across its hindquarters, and a white belly. It also has a distinctive tail that is dark colored on the top and bottom with white lines on both sides.

Reproduction

Breeding takes place in late winter or early spring. Gestation is 28 to 32 days in length. Anywhere from one to six young are born in a burrow in the spring, three being average. The young are cared for by their mothers and fathers and are weaned in 15 to 25 days. They reach sexual maturity in 60 to 84 days. They then leave the burrow and seek new territories within the colony to dig burrows of their own. Giant kangaroo rats have been known to live up to 9.8 years in the wild.

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual

Behavior

Giant kangaroo rats live in circular burrow systems called precincts at the center of their territories. Colonies consist of five to 50 precincts. Being highly territorial, only one adult animal inhabits each burrow. Home ranges average 239 m2 and adults rarely travel more than 47 m away from their burrows. On average males spend about 0.05% of their time away from their home ranges. Females will cross into the territories of males during the breeding season. Giant kangaroo rats are nocturnal and are away from the safety of their burrows as possible. They emerge shortly after sunset and spend an average of less than 20 minutes foraging for food before returning to their burrows. Unlike other kangaroo rats, they are not active before sunrise. They move by hopping with their powerful hind legs, using their long pointed tails as rudders and can move at speeds of up to three meters per second when avoiding predators.

Communication and Perception

Food Habits

Giant kangaroo rats are granivorous and prefer to eat the seeds and green parts of native desert plants. They are also known to eat grain and the seeds of commercially grown plants if fields are nearby. Food is cured in shallow pits or piles on the ground called 'haystacks.' It is then stored in the central cave of their burrow. They extract all the water they need from these sources.

Economic Importance for Humans: Positive

While providing no direct economic benefits, giant kangaroo rats help maintain the desert habitat in which they live by feeding on and collecting seeds. Kangaroo rats in general were popularized in Walt Disney's film, The Living Desert. As an easily recognizable species of kangaroo rat, the giant kangaroo rat possesses a degree of charisma and is seen as adding aesthetic value to the region.

Economic Importance for Humans: Negative

The burrow complexes of adults create very soft heaps of dirt that can collapse under the pressure exerted by livestock or a human. Because of this, sheep and cattle tend to avoid areas containing burrows; therefore, land inhabited by the rats is deemed less valuable to ranchers.

Conservation Status

The giant kangaroo rat was designated an endangered species by the California Department of Fish and Game (CDFG) in the early 1980s and is currently restricted to about 2% (under 17,000 hectares) of its historic range. The CDFG, together with the Nature Conservancy and the U.S. Bureau of Land Management, manages the Carrizo Plain Natural Area, which contains ninety percent of remaining habitat. Although protected in this area, giant kangaroo rats will likely be eliminated from all other areas unless habitat loss caused by urban and agricultural development in central California is stopped.

Other Comments

Water taken in by giant kangaroo rats from food is stored not only in their kidneys but in their urinary bladders. Their kidneys are extremely efficient and can concentrate urine to the highest degree known among North American mammals.

Contributors

Nathan Fostey (author), University of Michigan-Ann Arbor.

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

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.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

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.

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.

sexual

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

tactile

uses touch to communicate

References

Baumgardner, G. D. and M. L. Kennedy. 1994. Patterns of Interspecific Morphometric Variation in Kangaroo Rats (Genus Dipodomys). Journal of Mammalogy 75(1): 203-211.

Braun, S. E. 1985. Home Range and Activity Patterns of the Giant Kangaroo Rat, Dipodomys ingens. Journal of Mammalogy 66(1): 1-12.

Cypher, B. L., K. A. Spencer, and J. H. Scrivner. 1994. Food-item use by Coyotes at the Naval Petroleum Reserves in California. Southwestern Naturalist 39(1): 91-95.

Freye, H. 1975. Pocket Gophers. Pp. 272-274 in Grzimek's Animal Life Encyclopedia. Grzimek, B., ed. Van Nostrand Reinhold Company, New York, NY.

Hall, E. R. 1981. The mammals of north America, Vol. 1. John Wiley and Sons, New York. 579

Woods, C. A. 1990. Pocket Rodents. Pp. 131-140 in Grzimek's Encyclopedia of Mammals, Vol. 3. MacGraw-Hill Publishing Company, New York, NY.

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