Special Publications Museum of Texas Tech University NUMBER 39 THE MAMMALS OF BIG BEND RANCH STATE PARK, TEXAS Franklin D. Yancey, 11 Museum and Department of Biological Sciences, Texas Tech University This study was supported by the Natural Resources Program (David H. Riskind, Director), Texas Parks and Wildlife Department. This study is published as part of a cooperative effort between Texas Parks and Wildlife Department and Texas Tech University to create a natural history database to serve the people of the state of Texas. Layout and Design: Jessica M. Carrillo and R. Richard Monk Cover Design: R. Richard Monk Editor: Clyde Jones Copyright 1997, Museum of Texas Tech University 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. This book was set in Times New Roman and printed on acid-free paper that meets the guidelines for permanence and durability of the Committee on Production Guidelines for Book Longevity of the Council on Library Resources. Printed: 1 October 1997 Library of Congress Cataloging-in-Public at ion Data Special Publications of the Museum of Texas Tech University, Number 39 Series Editor: Robert J. Baker The Mammals of Big Bend Ranch State Park, Texas Franklin D. Yancey, II ISSN 0149-1768 ISBN 0-9640188-5-3 Museum of Texas Tech University Lubbock, TX 79409-3191 USA (806)742-2442 CONTENTS INTRODUCTION. 1 DESCRIPTION OF BIG BEND RANCH STATE PARK. 3 Location..> ■ 3 Human History. 3 Climate... 6 Physiography... 6 Geology. 9 Soils .... 10 Vegetation. 10 MATERIALS AND METHODS. 15 Data Acquisition. 15 Data Analysis... 16 RESULTS OF FIELD WORK......... 19 CHECKLIST OF SPECIES. 23 FAUNAL ANALYSIS. 27 Species Diversity and Similarity.. 27 Species Composition. 27 KEY TO THE SPECIES. 33 ACCOUNTS OF SPECIES.43 Native Species. 43 Nondomestic Introduced Species. 172 Domestic Species... 173 Species of Postulated Occurrence. 175 Extirpated Species. 179 CONCLUSIONS AND RECOMMENDATIONS. .181 ACKNOWLEDGMENTS.. 185 LITERATURE CITED. 187 APPENDIX I. DATABASE FOR ENTRY OF FIELD DATA. 203 APPENDIX II. GAZETTEER OF LOCALITIES SAMPLED 205 INTRODUCTION With an area of approximately 1100 km 2 } Big Bend Ranch State Park (hereafter, BBRSP) is one of the largest state-managed land areas in North America. The park, which is under the jurisdiction of the Texas Parks and Wildlife Department (TPWD), is located in the Trans-Pecos Region of Texas in Brewster and Presidio counties (Carrico, 1994). Texas in general, because of its large size and a geographic location where four major physiographic subdivisions of North America merge, has a mamma¬ lian diversity that is exceptionally high (Schmidly, 1983). Asa result, the mammals of the state have been the focal point of several major faunal studies. Bailey (1905), Davis (1960; 1966; 1974), and Davis and Schmidly (1994) provide general assessments of the mammalian fauna of the state. Regional studies, such as those by Schmidly (1983) for East Texas, Goetze (1995) for the Edwards Plateau of central Texas, Choate (1991) for the Llano Estacado of West Texas, Jones ct al. (1988) for the northern Panhandle, and Dalqucst and Homer (1984) for the north-central part of the state, added significantly to our understanding of Texas mam¬ mals. Mammals from the Trans-Pecos Region of Texas also have received considerable attention. Initially, parts of the region w r ere covered in Meams’ (1907) survey of mammals along the Mexican border. Later, based pri¬ marily on data from specimens in collections, Schmidly (1977a) assembled a synopsis of the mammals of the Trans-Pecos Region. Moreover, mammals from spe¬ cific sites within the Trans-Pecos have been investigated in detail. These places include Guadalupe Mountains National Park (Davis, 1940; Genoways et ah, 1979; Comely et al., 1981) the Sierra Vieja (Blair and Miller, 1949), the Davis Mountains (Blair, 1940), and Big Bend National Park (Borell and Bryant, 1942; Easterla, 1973; Jones et al., 1993). In addition, the mammals of adja¬ cent areas in Mexico have been studied in detail (Baker, 1956; Anderson, 1972). However, the area that is now BBRSP has received little attention. LoBcllo (1976) and Scudday (1976a; 19765; 1976c) conducted short¬ term studies of the vertebrate fauna of selected sections of the area. These works included superficial surveys of the mammals in those sections, but a comprehensive, detailed analysis of the mammalian fauna of BBRSP is nonexistent. The purpose of this research was three-fold. The first objective was to assess the diversity of mammals in BBRSP. By determining the kinds of mammals that occur in the park, opportunities are provided for vari¬ ous studies involving other aspects of mammalian biol¬ ogy. Wilson (1992:314) states, “As biodiversity sur¬ veys proceed at the several levels, the knowledge gath¬ ered becomes an ever more powerful magnet for other kinds of science.” The next goal was to determine the distribution of the various mammals within BBRSP. Mapping the structure of the mammals in the park is a key element in estimating the conditions under which each species lives. Also, patterns of mammalian distribution, when linked with other biological and physical elements of the park, should prove instrumental in assessing the effectiveness of the park as a reserve (Wilson, 1992). This informa¬ tion will be of value regarding future consideration of conservation and management issues. The final purpose of this study was to consolidate data on the natural history' and ecology of the mammals of BBRSP. According to Schmidly (1977a), very- little is known about various aspects of the life history of several species of mammals in the area. In addition to providing information to the overall understanding of the mammals of BBRSP, these data will be valuable when exploring potential long-term ecological studies, as well as designing management and interpretive pro¬ grams for the park. DESCRIPTION OF BIG BEND RANCH STATE PARK Location Big Bend Ranch State Park lies within the Trans- Pecos region of the extreme western part of Texas. This area is situated in the north-east corner of the Chihuahuan Desert. The park is positioned just north of the Mexican state of Chihuahua, from which it is separated by the Rio Grande, Big Bend National Park and the town of Lajitas occur to the east, and the city of Presidio is found to the w-cst. The major portion of BBRSP is situated in the southeast comer of Presidio County, whereas a small part of the park occurs in the southwest comer of Brewster County (Fig. 1). The to¬ tal area of the park is approximately 1100 km 2 (Alloway, 1995; Tucci, 1995). Human History More than 250 archeological sites throughout BBRSP provide information regarding the lives of the early human inhabitants of the area. The first humans arrived in the area between 8000-12,000 years before present (Wauer, 1992; Carrico, 1994; Sansom, 1995). For centuries, these people subsisted by hunting game and gathering the seeds, fruits, and roots of native plants. Later, with the introduction of com, beans, and squash, agriculture evolved along the Rio Grande (Maxwell, 1994; Sansom, 1995). Gradually, the life styles of the hunter-gatherers and the agriculturists merged. The human inhabitants of the area exhibited this mixed-cul¬ ture strategy when the Spaniard Cabeza de Vaca, the first European to visit the Big Bend, arrived in 1535 (Saunders, 1976a; 19766; 1976c; 1976c/; Wauer, 1992; Maxwell, 1994; Sansom, 1995). Significant colonizations of the area in the Sev¬ enteenth and Eighteenth centuries reached no further north than the Rio Grande. For almost three centuries following its discovery by Europeans, the Big Bend re¬ gion w f as dominated by hostile Indians, first by the Apaches, then by the Comanches Then, in the mid- 1800s, Texas was annexed by the United Slates and an important trade route linking Chihuahua, Mexico with Missouri was discovered. Part of this route, which later became known as the Chihuahua Trail, followed Alanuto Creek through what is now r BBRSP (Saunders, 1976a; 19766; 1976c; 197 6d). In response to the development of the Chihuahua Trail, an early settler named Ben Leaton opened a trad¬ ing post near where Alamito Creek empties into the Rio Grande. The trading post subsequently was called Fort Leaton and became the outpost of civilization in the Big Bend area. American interests in the region grew, which prompted an effort to subdue activities of the hostile Comanches. Shortly after the Civil War, those efforts were successful and the area opened up to settle¬ ment (Wauer, 1992; Maxwell, 1994). With an increase in colonization in the area, many Americans saw the Big Bend as a potential for eco¬ nomic success. Ranching was the dominant commer¬ cial endeavor of the early settlers. Milton Favor w'as a successful pioneer rancher, having founded four large longhorn cattle and sheep ranches just north of BBRSP (Saunders, 1976a; 19766; 1976c; 1976c/). The first to ranch w'ithin what is now BBRSP was Andres Madrid, who developed a sheep ranch at the east end of the park in the 1870s (Anonymous, 1992). In addition to ranching, early settlers profited from mining activities. In 1882, silver was discovered in Shafter, a small town near the northwest portion of BBRSP. Approximately 20 million dollars in silver w as acquired from the mines of Shafter during about 40 years of operation. Also, cinnabar, the ore from which mer¬ cury is extracted, was mined in the region. Nearly 80 years of mining cinnabar in the Big Bend yielded ap¬ proximately 25 percent of the mercury' produced in the United States (Saunders, 1976a; 19766; 1976c; 1976 d). One of the major mercury mines, the Whitroy Mine, lies within present day BBRSP. Although the products of mining activities were important commodities, land use in what was to be BBRSP was still dominated by ranching well mto the Twentieth Century', Around 1910, the Bogel brothers acquired small sheep outfits and began assembling Big 3 4 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Figure 1. Geographic position of Big Bend Ranch State Park, Texas, Bend Ranch. However, in the 1930s, their business went bankrupt when the area was struck by a severe drought. Soon after, the Fowlkes brothers acquired the Bogel property, as well as other holdings, and assembled a 300,000 acre sheep ranch (Saunders, 1976a; 19766; 1976c; 1976(7; Allovvay, 1995). But in 1958, follow¬ ing a seven-year drought, they were forced to sell the ranch to the Big Bend Ranch Corporation (Saunders, 1976a; 19766; 1976c; 1976 d\ Carrico, 1994). The property was sold to Robert Anderson in the 1950s, and subsequently was developed into the 320,000 acre Dia¬ mond A Cattle Company (Saunders, 1976a; 19766; 1976c; 1976 d). The land remained in Anderson’s possession un¬ til 1988, when TPWD purchased it, along with hold¬ ings owned by Walter Mischer, for 8.8 million dollars (Saunders, 1976a; 19766; 1976c; 1976c/; Anonymous, YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 5 1 A La Cienega B Botilla C Las Quevas D Sauceda E Los Alamos F Tres Papalotes G Whitroy Mine H Barton Warnock Center KfLOMEtERS Figure 2. Locations of various sites mentioned in the text. 1992; Carrico, 1994; Alloway, 1995). Originally, TPWD designated the property as Big Bend Ranch State Natural Area. In 1995, the name was changed to Big Bend Ranch State Park (Anonymous, 1995a). At present, BBRSP accounts for over half the state park lands in Texas (Alioway, 1995). Currently, BBRSP is still in the developmental stages. There arc no paved roads in the park, and most visitor accommodations are primitive at best. Fourteen primitive campsites and four marked hiking trails arc in existence, but much of the park is closed to the public. Most visitor activity is centered on areas along the Rio Grande or near the park headquarters at Sauecda Ranch. The current structure of the park, along with locations of places mentioned in this report, arc depicted in Figure 2. These place names arc defined in Table 1 6 SPECIAL PUBLICATIONS* MUSEUM TEXAS TECH UNIVERSITY Table 1. List and description of some place names mentioned in the text Place _ Barton Warnock Environmental Education Center Botilla Fort Leaton La Ciencga Las Cuevas Los Alamos Sauceda Tres Papalotes Wtiitroy Mine Description ___ Park visitor information and interpretive center located in Lajitas Vacated ranch often used as a research facility State historical park and visitor information center Vacated ranch currently used as a research facility Area of impressive tuff formations with considerable archeological significance Vacated ranch sometimes used as a research facility Park headquarters with visitor and research facilities Former ranch and proposed site of research center Vacated mercury mine at southeast end of park Although visitation is relatively low at present, public tours and interpretive programs administered by both park personnel and private vendors are popular. Research opportunities in the fields of biology, geol¬ ogy, and archeology attract a variety of scientists. Also, in an attempt to lure tourists with a ranching interest, a herd of 100 to 150 longhorn cattle is maintained at the park. The policy of grazing cattle on a state park is a topic of considerable debate between environmental¬ ists and those associated with the ranching community. In an effort to increase the quantity of visitors, as well as the quality of their stay, TPWD has developed an operational plan for future improvements of BBRSP. Some of these actions are as follows: expand public use of the Rio Grande Corridor, Fresno Canyon, the Bofccillos Mountains, and the Solitario; renovate ex¬ isting facilities, especially at Sauceda; improve exist¬ ing roads and open new roads; open approximately 70 additional miles of hiking trails; increase interpretive programs, install wayside exhibits; and increase visitor safety by developing sc arch-and-rescue, emergency operations, and law enforcement plans (Carrico, 1994). Climate The climate of the BBRSP area is characterized as semiarid to arid (Hanselka, 1976a; 19766; Schmidly, 1977a), with mean annual temperatures of about 21°C (Dietrich, 1965). The winter months are dry and mild, although minimum temperatures frequently fall below freezing. Summers arc hot, with mean daily maximum temperatures often over 40°C (Hanselka, 1976a; 19766). Moderate to strong winds are common tlirough- out the year. The amount of precipitation in the area is low, with an annual average rainfall of about 28 cm. Most precipitation is the result of occasional convective thun¬ derstorms, usually occurring towards the end of sum¬ mer (Hanselka, 1976a; 19766). However, infrequent winter snowfalls also may contribute to the annual level of precipitation. Short-term droughts are common throughout the Trans-Pecos region, w r hereas extended droughts occur about every' 10 to 15 years (Schmidly, 1977a). During the period of this study, the area was in the midst of a six-year drought (Anonymous, 1996). The total amount of precipitation in 1994 (recorded at Lajitas) was only about 15 cm (Anonymous, 19956); that recorded in 1995 (recorded at Sauceda) was about 21 cm. Climatological data taken at Presidio over a 30 year period are summarized in Table 2. Physiography The physiography of BBRSP is highly variable. The terrain consists of mountains, lowlands, arroyos, and deep canyons. With over 100 streams, springs, and seeps scattered throughout the park, the watershed is unique and extensive. In general, the park can be di¬ vided into six physiographic zones. They are: the Cicnega Mountains, Alamito Creek and Tcmcros Creek lowlands, the Bofecillos Mountains, the Rio Grande Corridor, the Solitario, and Fresno Canyon-Contrabando lowlands (Carrico, 1994), The locations in the park that each zone occupies is illustrated in Figure 3. The Cienega Mountains region of BBRSP con¬ sists of the southern slope of Ciencga Mountain and its surrounding lowlands. The area technically is in the foothills of the Chinati Mountains, a fairly large moun- YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 7 tain formation to the west. The highest point in this zone is at the summit of Cienega Mountain, which is 1590 m in elevation. This peak lies outside of the north¬ ern boundary of the park. Inside the park, the highest elevation in this zone is approximately 1500 m on the southern slope of Cienega Mountain. The remainder of the zone is relatively level or gently sloped, with an average elevation of about 1200 m. The major hydrologic feature of this area is Cienega Creek. This is a small, permanent stream that flows north to south through the western end of the zone. Eventually, the creek empties into Alamito Creek. Other sources of water in the area include Chupedero and Cat springs, which arc small, permanent seeps. The Alamitos Creek-Terncros Creek lowlands zone consists mostly of relatively level bottomlands. These flats typically are about 1000 m in elevation. The exceptions are Cerro Redondo and the Black Hills. Cerro Redondo is a small, round, hill-like