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OCCASIONAL PAPERS JUL ® 1974

HARVARD

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The University of Kansas Lawrence, Kansas

NUMBER 25, PAGES 1-39 JUNE 17, 1974

THE MAMMALS OF CARTER COUNTY, SOUTHEASTERN MONTANA

By

Richard P. Lampe,^ J. Knox Jones Jr.," Robert S. Hoffmann,^ and Elmer C. Birney^

This report treats the more than 50 species of mammals occurring in a segment of the Northern Great Plains defined by the political boundaries of Carter County, Montana, the southeasternmost county in the state. The mammalian fauna of this area has, until now, been relatively poorly documented.

Carter County (Fig. 1), organized in 1917 and named after Thomas Henry Carter, Montana's fii^st Congressional representative, has an area of approximately 3300 square miles and slopes north- eastward on the average at 10 feet to the mile (Bauer, 1924:233). The county is characterized by gently rolling hills, extensive flats, steep ridges, and occasional "badlands." The Boxelder Creek Valley drains northeastward through the center of the county. This valley varies in elevation from 3200 to 3500 feet above sea level and gener- ally is featureless except for the intermittent tributaries of Boxelder Creek that flow either northwestward or southeastward. The north- ern portion of the valley, referred to as Alkali Flats, is bordered by

^ Bell Museum of Natural History, University of Minnesota, Minneapolis, 55455. Tliis paper is based in part on research accomplished wliile the senior author was a graduate student at the Museum of Natmal History and Depart- ment of Systematics and Ecology, The University of Kansas.

^ Associate Vice President for Research and Dean of the Graduate School, Texas Tech University, Lubbock, 79409

^ Curator of Mammals, and Professor of Systematics and Ecology, Museum of Natural History, The University of Kansas, Lawrence, 66045

* Curator of Mammals, Bell Museum of Natural History, University of Minnesota, Minneapolis, 55455

OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY

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Fig. 1. Map of Carter County, Montana, showing location of place-names mentioned in text. Camp Crook, Harding Co., South Dakota, is located at the black dot on the right-hand margin of the map.

THE MAMMALS OF CARTER COUNTY. MONTANA 3

three disjunct pine-clad ridges, Chalk Buttes to the west ( maximum elevation, 4215), Ekalaka Hills to the north (maximum elevation, 4115), and Long Pine Hills to the east (maximum elevation, 4130). The Long Pine Hills and Ekalaka Hills are separated by Boxelder Creek, whereas the latter and Chalk Buttes are separated by a small valley drained by the intermittent Little Beaver Creek. Little Beaver and Boxelder creeks are tributaries of the Little Missouri River, which traverses the southeastern corner of the county. The extreme western part of the county lies in the Powder River drainage.

Largest of the three pine-clad ridges are the L-shaped Long Pine Hills, which extend north and south for approximately 18 miles with an east- west base of 11 miles. Lillegraven (1970:832) de- scribed the Long Pine Hills as part of a s\'stem of ". . . Tertiary erosional remnants standing above the Late Cretaceous rocks of northwestern South Dakota, southwestern North Dakota, and south- eastern Montana." The southern and western sides of these ridges tend to have more cliffs and support less vegetation than do the eastern and northern slopes, which slope gradually onto the plains (Bauer, 1924:233; Lillegraven, 1970:832). Landslides of Tertiary rocks in the Long Pine Hills and Finger Buttes have been part of the erosional sequence of the area (Gill, 1962:731).

South of Boxelder Creek Valley, the roHing landscape is broken by numerous, sparsely vegetated buttes. Formations such as Chim- ney Butte, Sheep Mountains, and Finger Buttes extend as a chain southwestvvard from the Long Pine Hills, forming the divide be- tween the drainages of Boxelder Creek and the Little Missouri River.

Soils of Carter County are of four t\'pes (Kellogg, 1938). Chest- nut soils of the Williams-Morton-Bainville series have developed over glacial tills, sandstone, and shale and are found in the northern and southwestern parts of the county. In the extreme northwestern corner, brown soils have developed over shale and sandstone. Litho- sols of the Pierre type, with parent material of Cretaceous shale, occur in southeastern Carter Count}'. The rough, eroded areas or "badlands" of the north-central part of the county have developed over clay and shale of Tertiary formation. Banks and washes of the many dry stream beds found throughout the count\' are sandy. Underhing or partial!)' exposed sedimentary rocks of Cretaceous deposits include Benton (shale), Niobrara (shale), Pierre (shale), and Fox Hill (sandstone). Tertiary deposits include the Ludlow and Hell Creek members of the Lance formation, the Tongue River member of the Fort Union formation, the White River formation, and the Arikaree fomiation ( Bauer, 1924; for additional information on geologic formations see also Alden, 1932, and Perry, 1962 ) .

