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UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY

Vol. 19, No. 5, pp. 361-393, 8 figs. January 18, 1971

Mammals of Northwestern South Dakota

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

UNIVERSITY OF KANSAS LAWRENCE 1971

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors of this number: Frank B. Cross, Philip S. Humphrey, William E. Duellman

Volume 19, No. 5, pp. 361-393, 8 figs. Published January 18, 1971

UNIVERSITY OF KANSAS Lawrence, Kansas

PRINTED BY THE UNIVERSITY OF KANSAS PRINTING SERVICE LAWRENCE, KANSAS 1971

[Transcriber's Note: Words surrounded by tildes, like ~this~ signifies words in bold. Words surrounded by underscores, like _this_, signifies words in italics.]

Mammals of Northwestern South Dakota

BY

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).

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.

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.

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.

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 buttes. The species may be mostly limited to these areas; an individual of unknown sex 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 Buttes, 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 buttes 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 buttes, 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.

_Myotis volans_ that we examined for ectoparasites harbored chiggers, _Leptotrombidium myotis_ (Ewing), and fleas, _Myodopsylla gentilis_ Jordan and Rothschild.

~Lasionycteris noctivagans~ (LeConte, 1831)

Silver-haired Bat

A single female, which contained two embryos that measured 4, represents the only record of a silver-haired bat from Harding County. This specimen was shot at dusk on June 1, 1968, as it foraged over a small pond in Deer Draw of the Slim Buttes (10 mi. S and 5 mi. W Reva). Several other bats believed to be of this species were seen at the same place that evening. We initially assumed that these were late migrants, but recent findings indicate that this species is a common summer inhabitant of the Long Pine Hills in adjacent Carter County, Montana, and likely, therefore, also a resident in favored sites in Harding County.

~Eptesicus fuscus pallidus~ Young, 1908

Big Brown Bat

_Specimens examined_ (11).--NW 1/4 sec. 15, R. 5 E, T. 22 N, 3; 7 mi. N, 2 mi. W Camp Crook, 3300 ft., 2; 10 mi. S, 5 mi. W Reva, 6.

The big brown bat is a common inhabitant of the Slim Buttes and North Cave Hills, where individuals were shot or netted as they foraged over water or among trees late in the evening.

Two May-taken females had enlarged uteri and one taken on July 8 was lactating. The testes of a May-taken male measured 5, whereas those of one obtained in early July measured 9. One of two males shot on August 4 was a young of the year; the other, an adult, was in fresh pelage as was an adult male shot on July 8. The July-taken lactating female and three June-taken specimens were in old pelage. Several specimens were parasitized on the ears by chiggers, _Leptotrombidium myotis_ (Ewing).

~Lasiurus cinereus cinereus~ (Palisot de Beauvois, 1796)

Hoary Bat

The hoary bat seemingly is an uncommon summer resident of Harding County as but one specimen, a non-pregnant female, has been taken there. This bat was shot on the evening of June 22, 1961, in the Slim Buttes as it foraged over a small pond in Deer Draw (10 mi. S and 5 mi. W Reva).

~Plecotus townsendii pallescens~ (Miller, 1897)

Townsend's Big-eared Bat

_Specimens examined_ (4).--2 mi. S, 3-1/4 mi. W Ludlow (Ludlow Cave), 2 (1 SDSU); 10 mi. S, 5 mi. W Reva, 2.

This big-eared bat evidently is uncommon in northwestern South Dakota. Of the four specimens examined, two were taken at Ludlow Cave and two were taken in June in the southern part of Slim Buttes--a female shot as it foraged over a pond in Deer Draw and another female netted over a water tank at Summit Spring about a half mile south of Deer Draw.