formation 1129 m in elevation, w'hich lies just north of Temeros Creek. The Black Hills is a group of small hills that occurs about midway between Temeros Creek and Alamito Creek. This formation has a peak elevation of 1109 m. The major source of water in this zone is Alamito Creek. It is a relatively large, permanent creek that drains into the Rio Grande. Temeros Creek, on the other hand, is dry the majority of die time, flowing only fol¬ lowing heavy rains. It too flows into the Rio Grande between Presidio and Redford. Alamo Seco and Black Hills creeks also arc ephemeral watersheds in the re¬ gion. The Bofecillos Mountains region is the largest physiographic zone in BBRSP. It is characterized by irregular arrays of mountains and mesas interspersed with spectacular canyons. Elevations range from 1565 m at the peak of Oso Mountain, die highest point in the park, to less than 1000 m at the bottom of some of the deeper canyons. Sources of water are abundant in the Bofecillos Mountains. Several natural seeps and springs of two types occur throughout the area. Primary springs are springs that are produced from ground water that has been discharged from bedrock aquifers present in un¬ derlying volcanic and sedimentary' rock. Secondary springs are those that form in the bottom of arroyos in response to water flowing underground that is forced to the surface by impermeable strata. These types of springs usually are in arroyos below primary' springs (Deal, 1976a). Table 2. Climatological data for the Big Bend Ranch State Park area , Figures reflect weather conditions monitored at Presidio, Texas from 1961 to 1990. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Average Temperature (°C): mean 10.6 13.4 17.8 22.6 26.7 30.3 30.7 29.6 27.0 21.9 15.5 11.3 21.4 maximum 13,2 16.2 20.9 25.6 29.1 33.9 33.6 31.5 29.5 24.1 19.1 14 1 22.4 minimum 7.9 10.2 15.2 18.9 24.0 28.4 27.8 27.2 23.8 18.3 12 2 9.4 20.3 High Temperature (°C): mean 20.2 23.8 28.6 33.1 36.7 39.2 38.6 37.4 35.0 30.9 25.2 20.8 30.7 maximum 24.1 28.1 32.1 35.8 39.5 42.4 41.3 41.2 37.8 34.9 28.7 24.9 31.8 minimum 16.4 20.3 25.0 29.6 32.7 36.4 34.9 34.4 30.9 27.2 21.1 17 4 29.6 Low Temperature CC): mean 0,9 3.0 7,0 11.9 16.7 21.4 22.7 21.7 18.9 12.8 5.8 1.7 12 1 maximum 4.6 5.3 10.6 15.3 19.0 25.4 26.1 234 21.4 15.7 9.3 5.8 13.7 minimum -2.5 -0.8 3.6 7.9 14.1 19.2 20.1 19.6 16.0 8.8 1.8 -1.3 10.7 Total Precipitation (cm): mean 0.8 0.9 0.4 0.9 1.5 4.2 4.3 4 8 5.0 2 6 1.0 11 27,5 maximum 3.0 6.6 3.6 8 8 4.5 9.6 10.8 13 3 16.8 124 5 1 8.8 46 4 minimum 0.0 0.0 0.0 0.0 0.0 0.1 00 0.3 0.9 0.0 0.0 0.0 12 2 8 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY i_i_i KILOMETERS Figure 3. General areas of the six physiographic zones that occur at Big Bend Ranch State Park. Two primary springs in the eastern part of the Bofecillos are major aquifers in the area. These are Chilcote or “Smith House Springs,” and Ojo Mexicana. These water sources feed Mexicana Falls above Ar¬ royo Segundo, which eventually feeds Fresno Creek. Additional primary springs in the area supply Madrid Falls above Chorro Canyon (Deal, 1976a). Other im¬ portant springs in the Bofecillos include Palo Aanarilto, Botilla, Rancherias, Aqua Adentro, and Ojito Adentxo. Water from the southern Bofecillos is drained by seven impressive canyons: Madera, Panther, Rancherias, Tapado, Las Burras, Auras, and Bofecillos canyons (Deal, 1976a; Smith 1976a), Water flow'ing YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 9 through each of these canyons form tributaries of the Rio Grande. The northern part of the Bofecillos Moun¬ tains is drained by northward flowing tributaries to Temeros Creek (Deal, 1976a). The Solitano is a circular mountain and basin fea¬ ture approximately 13 km in diameter. The outer rim consists of limestone mountains with elevations rang¬ ing from about 1300 to 1550 m. The central basin is mostly lowland flats with occasional resistant ridges comparable in elevation to the surrounding mountains. Elevations m the interior extend from 1250 to 1350 m (Deal, 19766; Smith, 19766). Permanent sources of water are lacking in the Solitario and flowing water is rare. However, follow¬ ing infrequent torrential rains, the basin is drained by four major streams or “shutups ” They are: the Lefthand Shutup, which drains the northern basin near Trcs Papalotes and eventually flows into Terlingua Creek to the east; the Lower Shutup, w4iich drains the southern interior and ultimately reaches Fresno Creek; and the Righthand and Los Portales shutups, which drain the western basin, also feeding Fresno Creek (Deal, 19766), Fresno Canyon is a deep canyon cut by Fresno Creek, a southw'ard-flowing tributary of the Rio Grande (Smith, 1976c). It separates the Bofecillos Mountains to the west from the Solitario to the east. Elevations in this zone range from approximately 1160 m in the floor of the canyon, to greater than 1600 m at its northwest¬ ern edge near the outer rim of the Solitario. The area is drained by Fresno Creek, which receives flow' from Arroyo Primero and Arroyo Segundo of the Bofecillos Mountains, and occasionally from the Low r er, Righthand, and Portales shutups of the Solitario (Deal, 1976c). The Rio Grande Corridor consists of the region along the southern boundary of BBRSP formed by the Rio Grande. To the east, the corridor consists of rela¬ tively flat lowlands with elevations as low' as about 700 m near Lajitas. Further west, the river cuts through deep canyons with sheer cliffs greater than 400 m in height. Elevations exceed 1500 m in some of the more mountainous areas along the river. These areas actu¬ ally are extensions of the Bofecillos Mountains to the north. Nearly all of the water from BBRSP eventually drains into the Rio Grande (Deal, 1976 cf). Geology The oldest and most complex rocks in the Big Bend area are those of Paleozoic age (550 to 300 million years ago). Following the deposition of these rocks, a series of orogenic events in the late Pennsylvanian-early Per¬ mian time resulted in the formation of the Ouachita fold belt. This continuous band of folding probably extended across a considerable portion of the southern United States and into North Africa, to which North America was in contact with at the time. Continental drift even¬ tually separated the North American fold belts from those of North Africa. This mountain-building period lasted up to 100 million years, during which consider¬ able erosion occurred simultaneously with active orog¬ eny. Another 50 million years of erosion took place following the termination of mountain building. This extensive erosion resulted in the formation of low, flat surfaces atop the complexly folded and faulted Paleo¬ zoic sediments (Deal, 19766). Following tire completion of the Ouachita Orog¬ eny, invasive Cretaceous seas deposited about 1200 m of thick, flat, limestone beds. Toward the late Creta¬ ceous and early Tertiary, a second orogenic event, the Laramide Orogeny, resulted in the formation of the American Cordillera. These folds are at nearly right angles to the Ouachita folds. As the result of continued orogeny, folding and faulting of the already complex Paleozoic rocks continued. Following the Laramide Orogeny, a series of igneous intrusions occurred and then volcanic eruptions covered the older limestone with ash and lava (Deal, 19766). Formation of the Solitario began in the early to middle Tertiary (45 to 20 million years ago). A lacolithic intrusion of magma into the Cretaceous limestone that failed to reach the surface caused the area to bulge. This activity formed the Solitario dome Subsequent ero¬ sion removed the Cretaceous rocks from the crest of the dome. This activity resulted in the formation of a bowl- shaped structure with an outer rim of Cretaceous lime¬ stone and an interior basin of Paleozoic sedimentary' rocks (Deal, 19766; Maxwell, 1994). While the Solitano w p as being formed by erosion, a large volcano up to 30 km in diameter and 1000 m in height, was forming the Bofecillos Mountains This volcano was formed atop the same complicated sequence 10 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY of Paleozoic and Cenozoic sedimentary rocks. Follow¬ ing a series of eruptions, the volcano remained as a gen¬ tly sloping cone consisting of alternating layers of solid lava, volcanic ash, and water-deposited sedimentary rocks. With time, eruptions became fewer and milder and several domed uplifls were formed when igneous intrusions failed to reach the surface. Subsequently, vertical