MAMMALIAN ZOOGEOGRAPHY OF A ROCKY MOUNTAIN-GREAT PLAINS INTERFACE IN NEW MEXICO, OKLAHOMA, AND TEXAS Walter W. Dalquest, Frederick B. Stangl, Jr., and J. Knox Jones, Jr. Special Publications, The Museum Texas tech university NUMBER 34 MAMMALIAN ZOOGEOGRAPHY OF A ROCKY MOUNTAIN-GREAT PLAINS INTERFACE IN NEW MEXICO, OKLAHOMA, AND TEXAS Walter W. Dalquest, Frederick B. Stangl, Jr., and J. Knox Jones, Jr. Texas Tech University Press 1990 Special Publications, The Museum Texas Tech University Number 34 Series Editor J. Knox Jones, Jr. Published 28 September 1990 Copyright 1990 Texas Tech University Press All rights reserved. No portion of this book may be reproduced in any form or by any means, including electronic storage and retrieval systems, except by explicit, prior written permission of the publisher. Special Publications of The Museum are numbered serially and published on an irregular basis. Institutions interested in exchanging publications should address the Exchange Librarian at Texas Tech University. ISSN 0149-1768 ISBN 0-89672-230-9 Texas Tech University Press Lubbock, Texas Contents Introduction.5 Methods and Acknowledgments. 6 Accounts of Species.7 Species of Possible Present or Past Occurrence.70 Historical Perspective.71 Literature Cited.75 Introduction The region encompassed by the present study comprises some of the least- known areas of New Mexico, Oklahoma, and Texas with respect to distribu¬ tion of mammals. The senior author initiated collecting in Union County, New Mexico, and nearby Texas counties in 1965, mostly to determine the presence or absence in Texas of several mammalian species with ranges mapped by Hall and Kelson (1959) as closely approaching the state. For two years, he was assisted by Midwestern State University graduate students Edward L. Roth and Robert L. Westmoreland, but the study was abandoned before completion. During the intervening years, Findley^ al. (1975) produced a work on the mammals of New Mexico, but it contained little information on Union County not already reported from collections made in the early 1900s. Two exceptions are Best's (1971) additions of several species to the known fauna, and his (1973) study on the distribution of three species of pocket gophers in the county. Hall's (1981) revised editon of The Mammals of North America incorporated information from the publications cited above, and served as the primary point of departure for this study. The Oklahoma Panhandle historically has been neglected by mam- malogists, with the exception of Black Mesa. The authors of the long- awaited book on mammals from that state (Caire et al ., 1990) summarized known specimens and further illustrated the lack of material from much of the region. In 1983, the senior and second authors initiated work toward completion of the original study, and expanded it to include the Oklahoma Panhandle and northern tier of counties in the Texas Panhandle (Fig. 1). Shortly there¬ after, the third author and colleagues began work in the northern Texas Panhandle, and the results of their efforts, incorporating our earlier Texas material, subsequently were published ( Jones et al ., 1988). In turn, we have included their published distributional records. However, with few excep¬ tions, our New Mexico and Oklahoma specimens are reported in the litera¬ ture for the first time. See also Jones and Manning (19906). Our principle concern has been the distribution of mammalian species in the study area. To this end, we herein report 19 new county records—eight from New Mexico, 10 from Oklahoma, and one from Texas. We have found, however, that the lack of information about mammals of the region has led to inconsistent treatment of subspecific distributions. For example, seven species of rodents occurring in the study area are represented, according to Hall (1981), by two or more subspecies. The boundary lines between races as mapped by him and others vary, however, and none closely approximates physiographic or environmental parameters in the area. Another feature that became apparent in the course of this work was evidence of westward invasion of parts of the region by grasslands and prairie-adapted mammals, and concomitant retreat of species of mammals 5 6 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Fig. 1 .—Map of tristate study region, comprised of Union County, New Mexico, Oklahoma Panhandle, and northern tier of Texas Panhandle counties. Figured are cities and towns (circles), major physical features (triangles), and waterways often referred to in text. Circled numbers refer to the following physical features: 1, Capulin Mountain; 2 , Sierra Grande Mountain; 3 , Rabbit Ears Mountain; 4 , Black Mesa. more adapted to coniferous woodlands and softer, moister soils. Mammals of our study area inhabit the boundary between the prairies of the Great Plains and the woodlands fringing the foothills of the southern Rocky Moun¬ tains. West of the panhandles, mammalian populations are dynamic, in a state of flux. Even in the two panhandles, there is some indication of change in the distribution of species other than that related to the obvious results of activities of man (the apparent recent increase of Microtus ochrogaster , for example). Supportive evidence is found in late Pleistocene (Dalquest and Stangl, 1989) and early Holocene (Dalquest et al ., 1990) faunas of the region. It is important, we think, to record the geographic ranges of mammals in the study area in some detail so that future changes may be identified. Methods and Acknowledgments Collections were made during all seasons of the year using standard col¬ lecting techniques. Most small mammals were taken by Victor rat and Museum Special snap traps, and in Sherman live traps. Bats were collected by hand, or with mist nets, and shrews were taken mostly in pitfall traps. Specialized commercial traps were used to capture pocket gophers and in an attempt to capture moles. Larger animals (lagomorphs and carnivores, for example) were hunted with guns, collected from trappers, or salvaged from roadways. Most specimens were prepared as museum study skins accom¬ panied by skulls; soft tissues (liver, heart, kidney, and muscle) were saved from selected specimens and are deposited in the Collection of Frozen Tissues DALQUEST ET AL —MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 7 at The Museum of Texas Tech University. Most voucher specimens are deposited in the Collection of Recent Mammals, Midwestern State University, and in The Museum, Texas Tech University. In the accounts that follow, all measurements are in millimeters and weights are in grams. We gratefully acknowledge the many landowners who permitted collecting on their property. For this and many other kindnesses, we especially thank the following individuals: Jack Wiggins and Bud Davis, of Cimarron County; Carlos Cornay, A. W. Layton, and A. W. Layton, Jr., of Union County; Jim Boussard, of Lipscomb County; and Layne Allen, formerly of Ochiltree County. For field assistance during the course of this study, we thank the following workers: R. M. Carpenter, L. L. Choate, R. R. Hollander, C. S. Hood, C. Jones, S. Kasper, M. J. Kocurko, R. W. Manning, D. A. McCullough, R. J. Pesaturo, J. W. Rogers, E. L. Roth, T. S. Schafer, F. M. Stangl, K. W. Wells, and R. L. Westmoreland. We also wish to acknowledge the curators and collection managers of the following collections (identifying acronyms in parentheses) for allowing access to specimens in their care: Museum of Natural History, The University of Kansas (KU); Museum of Vertebrate Zoology, University of California, Berkeley (MVZ); New Mexico State University (NMSU); Oklahoma State University (OSU); Texas Coopera¬ tive Wildlife Collection, Texas A&M University (TCWC); National Museum of Natural History, Smithsonian Institution (USNM); Texas Memorial Museum, University of Texas (UT); The Museum, Texas Tech University (TTU); and West Texas State University (WTSU). Finally, we thank the offices of the New Mexico Department of Game and Fish, Oklahoma Department