Part 11

~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 Buttes, Butte 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 assign them with certainty to a more circumscribed assemblage. 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 americanus, Ursus arctos, Procyon lotor, Mustela frenata, Mustela vison, Taxidea taxus, Mephitis mephitis, Lutra canadensis, Felis concolor, Lynx rufus, Cervus elaphus, Odocoileus hemionus, Odocoileus virginianus, 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 pronghorn and bison, are typical inhabitants of the interior grasslands 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, Thomomys 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 buttes. 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 Buttes.

Steppe species.--Taxa intimately associated with the Great Plains are: Lepus townsendii, Cynomys ludovicianus, Spermophilus tridecemlineatus, Perognathus fasciatus, Perognathus hispidus, Reithrodontomys montanus, Microtus ochrogaster, Mustela nigripes, and Spilogale putorius (subspecies interrupta). A few of these are endemic to the plains, but most occur in grassland 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 grasslands; 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 assignment 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 floridanus and Peromyscus leucopus can be identified as species primarily associated 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 Buttes.

Throughout its known range in the western part of the Northern Great Plains, P. leucopus is represented by small and disjunct populations associated 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 associated 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 assistance 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

1959. Building an empire: a historical booklet on Harding County, South Dakota. Buffalo Times-Herald, 108 pp.

BAILEY, V.

1915. Revision of the pocket gophers of the genus Thomomys. N. Amer. Fauna, 39:1-136.

1927. A biological survey of North Dakota. N. Amer. Fauna, 49: vi + 1-226 [this publication is dated 1926, but actually was published on January 8, 1927].

BAKER, C. L.