Kangaroo rats are small burrowing mammals with fur–lined cheek pouches, making up the rodent family Heteromyidae, found principally in North and Central America. There are five genera of rodents with external pouches in this family but only two of them are given the popular name of kangaroo. It derives from the fact that their front feet are very small and the back legs are quite large and strong, adapted for two–legged leaping. The thick tail helps in balance and serves as a third “leg” when standing still.
Kangaroo rats belong to the genus Dipodomys, which includes 21 species found from southern Alberta to central Mexico. Their heads and bodies may be 4–8 in (10–20 cm) long, plus a tail that is even longer. They are brown to yellow in color, with a lighter belly.
Unlike other rodents with cheek pouches, such as pocket gophers, kangaroo rats and mice live in very open country. They require unobstructed space in which to make their leaps, which may be as much as 6 ft (2 m) or more. They generally come out only at night to forage for seeds, fruit, and even small insects. The food is carried back to their burrows where it may be stored. Each adult has a separate burrow system.
Kangaroo rats do not drink water. Rather, they receive fluids from food. They have very special kidneys that function efficiently at ridding the body of poisons. An important part of their lives is dust bathing. They have an oil–secreting gland located on the back between the shoulders, and if they are not allowed to bathe in dust to remove the excess oil, their fur and skin becomes matted and irritated.
During the mating process, a male kangaroo rat seeks the attention of a female by thumping on the ground with his back feet. The female will produce one to six offspring in one of her two or three litters each year.
Several species of kangaroo rats are regarded as threatened or even endangered due to the destruction of their deserthabitat. The growth of agriculture through irrigation and the development of new residential areas can decimate a subspecies or even a species almost overnight.
The two species of smaller kangaroo mice belong to the genus Microdipodops, which live in the desert sands of Nevada. They look much like small furry balls with eyes and a single pair of long legs. Their fur is longer and silkier than the kangaroo rats’. Even their hind feet have special fur, called fringe, which broadens the base from which they spring. Perhaps because they burrow into sandy soil, their burrows are not as elaborate as those of other burrowing rodents. They are most active at night.
There are several other genera of pocket mice but they are not the leapers that kangaroo rats and mice are. The pocket mice of Mexico and the southwestern United States make up the genus Perognathus. Two genera of spiny pocket mice, Liomys and Heteromys, can be found in the arid regions and forest areas of central America. These animals have much stiffer fur than the other members of the family.
Genoways, Hugh H., and James H. Brown, eds. Biology of the Heteromyidae. Lawrence, KS: American Society of Mammalogists, 1993.
Hanney, Peter W. Rodents: Their Lives and Habits. New York: Taplinger Publishing Co., 1975.
Jean F. Blashfield