The white-tailed deer is less abundant in northwestern South Dakota than is _O. hemionus_, but a number were seen by members of our parties (in Deer Draw of the Slim b.u.t.tes, for example), and local residents reported many sightings to us. Visher (1914:82) earlier recorded this species as once "fairly plentiful in the forest reserves" in Harding County, but stated that it had become rare when he made his biological survey of the area in 1910 and 1912.

~Antilocapra americana americana~ (Ord, 1815)

p.r.o.nghorn

_Specimens examined_ (2).--Sec. 28, R. 8 E, T. 23 N, 1; 12 mi. S, 10 mi.

W Buffalo, 1.

This species is the most conspicuous (and possibly the most abundant) ungulate in Harding County. It ranges throughout the county on flat and rolling gra.s.slands where small groups, and occasionally herds of up to 50 individuals, were seen in 1960, 1961, 1963, 1968, and 1970. Visher (1914:88) reported that the p.r.o.nghorn was common in the area until about 1900, but that it was near the point of extinction when he visited the county in 1910 and 1912.

~Bison bison bison~ (Linnaeus, 1758)

Bison

According to historical accounts (Anonymous, 1959), the bison was rare or absent in Harding County at the time of settlement in 1876. By the early 1880's, however, herds were of regular occurrence, and there is one record (_op. cit._: 95-96) of thousands crossing the Little Missouri near Camp Crook in November of 1882.

One report has it that the last bison killed in the county was shot in the summer of 1884 (_op. cit._: 73-74), but Visher (1914:88) reported that an "old settler" had seen "a small bunch in 1886." Visher also reported finding bison remains, probably in 1910 or 1912, to the northeast of the North Cave Hills and west of the South Cave Hills.

~Ovis canadensis auduboni~ Merriam, 1901

Mountain Sheep

According to Visher (1914:88), mountain sheep formerly inhabited all the areas of b.u.t.tes in Harding County but were extirpated in the 1890's.

Sheep Mountain, a large b.u.t.te just below the south end of the Slim b.u.t.tes, was reported to be the last area in which these animals occurred. Over and Churchill (1945:54) mentioned both the Cave Hills and Slim b.u.t.tes as localities formerly inhabited by _O. c. auduboni_.

Early in 1961, the South Dakota Game Commission introduced 12 animals, four rams and eight ewes, from Alberta (subspecies _O. c. canadensis_) on the Slim b.u.t.tes, but none is known to have survived to 1968.

SPECIES OF UNVERIFIED OCCURRENCE

The ten species of mammals listed below are not known certainly to occur in Harding County, but there is a strong likelihood that some will be found in the area or once occurred there. Three were mentioned by Visher (1914) as having been seen or taken in the county at the time of, or prior to, his biological survey of 1910 and 1912, but his accounts were not supported by adequate doc.u.mentation. In addition to the kinds listed, several other mammals, such as Keen's bat (_Myotis keenii septentrionalis_), the red bat (_Lasiurus borealis borealis_), or the least weasel (_Mustela nivalis campestris_) are known to occur near enough to the area that the possibility of their presence cannot be discounted.

~Sorex cinereus haydeni~ Baird, 1858.--No shrews presently are known from Harding County. This species almost certainly will be found in relatively mesic habitats there, however, as our field parties have taken specimens in adjacent Bowman County, North Dakota, and only a few miles to the west of the county in the Long Pines Hills of Montana.

~Sorex merriami merriami~ Dobson, 1890.--This shrew inhabits somewhat more xeric areas than most other members of the genus and surely occurs in northwestern South Dakota. Specimens are on record from western North Dakota and northwestern Nebraska, and in the summer of 1970 a field party from The University of Kansas took one but a half mile west of the Harding County (state) line in Carter County, Montana.

~Spermophilus richardsonii richardsonii~ (Sabine, 1822).--Visher (1914:88) reported that he saw individuals of this species "in the extreme northwestern corner" of Harding County. However, the limits of the presently known range of the species are approximately 150 miles distant from that area.

~Sciurus niger rufiventer~ E. Geoffroy St.-Hilaire, 1803.--The fox squirrel presently is unrecorded from much of the West River part of South Dakota. Hoffmann _et al._ (1969:589), however, recently have reported specimens from along the Yellowstone River in eastern Montana and this squirrel now may occur also along the Little Missouri River. It was not surprising, therefore, when residents of Camp Crook reported to us that in recent years they have seen what were believed to be fox squirrels along the Little Missouri near that town. Specimens now are needed to verify these reports.

~Lagurus curtatus pallidus~ (Merriam, 1888).--The sagebrush vole undoubtedly occurs, albeit probably uncommonly, in areas of sage in northwestern Harding County, because specimens have been taken recently a few miles north and west of the county in North Dakota and Montana, respectively. We trapped unsuccessfully (900 trap nights) for this vole on sage flats to the north of Camp Crook and west of the Little Missouri River in the summer of 1970. "Sign," which appeared to be that of _Lagurus_, was found in this area, but only _Peromyscus maniculatus_ and _Spermophilus tridecemlineatus_ were trapped there.