of Wildlife Conservation, and Texas Parks and Wildlife Department, for providing collecting permits for their respective states. Accounts of Species Species are arranged in the following accounts in the order listed by Jones et al. (1986). Specimens examined that are deposited in the Midwestern State University Collection of Recent Mammals carry no institutional designation; others are identified by acronyms given in the section on methods and acknow¬ ledgments. Specimens are listed alphabetically by state and by county within each state. Within a single county, they generally are arranged from north to south or are grouped by place-name; at the same latitude, western localities usually precede those farther east. Unless otherwise listed, sources of literature records are as follows: for New Mexico, Findley et al., 1975; for Oklahoma, Caire^a/., 1990; and for Texas, Jones et al ., 1988. For the most part, natural history data in those three publications are not repeated here. On distribution maps, localities from which specimens were examined are represented by solid symbols, whereas open symbols are used to indicate 8 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY records from the literature. Species with one or only a few known distribu¬ tional records from the study area either are not mapped or are combined on a map with other taxa. To alleviate crowding of symbols, immediately adjacent localities for some species are not mapped or symbols are slightly offset. Didelphis virginiana virginiana Kerr, 1792 Virginia Opossum Records of the opossum from our study area are scarce. A. W. Layton reported that his dogs treed an opossum in cottonwoods along the Cimarron River in Union County, about 10 miles west of Kenton, Oklahoma, and that he had heard of another killed earlier in the same vicinity. The species probably occurs sparingly throughout the region where suitable riparian habitat exists along watercourses. Literature records. -Oklahoma. Cimarron Co.: 10 mi. W Felt. Texas. Lipscomb Co.: Higgins. Sorex merriami leucogenys Osgood, 1909 Merriam’s Shrew The only record of this species from the tristate region is that of George (1990), who obtained a single specimen in a pitfall trap in montane habitat on the peak of Sierra Grande (Fig. 2). The few other records of Merriam’s shrew from New Mexico (Findley et al. y 1975) were taken in fir forests, at elevations of approximately 8000 feet, and more than 100 miles to the southwest. Elsewhere, S. merriami is known to occur in more arid situations than other Sorex , and at considerably lower elevations (Armstrong and Jones, 1971). Much of Union County and parts of Cimarron County probably provide suitable habitat for this species. Use of pitfall traps in sagebrush areas, for example, may extend the known range farther east than Sierra Grande. We employ the subspecific name S. m. leucogenys on geographic grounds. Literature record.— New Mexico. Union Co.: Sierra Grande, 3 mi. S, 3 mi. W Des Moines (George, 1990). Sorex nanus Merriam, 1895 Dwarf Shrew We took no specimens of the dwarf shrew, but George (1990) reported one taken in the same pitfall trapline at the top of Sierra Grande that produced an individual of S. merriami (Fig. 2). Little is known of the ecology and distribution of this monotypic species (Hoffmann and Owen, 1980). Although most records are from high montane habitats, this shrew is known to extend into the lower foothills of the Rockies (Armstrong, 1972). As in the case of S. merriami , more intensive collecting efforts in using pitfall traps may better define the ecology and distribution of this species in the region. Literature record.- New Mexico. Union Co.: Sierra Grande, 3 mi. S, and 3 mi. W Des Moines (George, 1990). DALQUEST ET AL—MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 9 Fig. 2.—Distribution of Sorex mernami (diamond), S. nanus (square), Cryptotis parva (triangles), and Notiosorex crawfordi (circles) in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Cryptotis parva parva (Say, 1823) Least Shrew The least shrew is primarily an inhabitant of the eastern United States; on the southern Great Plains, it occurs in mesic grassland situations and riparian habitats. The species seems to be extending its range westward in the wake of agricultural land development (Armstrong, 1972; Owen and Hamilton, 1986), and it recently has been taken in extreme southeastern Colorado and southwestern Kansas (Choate and Reed, 1988), adjoining our study area to the north. C. parva doubtless occurs in suitable habitats throughout the study area. Our two specimens document the presence of the species in the Oklahoma Panhandle (Fig. 2). A mummified specimen was recovered from a dry stocktank in sandy grassland in Beaver County along the Beaver River. The shrew from Texas County was taken at an abandoned homestead where a partially buried gallon bucket served as a pitfall. Fragments of a variety of insects, mostly beetles, indicated the shrew fed on similarly trapped animals while available; it probably had died the same morning it was discovered. Specimens examined (2).— Oklahoma. Beaver Co.; 8 mi. W Beaver, 1. Texas Co.: 11.8 mi. E Hardesty, 1. 10 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Notiosorex crawfordi crawfordi (Coues, 1877) Desert Shrew The desert shrew is not well represented in most collections, and once was considered rare; most workers now agree that its apparent scarcity is reflec¬ tive of inadequacy of standard collecting techniques rather than actual rarity. N. crawfordi is notably tolerant of a wide variety of habitats, including some that are quite arid. However, we found this shrew to be at least locally common in rocky situations in the pinon-juniper zone of Cimarron County (Fig. 2). At the Wiggins Ranch, just north of Kenton, a specimen was caught by hand as it traveled across a small clearing bounded by a low cliff and basalt talus on one side and scattered cedar shrubs and a fallen cottonwood trunk on the other. Fifteen pitfall traps were set just to the south of the site, five among large boulders and 10 along a low cliff among tall trees and dense low vegetation. Over the next six weeks, four desert shrews were taken among the boulders, but none was taken in the more mesic site along the cliff. At Tollgate Canyon, 15 pitfalls were set among boulders and at the base of a cliff on a steep hillside in an oak-pine woodland. In six weeks of trapping, a single specimen was taken. Specimens examined (7).—New Mexico. Union Co.: Tollgate Canyon, 10 mi. N Folsom, 1. Oklahoma. Cimarron Co.: 4 mi. N Kenton, 1; 3 mi. N Kenton, 1; 2 mi. N Kenton, 3. Texas. Hansford Co.: 10 mi. S, 3 mi. E Gruver, 1 (KU). Literature records.— Oklahoma. Cimarron Co.: Tesequite Canyon. Texas Co.: 11.5 mi. N, 1 mi. E Goodwell. Scalopus aquaticus aureus (Bangs, 1896) Eastern Mole A single specimen from Lipscomb County (Yates and Schmidly, 1977) documents the presence of the eastern mole in our study area, although there are numerous records to the south in Texas ( Jones et al 1988), to the north in Kansas (Bee et al ., 1981), and in Colorado (Armstrong, 1972). Mole runs were noted in sandy areas along the Cimarron and Beaver rivers in the Oklahoma Panhandle, and T. L. Best (personal communication) reported mole sign north of Kenton, just a few miles from New Mexico. In many areas, mole runs were so common as to make walking difficult. However, our trapping efforts took place mostly during dry times of the year, and difficulty in distinguishing active burrow systems may account for our failure to collect specimens. Numerous workers (Findley^ al ., 1975; Jones et al. , 1988; T. A. Yates and T. L. Best, personal communications) have suggested that range of S. aquaticus probably extends into Union County, New Mexico. Although we did not note mole sign in that county, the species likely will be found there along river systems. Literature records .- Texas. Lipscomb Co.: Lipscomb (Yates and Schmidly, 1977). Ochiltree Co • Wolf Creek. DALQUEST ET AL—MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 11 Fig, 3.