Fig. 94. Distribution of the Ord kangaroo rat, Dipodomys ordii columbianus, in Washington.
Description.—The kangaroo rat with a body about the size of that of a chipmunk has an exceptionally large head and large, black eyes. The forelegs and forefeet are tiny but the hind feet and legs are large and powerful. The hind foot is almost a third as long as the head and body. The tail is long, longer than the head and body. Kangaroo rats possess fur-lined, external cheek pouches, like those of the pocket mice. The upper parts are soft buff in color. The underparts and a stripe on each flank are white. The tail is dusky above and below, with white sides; it is tufted at the tip.
Kangaroo rats are typical of the desert regions of the southwestern United States, where numerous species and subspecies are found. A single subspecies of the wide-ranging species ordii occurs into southeastern Washington, where it is restricted to sandy areas in the Upper Sonoran Life-zone. In the soft, drifted sand along the Columbia River where sagebrush and other desert shrubs are low and widely spaced kangaroo rats are abundant.
These rats are strictly nocturnal. When individuals are dug from their burrows in the daytime they usually hop about in a dazed manner and appear to be blinded by sunlight. Near Wallula, Walla Walla County, these rats were caught at night with a butterfly net as they stood "paralyzed" in the beam of a powerful searchlight. Such night hunting was unsuccessful on cloudy or windy nights when kangaroo rats seem not to move about.
As might be guessed from their powerful hind legs, kangaroo rats travel in bounds. Near Wallula, where we watched them in their natural habitat, they traveled, when unfrightened, in slow hops, each hop followed by a pause. As they struck the surface of the ground an audible thud could be heard for a distance of several feet. After each jump they paused for a second or so, perhaps to allow a pursuing enemy to over-run them.
Near Wallula the burrows of kangaroo rats were dug in large mounds of wind-blown sand. The burrows entered these natural mounds horizontally and branched two or three times. Their average length was about five feet. No nests or food stores were discovered although several kangaroo rats were caught as they burst from entrances at sides of the mounds. All entrances to burrows were plugged with soft sand. The air in the burrows seemed warm and humid.
Food found in the cheek pouches of kangaroo rats from Washington included the seeds of desert annuals, short sections of sprouts of an unidentified plant, grass seeds, and the leaves of the hop-sage.
A female taken March 22, 1939, contained 3 embryos.