displacements along several faults, followed by erosion by the Rio Grande and its tributaries, dissected the volcano and formed the mosaic of mesas and can¬ yons present today. The formation of the Bofecillos volcano was associated with other eruptive activity in the Big Bend area, including that responsible for the formation of the Cienega Mountains (Deal, 1976 a)- Soils Soil types arc highly variable throughout BBRSP. Soils in the mountainous areas usually are shallow and associated with igneous rocks and boulders. They are the result of weathering and erosion on moderately steep to steep slopes (Hansclka, 1976c). In Fresno Canyon, soils of this type are referred to as Brewster stony loams (Hanselka, 19766). Many lower areas below-the higher peaks and mesas have become Filled with shallow, grav¬ elly loams with stones up to 7.5 cm in diameter. Soils in shallow draws often are relatively deep and rich, with good soil-air-moisture-plant relationships (Hanselka, 1976a; 1976c). In the Fresno Canyon area, these soils are classified in the mimbres loam unit (Hanselka, 19766). In addition, cobbly, gravelly, sandy, silty, and clay loams occur in various regions throughout the park (Hanselka, 19766; 1976c). Rio Grande floodplane de¬ posits include Fine to medium sand, silt, and mud. Sidestreams typically deposit sand or sandy gravel (Deal, 1976 d). Vegetation Essentially all of the plants that occur in BBRSP belong to the northern Chihuahuan Desert flora (Powell, 1988). The vegetation of BBRSP can be grouped into four major habitat types: desert scrub, desen grass¬ land, riparian, and juniper roughland. Although there is considerable overlap in the species of plants that oc¬ cur in these habitats, each is defined by a dominant veg¬ etation. Currently, Chihuahuan Desert scrub (Fig. 4) prob¬ ably is the most widespread and abundant habitat type in the park, having replaced much of the former desert grassland (Powell, 1988). This plant community usu¬ ally is dominated by creosote-bush (Larrea tridentata ), but may consist of a mosaic of a number of scrub spe¬ cies such as ocotillo (Fouquieria splendens ), mesquite (Prosopis glcmdulosa ), acacia (Acacia sp.), mariola i-igure 4. Typical Chihuahuan Desert scrub habitat of Big Bend Ranch State Par! YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 11 (Parthenium incanum), lechuguilla ( Agave lechuguilla), candelilla {Euphorbia anti syphilitic a), leatherstem {Jatropha dioica), four-wing saltbush (Atriplex canescens), allthom ( Koeberlinia spinosa), agarito {Berberis trifoliolata), as well as several species of cacti ( Echinocereus sp., Mammillaria sp., Opuntia sp.) Historically, desert grassland (Fig. 5) was the dominant plant community throughout the area. Al¬ though a considerable portion of this habitat type has been modified by about 150 years of grazing by do¬ mestic livestock, a substantial amount of grassland re¬ mains m the park (Schmidly, 1977a; Powell, 1988). Species of grasses that dominate desert grassland in¬ clude blue grama {Bouteloua gracilis), side-oats grama (B. curtipendula), chino grama (B. ramosa), black grama {B. eriopodd), tobosa grass {Hilaria mutica), needlegrass {Stipa sp.), and bluestem ( Bothriochloa sp ). Other plants frequently associated with these grass¬ land habitats include sotol ( Dasylirion sp.), prickly pear cactus {Opuntia sp.), and yucca {Yucca sp.), to name a few. Water-associated or riparian habitats are scattered throughout the park wherever seeps, springs, streams, or rivers exist. Although only a small fraction of the habitats of the park can be described as riparian, this habitat may be the most significant in terms of biologi¬ cal diversity. The riparian flora of the interior of the park (Fig. 6) primarily consists of cottonwoods {Populus sp.), willows {Salix sp.), and seepwillows {Baccharis sp.), but often includes other plants such as catclaw acacia {Acacia berlandieri), common button- bush {Cephalanthus occidentalis), walnut {Juglans sp), and deergrass {Muhlenbergia sp.). Riparian habi¬ tats adjacent to the Rio Grande (Fig. 7) are dominated by salt cedar {Tamarix sp ), giant reed {Arundo donax), common reed {Phragmites australis), tree tobacco {Nic- otiana glauca), and various short grasses. Juniper roughland (Fig. 8) occurs only sparsely at higher elevations in isolated areas of the park. Such areas include the northern rim of the Solitario and the slopes of Cienega Mountain This habitat is composed of stands of red-berry juniper {Juniperus pinchotii) in rocky, upland terrain. Associated vegetation may in¬ clude various scrub species such as ocotillo, creosote, acacia, and prickly pear cactus. See Butterwick and Lamb (1976), and Butterwick and Strong (1976a; 19766; 1976c) for a comprehensive list of plants at BBRSP. SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Figure 6. Typical riparian habitat found in the interior of Big Bend Ranch State Park. Park. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK MATERIALS AND METHODS Data Acquisition The majority of the information used in this study was obtamed as a result of two years of field operations conducted at BBRSP. The focus of this field work in¬ volved the collection and preparation of mammals from numerous localities within the park boundaries. Several methods of capture as presented by Jones et al. (1996) were used to collect mammals. The use of mist nets as outlined by Kunz and Kurta (1988) was the primary method used to obtain bats. At dusk, nets were strung across selected springs, streams, or other small bodies of water that occur throughout the park. In some instances, nets were set in dry areas that ap¬ peared to be potential Byways for bats. Nets were ei¬ ther left overnight and tended to at dawn the follow ing morning or monitored throughout the night On occa¬ sion, when opportunity permitted, bats simply were re¬ moved from their roost by hand. Sherman live-traps baited with rolled oats were used extensively to capture rodents. Museum Special and Victor rat traps baited with peanut butter were used to a lesser degree. Line transects consisted of 30 to 250 traps set at 7 to 10 m intervals. On rare occasions, smaller arrays of traps were set in confined areas such as bams or sheds. Small arrays of Victor gopher traps were set in an effort to capture gophers. Traps typi¬ cally were set approximately one hour before sundown and retrieved approximately one hour after sunrise the following morning. Spring traps (Conibears, legholds), and wire mesh live traps (Havaharts) were used to capture carnivores. These traps were baited with small mammal carcasses or other scraps of meat, and sporadically set in arrays of 3 to 10 traps. They were set at sundown and checked the following morning at sunrise. In addition to the aforementioned capture meth¬ ods, mammals occasionally were taken with the use of firearms Also, some mammal specimens were obtained by salvaging already dead individuals, or parts thereof, which were found while doing field work Despite rough topography, limited number and poor condition of roads, and unpredictable weather, ever> f attempt was made to sample as much of the park and its various habitats as possible. Sampling locali¬ ties were accessed by four wheel drive vehicle, horse, and helicopter, as well as on foot. A sampling locality can be defined as the location where an array of traps was set, where an individual mist net was erected, or where an individual specimen was acquired by any of the other methods. All localities were acquired using a Magellan Meridian hand held global positioning sy s¬ tem (GPS). The unit is accurate to within 25 m (Anony¬ mous, 1993). However, due to a potential risk to na¬ tional security', the United States Department of Defense, which manages the system, periodically introduces a random error (termed Selective Availability or SA). When activated, SA reduces the accuracy of a position fix to w ithin 100 m of the actual location 95 percent of the time (August, 1993; Kerr, 1996) Therefore, in this report all given localities should be considered accu¬ rate ±100 m. Each locality' is based on Universal Trans¬ verse Mercator (UTM) coordinates. The globe is par¬ titioned into 60 zones, each of which is 6° w'ide as pro¬ jected from the Earth’s center. All localities were taken in zone 13. An easting coordinate refers to tine distance in meters east of a point 500,000 m west of the center of the zone. A northing coordinate is the distance in meters north of the Equator. For each trapline, a