Mammals of Northwestern South Dakota

by Kenneth W. Andersen; J. Knox Jones

KENNETH W. ANDERSEN and J. KNOX JONES, JR.

The mammalian fauna of the western Dakotas and adjacent Montana is relatively poorly known. Few published reports have dealt with mammals from this part of the Northern Great Plains, and none of these involved detailed study of a restricted area. The present report summarizes information gathered in Harding County, northwestern South Dakota, and includes material on the more than 50 species of mammals that are known to occur there.

Harding County has an area of approximately 2700 square miles (Fig. 1). The county first was organized in 1881, but the present boundaries were not fixed until 1908. Physiographically, it lies in that part of the Missouri Plateau frequently termed the "Cretaceous Table Lands." The general topography is one of rolling hills and flats—mostly range land vegetated by short grasses and sage—broken by spectacular buttes and hills that rise 400 to 600 or more feet above the surrounding plains. These monadnocks are "... part of a system of Tertiary erosional remnants standing above the Late Cretaceous rocks of northwestern South Dakota...," according to Lillegraven (1970:832), who went on to point out: "The butte tops are flat and grass-covered. The western sides are being actively cut away by slumping, and the topography below the western cliff walls is hummocky with sparse vegetation. The eastern flanks of the tables are, by contrast, less cliff-forming and less slumped and are generally well forested with coniferous and deciduous trees." Slim Buttes, the North and South Cave Hills, the East and West Short Pine Hills, and the Long Pine Hills, which barely enter the county north of Camp Crook, comprise the pine-clad buttes; other prominences, such as Table Mountain and Sheep Buttes, are all but nude of coniferous cover. The highest point in the county, "Harding Peak," is 4019 feet above sea level.

Sediments underlying northwestern South Dakota include rocks assignable to the Pierre (shale), Fox Hills (sand), and Hell Creek formations of Cretaceous age and the Ludlow and Tongue River formations of the Paleocene. These rocks may be exposed at the surface, but usually are overlain by relatively thin soils that are mostly derived from them; the best soil in the county for agricultural purposes is the loessal sandy or silty loam in the northeastern quarter, which is derived from Tongue River sediments (Baker, 1952).

Fig. 1. Map of Harding County, South Dakota, showing location of places named in text.

The climate of northwestern South Dakota is characteristic of the northern part of the interior grasslands of North America—that is, the winters are cold and the summers hot and dry. Weather data for the period 1896-1967 at Camp Crook are representative of those gathered at the several stations maintained in the county. At Camp Crook the mean temperature for January is 17.3 F, whereas that for July is 71.2 F; precipitation averages 13.17 inches annually, most falling in the months of April through September; snowfall amounts to an average of 33.2 inches per year and is recorded from every month from September through May (Climatogeography of the United States, no. 20-39, Camp Crook, South Dakota, 1969).

Major surface drainage systems in Harding County include the Little Missouri River, which flows northward through most of the western part of the county, the South Fork of the Grand River, which originates in the east-central part of the county and flows generally eastward, and by the North Fork of the Moreau River, which originates in the south and drains in a southeasterly direction. Permanent standing surface water was virtually unknown prior to the development of artificial impoundments.

Fig. 2. Central part of Slim Buttes as viewed from the east.

Vegetation of the grassland areas in the county is typical of that found throughout the semi-arid Northern Great Plains. Cover on upland soils, especially those that are clayey in substance, generally is sparse; areas along water courses and well-watered sites elsewhere tend to have denser stands of grasses such as bluestem (Andropogon). Dominant grasses of upland are gramma, buffalo grass, wheat grass, stipa, and tickle grass. Sage (Artemisia) and numerous forbs are prominent in many areas. These grasslands are used extensively for grazing of sheep and cattle.

Fig. 3. Fuller Canyon, North Cave Hills.

Fig. 4. Little Missouri River southwest of Ladner. Note beaver dam in background and nature of riparian community.

Fig. 5. Stand of pines on northern part of Slim Buttes.

Fig. 6. Draw with deciduous trees in North Cave Hills.

Fig. 7. Spring-fed artificial impoundment in Deer Draw, Slim Buttes.

Fig. 8. Farm land in northeastern part of Harding County.

The wooded buttes mentioned above are at least in part within the boundaries of Custer National Forest and support western yellow pine (Pinus ponderosa) and junipers (Juniperus sp.). In some ravines and other protected sites there are groves of deciduous trees such as cottonwood, aspen, boxelder, ash, hackberry, elm, dogwood, and hawthorn, usually associated with shrubs such as buckbrush, chokeberry, plum, currant, and gooseberry. These groves frequently are associated with small springs, as the one in Deer Draw of the Slim Buttes. The major water courses and their tributaries are essentially treeless, although occasional stands of cottonwoods and other deciduous trees and shrubs occur in some places—for example along the Little Missouri near Camp Crook. Some representative habitats in Harding County are illustrated in Figs. 2-8.

Our interest in Harding County dates from August of 1960, when one of us (Jones) and Robert R. Patterson visited the area briefly and obtained a small collection of mammals. Subsequently, field parties from the Museum of Natural History collected mammals in the county in the periods 14-30 June 1961, 23 March-11 April 1963, 5-7 July 1965, and 13 May-11 June 1968. Incidental collection also occurred in the extreme western part of the county in the period 29 June-24 July 1970 when a group was working primarily in the Long Pine Hills of adjacent Carter County, Montana.

There are few published references to mammals in Harding County. Visher (1914), in an early biological survey of the area, listed 40 species of mammals, but his accounts are mainly of historic value. Subsequently, publications by Bailey (1915), Young (1944), Goldman (1944), Over and Churchill (1945), Jones and Genoways (1967), and Henderson et al. (1969) have recorded mammals from the county.