PUBLICATIONS OF THE MUSEUM TEXAS TECH UNIVERSITY Two publications of The Museum of Texas Tech Uni¬ versity are issued under the auspices of the Dean of The Graduate School and Director of Academic Publications, and in cooperation with the International Center for Arid and Semi-Arid Land Studies. Shorter research papers are pub¬ lished as Occasional Papers, whereas longer contributions ap¬ pear as Special Publications. Both are numbered separately and published on an irregular basis. Institutional libraries interested in exchanging publications may obtain the Occasional Papers and Special Publications by addressing the Exchange Librarian, Texas Tech University, Lubbock, Texas 79409. Individuals may purchase separate numbers of the Occasional Papers for 50 cents each through the Exchange Librarian. Remittance must be enclosed with request. 1 ^ ' /s . ..k OCCASIONAL PAPERS THE MUSEUM TEXAS TECHUNIVERSITY L!3R/iRV NUMBER 6 - harvard - UNiVERClT/: MAMMALS FROM SOUTHWESTERN NORTH DAKOTA Hugh H. Genoways and J. Knox Jones, Jr. The distribution of the mammals in the southwestern part of North Dakota and their ecological and taxonomic relationships have not been well documented. In addition to Vernon Bailey’s (1927) survey of mammals of the state, based primarily upon field work conducted between 1912 and 1916, the only other principal studies dealing with the mammalian fauna of southwestern North Dakota were a prelim¬ inary report of the mammals of the state by Bailey et al. (1914) and the publication by J. A. Allen (1875) on mammals taken by the ex¬ pedition that surveyed a route for the North Pacific Railway. Our studies, which were confined to that part of North Dakota bordered on the east and north by the Missouri River (Fig. 1), began in 1961 when members of a summer field course in vertebrate zoology from The University of Kansas collected briefly in Slope County. In the summers of 1965 and 1970, other field classes worked in Billings, Bowman, and Dunn counties. Also in the summer of 1970, studies were conducted on small mammals on the Grasslands Biome Com¬ prehensive Site (International Biological Program) near Dickinson, Stark County, and in adjacent areas. Thirty-nine species of mammals were collected or observed in the course of field work in southwestern North Dakota. In the following accounts, we have attempted to summarize ecological and distri¬ butional data for each species, and have appended taxonomic com¬ ments where appropriate. It is hoped that this study, together with those by Andersen and Jones (1971) on northwestern South Dakota and one underway by Richard P. Lampe and associates (see Lampe, 1971) on southeastern Montana, will provide a better understanding of the mammalian fauna of this important region of the Northern Great Plains. !TOt s 3 NOVEMBER 1972 2 OCCASIONAL PAPERS MUSEUM TEXAS TECH UNIVEKSJ / Y Collecting Sites A short description of each major collecting site visited in south¬ western North Dakota is given below. Botanical nomenclature follows Stevens (1963). Killdeer Mountains, Dunn County. — The Killdeer Mountains are part of a system of Tertiary erosional remnants that form spectacular buttes and hills in southwestern North Dakota and adjacent parts of Montana and South Dakota (Andersen and Jones, 1971:363; Lillegraven, 1970:832). The Killdeers rise ap¬ proximately 700 feet above the surrounding plain to a highest elevation of 3314 feet. Although of the same geological formation as the buttes to the south and west, the Killdeer Mountains differ in being clad almost completely by decid¬ uous trees rather than conifers; the only species of the latter group that we noted was creeping cedar {Juniperus horizontalis), which grew in exposed situations at higher elevations. Deciduous trees obtain elsewhere on the hills and along streams that drain onto the surrounding lowlands. The following deciduous species were observed in various situations: green ash (Fraxinus pennsylvanicus), bur oak {Quercus macrocarpa), round-leaved hawthorn (Crataegus rot undifolia), American elm (Ulmus americanus), aspen (Populus tremuloides), cottonwood (Populus deltoides), river birch (Betula fontinalis), box-elder (Acer negundo), and willow (Salix sp.). Hazelwood (Corylus ameri- cana) and bird cherry (Prunus pennsylvanica) formed a dense layer under the trees in many places. Several streams with relatively moist banks ran along the edges of the Killdeers and away from them; numerous artificial impoundments used for watering cattle were located in the hills and in surrounding areas. The vegetation of the plains closely resembled that of the area around Dickinson. Vicinity of Dunn Center, Dunn County. — Several habitats were trapped in the vicinity of the Lake Ilo National Wildlife Refuge. The muddy lake lacked a riparian community except in the vicinity of the spillway where several short, woody shrubs, cattails (Typha latifolia), big bluestem (Andropogon gerardi), and sloughgrass (Beckmannia syzigachne) were found. The remainder of the refuge and fencerows elsewhere that had not been grazed or mowed supported tall stands (12 to 60 inches) of grasses and forbes including big bluestem, blue grama (Bouteloua gracilis), bromegrass (Bromus inermis), goatsbeard (Trago- pogon duhius), sunflowers (Helianthus annuus), sweetclover (Melilotus offici¬ nalis), and alfalfa. Northeast of Sentinel Butte, Golden Valley County. — In this area, trapping was conducted in several dry ravines and on the adjacent prairie. The relatively dense growth of woody vegetation found in the ravines included green ash (Fraxinus pennsylvanicus), cottonwood (Populus deltoides), willow (Salix sp.), wild rose (Rosa multiflora), buffaloberry (Shepherdia argentea), and poison ivy (Rhus rad leans). Above the ravines this woody vegetation gave way abruptly to sage and prairie grasses. Little Missouri River southwest of Medora, Billings County. — The valley of the Little Missouri River at this point was approximately one mile wide. Within 100 yards of the river, the sandy floodplain supported a riparian community dominated by cottonwoods (Populus deltoides) and numerous thickets of rose (Rosa multiflora). Other common plants on the floodplain included waving butterfly (Gaura coccinea), knotweed (Polygonum sp.), collomia (Collomia linearis), bluegrass (Poa sp.), bromegrass (Bromus sp.), and needle-and-thread GENOWAYS AND JONES — MAMMALS FROM NORTH DAKOTA 3 Fig. 1. — Map of southwestern North Dakota on which localities mentioned in text are plotted. grass (Stipa comatci). Beyond the riparian community on the floodplain, the vegetation consisted of numerous clumps of sage {Artemesia frigida) inter¬ spersed with grasses. The bluffs and rugged cliffs along the edges of the valley form part of the Little Missouri Bad Lands; generally these areas were denuded of vegetation. On the uplands above the bluffs (where the land was not in agri¬ cultural use), the vegetation consisted of short grass prairie characterized by the presence of blue grama {Bouteloua gracilis), buffalo grass (Buchloe dacty- loides), and needle-and-thread grass {Stipa comata). Vicinity of South Heart, Stark County. — Trapping at this place was con¬ ducted along the Heart River and in nearby roadside ditches. The river is nar¬ row at this point being only about six feet wide and is situated in a 10-foot-deep ravine. A riparian community is essentially nonexistent with only a narrow thicket of buffaloberry {Shepherdia argentea) and a few widely scattered cotton¬ woods lining the edge of the ravine. Most of the low-lying surrounding area was under agricultural usage and the uplands were in pastures of native grass. The roadside ditch in which we trapped had been planted to bromegrass and alfalfa. Vicinity of Dickinson, Stark County. — Much of the trapping in the vicinity of Dickinson was conducted on the Dickinson Site of the Grassland Biome Comprehensive Network (International Biological Program), which is located 4 OCCASIONAL PAPERS MUSEUM TEXAS TECH UNIVERSITY one mile north and one mile west of Dickinson. The site was situated on two low hills just to the north of Interstate 94. The grassland vegetation of the site, which is fairly typical of northern plains mixed grass prairie, has been desig¬ nated as the needle-and-thread, blue grama, sedge type (see Whitman, IBP Grassland Biome Technical Report no. 40). Principal grasses and sedges that composed 80 per cent of the total cover were needle-and-thread (Stipa comata), blue grama (Boutelous gracilis), western wheatgrass {Agropyron smithii), threadleaf sedge {Carex filifolia), and needleleaf sedge {Carex eleocharis). Im¬ portant secondary grasses (making up about 15 per cent of the total cover were prairie junegrass {Koeleria cristata), green needlegrass {Stipa viridula), plains reedgrass {Calamagrostris montanensis), prairie sandreed {Calamovilfa longi- folia), and Sandberg bluegrass {Poa secunda). Numerous species of broad-leaf plants accounted for about 5 per cent of the total cover. Much of the area in the vicinity of Dickinson and around the grassland site was planted to small grains or corn. Other trapping in this area was conducted mainly in bromegrass {Bromus inermis) planted in roadside ditches and the right-of-way along an interstate highway. Weather data recorded at the Dickinson Experiment Station for the period 1892 to 1960 can be considered as representative for southwestern North Da¬ kota, which is semiarid and with cold winters and hot summers. At Dickinson, the coldest month of the year is January with an average temperature of 11.0 F, whereas that for July, the hottest month, is 69.0 F. More than 75 per cent of the annual precipitation of 15.50 inches falls in the period April to September; June (average 3.50 inches of precipitation) is the wettest month, and December (average 0.40 inch) is the driest month. Snowfall amounts to an average of 31.8 inches annually and is recorded from every month from September through June (Climatography of the United States, no. 20-32, Dickinson, North Dakota). Two grids were extensively trapped on the IBP site northwest of Dickinson. One grid, on which snap traps were used, was located in a moderatley grazed pasture. It consisted of 12 by 12 stations, with a 15-meter interval between each station, giving the grid an area of 2.76 hectares and an effective trapping area of 3.24 hectares; two traps were set at each station for 10 nights during two trapping periods (16 through 25 June 1970 and 2 through 11 August 1970). A smaller grid on which live traps were used was located within an exclosure that had not been grazed