GPS fix w'as taken near the center of the line, and the corresponding UTM coordi¬ nates were assigned to all specimens captured on the transect. For all other methods of collection, UTM fixes w'ere taken at the exact site of collection. The majority' of mammals collected were retained as voucher specimens, In instances where an excessive number of a particular species was captured at the same locality, individuals were released following identifi¬ cation, Mammals retained were prepared as museum specimens in an appropriate manner Most individuals were prepared as standard skin and skull specimens fol¬ lowing Hall (1962) and DcBlasc and Martin (1981). In certain cases where retaining the skin was not pos¬ sible (excessive damage or decay in salvaged speci¬ mens), only the skull was kept Likewise, if the skull 15 16 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY was excessively damaged, only the skin was retained. Some specimens were preserved in fluids. Tissue speci¬ mens consisting of skeletal muscle, liver, heart, and kid¬ ney were collected from selected individuals. Upon re¬ moval, tissues were temporarily frozen in liquid nitro¬ gen pending deposition in an -80° C ultracold freezer for long-term storage. Samples of brain were collected from selected bats and carnivores, and submitted to the Texas Department of Health for rabies testing. Karyo¬ types of selected individuals were prepared following Robbins and Baker (1983). Stomach contents of se¬ lected bats were analyzed following Whitaker (1988). All voucher specimens, including frozen tissues, are deposited in the Natural Science Research Laboratory (NSRL) of the Museum of Texas Tech University (TTU). While in the field, data pertaining to each mam¬ mal captured were entered into a spreadsheet/databasc program installed in a Macintosh Powerbook portable computer. The database structure, which was created using Microsoft Excel, version 3.0, was in accordance with documentation standards set forth by the Ameri¬ can Society of Mammalogists (McLaren et al., 1996). The design of the database and a description of the da¬ tabase fields into which data were entered are presented in Appendix I. In addition to data obtained from mammals col¬ lected in the field, information pertaining to this study was acquired by several other avenues. Often, mam¬ mals were encountered during the course of field work, but it was not possible or practical to collect them as specimens. These observations included mammals de¬ tected by sight, sound, or sign (scats, tracks). Also, useful information was acquired from observations of mammals reported by park personnel. Under these cir¬ cumstances, data regarding each observation were re¬ corded and entered into a separate database. Additional information for this study was obtained by examining specimens of mammals from the vicinity of Big Bend Ranch Collections of mammals surv eyed included TTU; the Angelo State University Mammal Collection Laboratory: the Texas Cooperative Wildlife Collection, Texas A&M University; Sul Ross State University; the Museum of Southwestern Biology, Uni¬ versity of New Mexico; and the United States National Museum. Only the collection at Sul Ross State Univer¬ sity contained specimens from BBRSP. Data acquired from specimens housed at that institution, along with information obtained from a thorough review of the lit¬ erature, were useful supplements to the data obtained in the field. Data Analysis Data were organized and sorted using the spread¬ sheet and database capabilities of Excel. In addition, this program was used to calculate all descriptive sta¬ tistics presented in this document. The Geographic Information System (GIS) at TPWD was used to analyze and map the distribution of the mammals at BBRSP. UTM coordinates were down¬ loaded from Excel into Arc View software installed in a Sun SPARCstation 20 computer. These data will form the basis for a mammal layer added the BBRSP GIS database. Additional layers already present in the sys¬ tem include park boundaries, geologic formations, geo¬ logic faults, geologic symbols, roads and jeep trails, urban locations, hydrology, sediment samples, contours, and feature updates (Erickson, 1994). All distribution maps presented throughout this document were produced via this system. Because a considerable effort was applied to trap¬ ping rodents, the ecological affinities of several rodents to vcgetational communities were tested. Habitats con¬ sidered were desert scrub, desert grassland, and ripar¬ ian. Occasionally, rodents were taken in juniper wood¬ land, but, as this habitat is scarce in BBRSP, sample sizes were too small to include this habitat in compari¬ sons. Thus, for certain rodents, chi-square values for variables plotted against a resampled distribution ob¬ tained at 1000 iterations (Bruce, 1992, Simon, 1992) were used to determine if any differences in habitat use existed. The alpha level for this test was set at 0.05. If there was a significant difference detected (<0.05), then a multiple-comparison chi-square test was used to de¬ termine which of the three habitats were responsible for the difference. The alpha level of rejection for this test was determined using the Bonfcrroni inequality for¬ mula, k YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 17 where a^ 2 is the original alpha level of the chi-square test used with all groups combined, and k is the number of individual treatment groups considered in the origi¬ nal test (Glantz, 1992). In this analysis, there were three treatment groups, or habitat types, and an original alpha level value of 0.05. Thus, the alpha level derived for these individual tests was 3 Jaccard's coefficient (Jaccard, 1912) similarity index was used to assess the interrelationship between the mammalian fauna of BBRSP with that of other re¬ gions within the Chihuahuan Desert. This index con¬ siders only presence-absence data, and bases similarity on the ratio of shared species to the total number of species present at both sites. It does not consider that the joint absence of a species contributes to the similar¬ ity of the two areas. The formula for Jaccard s coeffi¬ cient (Sp is: S = a/(a+u) where a is the number of species shared by the two ar¬ eas under consideration, and u is the total number of unshared species in the two areas (Willig and Mares, 1989). Species composition of bats was derived from the number of individuals of each species caught per net night, whereas the species composition of rodents was derived from the number captured per 100 trapnights. The percentage of total captures of each species also was determined for both rodents and bats. For rodents, only those species that were trapped with Sherman live traps or Museum Special snap traps were considered. RESULTS OF FIELD WORK Field work for this study commenced in January, 1994, and concluded in December, 1995. During this period, 303 specific localities throughout the park were sampled. All localities sampled are mapped in Figure 9, and specific localities for each sampling method used in this study are listed in Appendix II. Sampling efforts applied to these localities are summarized in Table 3. As a result of these efforts, a total of 1444 mammals, represented by 48 species, was acquired. Frozen tis¬ sues were collected from 411 specimens, representing 20 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 42 species. A list of mammals collected, along with the nature and quantity of specimens retained for each spe¬ cies, is presented in Table 4. In addition to information obtained from the collection of specimens, data pertain¬ ing to 88 observations of mammals were recorded. These observations arc discussed in the accounts of species. Table 3. Summary of efforts to colled mammals in Big Bend Ranch State Park during 1994 and 1995, Method Localities Number of Lines Number Set Mammals Taken Percent Success Mist Nets 108 - 337 542 1.6 Traps: Shermans 168 198 11,597 797 6.9 Museum Specials 11 13 517 14 2.7 Rat 8 10 245 9 3.7 Gopher 7 12 45 6 13.3 Conibear 12 29 111 6 5.4 Havahart 16 24 55 3 5.5 Lcghold 3 7 48 1 2.1 Firearms 32 _ 44 . Hand-capture 3 - - 5 . Salvaged 14 - - 17 - YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 21 Table 4. Mammals, acquired along with voucher specimens and frozen tissues retained\ as a result of field work at Big Bend Ranch State Park during 1994 and 1995, SS=skin and skull, SK-skull only ; SO = skin only, AL=preserved in alcohol Species Number Caught Total SS Retained as