—Distribution of Myotis evotis (diamonds), M. ciliolabrum (squares), M lucifugus (circle), and M. thysanodes (triangle) in the tristate study region. Solid symbols represent specimens examined; open symbol represents literature record. Myotis evotis evotis (H. Allen, 1864) Long-eared Myotis The long-eared myotis has not been reported previously from the study area (Fig. 3), the nearest records being 12.5 mi. W Gardner, Colorado (Armstrong, 1972), and Vermejo River, New Mexico (Findley et al. , 1975). On 27 July, a bat was seen emerging from a crevice in a waist-high block of basalt near the top of a large pressure ridge north of Capulin Mountain. Shattered basalt littered the surface of the ridge, and numerous pinons, junipers, and small oaks grew from crevices at the surface. The crevice from which the bat had emerged was hastily blocked, and, using long forceps, three other M. evotis were captured. One was an adult female. Two, one of each sex, were nearly grown young-of-the-year. The crevice from which the bats were taken was about 10 centimeters deep and one centimeter wide at the top; when pried apart, the bottom of the crevice was found covered with bat droppings. Deeper parts of the crevice were filled with black silt that was permeated with termite tunnels. The silt may have resulted from an accumula¬ tion of bat guano. A mist net set near the crevice took no bats the following night, although many were heard and seen flying over the lava plain at the base of the pressure ridge. On 17 July, a long-eared myotis was taken in a mist net set over a stock tank on the Cornay Ranch, a mile north of where the three other specimens were collected. Tall pinons, junipers, and a few yellow pines grew nearby, and extensive grassy fields covered adjacent level areas. Barbour and Davis 12 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY (1969) noted a close association ofM evotis with yellow pine. Where these trees are scarce, tall junipers and pinons may, in part, serve as substitutes. Specimens examined (4).— New Mexico. Union Co.: 4 mi. N Capulin, 1; west base of Capulin Mountain, 3 mi. N Capulin, 3. Myotis ciliolabrum ciliolabrum (Merriam, 1886) Western Small-footed Myotis Glass (1949) and Glass and Ward (1959) reported several records of this small-footed myotis from Cimarron County, but Caire«< al. (1990) referred many of these to M. yumanensis . We netted for bats on several occasions near where undoubted specimens of this uncommon species had been reported (Fig. 3), but took none. Specimens examined (3).-Oklahoma. Cimarron Co.: North Carrizo Creek, below Black Mesa, 1 (OSU); mouth North Carrizo Creek, 1 (OSU); 3 mi. S, 1.5 mi. E Kenton, 1 (TTU). Myotis lucifugus carissima Thomas, 1904 Litde Brown Myotis The only record (Fig. 3) of this little brown bat from our study area is from Sierra Grande (Findley et al ., 1975). The main range of this species is the high country of New Mexico and Colorado, to the west and the north. M. lucifugus is known from south-central Kansas (Bee et al. , 1981) and may be found, therefore, to occur in eastern parts of the Texas and Oklahoma panhandles. Literature record.— New Mexico. Union Co.: Sierra Grande. Myotis thysanodes thysanodes Miller, 1897 Fringed Myotis The fringed myotis has not been recorded previously in the tristate area (Fig. 3), the nearest stations of record (Hall, 1981) being Wooten, Colorado, and Montezuma, New Mexico. On 16 August 1986, Jack Wiggins of Kenton took us to an old copper mine at the western base of Black Mesa, which had been abandoned at the turn of the century. The nearly straight shaft harbored approximately 300 M. thysanodes , 100 M. yumanensis , 200 Plecotus townsendn, and 50 Tadarida brasiliensis. Adult fringed myotis, all females, were found in association with young-of- the-year, which were nearly of adult size, but duller in color. The mine tunnel was drilled into the base of the mesa. At the top of the mesa, perhaps 100 feet higher but only a few hundred feet to the east, is a rock cairn that we took to be the boundary marker between Oklahoma and New Mexico. The fringed myotis certainly occurs in Oklahoma, but netting over springs, stock tanks, and streams east of the mine produced only M. yumanensis . Specimens examined (29).— New Mexico. Union Co.: 5 mi. NNW Kenton, Oklahoma, 29. DALQUEST ET AL.—MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 13 Fig. 4.—Distribution of Myotis veliftr (diamond), M volans (squares), and Myumanensis (circles) in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Myotis velifer magnamolaris Choate and Hall, 1967 Cave Myotis A single specimen of this species is known from the study area (Fig. 4), although it is known from caves and man-made structures in southern Kansas, and adjacent parts of Texas and Oklahoma, to the south and east. We follow Dalquest and Stangl (1984) in assigning bats of the Texas and Oklahoma panhandles to M. v. magnamolaris. Literature record..— Oklahoma. Cimarron Co.: Black Mesa State Park, 8 mi. SE Kenton. Myotis volans interior Miller, 1914 Long-legged Myotis The only records of the long-legged myotis from our study area are from the westernmost border of Union County (Fig. 4). The specimen examined is from a site where there are numerous cliffs cloaked in pihon and juniper, with a few scattered yellow pines. Specimen examined (1).— New Mexico. Union Co.: 4 mi. N Capulin, 1. Literature record.— New Mexico. Union Co.: Raton Range, Oak Canyon. Myotisyumanensisyumanensis (H. Allen, 1864) Yuma Myotis The Yuma myotis seems to be the common myotis of the pinon-juniper zone in Cimarron and Union counties (Fig. 4). Perhaps the lack of suitable daytime retreats explains the apparent absence of this species from prairies 14 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY to the east, although we did collect specimens on 27 July from the attic of an old garage near Gladstone, Union County—two lactating females and their young. The two young animals, still in gray juvenile pelage, each weighed 6.4, 0.1, and 0.2 grams more than their respective mothers. M. yumanensis was the second most common bat in the copper mine where M. thysanodes was taken. Although the bats tended to segregate by species into clusters of 10 to 30 animals, an occasional yuma myotis was found within groups of the larger fringed myotis. Specimens from our study area are quite uniform in color—dark brownish gray. They are darker than topotypes of M . y . yumanensis , the race Hall (1981) mapped as occurring in New Mexico, and darker than specimens in a comparative series from Trans-Pecos Texas. Pending a needed systematic review of the species, we only tentatively use the subspecific name yumanensis. Specimens examined (142).— New Mexico. Union Co.: 5 mi. NW Kenton, Oklahoma, 24; 4 km. N, 17 km. W Kenton, Oklahoma, 1; 2.7 mi. E Gladstone, 4; 15 mi. W Clapham, 1 Oklahoma. Cimarron Co.: Carrizo Creek, 6 mi. N Kenton, 3 (OSU); 5 mi. NNW Kenton, 3; 4 mi. N Kenton, 2; Kenton, 6 (OSU); 3 mi. N, 1 mi. E Kenton, 4 (TTU); 5 mi. S, 2 mi. E Kenton, 3 (TTU); 4.3-4.5 mi. S, 2.4 mi. E Kenton, 4 (TTU); 1.5 mi. S, 3 mi. E Kenton, 6 (TTU); 3 mi. S, 2 mi. E Kenton, 6 (TTU); 3 mi. SE Kenton, 3; Carrizo Creek, 1 (OSU); Cimarron River, 6 (OSU); Cimarron River, near mouth of North Carrizo Creek, 5 (OSU); Cimarron River, E mouth North Carrizo Creek, 3 (OSU); cave, Tesequite Canyon, 7 mi. SE Kenton, 21 (OSU); Pigeon Cave, 2 (OSU); cave, NW Tesequite Canyon, 13 (OSU); Tesequite Canyon Cave, 21 (OSU). Literature records.