since 1961. This grid, which was nearly triangular in shape, covered an area of about 1.1 hectares. Two traps were set at each of 56 stations for 10 days during two trapping periods (13 through 23 June 1970 and 2 through 1 1 August 1970). For computation of population densities, the effective trapping area was used for the snap-trap grid and the actual area trapped was used for the live-trap grid (the latter figure was used because the vegetation out¬ side the exclosure was sparse on two sides and it was elsewhere bordered by plowed fields). East of Dickinson, Stark County. — Here, along the Green River, a relatively well-developed riparian community was found. In the immediate vicinity of the river was a woodland consisting of cottonwood {Populus deltoides), willow {Salix amygdaloidcs), and green ash {Fraxinns pennsylvanica). Beyond this woodland and also forming an understory in it were buckbrush {Symphori- carpos occidental is), wild rose (Rosa multiflora), chokecherry (Prunus vir- giniana), and poison ivy (Rhus rad leans). The riparian community is mainly confined to the banks and slopes of the river. On the plains above the river, sage and grasses prevail; tall bromegrass grew in roadside ditches. GENOWAYS AND JONES— MAMMALS FROM NORTH DAKOTA 5 Little Missouri River northwest of Am idon. Slope County. — The valley of the Little Missouri River was relatively wide at this point and was generally vege¬ tated with short grasses and sage except along the edge of the river where some lush grasses were noted. However, many areas had been overgrazed. Several good stands of cottonwoods {Populus deltoides) grew in the valley; pines (Pinus ponderosa) and cedar {Juniperus scopidarum) adorned the slopes and hills of the valley sides, especially to the east. South oj Bowman, Bowman County. — Vegetation in this area consisted of tall, lush grasses and reeds adjacent to standing water in a marshy, low-lying area near a small creek. Tall stands of bromegrass grew along a highway right- of-way. Active and fallow wheat fields were located on higher ground above the marsh. Little Missouri River in southwestern Bowman County. — At this place along the Little Missouri River there is little typical riparian vegetation, with the exception of a narrow stand of tall grasses and a few willows between the river and the steep, 20-foot-high bank to the south. On the north side of the river and on the uplands to the south of the river were extensive stands of sage, short grasses such as blue grama (Bouteloua gracilis), buffalo grass (Buchloe dacty- ioides), and needle-and-thread {Stipa comata), as well as prickly pear (Opuntia poiycantha). The general area, especially south of the river, appeared to be heavily grazed. Some fields planted to wheat are found in the sandy upland away from the river. Accounts of Species Thirty-nine species of mammals collected or observed in south¬ western North Dakota are treated in the accounts that follow. Speci¬ mens that have been examined are listed in telegraphic style preceding remarks; counties have been arranged alphabetically and localities within each county are arranged from north to south in these lists. Unless noted otherwise, all specimens listed are deposited in the Museum of Natural History at The University of Kansas. All stand¬ ard external and cranial measurements are given in millimeters and weights are recorded in grams. Sorex cinereus haydeni Baird, 1 858 Specimens examined (7). — Bowman County: 2 mi. S Bowman, 1. Dunn County: 8 mi. N, 7 mi. W Killdeer, 2800 ft., 1; 6 mi. N, 6I/2 mi. W Killdeer, 2700 ft., 1; Vi mi. N, 2 mi. W Dunn Center, 1; % mi. S, P/2 mi. W Dunn Cen¬ ter, 1; % mi. S, 1 mi. W Dunn Center, 1. Stark County: 1 mi. N, 1 mi. W Dickinson, 2700 ft., 1. All specimens with the exception of one from near Dickinson were taken in mesic habitats. Those from the Killdeer Mountains were trapped along moist stream banks that were covered with tall reeds and grass and three from the vicinity of Dunn Center were collected in marshy lowlands adjacent to Lake Ilo. The specimen from south of Bowman was obtained in a low-lying, marshy area near a small creek. 6 OCCASIONAL PAPERS MUSEUM TEXAS TECH UNIVERSHY The one shrew from northwest of Dickinson was taken in a relatively dry roadside ditch, which was planted to bromegrass. Only one of the seven specimens was a female, which was found to be lactating when obtained 8 mi. N and 7 mi. W Killdeer on 25 July 1970. Dates of capture and length of testes of the six males follow: 30 June (3), 23 July (1), 1 August (3, 3, 4), and 4 August (2). No molt was in evidence on any of our specimens, all of which were in summer pelage. Myotis evotis evotis (H. Allen, 1864) Specimens examined (2). — Billings County: 1 mi. S, 1 mi. W Medora, 2300 ft,, 1. Dunn County: 5 mi. N, 6C2 mi. W Killdeer, 3000 ft,, 1. A specimen of this species from Billings County was shot on the evening of 26 June 1965 as it foraged among trees along the Little Missouri River. Another from Dunn County was obtained in a sink¬ hole, known locally as Medicine Hole Cave, near the top of the Kill¬ deer Mountains. Both specimens are adult males with testes 5 in length and in fresh pelage. D. G. Schall and W. Russ descended approximately 25 feet to the bottom of Medicine Hole Cave, which extended