Vouchers SK SO AL Tissues Collected Mormoops megatophylla 131 123 123 0 0 0 47 Myotis californicus 21 21 21 0 0 0 14 Myotis ciliola brunt 1 1 1 0 0 0 0 Myotis thysanodes 2 2 2 0 0 0 2 Myotis velifer 16 16 16 0 0 0 8 Myotis yumanensis 4 4 4 0 0 0 4 Eptesicus fuscus 56 50 49 1 0 0 15 Pipistrellus hesperus 194 118 114 4 0 0 13 Pipistrellus subfiavus 1 1 1 0 0 0 1 Lasiurus cinereus 6 6 6 0 0 0 4 Plecotus townsendii 11 10 10 0 0 0 9 Antrozous pallidus 44 44 44 0 0 0 9 Tadarida brasilien sis 77 54 54 0 0 0 8 Nyctinomops macrotis 1 1 1 0 0 0 1 Sylvilagus audubonii 8 8 8 0 0 0 2 Lepus californicus 10 10 10 0 0 0 2 Ammospermophilus interpres 2 2 2 0 0 0 2 Spermophilus spilosoma 3 3 2 0 0 1 2 Spermophilus variegatus l 1 0 0 1 0 0 Thomomys bottae 2 2 2 0 0 0 1 Cratogeomys castanops 4 4 4 0 0 0 2 Perognathus flavus 80 76 76 0 0 0 25 CUaetodipus eremicus 160 111 111 0 0 0 30 Chaetodipus hispidus 3 3 3 0 0 0 3 Chaelodipus intermedius 13 13 13 0 0 0 9 Chaetodipus nelsoni 76 74 74 0 0 0 28 Dipodomys merriami 133 118 117 1 0 0 25 Reilhrodontomys fulvescens 8 8 8 0 0 0 2 Reilhrodontomys mega lot is 11 11 11 0 0 0 6 Peromyscus eremicus 117 116 116 0 0 0 33 Peromyscus leucopus 71 70 70 0 0 0 45 Peromyscus maniculatus 59 58 58 0 0 0 18 Peromyscus pecloralis 56 55 55 0 0 0 13 Onychomys arenicola 10 10 10 0 0 0 6 Sigmodon hispidus 4 3 3 0 0 0 2 Sigmodon ochrognathus 1 l 1 0 0 0 1 Neotoma albigula 7 7 7 0 0 0 6 Neotoma mexicana 1 1 1 0 0 0 1 Neotoma micropus 12 11 11 0 0 0 3 Can is latrans 1 1 1 0 0 0 0 Urocyon cinereoargenteus 1 1 1 0 0 0 1 Bassariscus astutus 2 2 2 0 0 0 Procyon lotor 1 1 1 0 0 0 1 Conepatus mesoleucus 1 1 1 0 0 0 1 Mephitis mephitis 6 6 6 0 0 0 ft 4 A Tayassu tajacu 6 6 0 6 0 0 0 Odocoileus hem ion us 8 8 0 8 0 0 0 Capra hircus 1 1 0 1 0 0 0 Total 1444 1254 1231 21 1 1 411 CHECKLIST OF SPECIES The following checklist of mammals is divided into four groups: native species, nondomestic introduced species, domestic species, and species of postulated occurrence. The list of native species consists of 59 species of indigenous mammals known to occur within the boundaries of BBRSP as verified by any of the means described in the methods section. The list of nondomestic introduced species includes two wild bovids not native to BBRSP, but which now exist there as free-ranging populations following their introduction into the area by humans. The list of domestic species is comprised of seven mammals that have been domesti¬ cated by humans and are verified to occur in BBRSP. The list of species of postulated occurrence contains 27 mammals that, based on their overall distribution, may occur in BBRSP, but have not yet been documented there. Arrangement and nomenclature of taxa in the checklist are as presented in the accounts of species. Native Species Order Chiroptera Family Mormoopidae Mormoops megalophylla (ghost-faced bat) Family Vespertilionidae Myotis californicus (California myotis) Myotis ciliolabrum (western small-footed myotis) Myotis thysanodes (fringed myotis) Myotis velifer (cave myotis) Myotis yumanensis (Yuma myotis) Pipistrellus hesperus (western pipistrelle) Pipistrellus subjlavus (eastern pipistrelle) Eptesicus fuscus (big brown bat) Lasiurus cinereus (hoary bat) Plecotus townsendii (Townsend’s big-eared bat) Antrozouspallidus (pallid bat) Family Molossidae Tadarida brasiliensis (Brazilian free-tailed bat) Nyctinomops mac rods (big free-tailed bat) Eumops perotis (western mastiff bat) Order Lagomcrpha Family Leporidae Sylvilagus audubonii (desert cottontail) Lepus californicus (black-tailed jackrabbit) Order Rodentia Family Sciuridae Ammospermophilus interpres (Texas antelope squirrel) Spermophilus spilosoma (spotted ground squirrel) Spermophilus variegatus (rock squirrel) Family Geomyidae Thomomys bottae (Botta’s pocket gopher) Cratogeomys castanops (yellow-faced pocket gopher) Family Heteromyidae PerognathusJlavus (silky pocket mouse) Chaetodipus eremicus (Chihuahuan Desert pocket mouse) Chaetodipus hispidus (hispid pocket mouse) Chaetodipus intermedius (rock pocket mouse) Chaetodipus nelsoni (Nelson’s pocket mouse) Dipodomys merriami (Merriam’s kangaroo rat) Dipodomys ordii (Ord’s kangaroo rat) Family Castoridae Castor canadensis (American beaver) Family Muridae Reithrodontomys fulvescens (fulvous harvest mouse) Reithrodontomys megalotis (western pocket mouse) Peromyscus boylii (brash mouse) Peromyscus eremicus (cactus mouse) Peromyscus leucopus (white-footed mouse) Peromyscus maniculatus (deer mouse) Peromyscuspectoralis (whitc-anklco mouse) Onychomys aremcola (Meams' grasshopper mouse) Sigmodon hispidus (hispid cotton rat) Sigmodon ochrognathus (yellow-nosed cotton rat) 23 24 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Neotoma albigula (white-throated woodrat) Neotoma mexicana (Mexican woodrat) Neotoma micropus (southern plains woodrat) Family Erethizontidae Erethizon dorsatum (porcupine) Order Carnivora Family Canidae Canis latrans (coyote) Vulpes velox (kit fox) Urocyon cinereoargenteus (common gray fox) Family Ursidae Ursus americarms (black bear) Family Procyonidae Bassariscus astutus (ringtail) Procyon lotor (common raccoon) Family Mustelidae Taxidea taxus (American badger) Mephitis mephitis (striped skunk) Conepatus mesoleucus (common hog-nosed skunk) Family Felidae Felis concolor (mountain lion) Lynx rufus (bobcat) Order Artiodactyla Family Dicotylidae Tayassu tajacu (collared peccary) Family Cervidae Odocoileus hemionus (mule deer) Odocoileus virginianus (white-tailed deer) Family Antilocapridae Antilocapra americana (pronghorn) Nondomestic Introduced Species Family Bovidae Capra ibex (ibex) Ammotragus lervia (Barbary sheep, aoudad) Domestic Species Order Carnivora Family Canidae Canis familiaris (domestic dog) Family Felidae Felis catus (domestic cat) Order Perissodactyla Family Equidae Equus caballus (domestic horse) Equus asinus (burro) Order Artiodactyla Family Suidae Sus scrofa (domestic pig) Family Bovidae Bos taurus (domestic cow) Capra hircus (domestic goat) Species of Postulated Occurrence Order Didelphimorphia Family Didelphidae Didelphis virginiana (Virginia opossum) Order Insectivora Family Soricidae Notiosorex crawfordi (desert shrew) Family Talpidae Scalopus aquaticus (eastern mole) Order Chiroptera Family Phyllostomidae Leptonycteris nivalis (Mexican long-nosed bat) Family Vespertilionidae Myotis auriculus (southwestern myotis) Myotis lucifugus (little brown myotis) Myotis volans (long-legged myotis) Lasionycteris noctivagans (silver-haired bat) Lasiurus blossevillii (western red bat) Lasiurus borealis (eastern red bat) Euderma maculatum (spotted bat) Family Molossidae Nyctinomops femorosaccus (pocketed free-tailed bat) Order Lagomorpha Family Leporidae Sylvilagus Jloridanus (eastern cottontail) Order Rodentia Family Sciuridae Spermophilus mexicanus (Mexican ground squirrel) Family Heteromyidae Dipodomys spectabilis (banner-tailed kanganroo rat) YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 25 Family Muridae Reithrodontomys montanus (plains harvest mouse) Peromyscus nasutus (northern rock mouse) Sigmodon fulviventer (tawny-bellied cottonrat) Rattus norvegicus (Norway rat) Rattus rattus (roof rat) Mus muscuius (house mouse) Ondatra zibethicus (common muskrat) Order Carnivora Family Procyonidae Nasua narica (white-nosed coati) Family Mustelidae Muslela frenata (long-tailed weasel) Spilogale gracilis (western spotted skunk) Mephitis macroura (hooded skunk) Family Felidae Fells pardalis (ocelot) FAUNAL ANALYSIS Species Diversity and Similarity The documented native mammalian diversity of BBRSP was evaluated and compared with those of eight other areas within the Chihuahuan Desert. An effort was made to include areas throughout the Chihuahuan Desert that have a relatively well known mammalian fauna. Specific sites selected (with references used to construct faunal lists used in analysis in parentheses) were as follows: Big BendNational Park, Texas (Borell and Bryant, 1942; Easterla, 1973; Anonymous, 1989; Jones et al., 1993); the Davis Mountains region, Texas (Blair, 1940; Genoways et al., 1979; Stangl, 1992a; 19926); the Sierra Vieja region, Texas (Blair and Miller, 1949; Genoways et al., 1979; Genoways and Baker, 1988; specimens in the collection at TTU); Guadalupe Mountains National Park, Texas (Davis, 1940; Genoways et al., 1979); northwest Coahuila, Mexico (Baker, 1956); northeast Chihuahua, Mexico (Ander¬ son, 1972); Crockett County, Texas (Goetze, 1995); and the Animas Mountains region. New Mexico (Cook, 1986). Native species of mammals