Ord's Kangaroo Rat
Order Rodentia : Family Heteromyidae : Dipodomys ordii Woodhouse

Description. A five-toed kangaroo rat of medium size; tail relatively long, body actually and relatively short; tail seldom white-tipped; white patches at base of ears and above eyes usually conspicuous; upperparts pale cinnamon buff, intermixed with blackish; dark markings on face conspicuous. Juveniles similar to adults, but pelage duller and darker. External measurements of adults average: total length, 253 mm; tail, 159 mm; hind foot, 41 mm. Weight of adults, 60-70 g. Dental formula as in Perognathus flavescens.

Distribution in Texas. Known from the western and southern parts of the state.

Habits. Ord’s kangaroo rats, like many others of the genus, are dwellers of wastelands where shifting sands constitute a conspicuous part of the landscape. They are one of the few pioneer mammals that move into shifting dunes and establish themselves with pioneer plants. They rarely occur on hard and gravelly soils. Where they occur in areas with the smaller Merriam’s kangaroo rat, the latter usually inhabits gravelly or hard soils; the former, the sands.

To withstand the extreme climatic conditions in their range, these rats dig deep burrows into the sand that, when plugged from the inside, permit the occupants to spend the daylight hours in comfort, and to avoid the hot, desiccating sun or the cold, wintery wind. They become active again at night, leaving their dens after sundown, and go abroad even in the dead of winter when snow is on the ground in their quest for food. They have not developed the convenient ability to hibernate.

Their food consists largely of the seeds of various desert plants which they gather and place in their cheek pouches for transport to the burrow to be consumed at leisure. Mesquite, sandbur, tumbleweed, Russian thistle, sunflowers, and countless desert annuals provide them with a wide range of choice. Surface water is not important in their economy. Like many other desert animals, they can produce their needed water physiologically from nearly dry seeds. So averse and unaccustomed to water are they that they have not learned to swim!

In a two-year study conducted in the Texas Panhandle (Hemphill County), Jack Inglis found pregnant females of D. ordii in the period from August through February. Young individuals first appeared in his traps in November. Litter size, based on embryo counts, averaged slightly less than three with extremes of two and four. Rate of reproduction was associated with precipitation, food supply, and population densities of kangaroo rats and other rodents. After a prolonged drought period when the food supply declined, few females became sexually active and few young were born. After a favorable growing season for food plants, most females in the population became pregnant within the first 2 months of the breeding season and most of them produced two litters; young females born early in the season produced litters themselves before the season ended. The gestation period is about 30 days. The young are born in underground nests and remain there for nearly a month. They appear aboveground when they are about three-fourths grown and weigh between 40 and 50 g.

Because of the nature of their habits, they seldom come into serious conflict with man. In sandy lands near San Antonio, Texas, however, they are reputed to do considerable damage by gathering and consuming the seeds of watermelons and other row crops at planting time. Under such conditions they can be controlled by the use of poisoned bait or by trapping, but over most of their range they do no harm.

Photo credit: R.D. Porter.