~Rattus norvegicus~ (Berkenhout, 1769).--No records of this introduced murid are available from northwestern South Dakota, but it seems likely that the species has reached the area.

~Vulpes velox~ (Say, 1823).--Visher (1914:90) reported seeing a swift fox "along the Little Missouri Valley in North Dakota" and further noted that an early settler [Sol Catron] had "trapped a few" in Harding County. Whatever the former status of this fox in northwestern South Dakota may have been, the species evidently does not occur in the area today, or is rare, and the subspecific status of _V. velox_ throughout much of the Northern Great Plains is in question. A specimen obtained in February of 1970 at a place 9 mi. N and 2 mi. E Scranton, Slope Co., North Dakota, is the only swift fox taken north of Nebraska in recent years (Pfeifer and Hibbard, 1970:835).

~Urocyon cinereoargenteus ocythous~ Bangs, 1899.--Jones and Henderson (1963:288) reported a gray fox from Deer Ear b.u.t.tes, b.u.t.te Co., South Dakota, approximately 15 miles south of the Harding County line. This species appears to have dispersed westward in recent years, and its future occurrence in the county is likely.

~Gulo gulo luscus~ (Linnaeus, 1758).--The wolverine probably occurred sparingly in northwestern South Dakota until the time of early settlement, but we know of no verified records from Harding County or surrounding areas. A recent report of a specimen taken south of Timber Lake, Dewey Co., South Dakota (Jones, 1964:283), indicates that it may again be found in the area.

~Lynx canadensis canadensis~ Kerr, 1792.--We have no reports of this species in Harding County save that Visher (1914:90) noted that local residents claimed specimens had "been taken recently in the Cave Hills."

Hoffmann and Pattie (1968:53) reported that the lynx occurs presently in eastern Montana and we suspect that individuals may occasionally range into Harding County.

ZOOGEOGRAPHIC COMMENTS

Of the 53 mammals listed in the foregoing accounts, all but one (_Mus musculus_) are native North American species. These fall into five rather well-defined faunal groupings as outlined by Hoffmann and Jones (1970:364-365). A majority (27) can be characterized as "widespread species." Most of these have broad distributions over much of North America; a few do not, but are widely enough distributed that it is impossible to a.s.sign them with certainty to a more circ.u.mscribed a.s.semblage. Mammals from northwestern South Dakota that can be characterized as widespread are: _Myotis leibii_, _Myotis lucifugus_, _Eptesicus fuscus_, _Lasionycteris noctivagans_, _Lasiurus cinereus_, _Castor canadensis_, _Peromyscus maniculatus_, _Ondatra zibethicus_, _Erethizon dorsatum_, _Canis latrans_, _Canis lupus_, _Vulpes vulpes_, _Ursus america.n.u.s_, _Ursus arctos_, _Procyon lotor_, _Mustela frenata_, _Mustela vison_, _Taxidea taxus_, _Mephitis mephitis_, _Lutra canadensis_, _Felis concolor_, _Lynx rufus_, _Cervus elaphus_, _Odocoileus hemionus_, _Odocoileus virginia.n.u.s_, _Antilocapra americana_, and _Bison bison_. The above list is composed mainly of volant or relatively large and mobile mammals, several of which occur also in Eurasia or range well into the Neotropics.

A few widespread species deserve special comment. Two, the p.r.o.nghorn and bison, are typical inhabitants of the interior gra.s.slands of North America and might be considered steppe species save for the fact that each has an extensive distribution beyond that region. Four other species, _Erethizon dorsatum_, thought of primarily as a mammal of coniferous forests, and _Ursus arctos_, _Taxidea taxus_, and _Odocoileus hemionus_, all more or less western taxa, are not so broadly distributed as are other members of this grouping. Of the five bats, three are year-round residents, but _Lasiurus cinereus_ and evidently _Lasionycteris noctivagans_ are migrants.

The remaining 25 kinds of mammals are representative of four regional faunal groupings as follows: boreomontane species (10), steppe species (nine), species with Sonoran affinities (four), and species of the eastern deciduous forest (two).

_Boreomontane species._--Of the 10 mammals in this faunal group, three (_Eutamias minimus_, _Tamiasciurus hudsonicus_, and _Microtus pennsylvanicus_) are distributed both in the boreal forests to the north of the plains and in montane areas to the west. Six species (_Myotis evotis_, _Myotis volans_, _Plecotus townsendii_, _Th.o.m.omys talpoides_, _Neotoma cinerea_, and _Ovis canadensis_) are primarily montane in distribution and evidently reached northwestern South Dakota from the west in late Wisconsin or post-glacial times; all but the pocket gopher occur there now only in the vicinity of coniferous timber or rocky b.u.t.tes. The remaining species, _Zapus hudsonius_, is a glacial "relic."

The nearest populations now are far to the north, and this jumping mouse occupies only restricted habitats in northwestern South Dakota and adjacent regions. In Harding County, _Z. hudsonius_ presently is known only from Deer Draw in the Slim b.u.t.tes.