as a narrow crack to both the east and west, with the top of the crack located about 1 5 feet above the floor. They were able to move only a few feet in either direction before the passage became too narrow to follow. Although the squeaking of several bats could be heard, they were able to obtain but a single specimen of Myotis evotis. Netting the entrance to the sink that evening (24 July 1970) yielded three Myotis lucifugus. The locality in Dunn County is slightly to the east of the two other places in North Dakota from which evotis is known — the Medora site listed above and 4 mi. W Grinnell, Williams County (Bailey, 1927:217). Myotis leibii ciliolabrum (Merriam, 1886) Specimens examined (7). — Billings County: 1 mi. S, 1 mi. W Medora, 2300 ft,, 6. Slope County: 8 mi. N, IV2 mi. W Amidon, 1. This saxicolous species appeared to be the commonest member of the genus along the bluffs and badlands lining the Little Missouri River southwest of Medora. Of the six adult females collected there between 16 and 24 June 1965, two were pregnant; each contained a single embryo that measured 9(17 June) and 1 1 (24 June) in crown- rump length. The pregnant female obtained on 24 June was in the early stages of molt. An adult female from Slope County, which was reported previously by Jones and Stanley ( 1962:263), also contained a single embryo that measured 15 in crown-rump length on 29 June GENOWAYS AND JONES— MAMMALS FROM NORTH DAKOTA 7 1961. This specimen was captured just after midnight as it hung on the underside of a large rock that projected horizontally from a rocky slope bordering the valley of the Little Missouri River. The bats listed in this account are the only specimens of M. leibii known from North Dakota, Bailey’s (1927:216) account of this species actually applying to Myotis keenii (see Miller and Allen, 1928: 168). We follow Glass and Baker (1968:259) in the use of the specific name leibii for this species, formerly known as Myotis subulatus. Myotis lucifugus carissima Thomas, 1 904 Specimens examined (15). — Billings County: 1 mi. S, 1 mi. W Medora, 2300 ft., 3. Dunn County: IV2 mi. N, IV2 mi. W Killdeer, 2800 ft., 7; 7 mi. N, 9 mi. W Killdeer, 2800 ft., 2; 5 mi. N, 6V2 mi. W Killdeer, 3000 ft., 3. Three males from 1 mi. S and 1 mi. W Medora were shot on the evenings of 17 and 18 June 1965 as they flew among trees along the Little Missouri River. Two other males were shot on the evenings of 21 and 22 July 1970 at a place 7 mi. N and 9 mi. W Killdeer as they flew over a small impoundment in a grassy meadow surrounded on three sides by deciduous forest, and seven specimens (four males and three females) from IV2 mi. N and IV2 mi. W Killdeer were taken along with specimens of Eptesicus fuscus from the sill above a door in a garage. Three male M. lucifugus from 5 mi. N and 6V2 mi. W Kill¬ deer were taken in a mist net as they emerged from Medicine Hole Cave; other bats, some of which may have been this species, were seen leaving the cave but escaped our net owing to high winds. As pointed out earlier by Jones and Genoways (1966:89), bats of this species from western North Dakota are intergrades between M. /. carissima and M. /. lucifugus. In color, our specimens are inter¬ mediate between the two subspecies and, in fact, those from the Kill¬ deer Mountains, which are in fresh pelage, are relatively dark as com¬ pared with other specimens. In cranial characters, however, all our specimens most closely agree with carissima, to which we have as¬ signed them. None of the three adult females obtained on 24 July 1970 evinced gross reproductive activity. Nine adult males collected in the Killdeer Mountains between 21 and 25 July 1970 had testes that averaged 7.1 (6-8) in length, whereas two males obtained southwest of Medora on 1 8 June 1965 had testes that measured 4 in length. Myotis volans interior Miller, 1914 Specimen examined (1).— Billings County: 1 mi. S, 1 mi. W Medora, 2300 ft., 1. 8 OCCASIONAL PAPERS MUSEUM TEXAS TECH UNlVEKSl f V The only specimen of this species known from southwestern North Dakota was shot on 28 June 1965 as it foraged among trees along the Little Missouri River. An adult male, it weighed 6.8 and had testes that measured 4 in length. This specimen and nine reported from Granville, McHenry County, by Genoways (1967:355) are the north- easternmost known records for the species. Eptesicus fuscus pallidus Young, 1908 Specimens examined (36). — Billings County: 1 mi. S, 1 mi. W Medora, 2300 ft., 15. Dunn County: IV2 mi. N, IV2 mi. W Killdeer, 2800 ft., 20; 7 mi. N, 9 mi. W Killdeer, 2800 ft., 1. The big brown bat evidently is the commonest member of the order in southwestern North Dakota. Fifteen specimens were shot as they flew among and over trees along the Little Missouri River south of Medora. Another was shot as it flew over a small impoundment located just to the west of the Killdeer Mountains in a meadow sur¬ rounded on three sides by deciduous trees. The remaining 20 speci¬ mens from the Killdeer Mountains were collected along with seven specimens of M. lucifugus from the sill above a door in a garage on 24 July 1970. Of the 15 specimens taken southwest of Medora, eight were fe¬ males of which four were pregnant. One, taken on 17 June 1965, carried two embryos that were 1 2 in crown-rump