Much of Carter County is covered by mixed-grass prairie, com- plemented by pine-clad ridges and sagebrush flats. Part of the SioiLX Division of Custer National Forest, the Chalk Buttes, Ekalaka Hills

4 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY

(known also as the Ekalaka Forest), and Long Pine Hills support predominantly ponderosa pine (Pinus ponclerosa). Mature stands of this pine are relatively open; they usually are restricted to ridges and slopes, only seldom extending onto the grassy lower valleys that dissect the ridge formations. Northern and eastern slopes generally support denser stands than do southern and western slopes, which tend to be steeper and have more cliffs. Sawlog and pole stands generally accommodate an undcrstory of mixed grasses, forbs, and woody shrubs, whereas stands of saplings have a poorly developed understory in response to the greater density of young trees and consequent minimal sunlight penetration. Park-like stands of pine commonly occur on lower slopes and subordinate ridges along with snowberry (Symphoricarpos racemostis), various grasses, shrubs, and forbs. Juniper (Juniperus scopulonim) occurs irregularly and small stands of aspen (Popiilus tremiiloides) occupy some slopes.

Thickets of common snowberry, fleshy hawthorne {Crataegus sp. ), wild plum (Priinus sp. ), chokecherry (P. melanocarpa), buf- falo-berry (Shepherd ia sp.), gooseberry and currant (Rihes sp. ), serviceberry (Amelanchier alnifolia), and rose (Rosa sp.) occupy some of the wetter ravines. Boxelder (Acer negundo), green ash (Fraxiniis pennsylvanica), and some ponderosa pine are found in the drainageways leading from the ridges. The grassland drainages sup- port discontinuous stands of deciduous trees — mainly cottonwood (Popidus sargentii), willow ( Salix sp. ) , boxelder, and green ash — characterized as the Northern Floodplain Forest (Kiichler, 1964); the Little Missouri River is lined with a heavier growth of riparian forest than that found along smaller streams throughout the county.

Grasslands of the county are of the wheatgrass-needle grass com- munity (Kiichler, 1964) with dominants of western wheatgrass (Agropyron smithii), blue grama (Bouteloua gracilis), needle-and- thread grass (Stipa comata), and green needle-grass (Stipa viridula). Grasslands occupying the valleys and meadows of the Long Pine Hills are characterized as a sedge-blue grama-bluestem-wheatgrass community (Jonas, 1966:7) but ". . . under more favorable condi- tions needle-and-thread grass would possibly replace wheatgrass in importance." Flats in the northern and central areas of the county are commonly vegetated by fringed sagebrush (Artemisia frigida), big sagebrush (A. tridentata), and silver sagebrush (A. cana), with an understory of short grasses and prickly pear (Opuntia humifusa).

Carter County has a semiarid continental climate (Table 1) that is shielded from the northward flow of precipitation-laden air by the Black Hills. Slightly more than half of the mean annual precipi- tation falls in May, June, and July. Seasonal fluctuation in temper- ature is great and fluctuations are common from day to day. The contrast between summer and winter temperatures is exemplified by an average of 34 days with a maximum temperature above 90° F and

THE MAMMALS OF CARTER COUNTY, MONTANA 5

Table 1. Climatological data from Ekakka, Montana (1931-1952), and Camp Crook, South Dakota (1896-1967). Temperature is recorded in degrees Fahr- enheit and precipitation is measured in inches.

	Ekalaka,	Montana	Camp Crook, South Dakota
Temperature
Mean annual	44.1		43.8
Mean January	17.6		17.3
Mean July	71.8		71.2
Record high	108		114
Record low	-43		-57
Precipitation
Mean annual	13.27		13.71
Record maximum	21.97 (1963)	24.07 (1927)
Record minimum	6.35(1936)	4.73(1936)
Mean annual snowfall	22.3		33.2

an average of 33 days with a minimum temperature below zero. During winter, prevailing northwest winds often accompany snow storms, creating drifts in protected areas and leaving open fields bare. It is noteworthy that weather- conditions in July, 1972, were unseasonably cold and wet, including temperatures below 32°F and freezing rains.

Our interest in the mammals of Carter County stemmed from studies by one of us (Jones) conducted in Harding County, South Dakota, during the 1960's as well as pre\ ions work in Montana by Hoffmann. Kenneth Andersen visited the Long Pine Hills briefly in May of 1968 and obtaincxl a small collection of mammals. Subse- quently, in the period 29 June to 24 July 1970, a field party from The University of Kansas made extensive collections from the Long Pine Hills and other localities in northern and eastern Carter Count)^ and Jaime Pefaur, a graduate student at The University of Kansas, studied populations of small mammals on a north-facing slope at the eastern edge of the Long Pine Hills until mid-August of the same year. Birney and Lampe collected mammals for the Uni- versity of Minnesota in the Long Pine Hills, Ekalaka Hills, and Chalk Buttes in July 1971. Merlin Tuttle and Larry Heaney made additional collections for Minnesota in Carter County in July 1972.

Early reference to the mammals of Carter Count}' was made by Captain W. F. Reynolds (1S6(S) during his brief passage through the area in 1859. Subsequent military explorations in this area, such as General George Custer's expedition to the Black Hills in 1874, were concerned primarily with matters other than faunal observa- tions (see also Turner, 1974). E. A. Preble, in an undated manu- script, probably written about 1910, listed mammals from eastern Montana and briefl\- connnented on the habitat preference and abundance of 57 species. Other references in the literature to mam- mals of Carter County are those of Visher (1914), Couey (1946),

6 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY

Tryon (1947), Hoffmann et ah (1969a,b), Andersen and Jones (1971), Pefauer and Hoffmann (1971), and Jones et al. (1973). Several specimens from Carter County liave been incorporated in revisionary studies sucli as tliose by Nelson (1909), Bailey (1915), Hollister (1916), Jackson (1928), Howell (1929, 1938), and Gold- man (1944).