_Steppe species._--Taxa intimately a.s.sociated with the Great Plains are: _Lepus townsendii_, _Cynomys ludovicia.n.u.s_, _Spermophilus tridecemlineatus_, _Perognathus fasciatus_, _Perognathus hispidus_, _Reithrodontomys monta.n.u.s_, _Microtus ochrogaster_, _Mustela nigripes_, and _Spilogale putorius_ (subspecies _interrupta_). A few of these are endemic to the plains, but most occur in gra.s.sland habitats beyond the borders of the region. All clearly are well adapted to, and therefore presumably evolved in response to, the environment of the interior gra.s.slands; this zoogeographic unit, then, is characterized by truly steppe species that have relatively narrow habitat requirements and largely concordant patterns of distribution.

The case of the spotted skunk deserves brief commentary. This species was not taken or observed by members of our field parties and local residents made no claim to its presence except for a few vague recollections of spotted skunks having been seen "years ago." Visher (1914:91), however, reported that _Spilogale_ was much commoner than _Mephitis_ in the early part of the century. However that may have been, _Spilogale putorius_, as currently understood, would be judged to be a widespread species except that recent evidence strongly suggests that the plains race (_interrupta_) is not of the same species as spotted skunks to the west (subspecies _gracilis_). Furthermore, the ranges of the two are not in contact. Whatever its ultimate specific affinities may be, _S. p. interrupta_ clearly is a plains mammal, and thus is here considered in that zoogeographic unit.

_Sonoran species._--_Sylvilagus audubonii_, _Dipodomys ordii_, _Reithrodontomys megalotis_, and _Onychomys leucogaster_ are invaders to the Northern Great Plains from the Sonoran region to the southwest. The latter two, however, are rather broadly distributed on the Great Plains and their a.s.signment as Sonoran species is somewhat arbitrary. It is of interest that as many as nine mammals with southwestern affinities occur as far north as southwestern South Dakota and adjacent Wyoming.

_Eastern species._--Only _Sylvilagus florida.n.u.s_ and _Peromyscus leucopus_ can be identified as species primarily a.s.sociated with the eastern deciduous forest. The former is limited in northwestern South Dakota to brushy habitats in riparian communities, whereas _P. leucopus_ is restricted to relatively good stands of deciduous timber and presently is known to occur only in Deer Draw of the Slim b.u.t.tes.

Throughout its known range in the western part of the Northern Great Plains, _P. leucopus_ is represented by small and disjunct populations a.s.sociated with riparian deciduous timber. The known population nearest to Harding County is on the Black Hills to the south; next nearest are several isolated or semi-isolated populations along the Yellowstone River in eastern Montana. Presumably, this white-footed mouse spread northwestward into the western part of the plains region along river systems, in company with deciduous trees, in some post-glacial period when the climate was warmer and wetter than now. Subsequent drying altered substantially the distribution and perhaps composition of riparian forests, and isolated populations of _P. leucopus_ evidently survived only in restricted areas, such as Deer Draw, many of them probably marginal habitat for the species.

_Unverified species._--If the 10 species listed as of "unverified occurrence," it seems highly likely that as many as eight will be found to occur, or occurred within historic time, in Harding County. Among these eight are one steppe species (_Vulpes velox_), three with boreomontane affinities (_Sorex cinereus_, _Gulo gulo_, and _Lynx canadensis_), two (_Sciurus niger_ and _Urocyon cinereoargenteus_) that are a.s.sociated with the eastern deciduous forests, and two (_Sorex merriami_ and _Lagurus curtatus_) that are Great Basin elements.

It is noteworthy that the last-mentioned faunal unit is not known to be represented in northwestern South Dakota.

ACKNOWLEDGMENTS

For a.s.sistance in the field, we are especially grateful to the students who were enrolled in the Field Course in Vertebrate Zoology at The University of Kansas in the summers of 1961, 1965, and 1970, and to M.

A. Levy, R. R. Patterson, and T. H. Swearingen. In 1965 and 1970, the summer field course was supported in part by grants (GE-7739 and GZ-1512, respectively) from the National Science Foundation; Andersen was supported in the field in 1968 by a grant from the Kansas City Council for Higher Education. Personnel of the U.S. Forest Service (Sioux Division, Custer National Forest), particularly District Ranger Timothy S. Burns, were most helpful to us in the field, as were Wardens Wesley Broer and Merritt Paukarbek of the South Dakota Department of Game, Fish and Parks. Robert Kriege, Federal predator control agent stationed in Buffalo, was most generous in sharing with us his knowledge of rodents and carnivores in the area, and many present or former residents, particularly Carl Cornell and Spike Jorgensen, also provided useful information and were helpful in other ways.

Ectoparasites reported here were identified by Cluff E. Hopla (fleas), Richard B. Loomis (chiggers), and Glen M. Kohls (ticks). Other than mammals housed in the Museum of Natural History, we examined only three, two in the U.S. National Museum (USNM) and one in the collection at South Dakota State University, Brookings (SDSU).

LITERATURE CITED

ANONYMOUS