length, whereas the remaining three each carried a single embryo that measured 13 (17 June), and 1 1 and 21 (both 24 June). Six adult males from this place had testes that averaged 6.6 (4-9) in length. The colony from the garage near the Killdeer Mountains was a maternity colony as 10 of 20 bats collected there were young of the year. Some of these young, all of which were taken on 24 July 1970, were capable of flight but others were not; the largest had a forearm that measured 45.7, simi¬ lar in size to that of adults, and the smallest had a forearm measuring 36.9. Six of the nine adult females had completed lactation and also annual molt. The three lactating females, the one adult male present in the maternity colony, and the adult male shot to the west of the Kill¬ deer Mountains (21 July 1970) were all in early stages of molt and appeared to be following the sequence described by Jones and Geno¬ ways (1967:193) for this species in South Dakota. A nonpregnant fe¬ male taken on 17 June 1965 south of Medora was also in the early stages of annual molt. The adult males from the Killdeer Mountains had testes that measured 10 (21 July) and 3 (24 July). As first pointed out by Jones and Genoways (1966:90) and later by Long and Severson (1969:623), specimens of Eptesicus fuscus from GENOWAYS AND JONES— MAMMALS FROM NORTH DAKOTA 9 western North Dakota are best assigned to the subspecies pallidus rather than E. f. fuscus, under which name they were recorded by Bailey (1927:210). Lepus americanus americanus Erxleben, Mil Specimen examined (1). — Dunn County: 7 mi. N, 9 mi. W Killdeer, 2800 ft., 1. Although the snowshoe hare is a relatively common inhabitant of northern North Dakota, and has been reported from along the Mis¬ souri River at Buford, Elbowood, and Cannon Ball (Bailey, 1927: 139), the species evidently has not been reported previously from southwest of the river. Our one specimen, a juvenile female, was taken in a museum special trap on the night of 21 July 1970 in a stand of tall birch and aspen trees in the Killdeers. There was little under¬ brush or other cover beneath the trees, probably because of shading by the large trees. Although in a low lying valley, the area under the trees was not particularly wet at the time of our visit. Lepus townsendii campanius Hollister, 1915 Specimens examined (6). — Bowman County: 8 mi. S, 26 mi. W Bowman, 2900 ft., 2; 13 mi. S, 26 mi. W Bowman, 3000 ft., 2. Mercer County: 18*/i mi. S Beulah, 1. Stark County: 2 mi. N, 1 mi. W Dickinson, 1. Populations of white-tailed Jackrabbits were low in the summer of 1965 in the vicinity of Medora and in the summer of 1970 in the vicinity of Dickinson. No specimens were taken in more than a week of field work near Medora and only three individuals were seen in the vicinity of Dickinson in more than two weeks of work. However, these jackrabbits were abundant in southwestern Bowman County in the summer of 1970; four specimens were taken in three days there and numerous others were observed in the wild and dead along roads. The species also was abundant at this time in adjacent parts of South Da¬ kota and Montana. Four specimens from southwestern Bowman County, taken in an area of sagebrush and short grasses in mid-July, included two sub¬ adult males, a nonpregnant adult female, and an adult male (testes 5.5). An adult female from Stark County, taken on 1 8 June 1 970 in an area under cultivation in which small grains were the most important crop, carried seven embryos that measured 27 in crown-rump length, five in the left horn of the uterus and two in the right. The specimen from Mercer County, an adult male, was found dead along a road. James and Seabloom (1969) extensively studied reproduction of the white-tailed jackrabbit in southwestern North Dakota. 10 OCCASIONAL PAPERS MUSEUM TEXAS TECH UN1VERS17 Y Sylvilagus audubonii baileyi (Merriam, 1897) Specimens examined (3). — Billings County: 1 mi. S Medora, 2300 ft., 1. Bowman County: 11 mi. S, 26 mi. W Bowman, 2900 ft., 1; 16 mi. S, 27 mi. W Bowman, 2900 ft., 1. We found this upland species nowhere common in southwestern North Dakota. A female from 1 mi. S Medora, shot on 29 June 1965 in an area of tall grass and sagebrush along the eastern edge of the valley of the Little Missouri River, had four placental scars. A non¬ pregnant female was taken on 19 July 1970 in a similar habitat along Box Elder Creek at a place 16 mi. S and 27 mi. W Bowman, and a juvenile male was caught by hand on 19 July 1970 at a place a few miles to the north in an area of short upland grasses and clumps of sage located in the hills above the Little Missouri River. The desert cottontail is confined in North Dakota to the extreme southwestern part (see Bailey, 1927:134). Two species of ticks {Dermacentor andersoni and Haemaphy sails leparispaliestris) were found on specimens of Sylvilagus audubonii obtained southwest of Bowman. Sylvilagus floridanus similis Nelson, 1907 Specimens examined (7). — Billings County: 1 mi. S, 1 mi. W Medora, 2300 ft., 2. Dunn County: 7 mi. N, 9 mi. W Killdeer, 2800 ft., 2; 6 mi. N, 6Y2 mi. W Killdeer, 2700 ft., 1; 5 mi. N, 6I/2 mi. W Killdeer, 3000 ft., 1. Slope County: 8 mi. N, IV2 mi. W Amidon, 1. Our specimens of S. floridanus from southwestern North Dakota came from two basic habitats. Four were