Townsend's ground squirrel (Urocitellus townsendii ) is a species of rodent in the family Sciuridae. It is found in high desert shrublands in several areas of the United States.
Townsend's ground squirrel is found in the Great Basin and the Columbia Plateau. Its range includes south-central Washington, eastern Oregon, southern Idaho, western Utah, most of Nevada, and extreme eastern California. The subspecies are distributed as follows:
Townsend's ground squirrels typically inhabit arid grasslands and shrub-grasslands. Malheur ground squirrels, however, inhabit therelatively mesic and fertile Snake River Plain. Plant communities in which Townsend's ground squirrels occur include crested wheatgrass (Agropyron cristatum ), big sagebrush (Artemisia tridentata ) wheatgrass, rabbitbrush (Chrysothamnus spp.), shadscale (Atriplex confertifolia ), and winterfat (Kraschenninikovia lanata ) grasslands.
In southeastern Idaho, the density of Townsend's ground squirrel burrows is highest on winterfat-Sandberg bluegrass (Poa secunda ), intermediate in big sagebrush-Thurber needlegrass (Stipa thurberiana ), and lowest in shadscale-Indian ricegrass (Oryzopsis hymenoides ) and thread grass (Stipa comata ). Burrow densities were highly variable in mixed exotic annual communities, and negatively correlated with cheatgrass (Bromus tectorum ). They increase with increasing native grass cover, but the populations are unstable when native grass cover is overly high.
Although Townsend's ground squirrels occur in arid environments, within those environments they are most common around desert springs and irrigated fields. They also occupy ridgetops, hillsides, and valley bottoms, canal and railroad embankments, and old fields.As a burrowing species, Townsend's ground squirrels select sites with deep, friable, well-drained soils. In southeastern Idaho, 68% of Townsend's ground squirrel burrows were in sand, 28% in silt, and 4% in clay.
Smith and Johnson reported a mean home range of 1,357 square meters for 14 Snake Valley ground squirrels. Townsend's ground squirrel density can fluctuate greatly from year to year. Estimated population density of Snake Valley ground squirrels ranged from 3 to 32 individuals per hectare. Densities of 296 to 331 individuals per hectare have been reported for Piute ground squirrels.
Townsend's ground squirrels consume mainly green vegetation and some seeds and insects. Green grasses are apparently a staple from late winter until just prior to grass senescence and Townsend ground squirrel estivation, when seeds become the primary diet item. Seeds are an important source of calories just prior to estivation. Wherepresent, winterfat is browsed heavily, but only light browsing of other shrubs has been reported. From March through May on the Arid Land Ecology Reserve in eastern Washington, the Townsend's ground squirrel diet is 49% Sandberg bluegrass, 11% western yarrow (Achillea millefolium var. occidentalis ), 8% pinnate tansymustard(Descurania pinnata ) seed, 31% other plant species (mostly forbs), and 1% insects. On a big sagebrush-crestedwheatgrass community in southeastern Idaho, 80% of Townsend's ground squirrels trapped in June had consumed crested wheatgrass, and Townsend's ground squirrels became dormant after the crested wheatgrass senesced. Cheatgrass (Bromus tectorum ) is an important food item in some years. As an annual with wide year-to-year swings in productivity, however, it is not a reliable food source.
Adult cannibalism of unweaned young has been observed in the Townsend's ground squirrel.
