Townsend's ground squirrel (''Urocitellus townsendii'') is a species of

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...

in the family

Sciuridae Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squ ...

. It is found in high desert shrublands in several areas of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

Distribution

Townsend's ground squirrel is found in the

Great Basin The Great Basin is the largest area of contiguous endorheic basin, endorheic watersheds, those with no outlets, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California ...

and the

Columbia Plateau The Columbia Plateau is a geologic and geographic region that lies across parts of the U.S. states of Washington, Oregon, and Idaho. It is a wide flood basalt plateau between the Cascade Range and the Rocky Mountains, cut through by the Columbia ...

. Its range includes south-central Washington, eastern

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

, southern

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyom ...

, western

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

, most of

Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...

, and extreme eastern

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

. The subspecies are distributed as follows:Hall, E. Raymond. (1981). ''The mammals of North America''. 2nd ed. Vol. 2. New York: John Wiley and Sons *''Urocitellus townsendii artemesiae'' – south-central Idaho *''U. t. canus'' (

Merriam's ground squirrel Merriam's ground squirrel (''Urocitellus canus'') is a species of rodent in the family Sciuridae. It occurs in the western United States in Idaho, Nevada, and Oregon. Description Merriam's ground squirrel is a small, grey, ground squirrel with a ...

) – eastern Oregon; northeastern corner of California; northwestern corner of Nevada *''U. t. idahoensis'' – southwestern Idaho *''U. t. mollis'' (

Piute ground squirrel The Piute ground squirrel (''Urocitellus mollis'') is a species of rodent in the family Sciuridae. It is endemic to the Great Basin region of the western United States, where it is found in parts of California, Idaho, Nevada Nevada ( ; ) i ...

) – eastern California; southeastern Oregon; southern Idaho; western Utah; Nevada; most widely distributed subspecies *''U. t. nancyae'' – south-central Washington *''U. t. townsendii'' – south-central Washington *''U. t. vigilis'' – Snake River Canyon bottomlands of east-central Oregon and west-central Idaho Townsend's ground squirrels typically inhabit arid

grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...

s and shrub-grasslands. Malheur ground squirrels, however, inhabit the relatively mesic and fertile

Snake River Plain image:Snake River view near Twin Falls, Idaho.jpg, The Snake River cutting through the plain leaves many canyons and Canyon#List of gorges, gorges, such as this one near Twin Falls, Idaho The Snake River Plain is a geology, geologic feature ...

. Plant communities in which Townsend's ground squirrels occur include crested wheatgrass (''

Agropyron cristatum ''Agropyron cristatum'', the crested wheat grass, crested wheatgrass, fairway crested wheat grass, is a species in the family Poaceae. This plant is often used as forage and erosion control. It is well known as a widespread introduced species o ...

''), big sagebrush (''

Artemisia tridentata ''Artemisia tridentata'', commonly called big sagebrush,MacKay, Pam (2013), ''Mojave Desert Wildflowers'', 2nd ed., , p. 264. Great Basin sagebrush or (locally) simply sagebrush, is an aromatic shrub from the family Asteraceae, which grows in ari ...

'') wheatgrass, rabbitbrush (''

Chrysothamnus ''Chrysothamnus'', known as rabbitbrush, rabbitbush, and chamisa, are a genus of shrubs in the family Asteraceae. The native distribution is in the arid western United States, Canada, and northern Mexico. It is known for its bright white or yell ...

'' spp.), shadscale (''Atriplex confertifolia''), and winterfat (''Kraschenninikovia lanata'') grasslands.Nydegger, Nicholas C.; Smith, Graham W. (1986). "Prey populations in relation to ''Artemisia'' vegetation types in southwestern Idaho". In: McArthur, E. Durant; Welch, Bruce L., compilers. Proceedings – symposium on the biology of Artemisia and Chrysothamnus; 1984 July 9–13; Provo, UT. Gen. Tech. Rep. INT-200. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. pp. 152–156 In southeastern Idaho, the density of Townsend's ground squirrel burrows is highest on winterfat-Sandberg bluegrass (''

Poa secunda ''Poa secunda'' (variously known by the common names of Sandberg bluegrass, alkali bluegrass, big bluegrass, Canby's bluegrass, Nevada bluegrass, one-sided bluegrass, Pacific bluegrass, pine blugrass, slender bluegrass, wild bluegrass, and curly ...

''), intermediate in big sagebrush-Thurber needlegrass ('' Stipa thurberiana''), and lowest in shadscale-Indian ricegrass (''

Oryzopsis hymenoides ''Eriocoma hymenoides'' (common names: Indian ricegrass and sand rice grass) is a cool-season, perennial bunchgrass with narrow, rolled leaf blades.Mojave Desert Wildflowers, Pam MacKay, 2nd Ed., p287 It is native to western North America east of ...

'') and thread grass (''

Stipa comata ''Hesperostipa comata'', commonly known as needle-and-thread grass, is a species of grass native to North America, especially the western third. It has a wide distribution spanning from northern Canada to Mexico. Description ''Hesperostipa comat ...