collected in deciduous forests of the Killdeer Mountains and the other three are from the riparian community along the Little Missouri River. Two specimens from the Killdeers were shot at 4 pm as they fed in an alfalfa field adjacent to a dense stand of deciduous trees and shrubs. On 25 July 1970, another individual was shot in a stand of deciduous trees composed mainly of bur oak along the southeastern side of the mountains; in a similar situation, a juvenile eastern cottontail was caught in a museum special snap trap at a place 6 mi. N and 6V2 mi. W Killdeer on 23 July 1970. Along the Little Missouri River, one juvenile was trapped on 17 June 1965 and two adults were shot on 29 June 1961 and on 16 June 1965 in stands of cottonwood trees with an undergrowth of wild rose. Both adult females obtained were pregnant — one, from south of Medora, contained four embryos that measured 40 in crown-rump length on 16 June 1965 and the other, from the Killdeer Mountains, carried five embryos that measured 70 on 25 July 1970. An adult male obtained on 21 July 1970 had testes that were 30 in length. Three of GENOWAYS AND JONES^MAMMALS FROM NORTH DAKOTA 11 the four adults prepared as museum study skins were molting when taken on 29 June 1961, 21 July 1970, and 25 July 1970. Bailey (1927:134) reported S. floridanus from west of the Missouri River in North Dakota only from the immediate vicinity of the river and from Oakdale. Elsewhere in the western part of the state, he re¬ corded the presence of Sylvilagus nuttalli grangeri (from Ft. Buford, Goodall, Mikkelson, and Medora). We have re-examined the skulls of specimens assigned to 5. nuttalli by Bailey and concur that they represent that species. Seemingly, then, inasmuch as floridanus and nuttalli are thought to be allopatric, the former has replaced the latter over much, if not all, of the southwestern part of the state in recent years (specimens of nuttalli collected in 1887, 1913, and 1918). Cranially, Dakotan specimens of floridanus differ from those of nut¬ talli in being larger, having broader nasals and, therefore, a broader rostrum, postorbital processes that fuse posteriorly with the braincase, a larger and more triangular interparietal, and decidedly smaller auditory bullae and external auditory meatuses. Eutamias minimus pallidus (J. A. Allen, 1874) Specimens examined (27). — Billings County: 2 7/10 mi. W Medora, 2300 ft., 1; 1 mi. S, 1 mi. W Medora, 2300 ft., 8; Wi mi. S Medora, 2400 ft., 1. Dunn County: 8 mi. N, 7 mi. W Killdeer, 2800 ft., 1; 7 mi. N, 9 mi. W Killdeer, 2800 ft., 2; 5 mi. N, 6V2 mi. W Killdeer, 3000 ft., 1. Golden Valley County: IV2 mi. N, 8V^ mi. E Sentinel Butte, 3. Stark County: 9 mi. E Dickinson, 10. This chipmunk occurs in southwestern North Dakota mainly in badland areas and other rocky situations. Specimens were obtained in such areas as in the bluffs along the Little Missouri River south of Medora, in the riparian habitat along the bluffs near the Green River east of Dickinson, among trees and brush in a dry ravine northeast of Sentinel Butte, and in rocky outcrops in the Killdeer Mountains. Three specimens from the Killdeers were taken in areas of deciduous trees where there were numerous logs on the ground. South of Medora, three juveniles were obtained on 28 June 1965 at the opening of a hole located about 12 feet above the ground in a cottonwood tree. Evidently a litter, which consisted of at least six individuals, had been raised in the hollow. The tree was located on a brushy creek bank adjacent to a pasture and a short distance from the bluffs along the valley of the Little Missouri. None of our adult females, obtained between 17 June and 10 Au¬ gust, was pregnant, but five were lactating on the following dates: 1 7 June, 1 8 June, 28 June, 29 July, and 3 1 July. The lactating female taken on 29 July had three placental scars in the right uterine horn and one in the left. Females of the least chipmunk are thought to bear but 12 OCCASIONAL PAPERS MUSEUM TEXAS TECH UNIVERSITY one litter annually. Based on our limited data, it appears that most litters are born in late May and early June in southwestern North Dakota but that some females bear young as late as the end of June or early July. An adult male taken on 18 June had testes that were 9 in length, whereas those of one captured on 23 July measured 6. Individuals molting from one adult pelage to another were taken on 18 June, 23 July, 29 July, and 31 July. Those taken in June were beginning molt in the middorsal region just posterior to the ears, whereas those from July had nearly completed the process, molt being evident only on the rump or venter. New adult pelage is noticeably more ochraceous in comparison with the older grayish-white pelage. Specimens of a louse, Hoplopleura sciuricola, and a flea, Mono- psyllus eumolpi eumolpi, were obtained from Eutamias minimus in southwestern North Dakota. Spermophilus tridecemlineatus pallidus J. A. Allen, 1874 Specimens examined (15). — Bowman County: 11 mi. S, 26 mi. W Bowman, 2900 ft., 1. Dunn County: % mi. S, Wi mi. W Dunn Center, 1. Mercer County: 7 mi. S Beulah, 1. Stark County: 1 mi. N, 1 mi. W Dickinson, 2700 ft., 10; 1 mi. W Dickinson, 1; V2 mi. W Dickinson, 2500 ft., 1. Thirteen-lined ground squirrels are common in southwestern North Dakota