Acknowledgments

We acknowledge the field assistance of the students who were enrolled in the Field Course in Vertebrate Zoology at The University of Kansas in the summer of 1970 as well as the members of several other field parties from Kansas who visited Carter Count)' periodi- cally. Merlin D. Tuttle and Lawrence R. Heaney collected mam- mals in Carter County for the University of Minnesota for 10 days in July of 1972. The summer field course was financed in part by grant GZ-1512 from the National Science Foundation. Minnesota field parties in both 1971 and 1972 were supported by grants to Birney from the Graduate School, University of Minnesota and from the Grassland Biome Section of the International Biological Program (NSF Grant GB-13096).

We especially thank District Rangers T. S. Burns and Richard McElfresh and their staff for assistance and sincere interest in our study. We also wish to acknowledge the cooperation and hospitality shown our field parties by various U.S. Forest Service personnel (Sioux Division, Custer National Forest) and numerous residents of Carter County, Montana, and Harding County, South Dakota. Identifications of ectoparasites were provided by Drs. Eleanor K. Jones (ticks), J. M. Kinsella (fleas), Richard B. Loomis (chiggers), and Nixon Wilson ( mites ) .

ACCOUNTS OF SPECIES

The following accounts treat the 53 species of mammals pres- ently on record from Carter County, Montana. Additionally, com- ments on 15 species of unverified occurrence are appended. Speci- mens examined (a total of 488) are listed in telegraphic style and are ordered first from north to south and, secondarily, from west to east. All specimens examined are deposited in the Museum of Natural History at The University of Kansas or in the Bell Museum of Natural History at the University' of Minnesota (noted as MMNH). All measurements used are in millimeters (lengths of embryos are for crown-rump) and weights are expressed in grams. In certain cases, measurements are given as means, with extremes in parentheses.

THE MAMMALS OF CARTER COUNTY, MONTANA 7

Order Insectr'ora

Sorex cinereus haydeni Baird, 1858

Masked Shrew

Specimens examined (26). — 3 mi S, 1.75 mi E Ekalaka, 6 (MMNH); 5.5 mi N, 10 mi W Camp Crook, 3500 ft, 20 (17 MMNH).

The masked shrew evidently is a common inhabitant of pro- tected, mesic habitats in the pine-covered portions of tlie study area. Only three specimens, all adults, were captured during approxi- mately four weeks of intensive trapping in summer of 1970. Most trapping efforts were with break-back traps, although buried can traps were tried unsuccessfully in several areas in the Long Pine Hills that seemed suitable for shrews. Three additional specimens, two adult females and a shrew of unknown sex, were captured in 1971 in break-back traps in the mesic draw at Lantis Spring and in lush vegetation around a nearby bea\'er pond fed by the spring, the site of capture of two males in 1970. The third specimen from 1970, a female, was taken above the draw on snowbrush-covered ground near a clearing.

On 10 July 1972, five can-traps were set near water at Lantis Spring. Four of these contained masked shrews the following morn- ing. Eleven more can-traps and 75 Museum Specials then were set in mesic habitat along the spring and near the beaver pond. No shrews were captured in the Museum Specials, but six more were taken from the cans. Even after an additional 50 Museum Specials, baited with a mixture of rolled oats and peanut butter, were set near the spring, all four shrews subsequently captured were taken from the 16 buried cans. A few days later, two Sorex were among the animals taken from 202 Museum Specials set in tall grass and reeds near a marsh in the Ekalaka Hills. Seventeen can-traps set near the marsh yielded four additional masked shrews.

Brown (1967) and Spencer and Pettus (1966) demonstrated the efficiency of can-trapping for shrews. Our studies indicate that the masked shrew is not uncommon in Carter Countv'. Instead, it seems to be common in isolated or semi-isolated populations associated with permanent sources of water and relatively undisturbed habi- tats. Genoways and Jones (1972:5) trapped Sorex cinereus at seven localities in southwestern North Dakota, but Andersen and Jones (1971:388) did not report shrews from adjacent Harding County, South Dakota, although can-traps were not employed there. Three specimens from 5 mi SE Ekalaka were recorded by Jackson (1928: 53), and were probably those mentioned by Preble (MS) from the Sioux National Forest, near Ekalaka.

Testes of 12 males taken in mid-July 1972 were 4 mm in mean length. One of eight females collected at that time carried four embryos, each 12 mm in length; another had placental scars but apparently had completed lactation.

8 OCCASION.\L PAPERS MUSEUM OF NATURAL HISTORY

Sorex merriami leucogenys Osgood, 1909

Merriam Shrew

Specimen examined ( 1 ). — 5 nii N, 3.5 nii W Camp Crook, 3400 ft, 1.