Ludlow Cave, in the caprock on the southeastern edge of the North Cave Hills, was formed by water erosion, resulting in numerous pockets and crevises in the ceiling and walls. The cave faces northwest; the mouth measures approximately 10 feet in diameter. A few feet from the entrance the cave narrows and approximately 50 feet back it is no more than three feet in diameter, although in the first 30 feet or so the ceiling varies from 10 to 15 feet in height. A thorough search of this cave on June 18, 1961, revealed one bat, a male _Plecotus_, which was shot from the ceiling about 15 feet from the entrance. No bats were found when the cave was visited on May 16 and again on June 4, 1968. Visher (1914:92) reported that several _Plecotus_ were found there in early September, 1912. Probably Ludlow Cave, along with the several abandoned coal mines in the county, serves as a hibernaculum for some species of bats.

Order Lagomorpha

~Lepus townsendii campanius~ Hollister, 1915

White-tailed Jack Rabbit

_Specimens examined_ (15).--NW 1/4 sec. 23, R. 1 E, T. 23 N, 1; sec. 24, R. 1 E, T. 22 N, 1; 2 mi. N, 2 mi. E Ladner, 1; 4 mi. S, 7 mi. W Ladner, 2; 10 mi. S Ladner, 1; 6 mi. N, 2-1/2 mi. W Camp Crook, 1; 2 mi. N Buffalo, 1; sec. 30, R. 3 E, T. 19 N, 1; SW 1/4 sec. 26, R. 2 E, T. 19 N, 1; 10 mi. S, 5 mi. W Reva, 3; 12 mi. S, 5 mi. W Reva, 1; 17 mi. S, 4 mi. W Reva, 1.

This jack rabbit is abundant throughout the areas of short grass in the county and individuals occasionally utilize grassy slopes of buttes. Extensive favorable habitat and the paucity of natural predators resulting from control operations probably are the principal factors favoring the heavy concentrations of this hare noted by all of our field parties.

A female examined on May 21 carried five fetuses and each of two others examined late in May carried six; all fetuses were nearly of the same size (110 to 120) and were completely covered with hair. A female obtained on May 31 appeared to have recently weaned young and females examined on June 5 and 17 were lactating. A female shot on June 28 and another taken on July 12 proved to be approximately half grown, although young of the year collected on June 16, 26, and 28 were nearly of adult size.

In late March of 1963, white-tailed jack rabbits were molting to summer pelage from the white pelage of winter.

~Sylvilagus audubonii baileyi~ (Merriam, 1897)

Desert Cottontail

_Specimens examined_ (12).--2 mi. N, 5 mi. W Ludlow, 2; 10 mi. S, 4 mi. W Ladner, 1; 7 mi. N, 2-1/2 mi. W Camp Crook, 3300 ft., 1; 5 mi. W Buffalo, 1; 10 mi. S, 5 mi. W Reva, 7.

The desert cottontail is a common inhabitant of the uplands of Harding County, especially where varied local relief and in some instances brushy vegetation provide suitable cover. A female shot on May 26 in a dense stand of pines in the North Cave Hills carried five embryos that measured 75, another taken on July 4 was pregnant with six embryos that measured 18, and two females collected on June 16 and another on June 24 carried seven embryos that measured 32, 40, and 45, respectively. Two subadults collected in late June and two collected in early August were nearly full grown. The testes of an adult male obtained on March 28 measured 50.

The male mentioned above was completely in winter pelage. Adults taken on June 16, 23, and 24 had almost completed molt to summer pelage, but each retained some evidence of active hair replacement, most often over the shoulders; a pregnant female obtained on July 4 had only partially completed the molt to summer pelage. An adult female in summer pelage that was taken on August 4 was inexplicably molting on the sides and over the shoulders.

A May-taken female was parasitized by fleas, _Cediopsylla inaequalis_ (Baker).

~Sylvilagus floridanus similis~ Nelson, 1907

Eastern Cottontail

_Specimens examined_ (2).--4 mi. S, 7 mi. W Ladner, 1; 10 mi. S, 5 mi. W Reva, 1.

This rabbit is uncommon in northwestern South Dakota and evidently is strictly associated with riparian habitats. Our only specimens were taken along the Little Missouri River, where thickets and small cottonwood trees were prevalent, and at the edge of a thicket in spring-fed Deer Draw of the Slim Buttes.