in short grass situations and along roadsides that are mowed regularly. The species was especially abundant northwest of Dickinson where sandy soils and a ready food supply provided near optimum conditions. Ground squirrels in this area were feeding on seeds and young plants of corn and wheat. During the first trapping period (13 to 25 June 1970), at the Dickinson IBP site, six individuals were marked on a live-trap grid (area 1.1 hectares) and three were taken on the snap-trap grid (area 3.24 hectares); in the second trapping period seven and six were taken on these grids, respectively. However, because of the relatively high vagility and diurnal activity pattern of thirteen-lined ground squirrels, it is doubtful that the species was adequately sampled by the methods used in the IBP study. A female taken on 20 June 1970 was lactating and evinced nine placental scars. Testicular length of adult males follows (date of cap¬ ture in parentheses); 7(16 June); 8 and 12(19 June); 10 (24 June); 7 (6 August). An adult male obtained on 6 August 1970 was molting over much of the dorsum. We found specimens of Spermophilus tridecemlineatus to be par¬ asitized by a mite (Androlaelaps fahrenholzi) and two species of fleas, Opisocrostis bruneri and Thrassis bacchi bacchi. GENOWAYS AND JONES— MAMMALS FROM NORTH DAKOTA 13 Cynomys ludovicianus ludovicianus (Ord, 1815) Specimens examined (3). — Billings County: 1 mi. S, 1 mi. W Medora, 2300 ft., 3. Although this species once was abundant southwest of the Missouri River in North Dakota (Bailey, 1927:63), its numbers have been greatly reduced by the use of poisons in rodent control programs. We saw only one small prairie dog town, located in a depression between rolling hills just above the valley of the Little Missouri River, in all of our work in the area. The town covered no more than 1 5 acres and contained 50 to 75 individuals including young of the year. Two of the three specimens obtained on 29 June 1965 were lactating adult fe¬ males and the third was a juvenile male, with the third molar un¬ erupted, that weighed 383.3 grams. Sciurus carolinensis pennsylvanicus Ord, 1815 Specimen examined (1). — Dunn County: 5 mi. N, 6 Vi mi. W Killdeer, 3000 ft., 1. A gray squirrel was shot by E. J. Spicka in a stand of bur oak along the southeastern edge of the Killdeer Mountains on the morning of 24 July 1970. According to Hibbard (1956:529), 12 gray squirrels were intorduced into the Killdeer Mountains in 1951 and 1952 from stock obtained in Burlington, Wisconsin. Hibbard {op. cit., 527) also noted that 18 fox squirrels {Sciurus niger) from along the Missouri River at Bismarck were introduced into the Killdeers in 1953 and 1954. Thomomys talpoides rufescens Wied-Neuwied, 1839 Specimens examined (60). — Billings County: 1 mi. S, 1 mi. W Medora, 2300 ft., 27. Bowman County: 2 mi. S Bowman, 1; 11 mi. S, 26 mi. W Bow¬ man, 2900 ft., 4; 13 mi. S, 26 mi. W Bowman, 3000 ft., 1. Dunn County: 7 mi. N, 9 mi. W Killdeer, 2800 ft., 8. Slope County: 8 mi. N, IV2 mi. W Amidon, 1. Stark County: 1 mi. N, 1 mi. W Dickinson, 2700 ft., 3; Vi mi. W Dickinson, 2500 ft., 15. We found the northern pocket gopher to be at least locally abundant throughout much of southwestern North Dakota (see also Bailey, 1 927: 130-133). Along the Little Missouri River (south of Medora, north¬ west of Amidon, and southwest of Bowman), pocket gophers were commonest in relatively undisturbed vegetation of grasses and some sagebrush on the sandy flood plain of the river. All of our specimens from northwest of Killdeer were taken from a single alfalfa field. Those from V2 mi. W Dickinson were taken in a vacant lot that was being prepared for a housing development, whereas gophers from 14 OCCASIONAL PAPERS MUSEUM TEXAS TECH UNIVERSITY 1 mi. N and 1 mi. W Dickinson were trapped in sandy soil under native grasses. None of our adult females, taken between mid-June and the first part of August, was pregnant. Three females, however, possessed placental scars numbering five, six, and seven. Four adult males had the following testicular lengths on the dates indicated: 17 (20 June); 12, 12 (26, 27 June); 10 (22 July). The sample from south of Medora, collected between 25 and 29 June 1 965, is of interest because two size classes are easily discernable. One is composed of individuals that are 200 millimeters or less (158 is smallest) in total length that evidently were born in the spring; the other is composed of adults 210 millimeters or more in total length that most likely overwintered. Other young individuals were taken on 22 July 1970 (total length 143), 23 July 1970 (194), and 1 August 1970 (155). Our data seem to indicate that a majority of young are born in May and early June but that at least some are born as late as mid-July. Two subspecific names possibly are applicable to specimens from southwestern North Dakota — rufescens, with type locality at Fort Clark on the Missouri River in southwestern North Dakota, and bul- latus, with type locality at Powderville, Montana, approximately 50 miles south and west of the southwestern corner of North Dakota. Bailey (1915:98-99 and 1927:130-131) assigned specimens from Oakdale, Dickinson, Grafton, Glen Ullin, and along the Cannon Ball River to rufescens and specimens from Buford to bullatus, although