Our specimen of Merriam's shrew, the fifth to be recorded from Montana (Pefaur and Hoffmann, 1971:247), was trapped on 22 July on a nortli-facing grassy slope at the eastern edge of the Long Pines. An adult male with enlarged flank glands and testes 5 mm in length, it had the following selected external and cranial measurements: total length, 101 mm; tail length, 39 mm; hind foot length, 11 mm; weight, 4.8 gms; condylobasal length, 16.5 mm; palatal length, 7.2 mm; cranial breadth, 8.3 mm; least interorbital breadth, 3.7 mm; maxillary breadth, 5.2 mm; maxillaiy toothrow length, 6.2 mm. Owing to the large size of this shrew, especially apparent in the cranial dimensions, we assign it to the subspecies leucogenys (see Long, 1965, and Hooper, 1944, for representative measurements of S. 772. leucogenys and S. m. merriami), even though the type locality of S. m. 7nerriot7ii lies only approximately 150 miles to the west.

Order Chiroptera

Seven species of bats were collected in Carter County in 1970. Collections were made principally in the Long Pine Hills, but a few bats were obtained in adjacent areas and at Medicine Rocks. Speci- mens obtained during that summer were reported by Jones et al. (1973) together with comments on habitat, reproduction, molt, ac- tivity, dietary habits, and ectoparasites of these seven bats. Included in the present accounts arc specimens obtained in the Long Pine Hills, Ekalaka Hills, and Chalk Buttes in 1971 and 1972. One spe- cies, Plecotus townsenclii, was not captured in Carter County until July 1972 and thus was not treated by Jones et al. ( 1973 ) .

Myotis evotis evotis (H. Allen, 1864)

Long-eared Myotis

Specimens examined (7). — 4 mi S, 1 mi E Ekalaka, 4 (MMNH); 5.5 mi S, 1 mi E Ekalaka, 1 (MMNH); 7 mi N, 10 mi W Camp Crook, 3800 ft, 2 (MMNH).

All Specimens are adults, and were netted over reservoirs in the Long Pine Hills and the Chalk Buttes and in a campground clearing in the Ekalaka Hills. At Stagville Spring, 4 mi S and 1 mi E Eka- laka, 11 long-eared myotis were collected over a spring-fed watering tank located in a brush-lined ravine. Seven of these were banded and released. Three of four banded females were lactating; the three males gave no external evidence of reproductive activity.

Four adult males taken in mid-July had testes that were 3, 3, 4, and 5 mm in length, and three were in the process of seasonal molt.

THE MAMMALS OF CARTER COUNTY, MONTANA 9

Myotis leibii ciliolabrum (Merriam, 1886)

Small-footed Myotis

Specimen examined (1). — 4 mi S, 1 mi E Ekalaka, 1 (MMNH).

A lactating female in the process of seasonal molt was netted 18 July above a livestock tank in the Ekalaka Hills. This specimen is the only small-footed myotis known from the county outside of the Long Pine Hills, where six were obtained in 1970 (Jones et ah, 1973).

Myotis lucifugus carissima Thomas, 1904

Little Brown Myotis

No specimens of the little brown myotis were captured in 1971 or 1972. Jones et al. (1973) reported 12 individuals that had been netted or shot over water in the Long Pines in 1970.

Myotis volans interior Miller, 1914 Long-legged Myotis

Specimens examined (7). — 4 mi S, 1 mi E Ekalaka, 2 (MMNH); 5.5 mi S, 1 mi E Ekalaka, 3 (MMNH); 7 mi N, 10 mi W Camp Crook, 2 (MMNH).

We found the long-legged myotis to be common in most areas of buttes and ridges in Carter Countv' although none was taken in the Chalk Ikittes. All specimens collected in mid-July are adults. One female was lactating and two males had testes that were 3 and 4 mm in length. Se\en adults were netted over a lixestock tank near Stag- ville Spring in the Ekalaka Hills on 17 Juh' 1971; of five subsetjuently banded and released, two were reproductively active females, one lactating and the other pregnant.

Lasionycteris noctivagans (Le Conte, 1831)

Silver-haired Bat

Although found to be common in the Long Pine Hills in 1970 (Jones et al, 1973), only a single silver-haired bat was captured in the subsequent two summers. This specimen, an adult male netted over a beaver pond at Slick Creek Spring, 7 mi N, 10 mi W Camp Crook, was banded and released.

Eptesicus fuscus pallidas Young, 1908

Big Brown Bat

Specimens examined (4). — 11 mi S, 7.5 mi W Ekalaka, 1 (MMNH); 7 mi N, 10 mi W Camp Crook, 3800 ft, 3 (MMNH).

Two adult male big brown bats were banded and released at the locality (Slick Creek Spring) listed above, and an additional two adult females and one adult male were preserved. An adult male (testes 8 mm in length) was netted ()\'er a small reservoir in the Chalk Buttes in 1971. We failed to capture this species in south- eastern Montana in 1972.

10 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY

Lasiurus cinereus cinereus (Palisot de Beavois, 1796)

Hoary Bat

Specimens examined (6). — 4 mi S, 1 nii E Ekalaka, 1 (MMNH); 11 mi S, 7.5 mi W Ekalaka, 2 (MMNH); 7 mi N, 10 mi W Camp Crook, 3800 ft, 3 (MMNH).