— New Mexico. Union Co.: 5.5 mi. NE Folsom; 6 mi. S, 3 mi. W Kenton, Oklahoma; 0.5 mi S, 0.5 mi. W Moses; Clayton, Apache Canyon. Lasionycteris noctivigans (Le Conte, 1831) Silver-haired Bat The silver-haired bat, which is a monotypic species, has not been recorded previously from the study area. Our specimens are all from the vicinity of Black Mesa in Oklahoma. We are uncertain whether this bat is resident in the western part of the study area or occurs there only as a migrant, which seems more likely. Three were captured in nets set over a spring on the Wiggins Ranch just north of Kenton on 18 April, but nets over the same spring took no specimens on 21 June. All three specimens were females, and none exhibited gross reproductive activity. The other eight individuals were collected in September (two) and October, all presumably migrants moving southward (Jones and Manning, 19906). Specimens examined {11 ). -Oklahoma. Cimarron Co.: 4.5 mi. N Kenton, 3; 1.5 mi S 3 mi E Kenton, 6 (TTU); 3 mi. S, 2 mi. E Kenton, 2 (TTU). Pipistrellus hesperus maximus Hatfield, 1936 Western Pipistrelle The western pipistrelle emerges quite early in the evening from rock crevices where it spends the day. It flies in a characteristic, fluttery fashion and individuals are relatively easy to shoot by evening light. We would have expected the species to be relatively abundant throughout the pihon-juniper DALQUEST ET AL—MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 15 Fig. 5 —Distribution of Eptesicus fuscus in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. zone, but we took none in that habitat. Nevertheless, it apparently is an uncommon resident, based on the single literature record. Literature record.— New Mexico. Union Co.: 3 mi. W Kenton, Oklahoma. Eptesicus fuscus fuscus (Palisot de Beauvois, 1796) Big Brown Bat The big brown bat has a widespread distribution (Fig. 5), but Manning et al. (1989) have demonstrated that the species actually is quite localized in the Texas Panhandle. Records indicate that E. fuscus is present in the eastern and western parts of our study area; we believe that absence of records from else¬ where in the Texas and Oklahoma panhandles are not artifactual. The limiting factor may be the unavailability of suitable daytime retreats because there are no caves and few hollow trees on these prairies. However, big brown bats use man-made structures for roosts as well. On 24 June 1987, Jim Brussard took us to an old barn, 3 mi. E Lipscomb, where bats had been permitted to live for many years. Approximately 100 Eptesicus were found residing in the barn; most were females with small, non¬ volant young attached to their teats. Representative adult and young animals were retained, although in the process, the colony was disturbed and we were unable to ascertain individual litter sizes. Records from the Black Mesa regions of Oklahoma and New Mexico come from both the pinon-juniper zone, and from where level prairies inter- digitate with wooded canyons leading to the Cimarron River. Manning et al. (1989) tentatively referred specimens from northwestern Texas, including the Panhandle, to the subspecies E. f pallidus , noting that 16 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Fig. 6 .—Distribution of Lasiurus borealis in the tristate study region. Solid symbols represent specimens examined; open symbol represents literature record. they resembled the latter in color but E. f fuscus of eastern Texas in size. These authors, however, had no data from northwestern Texas on litter size—female pallidus typically bear a single offspring whereas those o{fuscus normally have twins. In the spring of 1989, Jones and Manning (199ftz) took females in Garza County that carried twin fetuses, prompting them to opine that big brown bats from the Panhandle region, although intergrades, should be assigned to the race fuscus (see also Burnett, 1983). Specimens examined (12).— Texas. Hansford Co.: Spearman, 1 (TTU). Lipscomb Co.: 3 mi. E Lipscomb, 7. Ochiltree Co.: Perryton, 4 (TTU). Literature records.- New Mexico. Union Co.: 3 mi. W Kenton, Oklahoma. Oklahoma. Cimarron Co.: N Carrizo Creek; Carrizo Creek, 6 mi. N Kenton; Dripping Springs, 6 mi. N, 4 mi. E Kenton. Lasiurus borealis (Muller, 1776) Eastern Red Bat Records indicate that the red bat occurs sparingly along riparian habitat throughout the Texas and Oklahoma panhandles, where large trees afford suitable roosting situations (Fig. 6). We follow Baker*/ al . (1988) in listing L. borealis as a monotypic species. Specimens examined (4).-Oklahoma. Cimarron Co.: 1.5 mi. S, 3 mi. E Kenton 2 tTTUL Texas. Hansford Co.: Gruver, 1 (KU). Lipscomb Co.: 8 mi. NW Higgins, 1 (TTU) Literature record. —Oklahoma. Texas Co.: Guymon. DALQUEST ET AL—MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 17 Fig. 7.—Distribution of Lasiurus cinereus in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Lasiurus cinereus cinereus (Palisot de Beauvois, 1796) Hoary Bat The hoary bat is a tree-roosting migrant. Most of our records are from April and May from the pinon-juniper zone (Fig. 7), and of migrants from September and October. Migrating individuals might be expected to occur anywhere in the region where suitable habitat prevails. Jones et al. (1988) speculated that L. cinereus spends the warmer months, and presumably also rears young, north of the Texas Panhandle, although a female obtained on 16 May from Roberts County, Texas (adjacent to Ochiltree County), to the south was pregnant with two fetuses (crown-rump length, 12). On 13 May, a pregnant female carrying two near-term fetuses of similar size was taken in southern Union County. It is possible that at least some females are residents of the region during warmer months of the year. One from 3 mi. SE Kenton, taken on 20 April, was not visibly pregnant. Most of our specimens were late summer or autumn migrants ( Jones and Manning, 1990&). Specimens examined (26).— New Mexico. Union Co.: 15 mi. W Clapham, 2. Oklahoma. Cimarron Co.: 5 mi. NNW Kenton, 3; 3 mi. S, 2 mi. E Kenton, 12 (TTU); 4 mi. S, 2 mi. E Kenton, 2 (TTU); 4.3-4.5 mi. S, 2.4 mi. E Kenton, 4 (TTU); 1.5 mi. S, 3 mi. E Kenton, 2 (TTU); 3 mi. SE Kenton, 1. Literature records.— New Mexico. Union Co.: N of Moses. Oklahoma. Beaver Co.: 3 mi. S, 2 mi. W Elmwood. Cimarron Co.: 2.5 mi. SE Kenton; Carnzo Creek, 6 mi. N Kenton. Texas Co.: Guymon. Texas. Hansford Co.: Gruver (Cutter, 19596). 18 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Fig, 8 ,—Distribution of Plecotus townsendii in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Plecotus townsendii pallescens (G. S. Miller, 1897) Townsend’s Big-eared Bat Availability of caves for daytime retreats is probably the factor limiting distribution of Townsend’s big-eared bat. In northwestern Cimarron County and in northeastern Union County, the Cheyenne Sandstone is a cliff- and cave-forming stratum that supports colonies of this and other species of bats. Farther west, in the basalt lava flows in the Capulin Mountain volcanic region, lava caves support populations of Plecotus. Because the big-eared bat also roosts in sheltered attics and barns, it may range occasionally into the prairie parts of the study region, but we know of none taken east of the Black Mesa-Kenton area (Fig. 8). This species is more abundant than our collections indicate, because many individuals were released from mist nets or examined but left unmolested in caves. Specimens examined (9). -New Mexico. Union Co.: 8 mi. S Capulin, 1; 5 mi. NW Kenton, Oklahoma, 4. Oklahoma. Cimarron Co.: 4 mi. SSE Kenton, 4. Literature records.- New Mexico. Union Co.: 3 mi. W Kenton, Oklahoma. Oklahoma. Cimarron Co.; Tesequite Canyon Cave. Antrozous pallidus btmkeri Hibbard, 1934 Pallid Bat The pallid bat is a colonial species, spending the day in small groups in rock crevices, spaces between support beams of bridges, or in gaps between boards of old buildings. Although a heavy-bodied bat, individuals can creep into surprisingly narrow spaces. Suitable daytime roosts are found throughout most of the tristate region. Habitat, and not available roosting DALQUEST ET AL —MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 19 Fig. 9.—Distribution of Antrozous pallidus in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. sites, seems to govern the range of this species. Manning^ al. (1988) recently assigned pallid bats from the Texas and Oklahoma panhandles and adjacent parts of New Mexico to the subspecies .4. p. bunkeri. All known specimens from our study area are from New Mexico and the Black Mesa region of Oklahoma (Fig. 9). Most were caught in mist nets set over water. Surrounding land was usually arid, with cliffs and adjacent grasslands nearby. Many netted individuals were released after representative voucher material had been secured. Females taken from mid-July to early August were lactating, and accompanied by nearly adult-sized juveniles. Specimens examined ( 19).