he suggested that the latter probably occurred also along the Little Mis¬ souri River and in the Badlands. Examination of our material from southwestern North Dakota (Table 1) along with specimens of bul¬ latus from near the type locality and specimens of rufescens from eastern South Dakota reveals little significant variation among the samples. Specimens from the east are darker than those from the west, but even this differentiation is not striking and no doubt is clinal. We find no justification for recognizing two races of the northern pocket gopher in southwestern North Dakota, because individuals in samples from Medora and Bowman County are indistinguishable from speci¬ mens from Dickinson and Killdeer. The exact relationship between the nominal subspecies rufescens and bullatus needs more extensive study; if, as our results suggest, the two are indistinguishable the name rufescens would apply. Lice, Geomydoecus dakotensis and G. wardi, and a flea Foxella ignota albertensis, were obtained from specimens of the northern pocket gopher. Table 1. — Weights and selected measurements of adult Thomomys XSL\poidcs from four localities in soiithw estcni GENOWAYS AND JONES — MAMMALS FROM NORTH DAKOTA 15 Q JO Mojqjooj 'x^ui JO SjBSBU JO m^uani qipBajq pioiSBp/\i UOIPUJSUOD jBjiqjojajui qjpBSjq DnBUJoSX2 Iin^sjo qjSuai JS9P3JO JB3 JO qi3u9i looj pum JO [jBj JO qj3u9i qj3u9| \T3\o± X9S pUB j^qiunu 3o|bjbd JO SOUSfJBJS l/~. o Tf O ON O (N /“. 2;=::;+i ON >>^1 r«^ nO •'"i NO O rN (N (N 0 O r- m ^1 nD o fN q q q oon, n nO O CnI fN (N OnI m r j ^1 r^ c<-i n — ' q q r^* 00 o +1 - 00 (nr^Nor^NOr^i — in no no O +1 ONr^NOm — m,— — ’ d ON d On — d ^Csl (N — fN — ' (N j| S o G O O q q q — . ^ nO NO NO nO* n" d Oc +1 c OQ o 5j q r-' (N - On : '^qooooqqq 00 00 r' On o +1 o o o Tj-’ od On «n m r4 q q q oi in NO q q q d »n nO Tt m nJ (N (N (N •o o o "DDD q q d ON 00 no n in il- Os) CM (N q q q od r^’ od q q q Nt r*', r^i 00 — m od d ON — (N <— 00 nO nO NO nO nO s: 5 q — ; q O rn in d q (N (N (N s: a S — in (N ^ On ON od m > c3 (/5 03 3 “O T3 C <3J lii a 3 C/) 16 OCCASIONAL PAPERS MUSEUM TEXAS TECH UNIVERSITY Table 2. — Reproductive data for adult Perognathus fasciatus //"CJm southwestern North Dakota. Measurements are crown-rump for embryos and length for testes (in millimeters). Date Locality Reproductive data 16 June Medora 1 9 17 June Medora 59 Dickinson 1 9 18 June Medora 39 19 June Medora 29 Dickinson 2d 22 June Dickinson 1 9 23 June Dickinson 1 9 25 June Medora 49 27 June Medora 1 d 19 July Bowman 1 9 20 July Bowman 29 1 d 22 July Bowman 1 9 25 July Killdeer 1 d 1 August Dickinson 29 (5 embryos X 8) (no embryos), 26 (testes 7, 7) (6 placental scars) (no embryos) (no embryos), 5d (testes 4, 4, 6,1,1) (testes 7, 8) (no embryos) (no embryos) (2, 3, 6, 6 embryos X 16, 6, 5, 4) (testes 7) (7 embryos X 3) (5 embryos X 10; one no embryos) (testes 8) (7 embryos X 1 1), Id (testes 7) (testes 5) (5 embryos X 8; juvenile) Perognathus fasciatus fasciatus Wied-Neuwied, 1839 Specimens examined (38). — Billings County: 1 mi. S, 1 mi. W Medora, 2300 ft., 23; SVi mi. S, 2 mi. W Medora, 2400 ft., 1. Bowman County: 11 mi. S, 26 mi. W Bowman, 2900 ft., 4; 13 mi. S, 26 mi. W Bowman, 3000 ft., 2. Dunn County: 7 mi. N, 51/2 mi. W Killdeer, 2500 ft., 1. Stark County: 1 mi. N, 1 mi. W Dickinson, 2700 ft., 7. The olive-backed pocket mouse is a relatively common inhabitant of grassy areas throughout southwestern North Dakota. Along the Little Missouri River south of Medora in June 1965, this species was particularly abundant in sandy areas on the flood plain of the river; 23 individuals were taken there in eight nights of trapping. On the 3.24-hectare snap-trap grid at the Dickinson IBP site, four P. fasciatus were obtained in the period 16 to 25 June 1970, yielding a population estimate of 1.23 individuals per hectare in relatively dry, moderately- grazed upland grasslands. On the nearby, but much smaller (1.1 hec¬ tare) and ungrazed, live-trap grid, two individuals were taken between 13 and 23 June 1970 giving an estimate of 1.81 individuals per hectare. Notes on reproduction and food habits of Perognathus fasciatus from the vicinity of Medora were presented earlier by Turner and Bowles (1967:266-267). Their reproductive data and more recently acquired information are combined in Table 2. CiENOWAYS AND JONES— MAMMALS FROM NORTH DAKOTA 17 Q >3 <4; >■ O C/3 3 4— » 'o c/3 ciS c/3 3 ^4— » cj C (30 o u (U a. ■T3 CT) <4/ •2 (-> 1- r*', LU _l cc ■<. LUniUBJD jo qjdaa Mojqjooi •XBui JO m3u9T qjpBSjq pjojSBp/\i U0UDIJ1SU03 I^jjqjoj9jui Iin^sjo qj§U9| JS9JB9JO jqgi9/W JB9 JO qjSuaq JOOJ puiq JO qjSu9T jiBj JO qi§U9i qj9u9i |t?jox X9S pUH jaqiunu go|BjBD JO SD|}SUBJS • 0 ^ 00 (N 00 00* od c5 +1 ON q q rj q m rj r«N O +1 On O od 00* od o +1 0^0 m od rj • • • r/^ < 03 tu ^52 •o >/^i »o NO /^< (N :2 V N (N o s: (N On) (N +1 2 (N ». (3 r /n m o q q q q q q q o On NO oi 4— r-’ od ON d >o lo NO +1 NO «/n NO +1 ir-, NO m m o ON >/"i NO T3 0/ o3 O c c x: *a (U 00 03 (U > o3 t/D 03 3 T) ■o C (U cie (U •4— > 03 o ■5 c (/) u. (U X) E 3 C O c/3 u -t-j a> H c/5 (U < - 0) o ID OX) c 03 0^ (U ^ OX) o 03 >' t- < c/5 (U ■I— < 03 Q in rx rx (N I Os O X> in I Os I Os in Os oo od (N m m m ON I (N OO in in rx '4 ON rx NO in r-- I m in nx nx 00 m NO 00 (N I m od m NO ON in CA > OX) 1 c 1 c 3