Volant juvenile hoary bats were netted in mid-July in both 1971 and 1972. Two adults, a lactating female and a male, also were cap- tured. Testes of the male were 8 mm in length on 13 July. One juvenile female was banded and released in the Long Pines in 1971.

Plecotus townsendii pallescens (Miller, 1897)

Townsend's Big-eared Bat

Specimen examined (1). — 7 mi N, 10 mi W Camp Crook, 1 (MMNH).

A reproductively inactive, adult female Plecotus was captured in a mist net stretched over a beaver pond in the Long Pine Hills on 12 July 1972. Preble ( MS ) reported the species from adjacent Powder River County and Hoffmann et ah (1969b: 741) considered it wide- spread in Montana. Andersen and Jones (1971:372) considered big- eared bats uncommon in Harding County, South Dakota. The ab- sence of this bat in our 1970 collections (Lampe, 1971; Jones et al., 1973) and in 1971 and the paucity of specimens from adjacent areas attest to the apparent rarity of the species in this portion of its range.

Order Lagomorpha

Lepus townsendii campanius Hollister, 1915

White-tailed Jackrabbit

Specimens examined (9). — 12 mi E Ekalaka, 3200 ft, 1; 6.5 mi N, 5.5 mi W Camp Crook, 3400 ft, 1; 5.5 mi N, 3 mi W Camp Crook, 1; 2 mi N, 14 mi W Camp Crook, 1; 2 mi N, 4.5 mi W Camp Crook, 3700 ft, 1; 2.5 mi S, 3 mi W Camp Crook, 3200 ft, 1; 5.5 mi S, 3.5 mi W Camp Crook, 1; 6 mi S, 3 mi W Camp Crook, 3200 ft, 1; 12 mi S, 4 mi W Camp Crook, 1.

White-tailed jackrabbits are common in the grasslands of Carter County, particularly in the meadows and broad valleys within the Long Pine Hills. All of our specimens were collected in 1970 from along roads or roadside ditches.

An adult female taken on 3 July carried tlii'ee embryos, each of which was 48 mm in length. Another examined on 7 July was lac- tating; both females were actively molting. Three subadult males collected in early and mid- July had testes that were 24, 18, and 15 mm in length, whereas an adult male obtained on 5 July had testes 55 mm long. One jackrabbit was parasitized by ticks, Dennacentor andersoni.

Sylvilagus audubonii baileyi (Merriam, 1897) Desert Cottontail Specimens examined (2). — 17 mi E Ekalaka, 3200 ft, 2. This cottontail was seen on sagebrush flats and in grasslands as

THE MAMMALS OF CARTER COUNTY, MONTANA 11

well as on the pine-covered ridges of the Long Pine Hills. Two S. aiidtibonii were obtained from a small formation in the "badlands" north of the Long Pines. Preble (MS) listed specimens from the "head of Boxelder Creek," no doubt the same individuals reported by Nelson (1909:234) as simply from "Boxelder Creek." Addition- ally, Andersen and Jones (1971:373) reported a specimen obtained on a sparsely covered pine ridge at the extreme eastern edge of the Long Pines in Harding County, South Dakota.

A subadult male examined on 8 July had testes 14 mm in length. An adult female shot on 9 July was actively molting and carried six embryos ( three in each uterine horn ) in addition to a seventh in the right uterine horn that, in light of its smaller size (9 mm in length as compared to 14 mm for the others), was apparently being re- sorbed.

Sylvilagus floridanus similis Nelson, 1907 Eastern Cottontail

Specimem examined (4). — 5.5 mi N, 10 mi W Camp Cronk, 1 (MMNH); 2 mi N, 4.5 mi W Camp Crook, 3700 ft, 1; 8 mi S, 3 mi W Camp Crook, 3200 ft, 2.

The eastern cottontail occurs in Montana only in Carter County, where it is restricted to riparian habitats. One specimen was shot along a small spring-fed stream at the southeastern edge of the Long Pine Hills and a juvenile was trapped in a thicket on high ground at Lantis Spring; the other two \\'ere collected in dense, woody vege- tation along the Litde Missouri River. Hall and Kelson (1951:52) reported specimens of S. /. similis from Boxelder Creek (25 mi SW Sykes— Hall, 1951:159), Capitol, and the Little Missouri River (7 mi NE Albion — Hall, loc. cit. ) in southern Carter Count}-.

It is of interest that our four specimens and those cited by Hall and Kelson (loc. cit.) all were collected in the eastern third of Carter County. The apparent absence of S. floridanus in western Carter County may be of importance with respect to the distribution of S. nutiaUii, which evidently has been displaced by S. -floridanus in ad- jacent states (Genoways and Jones, 1972:11; Turner, 1974:61).

A female taken on 30 June carried six embryos. Two males shot in early July had testes 40 and 55 mm in length. These three speci- mens, all adults, were actively molting from winter to summer pelage.

