Mammals of Northwestern South Dakota.

by Kenneth W. Andersen.

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 gra.s.ses and sage--broken by spectacular b.u.t.tes 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 b.u.t.te tops are flat and gra.s.s-covered. The western sides are being actively cut away by slumping, and the topography below the western cliff walls is hummocky with spa.r.s.e 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 b.u.t.tes, 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 b.u.t.tes; other prominences, such as Table Mountain and Sheep b.u.t.tes, 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 a.s.signable to the Pierre (shale), Fox Hills (sand), and h.e.l.l 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).

[Ill.u.s.tration: 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 gra.s.slands 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.

[Ill.u.s.tration: FIG. 2. Central part of Slim b.u.t.tes as viewed from the east.]

Vegetation of the gra.s.sland 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 spa.r.s.e; areas along water courses and well-watered sites elsewhere tend to have denser stands of gra.s.ses such as bluestem (_Andropogon_). Dominant gra.s.ses of upland are gramma, buffalo gra.s.s, wheat gra.s.s, stipa, and tickle gra.s.s. Sage (_Artemisia_) and numerous forbs are prominent in many areas. These gra.s.slands are used extensively for grazing of sheep and cattle.

[Ill.u.s.tration: FIG. 3. Fuller Canyon, North Cave Hills.]

[Ill.u.s.tration: FIG. 4. Little Missouri River southwest of Ladner. Note beaver dam in background and nature of riparian community.]

[Ill.u.s.tration: FIG. 5. Stand of pines on northern part of Slim b.u.t.tes.]

[Ill.u.s.tration: FIG. 6. Draw with deciduous trees in North Cave Hills.]

[Ill.u.s.tration: FIG. 7. Spring-fed artificial impoundment in Deer Draw, Slim b.u.t.tes.]

[Ill.u.s.tration: FIG. 8. Farm land in northeastern part of Harding County.]

The wooded b.u.t.tes 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 a.s.sociated with shrubs such as buckbrush, chokeberry, plum, currant, and gooseberry. These groves frequently are a.s.sociated with small springs, as the one in Deer Draw of the Slim b.u.t.tes. 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 ill.u.s.trated 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.

ACCOUNTS OF SPECIES

Fifty-three species of mammals known from Harding County, South Dakota, are treated in the accounts that follow. Appended is a brief discussion of 10 additional species that may be found there. In most accounts, specimens that have been examined (a total of 644) are listed in telegraphic style preceding remarks; localities are arranged from north to south in such lists. Unless otherwise noted, specimens are housed in the Museum of Natural History. All measurements are in millimeters (those of embryos are crown-rump lengths) and weights are given in grams.

Order Chiroptera

~Myotis evotis evotis~ (H. Allen, 1864)

Long-eared Myotis

_Specimens examined_ (20).--NW 1/4 sec. 15, R. 5 E, T. 22 N, 2; 5 mi. N, 2 mi. W Camp Crook, 1; 10 mi. S, 5 mi. W Reva, 16; 7 mi. S, 4-1/2 mi. E Harding, 1.

The long-eared myotis is not uncommon in and around wooded b.u.t.tes. The species may be mostly limited to these areas; an individual of unknown s.e.x found dead in a small stream southeast of Harding (several miles south of the East Short Pine Hills) is the only specimen not taken in such a situation. North of Camp Crook, on the eastern edge of the Long Pine Hills, several _M. evotis_ used an abandoned shed as a night roost in the summer of 1970; one was captured in a bat trap set at one of the entrances to the shed.

Females obtained on May 29 and June 17 and 19 carried single embryos that measured 3, 14, and 15, respectively. A male young of the year taken on August 6 was nearly of adult size. Testes of two May-taken males measured 4 and 2, whereas those of one taken on July 17 and another captured on August 3 measured 6.0 and 7.5, respectively.

Of seven adults collected in the period August 3 to 6, three females and two of four males were in fresh pelage; molt was nearly completed on the two remaining males. A male taken in mid-July was in an early stage of molt. New pelage is pale yellowish brown in contrast to the golden brown pelage of specimens taken in May and June.

Chiggers, _Leptotrombidium myotis_ (Ewing), were found on the ears of one long-eared myotis.

~Myotis leibii ciliolabrum~ (Merriam, 1886)

Small-footed Myotis

Eight males of this saxicolous species were shot or netted as they foraged over a small man-made pond in wooded Deer Draw in the Slim b.u.t.tes, 10 mi. S and 5 mi. W Reva--six in late June and two in early August. Probably this bat will be found in rocky areas elsewhere in the county. One specimen taken on June 23 was molting over much of the body.

~Myotis lucifugus carissima~ Thomas, 1904

Little Brown Myotis

_Specimens examined_ (27).--2 mi. N, 5 mi. W Ludlow, 1; NW 1/4 sec. 15, R. 5 E, T. 22 N, 4; NE 1/4 sec. 24, R. 8 E, T. 21 N, 20; 4 mi. S, 7 mi.

W Ladner, 1; 10 mi. S, 5 mi. W Reva, 1.

This bat is widely distributed in northwestern South Dakota and was the only species of _Myotis_ reported by Visher (1914:91) in his early natural history survey of Harding County. We took specimens from several of the wooded b.u.t.tes and also in areas well-removed from timber; one was shot, for example, as it foraged over the Little Missouri River in the extreme western part of the county. On May 28, 1968, a barn was located in which an incipient maternal colony (several hundred adult females) roosted between double rafters supporting a metal roof. The owner of the barn, Robert Parks of Ralph, stated that bats have utilized this place as a summer roost for several years. The barn stands adjacent to the nearly treeless Big Nasty Creek, which flows through the hilly terrain of the northeastern section of the county.

Fourteen of 20 females taken from the colony each carried a single embryo (crown-rump lengths measured 2 to 11 with a mean of 5.4). The other six were not visibly pregnant upon gross examination but had enlarged uteri, possibly indicating recent implantation. Of the remaining females from Harding County, three collected on May 29 had enlarged uteri, whereas two collected in late June evidenced no gross reproductive activity. A male obtained May 29 had testes that measured 4.

Ectoparasites obtained from this species include chiggers, _Leptotrombidium myotis_ (Ewing), a tick, _Ornithodoros kelleyi_ Cooley and Kohls, fleas, _Myodopsylla gentilis_ Jordan and Rothschild and _M.

insignis_ (Rothschild), and an unidentified species of mite.

~Myotis volans interior~ Miller, 1914

Long-legged Myotis

_Specimens examined_ (43).--2 mi. N, 5 mi. W Ludlow, 4; NW 1/4 sec. 15, R. 5 E, T. 22 N, 12; 10 mi. S, 5 mi. W Reva, 27.

The long-legged myotis is one of the commonest bats of the wooded b.u.t.tes, accounting for almost half of all chiropterans taken in these areas. Most of our specimens were shot as they foraged among trees and over water in the evening; a few were captured in mist nets.

Uteri of eight females obtained in the period May 23 to 31 were enlarged; two females collected on June 29 carried single embryos that measured 20 and 22. A lactating female was taken on August 3, but three other adult females taken early in the same month evidenced no reproductive activity. Testes measured 2 to 4 in three May-taken males and 4 in each of two from June.

Two males obtained June 16 and 23 were molting as evidenced by new hairs under the old pelage over much of the body.