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.