Order Rodentia

Eutamias minimus pallidas (J. A. Allen, 1874)

Least Chipmunk

Specimens examined (15). — 17 mi E Ekalaka, 3200 ft, 1; 4 mi S, 1 mi E Ekalaka, 2 (MMNH); 4.5 mi S, 1 mi E Ekalaka, 2 (MMNH); 4 mi N, 8 mi W Camp Crook, 3650 ft, 4; 4 mi N, 7.5 mi W Camp Crook, 3800 ft, 1; 2 mi N, 4.5 mi W Camp Crook, 3700 ft, 3; 1.5 mi N, 5 mi W Camp Crook, 4100 ft, 2.

12 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY

Chipmunks are common in the pine-covered hills of southeastern Montana. Specimens were obtained from ridges and roadsides where fallen logs and rocks provided suitable cover. Two adult males were collected at Capitol Rock, a large butte along the south- em edge of the Long Pine Hills, 1.5 mi N and 5 mi W Camp Crook, that is characterized by gullies, steep and eroded slopes, and pale- colored soils. An adult male obtained from a similar, but smaller area of "badlands" isolated in the grasslands of northeastern Carter County, 17 mi E Ekalaka, was markedly grayer than specimens col- lected in the Long Pines and Ekalaka Hills. This animal was actively molting on 8 July. A chipmunk was observed running over a bare, vertical cliff-facing at the crest of Trenk Pass, 11 mi S, 6.5 mi W Ekalaka, in July 1971, but no specimens were collected in the Chalk Buttes.

An adult female obtained in late June and one taken in July were lactating and still retained winter pelage. Eleven subadults taken in July were molting. A young individual, one of four obtained on 25 July from 4 mi N and 8 mi W Camp Crook, had a scar, no doubt caused by a cuterebrid larva, on the right shoulder.

Preble (MS) mentioned specimens from the Sioux National For- est and Alzada and commented tliat chipmunks inhabited "indiffer- ently the evergreen forests, bushy canyons, and even sections almost without forest cover. ..." Howell (1929:44) reported specimens from Alzada, Ekalaka, 8 mi E Svkes, and 5 mi E Svkes.

Spermophilus tridecemlineatus pallidus J. A. Allen, 1874

Thirteen-lined Ground Squirrel

Specimens examined (33). — 11.5 mi N, 3 mi E Ekalaka, 5; 16 mi E Eka- laka, 2; 1 mi S, 1 mi W Ekalaka, 1 (MMNH); 3.5 mi S, .25 mi W Ekalaka, 2 (MMNH); 3.75 mi S, 2.25 mi W Ekalaka, 3 (MMNH); 4 mi S, 1.5 mi W Ekalaka, 1 (MMNH); 5 mi N, 3.5 mi W Camp Crook, 3400 ft, 18; 6 mi S, 4.5 mi W Camp Crook, 3200 ft, 1 .

This ground squirrel is common in short grass and sagebrush throughout the area of study. Juveniles represented more than half of the total number of specimens obtained. Eight of eleven speci- mens collected in an upland meadow along the eastern edge of the Long Pine Hills during the period 8 to 13 July were ju\'eniles, and only one of seven individuals from southwest of Ekalaka was adult.

Preble (MS) commented on the destruction of crops caused by thirteen-lined ground squirrels, "especially in the southeastern part of the state." Howell (1938:114) reported specimens from Albion, Capitol, and Medicine Rocks.

An adult female taken on 14 July had seven placental scars and eight corpora albicantia. The testes of eight adult males obtained in mid-July had a mean length of 5.8 mm; those of eight juNcniles collected on comparable dates averaged 4.9.

THE MAMMALS OF CARTER COUNTY, MONTANA 13

Fleas, Thrassis sp., and ticks, Ixodes sculptus, were found on these thirteen-lined ground squirrels.

Cynomys ludovicianus ludovicianus (Ord, 1815) Black-tailed Prairie Dog

Specimens examined (4). — 5 mi N, 6 mi E Ekalaka, 3400 ft, 3; 1 mi S, 13 mi E Ekalaka, 3200 ft, 1.

Once a common inhabitant of grasslands throughout Carter County, the prairie dog was found in areas overgrazed by herds of bison and other ungulates. With the decline of native herbivore populations, the prairie dog became associated with domestic live- stock, often becoming a "pest," particularly in areas overgrazed by cattle and sheep. Visher (1914:89) reported the existence of large "towns" in Harding County, South Dakota, in the early 1900's, one of which covered "several sections . . . west of the Little Missouri River." Such colonies most likely occm-red also in Carter County. Rather than directly treating the cause of poor range condition, rodent control campaigns tended to treat only symptoms — that is, large populations of prairie dogs. The cflBciency of programs de- signed to eradicate this sciurid is attested to by the fact that Cyno- mys now occurs only in relatively small, disjunct populations in Carter County and adjacent regions.

Three prairie dogs were shot in mid-day from a colony of approx- imately 200 individuals northeast of Ekalaka. The colony was lo- cated on flat ground covered with sagebrush (Artemesia tridentata), below the dam of a farm pond. Another specimen was obtained from a half-grown badger tliat was observed crossing a road with a prairie dog in its mouth. As members of our field party approached the badger, it dropped the prey and took shelter in a nearby burrow.

Hollister (1916:14) reported a specimen from Boxelder Creek and Andersen and Jones (1971:375) noted two specimens from the grasslands of northwestern Harding County, South Dakota, border- ing the eastern Long Pine Hills.