— New Mexico. Union Co.: 4 km. N, 17 km. W Kenton, Oklahoma, 2; 15 mi. W Clapham, 1. Oklahoma. Cimarron Co.: 5 mi. NNW Kenton, 2; 4.5 mi. N Kenton, 2; 4 mi. N Kenton, 1; 3 mi. S, 2 mi. E Kenton, 2 (TTU); 1.5 mi. S, 3 mi. E Kenton, 1 (TTU); 3 mi. S, 2.4 mi. E Kenton, 1 (TTU); 4.3 mi. S, 2.4 mi. E Kenton, 2 (TTU); 3 mi. SSE Kenton, 5. Literature records.— New Mexico. Union Co.: 6 mi. S, 3 mi. W Kenton, Oklahoma; 3 mi. W Kenton, Oklahoma. Oklahoma. Cimarron Co.: Carnzo Creek; Asa Jones bam, Kenton; Regnier Ranch, 2 mi. N, 1 mi. E Kenton; Regnier Ranch, 2 mi. S, 1 mi. E Kenton; north side Black Mesa, 6 mi. N Kenton, 3 mi. N Kenton; Pigeon Cave, 0.5 mi. N, 2 mi. E Kenton; 5 mi. S Kenton; bat cave, Tesequite Canyon; Tesequite Bat Cave; Tesequite Canyon Cave. Tadarida brasiliensis mexicanus (Saussure, 1860) Brazilian Free-tailed Bat This free-tailed bat is common throughout the southern United States. It is a colonial species, occupying attics of buildings and sometimes forming enormous colonies in caves. Absence of records from the eastern part of the study area (Fig. 10) probably reflects a paucity of suitable daytime retreats. Habitat preferences are variable inasmuch as this insectivorous species may 20 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Fig. 10.—Distribution of Tadarida brasiliensis (circles) and Nyctinomops macrotis (squares) in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. feed at relatively great heights and at relatively great distances from roosting sites. The pinon-juniper zone of the western part of the study area would seem to be ideal for T. brasiliensis , with abundant cliffs and mountains of sandstone and basalt. However, we found it to be only moderately common there. About 50 individuals were noted in a copper mine in northeastern Union County on 15-16 August. Seven were taken in a mist net set across a cave entrance in Tesequite Canyon on 20 April, and another was netted on 23 August over the plunge pool of Folsom Falls in western Union County. Many specimens, all female, were released after examination. Specimens examined ( 14).—New Mexico Union Co.: 5 mi. NW Kenton, Oklahoma, 3; Folsom Falls, 4 mi. NE Folsom, 1 . Oklahoma. Cimarron Co.: 4.4-4.5 mi. S, 2.4 mi E Kenton 9 (TTU) 3 mi. S, 2 mi. E Kenton, 5 (TTU); 4 mi. SSE Kenton, 3. Literature records.-N ew Mexico. Union Co.: 3 mi. W Kenton, Oklahoma. Oklahoma. Beaver Co.: T. 4 S, R. 13 E, sec. 7; Cimarron Co.: Pigeon Cave; Tesequite Canyon Cave. Nyctinomops macrotis (Gray, 1839) Big Free-tailed Bat Less colonial than the smaller Tadarida brasiliensis, the big free-tailed bat is a strong, far-ranging flier. Records from extreme ends of the Oklahoma Panhandle (Fig. 10) indicate this species may be taken any place in the tristate region during seasonal migration. It is doubtful that this monotypic species is a summer resident there. Specimen examined (1).-Oklahoma. Cimarron Co.: 2 mi. E, 3 mi. S Kenton (TTU). Literature record. -Oklahoma. Texas Co: 4 mi. S Elkhart; Guymon. DALQUEST ET AL.—MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 21 Fig. 11 .—Distribution of Sylvilagus audubonii in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Dasypus novemcinctus mexicanus Peters, 1864 Nine-banded Armadillo We have no voucher specimens of the armadillo from the study area, although Hollander et al. (1987) noted a road-killed animal from Lipscomb County. Armstrong (1972) suspected that armadillos occur at least intermit¬ tently along the Cimarron River and its tributaries. Records from north¬ eastern Colorado (Choate and Pinkham, 1988) indicate an expanding range, and the species is probably at least an occasional member of the fauna. Literature record.— Texas. Lipscomb Co.: 7 mi. NW Higgins (Hollander et al. , 1987). Sylvilagus audubonii neomexicanus Nelson, 1907 Desert Cottontail The desert cottontail is the most widely distributed of the three cottontails in the study area, especially to the west (Fig. 11), and also is the most abundant. It retreats by day to cover in thickets and rocks, or, if these are not available, the shade of an isolated mesquite or clump of grass. At night, it ranges over grassy areas and openings in pirion-juniper brushland. Roadside greenery evidently is tempting to these rabbits because many individuals are killed on roadways by motor vehicles. In the western part of the tristate region, this rabbit may be distinguished from S. nuttallii by its paler color. Farther east, in the Texas and Oklahoma panhandles, it is sometimes difficult to separated, audubonii from S. flondanus based solely on external characters, although the latter has shorter ears. Skulls can be separated readily by the large size of the bullae of the desert 22 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY cottontail, and it also can be distinguished from other cottontail species in the area by characters of the lower P4 (Dalquest et al ., 1989). Half-grown or smaller individuals were taken near Kenton on 30 July and 15 August. Adult males obtained on 18 April and 30 July had scrotal testes (38 and 46 in length). Specimens examined (14).— New Mexico. Union Co.: 8 mi. NNE Folsom, 1; Rabbit Ears Mountain, 1. Oklahoma. Cimarron Co.: 5 mi. N Kenton, 2; 5 mi. NNW Kenton, 4; 4.5 mi. NNW Kenton, 1; 3.4 mi. S, 2.4 mi. E Kenton, 1 (TTU). Texas. Lipscomb Co.: 2.5 mi. E Booker, 1 (WTSU); 4 mi. E Booker, 1 (WTSU). Ochiltree Co.: 2 mi. S, 4 mi. E Perryton, 1 (TTU); 7 mi. S, 2 mi. E Perryton, 1 (TTU). Literature records.— New Mexico. Union Co.: Clayton, Apache Canyon; 7 mi. W Clayton; Perico Arroyo, W Mt. Clayton; Emory Peak; Sierra Grande. Oklahoma. Beaver Co.: 10.4 mi. E Elmwood. Cimarron Co.: Boise City; N Canadian River, S Boise City; 3 mi. W Boise City; 4 mi. N Boise City; 0.5 mi. S, 4.5 mi. E Boise City; 17 mi W Boise City. Cimarron Co.: 3 mi. WSW Felt; Kenton; 0.5 mi. SE Kenton; 2 mi S, 4 mi. E Kenton; 2 mi. S, 5 mi. E Kenton; 0.8 mi. S, 2.1 mi. E Kenton; 2.5 mi. S Kenton; 2.5 mi. S, 4 mi. E Kenton; 3 mi. N Kenton; 3 mi. NE Kenton; 3 mi. S Kenton; 2.5 mi. S Kenton; 2.5 mi. SE Kenton; 4 mi. NE Kenton; 5 mi. N Kenton; 6 mi. N Kenton; 6 mi. S, 2 mi. E Kenton; 8 mi. S Kenton; Tesequite Canyon; Tesequite Canyon, 4.4 mi. from hwy. Texas Co.: 2 mi. E Eva. Texas. Dallam Co.: 16 mi. ENE Texline; Texline (Nelson, 1909); Buffalo Springs (Bailey, 1905). Lipscomb Co.: Lipscomb (Nelson, 1909). Sylvilagus jloridanus Itanensis Blair, 1938 Eastern Cottontail The eastern cottontail ranges across the panhandles of Texas and Oklahoma, but there are few actual records from the latter state (Fig. 12). Although occupying much the same general areas as the desert cottontail, the two species are generally found in different habitats. S. Jloridanus prefers agricul¬ tural lands, pastures, and the environs of towns and buildings. The desert cottontail generally avoids mesic habitats, preferring sheltered areas on open prairie and arid brushland. In the pinon-juniper zone of the Black Mesa area, we found S. audubonii only, but we suspect that S. Jloridanus occurs in eastern and southern Cimarron County. Findley et al. (1975) did not record the eastern cottontail from Union County. However, we found it present in at least the extreme eastern part of the county. An adult female collected in Beaver County on 17 May was lactating. Specimens from the Texas and Oklahoma panhandles clearly are referable to S. / llanensis. Hall (1981) mapped a distributional hiatus in eastern New Mexico as separating populations from the panhandles from those of eastern New Mexico. The specimen from west of Clayton bridges this gap, and compares favorably with S. /. llanensis to the east. Specimens examined { 11).