'') . 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.Knick, Steven T. (1993). "Habitat classification & the ability of habitats to support populations of Townsend's ground squirrels and black-tailed jackrabbits". In: Steenhof, Karen, ed. ''Snake River Birds of Prey National Conservation Area research and monitoring annual report'': 1993. oise, ID U.S. Department of the Interior, Bureau of Land Management, Boise District. pp. 237–263

Preferred habitat

Although Townsend's ground squirrels occur in arid environments, within those environments they are most common around desert springs and irrigated fields.Hansen, Richard M. (1954). ''Ground squirrels (Citellus) of Utah''. Salt Lake City, UT: University of Utah. Dissertation They also occupy ridgetops, hillsides, and valley bottoms, canal and railroad embankments, and old fields.Davis, William B. 1939. The recent mammals of Idaho. Contribution Museum of Vertebrate Zoology, Berkeley, CA. Caldwell, ID: The Caxton Printers, Ltd 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

Timing of major life events

Townsend's ground squirrels become dormant in late spring or early summer, after grasses cure. They emerge from dormancy in late winter. Dormancy lasts 7.5 to 9 continuous months. It is shorter in wet years, when green forage is available later in summer, than in dry years. Females breed as yearlings. Most males also breed as yearlings, although male Snake Valley ground squirrels breed at 2 years of age. Most breeding occurs in late January or early February, just after dormancy ends. Piute ground squirrels breed from mid-February to early March, somewhat later than other subspecies. Gestation is about 24 days. One litter is produced per year, with 6 to 10 pups per litter. Pups are born hairless and with eyes closed. Early postnatal development of Townsend's ground squirrels is relatively slow compared to development of other Spermophilus species. Pups open their eyes at 19 to 22 days of age, and are weaned shortly thereafter.

Cover requirements

Townsend's ground squirrels occupy open habitats and use burrows for shelter, protection from predators, and food storage. Burrows are often grouped into colonies, but some Townsend's ground squirrels are solitary. Except when mothers have pups, there is only one Townsend's ground squirrel per burrow. Burrows have one to many openings and may have numerous auxiliary burrows in addition to the "home" or nest burrow. Burrow dimensions of Townsend's ground squirrels in southeastern Idaho ranged from 2.6 to 3.8 inches (6.5–9.6 cm) horizontally and from 1.7 to 2.5 inches (4.3–6.3 cm) vertically. Townsend's ground squirrels have been observed climbing shrubs while foraging, apparently for cover and to spot palatable vegetation.

Food habits

Townsend's ground squirrels consume mainly green vegetation and some seeds and insects.Clary, Warren P.; Medin, Dean E. (1992). "Vegetation, breeding bird, and small mammal biomass in two high-elevation sagebrush riparian habitats". In: Clary, Warren P.; McArthur, E. Durant; Bedunah, Don; Wambolt, Carl L., compilers. Proceedings – symposium on ecology and management of riparian shrub communities; 1991 May 29–31; Sun Valley, ID. Gen. Tech. Rep. INT-289. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. pp. 100–110 Green grasses are apparently a staple from late winter until just prior to grass senescence and Townsend ground squirrel

estivation Aestivation ( la, aestas (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and ...

, when seeds become the primary diet item. Seeds are an important source of calories just prior to estivation.Rickart, Eric Allan. (1982)
''The ecology of Townsend's ground squirrel, Spermophilus townsendii mollis''
Salt Lake City, UT: University of Utah. Dissertation Where present, 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-crested wheatgrass 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.

Predators

Townsend's ground squirrels are the primary prey of ferruginous hawks (''

Buteo regalis The ferruginous hawk, (''Buteo regalis''), is a large bird of prey and belongs to the broad-winged buteo hawks. An old colloquial name is ferrugineous rough-leg, due to its similarity to the closely related rough-legged hawk (''B. lagopus''). ...

'') in the Great Basin and Columbia Plateau. They are also a major and often primary diet item of prairie falcons (''

Falco mexicanus The prairie falcon (''Falco mexicanus'') is a medium-large sized falcon of western North America. It is about the size of a peregrine falcon or a crow, with an average length of 40 cm (16 in), wingspan of approximately 1 meter (40&n ...

''). The Townsend's ground squirrel has been rated one of the two most important prey species in southeastern Idaho because of its importance to ferruginous hawks and prairie falcons. Other important predators of Townsend's ground squirrels include other hawks (''Accipiter'' and ''Buteo'' spp.) and falcons (''Falco'' spp.), common crows (''Corvus corax''), badgers (''Taxidea taxus''), coyotes (''Canis latrans''), long-tailed weasels (''Mestrela frenata''), western rattlesnakes (''Crotalus viridis''), and gopher snakes (''Pituophis melanoleucus'').Janes, Stewart W. (1985). "Habitat selection in raptorial birds". In: Cody, Martin L., ed. Habitat selection in birds. Academic Press Inc.: pp. 159–188

References

{{DEFAULTSORT:Townsend's Ground Squirrel Urocitellus Ground squirrel, Townsend Ground squirrel, Townsend Ground squirrel, Townsend Mammals described in 1839 Taxonomy articles created by Polbot Taxa named by John Bachman