An adult female taken on 14 July contained eight placental scars and eight corpora albicantia. Two males, an adult and subadult, collected on 14 July both had testes 8 mm in length. Fleas, Opiso- crostis hirsuttis, and ticks, Ixodes kinp^i, were found on one of three individuals collected nortlieast of Ekalaka.

Sciurus niger rufiventer E. Geoftroy St.-Hilaire, 1803

Fox Squirrel

Specimens examined (2). — Sec. 16, T 5 S, R 62 E, 2.

Although fox squirrels are known to occur in the riparian cotton- wood forests of the Yellowstone and Big Horn rivers in central Mon- tana (Hoffmann et ah, 1969a: 589), their presence in southeastern Montana has not been documented previously. Hibbard (1956:525)

14 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY

discussed the westward spread of fox squirrels in North Dakota along the Missouri and James rivers as well as their wooded tribu- taries in the south-central part of that state. Our specimens verify the occurrence of fox squirrels in the Little Missouri drainage. Be- cause we know of no introductions of this species in tliis area of Montana, our records probably indicate a southward migration from the valley of the Missouri River.

Both specimens are adult males in winter pelage, collected along the Little Missouri River in east-central Carter County on 14 Jan- uary 1971 by John Teigen, Jr. In this area, the banks and flood plain of the Little Missouri support riparian stands of boxelder, green ash, plains Cottonwood, and willows.

Selected external and cranial measurements of our specimens are: total length, 490, 488 mm; tail length, 212, 208 mm; hind foot length, 68, 68 mm; ear length, 28, 28 mm; weight, 645, 623 gms; condylobasal length, 56.8, 58.8 mm; palatal length, 32.1, 32.5 mm; zygomatic breadth, 35.2, 35.2 mm; mastoid breadth, 27.6, 27.2 mm; postorbital breadth, 19.2, 19.1 mm; maxillary toothrow length, 11.4, 11.5 mm; testes length, 23, 25 mm.

Tamiasciurus hudsonicus dakotensis (J. A. Allen, 1894)

Red Squirrel

Specimens examined (14). — 5.5 mi S, 1 mi E Ekalaka, 2 (MMNH); 7 mi N, 10 mi W Camp Crook, 3800 ft, 1; 6 mi N, 10 mi W Camp Crook, 1 (MMNH); 5.5 mi N, 10 mi W Camp Crook, 2 (MMNH); 4 mi N, 9 mi W Camp Crook, 3950 ft, 5; 3.75 mi N, 7.75 mi W Camp Crook, 2 (MMNH); sec. 1, T3S, R61E, 1.

Red squirrels were collected in moderately dense stands of pon- derosa pine. Two were taken in the Ekalaka Hills in 1972 and others were collected in the central part of the Long Pine Hills in all three years of field work. Red squirrel "sign" was noted by Lampe and Birney in the Chalk Buttes, but no individuals were seen. Five squirrels were obtained in 1970 from an immature pine stand of 10 to 15 acres located on a gentle westward-facing slope marked by small ravines. Additional areas were hunted thoroughly, but only two other specimens were taken; a third was sighted 6 mi N and 10 iTii W Camp Crook. Three individuals were feeding on ponderosa pine cones when shot, but no indication of regular feeding stations was observed in 1970.

Tliree red squirrels were shot and numerous others were seen during a two-day visit to the central Long Pine Hills in 1971. A midden with a surface area of approximately 60 square feet was found on a small north-facing slope at a place 8.5 mi N and 11 mi W Camp Crook. The midden was extremely moist as a result of its proximity to a nearby spring. Smaller caches and middens were seen elsewhere in the Long Pines around fallen and hollow trees.

THE MAMMALS OF CARTER COUNTY, MONTANA 15

The scarcity of caches on the forest floor in stands of ponderosa pine was discussed by Finley (1969:238). The dryness of sites oc- cupied by this pine, the increased circulation of air and penetration of sunlight caused by the lack of lower limbs, and the open nature of stands create conditions unsuitable for the storage of cones. Caches seen in the Long Pines were associated with mesic or shel- tered conditions, whereas those observed in the Chalk Buttes were small, shallow subterranean chambers. The marked \'ariability in cone production of ponderosa pine (Finley, 1969:261) may account for much of the variation in red squirrel population density noted in the three years of our study.

Preble (MS) mentioned that red squirrels were fairly common near Ekalaka and east of Sykes and that specimens from these places appeared to be typical T. h. dakotensis. Visher ( 1914:88) reported a specimen shot in the Long Pines in July of 1910, and Miller and Kellogg (1955:263) included southeastern Montana in the range of dakotensis. Andersen and Jones (1971:375) commented that speci- mens from the Long Pine Hills were clearh' assignable to dakotensis on the basis of color (see also Hoffmann and Jones, 1970:374, fig. 7; and Turner, 1974:80).