-New Mexico. Union Co.: 1 mi. W Clayton, 1 . Oklahoma Beaver Co.: 2 mi. N Beaver, 1. Texas. Dallam Co.: 10 mi. E Texline, 2 (TTU); 16 mi E Dalhart 1 (TTU). Hansford Co.: 10 mi. S, 3 mi. W Gruver, 1 (KU). Lipscomb Co.: 4 mi. E Booker’ 1 (WTSU). Ochiltree Co.: 2 mi. S, 4 mi. E Perryton, 1 (TTU); 12 mi. S, 9 mi. E Perryton, 1 (TTUV 9 mi. S, 11 mi. E Spearman, 2 (TTU). DALQUEST ET AL.—MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 23 Fig. 12.—Distribution oiSylvilagus floridanus (circles) and S. nuttallii (squares) in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Literature records.— Oklahoma. Beaver Co.: 5 mi. E, 3 mi. N Elmwood; N Canadian River, 4 mi. S Floris. Cimarron Co.: 6.6 mi. W Boise City; 8 mi. E Felt. Texas. Dallam Co.: 6 mi. SW Stratford. Lipscomb Co.: Lipscomb (Nelson, 1909). Sylvilagus nuttallii pinetus (J. A. Alien, 1894) Nuttall’s or Mountain Cottontail The mountain cottontail has been recorded previously from Oak Canyon in extreme northwestern Union County (Fig. 12). A desert cottontail was taken in typical habitat for S. nuttallii in adjacent Tollgate Canyon. We suspect that, in this area at least, S. audubonii is invading areas formerly occupied by the mountain cottontail. However, in the Capulin Mountain area a short distance to the south, S. nuttallii still occurs, and at considerably lower elevations than in Tollgate Canyon. A recently weaned young animal (112.5 in weight) was obtained north of Capulin on 19 July. Specimens examined (3).— New Mexico. Union Co.: 5 mi. N Capulin, 1; base of Capulin Mountain, 2. Literature records.— New Mexico. Union Co.: Raton Range, Oak Canyon, 5 mi. N Folsom; Sierra Grande Lepus califomicus melanotis Mearns, 1890 Black-tailed Jackrabbit In past years, the black-tailed jackrabbit had been an abundant animal throughout most of the study area. This was true when our collecting efforts first were begun in the 1960s. However, when our activities were resumed 24 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Fig. 13.—Distribution of Lepus californicus in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. in 1983, we found jackrabbits to be uncommon. Whereas in past years road- killed corpses littered the highways, one can now travel for many miles without seeing one. Jackrabbits still are widely distributed throughout the study area (Fig. 13), and even occur in clearings in the pinon-juniper zone, but seem to be absent in higher clearings, at the margin of yellow pines. Specimens examined (7).— Oklahoma. Cimarron Co.: 27 mi. WNW Boise City, 1. Texas. Hansford Co.: 1 mi. S, 2 mi. E Gruver, 1 (KU). Lipscomb Co.: 1.5 mi. N, 3 mi. W Catesby, Oklahoma, 1 (WTSU); 2 mi. E Booker, 1 (WTSU). Ochiltree Co.: 0.25 mi. S Perryton, 1 (TTU); 9 mi. S, 11 mi. E Spearman, 1 (TTU). Sherman Co.: 5 mi. N Stratford, 1 (TTU). Literature records .—New Mexico. Union Co.: Clayton. Oklahoma. Beaver Co.: 0.5 mi. S, 5 mi. W Gray; Cimarron Co.: 4.6 mi. W Boise City; 6 mi. W Boise City; 17 mi. E, 5 mi. N Boise City; 17 mi. W Boise City, 4.4 mi. N, 1 mi. W Kenton; 1 mi. N, 10 mi. E Wheeless; 1 mi. N, 15 mi. E Wheeless; T. 4N.R.3E., sec. 36. Texas Co.: 6 mi. N, 14 mi. W Guymon. Texas. Dallam Co.: Texline (Nelson, 1909); 5 mi. N Dalhart. Lipscomb Co.: Lipscomb (Nelson, 1909). Tamias quadrivittatus quadrivittatus (Say, 1823) Colorado Chipmunk The Colorado chipmunk is found throughout much of the higher parts of the pinon-juniper zone of Union County and on the Black Mesa of Oklahoma (Fig. 14). Despite its extensive range, we found it uncommon and collected few specimens. At Trampiros Creek in southern Union County, we noted remains of pinon cones, scattered on large boulders, that appeared to have been opened by chipmunks. In the summer of 1968, Dalquest noted a chipmunk on the eastern peak of Rabbit Ears Mountain, in Union County, just a few miles from the Texas border. Subsequent attempts to secure chipmunks, or find evidence of their DALQUEST ET AL.-MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 25 Fig. 1 4.—Distribution of Tamias quadrivittatus in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. continued presence there, have failed. An adult male taken near Kenton on 18 April had scrotal testes measuring 17 in length. Specimens examined (4).— New Mexico. Union Co.: 10 mi. N Folsom, 1; 4 km. N, 17 km. W Kenton, 1. Oklahoma. Cimarron Co.: 5 mi. NNW Kenton, 1; 4.5 mi. NNW Kenton, 1. Literature records.-- New Mexico. Union Co. : Emory Peak; Folsom; Sierra Grande. Oklahoma: Cimarron Co.: canyon, E of North Carrizo Creek; 0.5 mi. SE Kenton; T. 4 N, R. 1 E, sec. 5, 3.5 mi. S, 0.5 mi. W Kenton; 1 mi. S, 2 mi. E Kenton; 6 mi. S, 2 mi. E Kenton; 3 mi. S, 2.5 mi. E Kenton; 4 mi. SE Kenton; 4.2 mi. S, 0.5 mi. E Kenton; 4.2 mi. S, 0.8 mi. W Kenton; 4.5 mi. SE Kenton; rocks above Spring Canyon, Regnier Ranch, 5 mi. S Kenton; 1.5 mi. S, 5.5 mi. E Kenton. Spermophilus spilosoma marginatus Bailey, 1902 Spotted Ground Squirrel The spotted ground squirrel is found throughout the panhandles, exclusive of the pihon-juniper zone of Oklahoma (Fig. 15). Its range seems to be governed by presence of sandy soils, and consequently its distribution is correlated mostly with the sandy terraces of streams. Such sandy areas are of limited value for agriculture and, therefore, are left as uncultivated sandsage. Where roads pass through these areas, spotted ground squirrels may be seen standing upright, or scurrying for cover from oncoming vehicles. The species is rarely prominent, and is quite shy and secretive for a ground squirrel, accounting for relatively few records. Specimens examined (8).— Texas. Dallam Co.: 10 mi. E Texline, 4 (TTU); 21 mi. N Dalhart, 1 Lipscomb Co.: Lipscomb, 1 (USNM); 2 mi. NW Lipscomb, 2. Literature records .—Oklahoma. BeaverCo., lOmi. N, 12 mi. E Beaver Cimarron Co.: 13 mi. S Boise City; 14 mi. W Boise City; 15 mi. W Boise City. Texas Co : 4.5 mi. N Guymon; 5.5 mi. N Guymon; 1 mi. S, 6 mi. E Hardesty; 1 mi. S, 7 mi. E Hardesty. Texas. Dallam Co.: Dalhart. 26 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Fig. 1 5 —Distribution of Spermophilus spilosoma in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Spermophilus tridecemlineatus (Mitchill, 1821) Thirteen-lined Ground Squirrel This ground squirrel occupies the same general distribution as the spotted ground squirrel (Fig. 16) but has a broader ecological tolerance, living on firm or even hard-packed soils. The two species may occur in the same local areas. In Lipscomb County, a thirteen-lined ground squirrel was flooded from its burrow along the margin of a shallow wash where, less than a half mile away, an individual of S. spilosoma similarly was taken. These squirrels commonly live in or near towns, ranch houses, and prairie dog colonies. Short-grass areas are preferred; brushy areas are avoided. The mowed margins of roads also are favored habitat. Females taken in May and July were lactating. Hall (1981) mapped the entire study site as within the range of S. t. arenicola. Our specimens from New Mexico, Texas, and the westernmost two Oklahoma counties are referable to this taxon. However, specimens from Beaver County are darker, and indistinguishable from individuals of S. t . texensis from southwestern Oklahoma and north-central Texas. Spermophilus tridecemlineatus arenicola (A. H. Howell, 1928) Specimens examined (29). -New Mexico. Union Co.: 8 mi. S Capulin, 1; Clayton 1 Oklahoma Cimarron Co : 2 m., EBo.se City, 1 Texas Co.: Guymon, 1; near Guymon, 1.’ Texas Dallam Co.: 1 mi. N, 3 m.. W Dalhart, 1 (TTU). Hansford Co.: 8 mi. N Spearman. 1 (WTSUV Gruver 2 (KU); 8 mi S Spearman, 1 (TTU). Lipscomb Co.: 2 mi. E Booker, 1 (WTSU); Lipscomb 3 (USNM); 13 mi. S, 13.5 mi W Lipscomb, 1 (TTU); 2 mi. NW Lipscomb, 1. Ochiltree Co ■ Perryton, 12 (TTU). Sherman Co.: 3 mi. SW Texhoma, 1 (TTU) Literature records.- New Mexico. Union Co.: Clayton; Folsom. Oklahoma. Cimarron Co • Black Mesa; 1 mi. S, 3 mi. E Boise City; 2.5 mi. S, 4 mi. E Boise City; 14 mi. E Boise City Texas DALQUEST ET AL.-MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 27 Fig. 16 —Distribution of Spermophilus tridecemlineatus in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Co.: 2 mi. E Eva; Coldwater Creek, S Guymon; NE Guymon. Texas. Dallam Co.: 20 mi. E Texline (Howell, 1938). Spermophilus tridecemlineatus texensis Merriam, 1898 Specimens examined (3).— Oklahoma. Beaver Co.: Beaver, 3. Literature record.— Oklahoma. Beaver Co.: Lake Evans Chambers. Spermophilus variegatus grammurus (Say, 1823) Rock Squirrel The rock squirrel probably is found throughout the rough and broken lands of Union and Cimarron counties (Fig. 17); Blair’s (1939) record from Beaver County seems an anomaly. We found this species to be rare and shy. Individuals were seen at a number of sites in Union County and in the Black Mesa area of Oklahoma, but the squirrels invariably took shelter quickly. Specimen examined(l). -Oklahoma. Cimarron Co.: 4.5 mi. N Kenton, 1. Literature records.— New Mexico. Union Co.: Clayton, Apache Canyon; Folsom; Sierra Grande. Oklahoma. Beaver Co.: no specific locality (Blair, 1939). Cimarron Co. . Black Mesa; Clark Ranch, 15 mi. N, 5 mi. W Boise City; 1.7 mi. E Kenton; 3 mi SE Kenton; 2.5 mi. SE Kenton; 4 mi. N Kenton; 4.2 mi. S Kenton; 4.2 mi. S, 0.5 mi. E Kenton; canyon, east side North Carrizo Creek, 6 mi. N Kenton. Cynomys ludovicianus ludovicianus (Ord, 1815) Black-tailed Prairie Dog Prairie dog “towns” are found in every county of the study area (Fig. 18). These colonies often are destroyed by ranchers and farmers, but the animals remain moderately common, especially in Cimarron County. 28 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Fig. 17.-Distribution of Spermophilus vanegatus in the tristate study region. Solid symbol represents specimen examined; open symbols represent literature records. Fig. 18.—Distribution of Cynomys ludovicianus in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Individual sightings of animals running across roads during spring and summer months, often miles from any known prairie dog town, probably represent dispersers. Specimens examined (12).— Oklahoma. Cimarron Co.: 12 mi. ENE Boise City, 1. Texas. Dallam Co.: 20 mi. ENE Texline, 1 (USNM); 10 mi. E Texline, 2 (TTU); 6 mi N Conlen, 2 (WTSU); 15 mi. W Stratford, 1 (WTSU) Hansford Co.: 2 mi W Gruver, 1 (KU). Lipscomb Co.: Lipscomb, 1 DALQUEST ET AL —MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 29 FlC. 19.-Distribution of Sciurus aberti (square) and 5. niger (circles) in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. (USNM). Ochiltree Co.: 8 mi. N Perryton, 1 (KU); 7 mi. S, 6 mi. E Perryton, 1 (TTU); 23 mi. S ^^^itm’ture^TCCords .—New Mexico. Union Co.: near Clayton (Seton, 1929); 12.8 km. S Clayton (Chesser, 1983); 8.5 km. NE Des Moines (Chesser, 1983); 9.6 km. E Hayden (Chesser, 1983). Oklahoma. Beaver Co.: 11 mi S, 4 mi. W Beaver City; 8 mi. S, 4.5 mi. E Elmwood Cimarron Co • 1 mi. S, 2 mi. W Boise City; 5.2 mi. S, 5.1 mi. E Boise City; 8 mi. E Kenton; 7 mi. N, 2 m. L Kenton 1 mi S, 1 mi. W Wheeless; 0.5 mi. S, 1.3 mi. E Wheeless. Texas Co : 4 m. N Guymon; 4.5 mi. N, 5.5 mi. W Guymon; 3 mi. S, 4.5 mi. W Turpin. Texas. Lipscomb Co.: Higgins. Sciurus aberti ferreus True, 1894 Abert’s Squirrel We were surprised to find this squirrel on the Cornay Ranch just north ol Capulin Mountain (Fig. 19). Two were seen on the steep slopes just west of the ranch house, in thick woodlands of large jumpers and oaks. Large ponderosa pines, reportedly (see, for example, Armstrong, 1972; Findley et al., 1975; Keith, 1965) a major limiting resource for this species, also were Recently published records of S. aberti (Davis and Bissell, 1989) have extended considerably the known range of the species in Colorado, the result of either active range expansion or simply the discovery of populations overlooked by earlier workers. Our specimen is assigned on geographic grounds to S', a. ferreus following Hoffmeister and Diersing (1978), who considered S. a. mimus Mernam, 1904, to be a synonym of ferreus. Specimen «amm«/(l).-NEW Mexico. Union Co.: 5 mi. N Capulin, 1 30 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Fig. 20 -Distribution of Thomomys bottae in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Sciurus niger rufiventer E. Geoffroy St.-Hilaire, 1803 Fox Squirrel Fox squirrels occur in riparian habitat along watercourses of the Texas Panhandle, and just enter our study area to the south (Fig. 19). They were looked for without success along the Beaver and Cimarron rivers of the Oklahoma Panhandle. Specimens examined { 9). -Texas. Hansford Co.: 3 mi. S, 6 mi. W Gruver, 6 (3 KU, 3 TTU); 10 mi. S, 3 mi. W Gruver, 3 (TTU). Literature records. -Texas. Lipscomb Co.: Wolf Creek. Ochiltree Co.: Wolf Creek. Thomomys bottae cultellus Kelson, 1951 Botta’s Pocket Gopher T. bottae does not occur in the Texas and Oklahoma panhandles (Fig. 20), although Best (1973) recorded specimens from just north of Clayton, less than 20 miles west of Dallam County, Texas. These may represent a relict population. In western Union County, especially in clearings in coniferous woodlands and along roadsides in wooded areas, the species is common, and is the only pocket gopher present. Sympatry or near sympatry of three genera of pocket gophers in Union County, northwestern Cimarron County, and adjacent parts of southeastern Colorado, has drawn the interest of other investigators. Best (1973) made an exhaustive study of gophers in Union County. Moulton^ al. (1983) made a similar study in Colorado and parts of Union and Cimarron counties. With DALQUEST ET AL—MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 31 such large collections on record, our efforts were limited mostly to study of comparative material. Botta’s pocket gopher reaches its eastern distributional limit in Union County. Here, the species does not occur together with either Cratogeomys or Geomys (Best, 1973), although elsewhere (Moulton etal., 1983) Thomomys may occur in sympatry with the larger Cratogeomys. Best (1973) thought that the three genera, in areas of sympatry or near- sympatry, were separated by complex and interwoven ecological factors, and that soil type was most important. Thomomys prefers relatively mesic conditions, and thrives in clay-loam soils with some consolidated particles. Our observations in Union County substantiate this. Moulton^ al. (1983) considered soil type less important a factor, but found that Thomomys burrows were consistently shallower than those of sympatric Cratogeomys. This was considered by them as an intermediate stage in interspecific competition, and that Cratogeomys eventually would displace the smaller Thomomys. It seems probable that T. bottae in western Union County, where it is the only species of pocket gopher present, represents part of the original population, still unthreatened, whereas gophers occurring farther to the east are relict populations on the verge of extinction. Dalquest et al. (1990) examined ancient beaver dam sediments of Holocene age from four sites on the Black Mesa and southeastern Union County. Remains of Thomomys were found south of Clayton ( ca . 530 years BP), in extreme northeastern Union County {ca. 2630 years BP), and at the Black Mesa of Oklahoma {ca. 2700 years BP), but Geomys and Cratogeomys were absent. A Pleistocene site at Tesequite Canyon {ca. 31,000 years BP), reported on by Dalquest and Stangl (1989), also produced only Thomomys. Some females collected in May and July were lactating. Three from northeastern Union County carried small fetuses (litter sizes four, four, and five) that were 5-6 in crown-rump length. Scrotal testes of males averaged larger (length 20 or greater) in May than in July. A half-grown animal was taken on 27 July. Specimens examined (41).— New Mexico: Union Co.: 5 mi. N Capulin, 10; Capulin Mountain, 5 mi. NNE Capulin, 6; N side Capulin Mountain, 3; Capulin Mountain, 3; 4 mi. N Capulin, 2; 3 mi. N Capulin, 1; 10 mi. N Folsom, 1; Folsom Falls, 4 mi. NE Folsom, 13; 8 mi. S Capulin, 1; Hwy. 453 and Carrizo Creek, 26 mi. W Clayton, 1 Literature records.