A female obtained on June 26 carried eight embryos that measured 26, and was in process of seasonal molt. Testes of a male shot on May 20 measured 35.

Order Rodentia

~Eutamias minimus pallidus~ (J. A. Allen, 1874)

Least Chipmunk

_Specimens examined_ (31).--2 mi. N, 5 mi. W Ludlow, 15; NW 1/4 sec. 15, R. 5 E, T. 22 N, 2; 2 mi. S, 3-1/4 mi. W Ludlow, 2; NW 1/4 sec. 32, R. 1 E, T. 20 N, 1; 9 mi. S, 7 mi. W Reva, 1; 10 mi. S, 5 mi. W Reva, 9; NE 1/4 sec. 8, R. 8 E, T. 16 N, 1.

The least chipmunk is common in the buttes and associated badlands where it most frequently inhabits rocky areas. Visher (1914:88) reported _E. minimus_ from Harding County ("abundant in badlands"), but his paper has been overlooked by most subsequent workers. Visher's mention of a chipmunk from the mouth of the Moreau River in north-central South Dakota, incidentally, would seem to be in error, as would the report by Over and Churchill (1945:28) of _Eutamias_ inhabiting "... thickets along the Little Missouri River of Harding County."

Females evidently bear but one litter annually (in late May) in northwestern South Dakota and young are weaned by the latter part of June. Females taken on May 15 and 19 carried embryos (five measuring 30 and three measuring 28, respectively). A lactating female with five placental scars was obtained on May 24, but eight adult females taken after June 23 previously had weaned young. Juveniles were collected on June 24 and 25. Testes of two adult males collected in mid-May measured 11 and 18, but males taken in summer had much smaller testes.

In late spring, most adult least chipmunks molt from the worn, drab-gray pelage of winter to a brighter, more tawny summer pelage, but molt in a few females, perhaps originally delayed by reproductive activity, continues well into the summer months. Of seven specimens taken between May 15 and 24, two (one male and one lactating female) were in an early stage of molt, whereas the remainder were in winter pelage. Nine specimens (four females and five males) taken in mid- and late June were molting, but two females collected then were in winter pelage, and three animals, two males and a female, had completed molt to summer pelage. One adult female taken on August 5 had yet to complete molt to summer pelage. In our material, the first indication of molt from winter to summer pelage appears on the top of the head and the cheeks. Thereafter, molt proceeds posteriorly over the shoulder region and more or less evenly along the back and sides. In two specimens, small patches of molt preceded the general molt line. Molt on the venter apparently begins after molt on the dorsum approaches completion, but we could discern no definite pattern; on four specimens, hair was being replaced on the venter in scattered patches.

An August-taken young of the year engaged in post-juvenal molt had new adult pelage in a vague hour-glass pattern in the dorsal trunk region as well as on the cheeks and anterior part of the head. It was actively molting on top of the head, between the ears, over the shoulders, laterally behind the front feet, and along the sides, and had old pelage on the rump. Ventrally, the new adult pelage was evident only along the midline.

One adult male examined for ectoparasites harbored a tick, _Dermacentor andersoni_ Stiles, and fleas, _Monopsyllus eumolpi_ Rothschild.

~Spermophilus tridecemlineatus pallidus~ J. A. Allen, 1874

Thirteen-lined Ground Squirrel

_Specimens examined_ (22).--2 mi. N, 5 mi. W Ludlow, 5; 19 mi. N, 1 mi. E Camp Crook, 2; 2 mi. S, 2 mi. W Ladner, 1; 6-1/2 mi. N, 2 mi. W Camp Crook, 1; 1/2 mi. W Reva, 3; 4 mi. S, 1/2 mi. W Reva, 1; 6 mi. W Reva, 7; 15 mi. S, 4 mi. W Reva, 1; 7 mi. S, 4-1/2 mi. E Harding, 1.

Ground squirrels are common in areas of short grass; we observed them most frequently along roadways and fencerows in otherwise overgrazed flats. Many of our specimens were shot or taken in break-back traps baited with rolled oats in just such situations.