Average (and extreme) external and cranial measurements of 12 adults (five females, seven males) are: total length, 343.4 (322-365) mm; tail length, 133.9 (115-144) mm; hind foot length, 53.9 (50-58) mm; ear length, 28.0 (25-30) mm; condylobasal length (four fe- males, seven males), 47.6 (46.7-49.1) mm; palatal length, 26.7 (26.0-27.3) mm; zygomatic breadth (four females, five males), 29.2 (28.9-30.4) mm; mastoid breadth (three females, six males), 24.1 (23.3-24.5) mm; postorbital breadth (four females, seven males) 14.2 (13.5-14.7) mm; maxillary toothrow length, 9.0 (8.8-9.2) mm.

Five of seven females collected from late May through July were lactating; two contained three placental scars each. Two females obtained on 18 and 20 July were xoung of the year. Seven adult males taken during Julv had testes that had an average length of 14.2 (10-20) mm.

Thomomys talpoides bullatus Bailey, 1914

Northern Pocket Gopher

Specimens examined (34). — 16 nii E Ekalaka, 1; .5 mi S, 12 mi E Ekalaka, 1; 3 mi S, 1 mi E Ekalaka, 1 (MMNH); 3 mi S, 1.75 mi E Ekalaka, 3 (MxMNH); 12 mi S, 16 mi E Ekalaka, 3600 ft, 3; 8 mi N, 8 mi W Camp Crook, 2; 7 mi N, 3 mi W Camp Crook, 3400 ft, 1; 6 mi N, 10 mi W Camp Crook, 1; 6 mi N, 9 mi W Camp Crook, 4000 ft, 1; 5.5 mi N, 10 mi W Camp Crook, 1 (MMNH); 5.5 mi N, 9.5 mi W Camp Crook, 1; 5 mi N, 6 mi W Camp Crook, 3500 ft, 2; 5 mi N, 3.5 mi W Camp Crook, 3400 ft, 12; 2 mi N, 4.5 mi W Camp Crook, 3700 ft, 1; 6 mi S, 4.5 mi W Camp Crook, 3200 ft, 3.

The northern pocket gopher is common in Carter County. Our specimens were collected primaril)' in the Long Pine Hills from

16 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY

roadside ditches, sparsely pine-clad ridges, and meadows. Four in- dividuals were trapped in similar habitats in the Ekalaka Hills and adjacent areas. Three were taken along a sandy arroyo located 6 mi S and 432 mi W Camp Crook,

Bailey (1915:102) referred a specimen from Alzada to Thomo- inijs talpoides biillatus, the type locality of which is just to the west of Carter County at Powdemlle, Powder River County. Swenk (1941:3) later included this specimen in his description of T. t. pierreicolus, a subspecies supposedly delimited by the distribution of soils of the Pierre series. Andersen and Jones (1971:376) exam- ined a specimen from Harding County, also referred by Swenk (1941:3) to pierreicolus, and found it clearly referable to hullatus.

Five adults collected in early and mid-July and a subadult taken in early July were molting. Two adult males obtained on 8 July had testes that were 10 and 13 mm in length, whereas those of a subadult taken the same day were 4 mm. An adult and a subadult collected on 18 July had testes that were 6 and 5 mm, respectively. An adult female taken on 8 July and two obtained 12 July contained, re- spectively, 13, 10, and six placental scars.

The following ectoparasites were found on our specimens of Thomomys talpoides: a flea, Foxella ignota alhertensis; four mites, Amlrolaelaps geomys, Androlaelaps fahrenhoizi, Haemogamasiis sp., and Hirstionyssus sp.; two ticks, Ixodes kingi and 7. sculptiis; and two lice, Geomydoecus thomomiis and G. wardi. Fleas, mites, ticks and lice were found together on one specimen from the Long Pine Hills.

Perognathus fasciatus olivaceogriseus Swenk, 1940

Olive-backed Pocket Mouse

Specimens examined (30). — 11.5 mi N, 3 mi E Ekalaka, 1; 17 mi E Eka- laka, 3200 ft, 1; 4.5 mi S, 1 mi E Ekalaka, 1 (MMNH); 5.5 mi N, 3.5 mi W Camp Crook, 3400 ft, 22; 6 mi S, 4.5 mi W Camp Crook, 3200 ft, 5.

The olive-backed pocket mouse was found to be common in grazed and ungrazed meadows on sandy soils. A series of 11 adults and 11 young was collected from a north- facing slope at the eastern edge of the Long Pine PI ills. Five individuals were obtained in an area of short grass and sage 6 mi S and 4.5 mi W Camp Crook, along a sandy arroyo. Specimens from 8 mi NE Albion were mentioned by Preble (MS).

Adult females taken on 7 and 8 July carried embryos ( five meas- uring 11 mm and nine measuring 13 mm, respectively). A female bearing three placental scars was obtained on 9 July and one of two adult females taken on 10 July carried three embryos and had seven placental scars, whereas one of two taken on 11 and 12 July con- tained five embryos in addition to six placental scars. Two females trapped on 16 and 17 July carried seven and six embryos, respec-

THE MAMMALS OF CARTER COUNTY, MONTANA 17

tively, the latter also containing five placental scars. One taken on 19 July had four corpora lutea and one obtained on 25 July was nonparous. An adult female examined on 29 July contained 11 pla- cental scars of at least two ages. One obtained on 1 August was lactating and had nine placental scars, and another trapped on 5