—N ew Mexico. Union Co.: Folsom; Oak Canyon, Raton Range; Sierra Grande. All Union County records as follows are from Best (1973): 9 mi. N, 2 mi. E Folsom; 3.6 mi. N, 3.3 mi. E Folsom, 1.4 mi. N, 2.7 mi. W Folsom; 0.4 mi. S, 0.8 mi. W Folsom; 3.2 mi. N, 0.9 mi. E Capulin; 1.7 mi. E Des Moines; 1.4 mi. S, 3.5 mi. E Des Moines; 2.4 mi. S, 10.3 mi. E Des Moines; 8.8 mi. N, 2 mi. E Grenville; 4.5 mi. S, 8.7 mi. E Des Moines; 4.5 mi S, 5.1 mi E Des Moines; 5.6 mi. S, 2.3 mi. E Des Moines; 2.2 mi. N, 6.3 mi. W Grenville; 2 mi S, 1.2 mi E Grenville; 5.9 mi. N, 5.1 mi. W Clayton; Mt. Dora; 1.5 mi. S, 6 mi. E Mt. Dora; 1.7 mi. S, 5.8 mi E Mt. Dora; 2.4 mi. N, 7.6 mi. W Clayton; 2.8 mi. N Sofia; 2 mi. N Sofia; 2.5 mi. S, 5.3 mi. W Mt Dora; 1.7 mi. W Sofia; 1.8 mi. E Sofia; 10.2 mi. E Sofia; 5.5 mi. E Sofia; 4.3 mi. S Mt Dora; 8.6 mi N, 1 mi. E Gladstone; 6.1 mi. N Gladstone. 32 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Fio. 21.-Distribution of Geomys bursarius in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. Geomys bursarius (Shaw, 1800) Plains Pocket Gopher The plains pocket gopher occurs in all counties of the study area (Fig. 21), but its distribution is not so general as records might suggest. It does not penetrate into western Union County, where only Thomomys occurs. Else¬ where in that county, Geomys appears to be a recent immigrant, as suggested by lack of remains from Pleistocene (Dalquest and Stangl, 1989) and Holocene sediments (Dalquest et al , 1990) from as recent as 500 years BP. The natural range of the plains pocket gopher in the study area is dendritic, confined to terraces and meadows of stream valleys. Human disturbance of the land has created more extensive habitat, and the species now occupies farmlands, roadsides, and gardens. Gopher mounds found in artificially created habitats were invariably those of G. bursarius. Geomys seems not to come into contact with Thomomys in Union County, although ranges of the two genera approach closely. In Colorado to the north, this also appears true (Moulton et al ., 1983). Ranges of Geomys and Cratogeomys castanops exhibit considerable general sympatry, although the two are ecologically separated. In such areas, Moulton et al. (1983) found Geomys restricted to roadside ditches, whereas Cratogeomys occupied open rangeland. Two females from Lipscomb County were pregnant. One taken on 31 March contained two fetuses measuring 22, and another collected on 1 April carried five, measuring 13. Two nominal races of the plains pocket gopher occur in our study area. G. b. jugossicularis occupies Union County, New Mexico (Best, 1973), and adjoining Dallam County, Texas (Jones et al ., 1988). Our one specimen DALQUEST ET AL—MOUNTAIN-PLAINS INTERFACE ZOOGEOGRAPHY 33 from Cimarron County also appears referable to this taxon. Although we have seen no specimens from Texas County, our two gophers from Beaver County and those from elsewhere in the Texas part of our study area are referred to G. b. major. Geomys bursarius jugossicularis Hooper, 1940 Specimens examined ( 12). -Oklahoma. Cimarron Co.: 1 mi. E Boise City, 1 . Texas. Dallam Co.: 12 mi. E Texline, 4 (TTU); 5 mi. E Perico, 4 (WTSU); 1 mi. N, 3 mi. W Dalhart, 2 (TTU); 2.5 mi. E Dalhart, 1 (TCWC). Literature records.—N ew Mexico. Union Co.: 4 mi. S Clayton, Perico Creek. All Union County records as follows are from Best (1973): 13.3 mi. N, 14.8 mi. E Grenville; 2.6 mi. N, 3.8 mi. W Moses; 10.3 mi. N, 17.2 mi. E Grenville; 10.3 mi. N, 18.5 mi. E Grenville; 3.1 mi. E Moses; 0.7 mi. S, 0.5 mi. W Moses; 7.3 mi. N, 1 mi. W Grenville; 10.5 mi. N, 10 mi. E Mt. Dora; 4.7 mi. N, 2 mi. E Grenville; 2 mi. N, 3.4 mi. W Seneca; 0.7 mi. N Seneca; 1.3 mi. N, 1.5 mi. E Grenville; 5.9 mi. N, 10.2 mi. E Mt. Dora; 7.9 mi. N, 10.1 mi. E Clayton; 4 mi. S, 1.1 mi. W Seneca; 5.7 mi. N, 10 mi. E Clayton; 2 mi. S, 9.3 mi. W Clayton; 1.8 mi. S, 4.8 mi. W Clayton; 3.7 mi. W, 4.8 mi. S Clayton; 5.5 mi. S Clayton; 6.8 mi. S, 4.25 mi. E Clayton; 1.5 mi. N, 5.2 mi. E Pasamonte; 2.2 mi. N, 12.8 mi. E Pasamonte; 9.1 mi. S, 7.8 mi. E Clayton; 10.1 mi. S Clayton; 1 mi. N, 1 mi. E Thomas; 13.5 mi. S Clayton; 14.6 mi. S Clayton; 6 mi. N, 4.9 mi. E Sedan; 1.6 mi. N, 3 mi. W Sedan; 3.2 mi. N, 2.4 mi. W Amistad; 3.7 mi. S, 0.4 mi. W Amistad. Oklahoma. Cimarron Co.: N Boise City; 8 mi. W Boise City. Texas. Dallam Co.: 15 mi. E Texline (Hall and Kelson, 1952). Geomys bursarius major Davis, 1940 Specimens examined (17).— Oklahoma. Beaver Co.: 2 mi. N Beaver, 2. Texas. Lipscomb Co.: 2 mi. NNW Lipscomb, 3; 3.2 km. NNW Lipscomb, 2; 2 mi. N, 8 mi. E Lipscomb, 2 (TTU); 1 mi. N, 1 mi. W Lipscomb, 1; Lipscomb, 4(USNM); 9 mi. E Lipscomb, 1 (TTU); 8 mi. NW Higgins, 1 (TTU). Ochiltree Co.: 25 mi. SEPerryton, 1 (TCWC). Literature records.— Oklahoma. Beaver Co.: 2 mi. W Forgan; 3 mi. S, 3 mi. E Slapout. Texas Co.: Guymon; RR at Hooker. Cratogeomys castanops perplanus (Nelson and Goldman, 1934) Yellow-faced Pocket Gopher This pocket gopher ranges throughout much of the study area (Fig. 22), but its distribution is discontinuous and it may be rare or absent locally. These large gophers are powerful diggers, able to penetrate even the caliche layer often underlying the thin prairie soil. They also occupy disturbed, loamy soils of roadsides, and are found in sandy areas in the absence of Geomys. The species seems to be absent from much of the eastern parts of the two panhandles, where Geomys occupies habitat that otherwise could be inhabited by Cratogeomys. This distribution suggests that C. castanops is a recent immigrant from the south or west. Half-grown animals were taken in April and June from near Kenton, and an adult female taken on 31 July was lactating. We follow Hollander’s (1990) recent revision of this species in assigning all Cratogeomys from within our study area to C. c. perplanus. Specimens examined (45). -New Mexico. Union Co.: Rabbit Ears Mountain, 2; 3 mi. ENE Seneca, 1. Oklahoma. Cimarron Co.: 5 mi. N Kenton, 1,4.5 mi. N Kenton, 2; 4 mi. N Kenton, 3; 3 mi. N Kenton, 1; 4.3 mi. S, 2.4 mi. E Kenton, 2 (TTU); 3 mi. S, 2 mi. E Kenton, 1 (TTU); 1.5 mi. S, 3 mi. E Kenton, 6 (TTU). Texas. Dallam Co.: 12 mi. E Texline, 1 (TTU); 1.7 mi. S, 0.3 mi. W Texline, 1 (NMSU); 2.4 mi. S, 0.3 mi. W Texline, 2 (NMSU). Hansford Co.: 5 mi. SW Gruver, 2; 6 mi. S, 3 mi. W Gruver, 1 (KU); 11 mi. SW Gruver, 1 Lipscomb Co.: 5 mi. S Booker, 34 SPECIAL PUBLICATIONS MUSEUM TEXAS TECH UNIVERSITY Fig. 22.-Distribution of Cratogeomys castanops in the tristate study region. Solid symbols represent specimens examined; open symbols represent literature records. 4 (WTSU). Ochiltree Co.: 11 mi. S, 4 mi. E Perryton, 1 (TTU); 12 mi. S, 9 mi. E Perryton, 9 (TTU). Sherman Co.: Stratford, 3 (TTU); 8 mi. S, 2 mi. E Stratford, 1 (TTU). Literature records.— New Mexico. Union Co.: Clayton. All other Union County records as follows are from Best (1973): 9 mi. N, 34 mi. E Folson; 29.5 mi. N, 0.9 mi. E Mt. Dora; 33 mi. N, 6.3 mi. W Clayton; 6 mi. N, 2.6 mi. E Moses; 3.3 mi. N, 2.2 mi. E Moses; 0.5 mi. E Clayton Lake; 6.5 mi. N, 3.5 mi. E Clayton; 9 mi. E, 4.1 mi. N Clayton; 2.9 mi. N, 1.7 mi. W Clayton; 1.1 mi. N, 2.3 mi. W Clayton; 0.25 mi. S Clayton; 0.5 mi. S Clayton; 6.6 mi. S, 3.5 mi. E Mt. Dora; 4.5 mi. N, 5.2 mi. E Pasamonte; 4.9 mi. S, 12.9 mi. W Clayton; 7.4 mi. S, 17.3 mi. W Clayton; 1.2 mi. N, 3.6 mi. E Pasamonte; 1.2 mi. N, 7.2 mi. E Pasamonte; 1.2 mi. E Gladstone; 2.2 mi. E Gladstone; 9.7 mi. S Clayton; 0.6 mi. N, 0.5 mi. W Amistad. Oklahoma. Beaver Co.: 4 mi. E Elmwood Post Office. Cimarron Co.: 25 mi. NW Boise City; Pigeon Cave, 0.5 mi. N, 2 mi. E Kenton; 3.75 mi. S, 9.25 mi. E Kenton; 2.5 mi. SE Kenton; 2.6 mi. NNE Kenton; 4.4 mi. N, 0.4 mi. W Kenton; 2 mi. S, 5 mi. E Kenton; 5 mi. SE Kenton; 6 mi. N Kenton; north side Black Mesa, 6 mi. N Kenton; Tesequite Canyon, 7 mi. SE Kenton; 9 mi. SE Kenton; 10 mi. NW Kenton; 0.25 mi. S Colorado line on North Carrizo Creek; Tesequite Canyon; Tesequite Canyon, 4 mi. from Highway 325; T. 4 N, R. IE, sec. 4. Texas Co.: W Hooker. Perognathus Jlavescens copei Rhoads, 1894 Plains Pocket Mouse The plains pocket mouse is known from north (Bee