known to occur in the nine areas considered for analyses (including BBRSP) are summarized in Table 5. Using this data matrix, Jaccard’s coefficient similarity index was cal¬ culated for each possible pair-wise comparison. The richness and interrelationship of the mammalian fau¬ nas of the nine areas considered are summarized in Table 6 . Of the nine areas analyzed, Big Bend National Park and the Animas Mountains region were the most diverse with 70 species of mammals occurring in each area. Crockett County was the least diverse with 41 species. With 59 species, BBRSP ranked sixth in terms of species richness. Four of the five areas that ranked above BBRSP were larger in total area. Because the number of species in an area is positively correlated with the size of the area (Williamson, 1981; Wilson, 1992) area, no doubt, was a factor in this case. In addi¬ tion, areas with large ranges of elevations tend to have greater species diversity than those comprised of lower variability of elevations (Williamson, 1981). Thiscon- cept is consistent with my results, as all areas with a diversity level greater than that of BBRSP contained more high-elevation (>1500 m) mountainous regions. Big Bend National Park and the Davis Mountains region ranked first and second, respectively, in terms of a mammalian fauna resembling that of BBRSP. Both of these areas are within close proximity to BBRSP, and there are no imposing barriers separating them. Guadalupe Mountains National Park, the Sierra Vieja region, northwestern Coahuila, and northeastern Chi¬ huahua all had intermediate levels of similarity with BBRSP. The former two are further distances away, but are included within the Trans-Pecos, and no signifi¬ cant dispersal barrier exists between sites. Coahuila and Chihuahua are adjacent to BBRSP, but are sepa¬ rated from BBRSP by the Rio Grande. This river has been shown to act as a major filter barrier to the dis¬ persal of Chihuahuan Desert mammals (Schmidly, 19776), The least similar sites were the Animas Moun¬ tains and Crockett County. Both are situated consider¬ able distances from BBRSP. Furthermore, imposing barriers occur between the sites. Crockett County lies immediately to the east of the Pecos River, which is known to affect the distribution of mammals between the Trans-Pecos and areas to the east (Hollander et al., 1990). The Animas Mountains region of southwestern New Mexico is the most distant site analyzed, and sev¬ eral potential distributional barriers, including the Rio Grande, lie in-between Species Composition Whereas species diversity or richness applies to the number and types of species present in an area, spe¬ cies composition refers to the relative abundance of each species (Hall and Willig, 1994). Because a consider¬ able effort was applied in obtaining bats and rodents, it was possible to calculate indices of species composi¬ tion for members of these taxa The species composi¬ tion of bats in BBRSP was derived from the number of individuals of each species caught per net night, whereas the species composition of rodents is based on number captured per 100 trapnights The percentage of total captures of each species also was determined for both rodents and bats. For rodents, only those species readily trapped with Sherman live traps or snap traps were con- 27 28 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Table 5. Matrix depicting the mammalian fauna of nine areas within the Chihuahuan Desert. Areas represented are: Big Bend Ranch State Park, Texas (BBR), Big Bend National Park, Texas (BBN), the Davis Mountains region, Texas (DM), the Sierra Vieja region, Texas (SV), Guadalupe Mountains National Park, Texas (GM), northwestern Coahuila, Mexico (CO), northeastern Chihuahua, Mexico (CH), Crockett County, Texas (CC), and the Animas Mountains region, New Mexico (AM). Species BBR BBN DM SV GM CO CH CC AM Didelphis virginiana + 4 Sorex arizonae 4 Sorex milleri 4 Notiosorex crawfordi 4- 4 4 4 Scalopus aquaticus 4 Mormoops megalophylla 4 4 4 4 Leptonycleris curasoae 4 Leptonycteris nivalis 4- 4 Choeronycteris mexicana 4 Myotis auriculus 4 Kiyotis californicus + 4 4 4 4 4 4 Myotis ciliolabrum 4 4 4 4 4 4 4 4 Myotis thysanodes 4 4 4 4 4 4 4 4 Myotis velifer 4 4 4 4 4 4 4 4 4 Myotis volans 4 4 4 4 4 4 Myotis yumanensis + 4 4 4 4 4 Lasionycteris noctivagans 4 4 4 Pipistrellus Hesperus + 4 4 4 4 4 4 4 Pipistrellus subflavus + Eptesicus fuscus 4 4 4 4 4 4 4 Lasiurus blossevillii 4 Lasiurus borealis 4 4 4 4 Lasiurus cinereus + 4 4 4 4 4 4 4 Lasiurus ega 4 4 Euderma maculatum 4 Plecotus townsendii 4 4 4 4 4 4 4 Antrozous pallidus 4 4 4 4 4 4 4 4 4 Tadarida brasiliensis + 4 4 4 4 4 4 4 4 Nyctinomops femorosaccus 4 Nyctinomops macrotis + 4 4 4 4 4 Eumops perotis + 4 Dasypus novemcinctus 4 Sylvilagus audubonii + 4 4 4 4 4 4 4 Sylvilagus Jloridanus 4 4 4 4 4 4 4 Lepus californicus + 4 4 4 4 4 4 4 4 Lepus callotis 4 Tamias canipes 4 Tamius dorsalis 4 -J- 4 Ammospermophilus harrisii 4 Ammospcrmophillus interpres + 4 4 4 4 4 4 Spermophilus mexicanus 4 4 Spermophillus spilosoma 4 4 4 4 4 4 4 Spermophillus variegalus + 4 4 4 4 4 + 4 4 Siurus niger 4 Cynomys ludovicianus 4 4 4 _L Thomomys bottae 4 4 4 4 4 -I- 4 Thomomys umbrinus Cratogeomys cast an ops 4 4 4 4 4 4 4 4 Perognalhus flavus + 4 4 4 4 4 4 Chaetodipus eremicus + 4 4 4 + Chaetodipus hispidus 4 4 4 4 T + + 4 YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 29 Table 5. (continued) Species BBR BBN DM SV GM CO CH cc AM Chaetodipus intermedins 4 4 4 4 Chaetodipus nelsoni Chaetodipus penicillatus + + + + 4 4 4 Dipodomys merriami + 4 + 4- 4 4 4 4 4 Dipodomys nelsoni 4 4 Dipodomys ordii 4 + + 4 4 4 4 Dipodomys spectabilis Castor canadensis 4 4 + 4 4 4 4 4 Reithrodontomys fulvescens 4 + + 4 4 4 Reithrodontomys mega lot is + + + 4 4 4 4 Reithrodontomys montanus + 4 Peromyscus attwateri Peromyscus boylii + + + 4 4 4 4 Peromyscus eremicus + 4 + + 4 4 4 4 Peromyscus leucopus 4 + + + 4 4 4 4 4 Peromyscus maniculatus 4 + + + 4 4 4 4 Peromyscus nasutus 4 4 Peromyscus pectoralis 4 + + + 4 4 4 4 Peromyscus truei Baiomys taylori 4 4 Onychomys arenicola + + + 4 4 4 4 Onychomys leucogaster Onychomys torridus + 4 4 4 4 Sigmodon fulviventor 4 4 Sigmodon hispidus 4 + + 4 4 4 4 4 Sigmodon ochrognathus 4 + + 4 4 Neotoma albigula + + + 4 4 4 4 4 Neotoma goldmani Neotoma mexicana 4 4 + + 4 4 4 4 Neotoma micropus 4 + + 4 - 4 4 4 Microtus mexicanus 4 Ondatra zibethicus Erethizon dorsatum 4 4 + + 4 4 4 4 4 Canis latrans 4 + + + 4 4 4 4 4 Vulpes velox 4 + + 4 4 Vulpes vulpes 4 Urocyon cinereoargenteus + + + 4 4 4 4 + Ursus americanus 4 + + 4 4 + Bassariscus as tutus 4 + + 4 4 4 4 4 Procyon lotor + + + 4 4 4 4 4 Nasua narica + Mustella frenata + 4 Taxidea taxus 4 + + 4 4 4 Spilogale gracilis 4 + Spilogale putorius + + 4 4 Mephitis macroura Mephitis mephitis 4 + + + + 4 4 4 4 4 4 + + 4- Conepatus mesoleucus + + + 4 Felis concolor + + + 4 4 + T Lynx rufus Tayassu tajacu 4 + + + + + 4 4 4 4 4 4 4 4 4 4 Cervus elephus -f 4 . Odocoieus hemionus + + + 4 4 Odocoileus virginianus 4 + + 4 4 4 4 4 4 4 + Antilocapra americana 4 + + 4 Ovis canadensis + + 30 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Table 6. Matrix depicting the diversity and similarity of the mammalian fauna among nine geo¬ graphic regions within the Chihuahuan Desert. Bold-faced numbers running diagonally from the upper left to the lower right represent the number of species of mammals verified to occur in a given area. Entries to the left of the diagonal represent calculated Jaccard’s coefficient of similarity between two areas , whereas entries to the right depict the number of mammal species shared by Imv particular areas. Definitions of abbrevia¬ tions are the same as in Table 5. Geographic Region BBR BBN DM SV GM CO CH CC AM Big Bend Ranch State Park, Texas 59 56 52 45 49 49 41 34 48 Big Bend National Park, Texas 0.77 70 58 50 52 54 40 29 52 Davis Mountain Region, Texas 0.72 0.75 65 49 51 50 39 35 53 Sierra Vieja Region, Texas 0.67 0.68 0.71 53 45 44 32 28 42 Guadalupe Mountains National Park, Texas 0.68 0.65 0.67 0.64 62 47 36 33 48 Northwestern Coahuila, Mexico 0.67 0.68 0.64 0.61 0.60 63 40 31 48 Northeastern Chihuahua, Mexico 0.62 0.51 0.53 0.46 0.49 0.56 48 27 36 Crockett County, Texas 0.52 0.40 0.49 0.42 0.47 0.42 0.39 41 29 Animas Mountains Region, New Mexico 0.59 0.59 0.65 0.52 0.57 0.56 0.44 0.35 70 Table 7. Species composition of bats at Big Bend Ranch State Park based on the results 337 net nights. Species Number Caught Number per Net Percent of all Captures Morm oops megalophylla 131 0.389 23.2 Myotis californicus 21 0.062 3.7 Myotis ciliolabrum 1 0.003 0.2 Myotis ihysanodes 2 0.006 0.4 Myotis velifer 12 0.036 2.7 Myotis yumanensis 2 0.006 0.4 Eptesicus fuse us 55 0.163 9.9 Pipistrellus hesperus 180 0.534 34.4 Pipistrellus subjlavus 1 0.003 0.2 Lasiurus cinereus 6 0.018 1.1 Piecotus tomisendii 9 0.027 2.0 Antrozous pallidus 44 0.131 7.8 Tadarida brasiliensis 77 0.228 13.7 Nyctinomops macrotis 1 0.003 0.2 sidered. The results of these species composition cal- and 8, respectively. Discussions on the composition of culations for bats and rodents are presented in Tables 7 each species are included in the accounts of species. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 31 Table 8. Species composition of rodents at Big Bend Ranch State Park based on the results of12,359 trapnights. Only those species readily trapped with Sherman or snap traps are included. Species Number Caught Number per 100 Trapnights Percent of all Captures Perognathus jlavus 80 0.647 9.8 Chaetodipus eremicus 160 1.295 19.5 Chaetodipus hispidus 3 0.024 0.4 Chaetodipus intermedius 13 0.105 1.6 Chaetodipus nelsoni 76 0.615 9.3 Dipodomys merriami 133 1.076 16.2 Reithrodontomys fulvescens 8 0.065 1.0 Reithrodontomys megabits 11 0.089 1.3 Peromyscus eremicus 114 0.922 13.9 Peromyscus leucopus 71 0.574 8.7 Peromyscus maniculatus 59 0.477 7.2 Peromyscus pectoralis 56 0.453 6.8 Onychomys arenicola 10 0.081 1.2 Sigmodon hispidus 4 0.032 0.5 Sigmodon ochrognathus 1 0.008 0.1 Neotoma albigula 7 0.057 0.9 Neotoma mexicana 1 0.008 0.1 Neotoma micropus 12 0.097 1.5 KEY TO THE SPECIES The following key to the species of mammals is based on both external and cranial characters. Descriptions apply to non-aberrant, adult individuals. The key includes native mammals known to occur in BBRSP, as well as introduced species, domestic species, and species of postulated occurrence. In addition two extirpated species, the gray wolf (Canis lupus) and the bighorn sheep (Ovis canadensis ), have been included because both species cur¬ rently are under consideration for reintroduction into the area. Once an identification is made using the key, the user should refer to the account of the species in the follow¬ ing section. Information in the account regarding distribution, description, and habitat affinities may help in con¬ firming or discrediting an identification. Data acquired during this study, along with information provided by Anderson (1972), Schmidly (1977a), Comely et al. (1981), DeBIase and Martin (1981), Glass (1981), Hall (1981), Nowak (1991), Jones and Manning (1992), and Davis and Schmidly (1994) were used to construct this key. 1 Forelimbs modified as wings ........... 2 1' Forelimbs not modified as wings...................... 25 2 Prominent nose leaf at end of elongated snout; molars 2/2. Leptonycteris nivalis 2' Nose leaf absent; molars 3/3 ..................3 3 Tail protruding from dorsal surface of uropatagium; conspicuous grooves and flaps on chin;braincase of skull broader than long. Mormoops megalophylla 3 f Tail extending through or beyond uropatagium; grooves or flaps on chin absent; braincase of skull longer than broad..4 4 Posterior third of tail extending beyond uropatagium; palate terminating slightly behind third upper molar ............. 5 4 1 Tail terminating at free edge of uropatagium; palate extending well beyond third upper molar...... 8 5 Base of ears not fused at midline of head; incisors 1/3 or 1/2 ... Tadarida brasiliensis 5' Base of ears fused at midline of head; incisors 1/2..... 6 6 Vertical wrinkles on lips absent; forearm greater than 70 mm; greatest length of skull greater than 30 mm .. Eumops perot is 6‘ Vertical wrinkles on lips present; forearm less than 70 mm; greatest length of skull less than 30 mm... . 7 7 Forearm greater than 52 mm; greatest length of skull greater than 21 mm .. Nyctinomops macrotis T Forearm less than 52 mm; greatest length of skull less than 21 mm.. Nyctinomops femomsaccus 8 Ears large (greater than 23 mm). 8’ Ears not noticeably large (less than 23 mm) 33 34 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 9 Color black, with three large, white spots on dorsum. ...Euderma maculatum 9' Color light brown or pale yellow ..........*.-... 10 10 Color light brown; conspicuous lumps present on both sides of snout; incisors 2/3; premolars 2/3; total teeth, 36 ...... Plecotus towmendii 10’ Color pale yellow; conspicuous lumps absent from sides of snout; incisors 1/2; premolars 1/2; total teeth 28 ...... Antrozouspallidus 11 Anterior third or more of dorsal surface of uropatagium hairy........ 12 IT Entire dorsal surface of uropatagium naked or only scant ly haired....... 15 12 Color black, with many individual hairs tipped with silver; incisors 2/3.. Lasionycteris noctivagans 12' Color not as above; incisors 1/3.....-.■. 13 13 Color dark brown with considerable white frosting; forearm greater than 45 mm; greatest length of skull usually greater than 15 mm... Lasiurus cinereus 13' Color reddish; forearm less than 45 nun; greatest length of skull less than 15 mm.......-. 14 14 Hairs tipped with white; dorsal surface of uropatagium entirely haired ....... Lasiurus borealis 14' Hairs not tipped with white; posterior third of dorsal surface of uropatagium naked or only sparsely haired.... Lasiurus blossevillii 15 Tragus short, curved, and blunt............... 16 15' Tragus long, straight, and pointed.............. 17 16 Color brown; size large (forearm greater than 40 mm; greatest length of skull greater than 17 mm); premolars 1/2 .... Eptesicus fuscus 16' Color grayish; size small (forearm less than 32 mm; greatest length of skull less than 14 mm); premolars 2/2..... Pipistrellus Hesperus 17 Dorsal fur tricolored, black at the base, yellowish brown in the middle, dark brown at the tips; dactylopatagium minus much paler than remainder of wing membrane; premolars 2/2......... Pipistrellus subflavus 17' Dorsal fur uni- or bicolored, lacking a light middle band; wing membrane uniform in color; premolars 2/3 or 3/3 ....... 18 18 Calcar with a well-developed keel........... 19 18' Calcar without a well-developed keel ...........21 19 Color dark brown; size large (forearm greater than 36 mm); underside of wing membrane heavily furred to elbow..... ... ...Myotis volans 19' Color light brown to reddish; size small (forearm less than 36 nun); underside of wing membrane not furred to elbow.......20 YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 35 20 Color usually reddish; braincase rising sharply above rostrum presenting a prominent forehead...... Myotis californicus 20' Color usually buff brown, less reddish; braincase rising gently above rostrum presenting a flattened appearing skull.... Myotis ciliolabrum 2 1 Short, stiff hairs present on free edge of uropatagium ......... . Myotis thysanodes 2Y Hairs absent from free edge of uropatagium .. 22 22 Ears relatively large (greater than 17 mm)............ Myotis auriculus IT Ears relatively short (less than 17 mm).. 23 23 Forearm greater than 40 mm........... Myotis velifer IT Forearm less than 40 mm.. 24 24 Dorsal pelage dark brown, usually with a slight sheen; forearm greater than 36 mm. Myotis lucifugus 24’ Dorsal pelage buff or light gray; forearm less than 36 nun... Myotis yumanensis 25 Hooves present on one or more toes of each foot. 26 25' Hooves absent, toes usually clawed.........37 2 6 One large hoof on each foot... 27 26* Two or more hooves on each foot. 28 27 Color variable, but usually without a dark cross on shoulders; mane usually of long, hanging hairs; facial part of skull long. Equus caballus IT Color usually grayish, usually with a dark cross on shoulders; hairs of mane usually erect; facial part of skull shorter.. .. Equus os in us 28 Body short, pig-like; end of nose a flat, round disk; upper incisors and canines present; appendages on frontal bones absent; postorbital bar incomplete........ 29 28' Body taller, not pig-like; end of nose not a flat, round disk; upper incisors and canines absent; appendages on frontal bones, at least in males; postorbital bar complete...... 30 29 Three toes on each hind foot; yellowish collar present above shoulders; upper canines straight, directed downward; incisors 2/3; premolars 3/3. Tayassu iajacu 29’ Four toes on each hind foot; yellowish collar above shoulders absent; upper canines curved outward and upward; incisors 3/3; premolars 4/4... Sus scrofa 30 Frontal appendages antlers, composed entirely of bone and arising from the skull well posterior of orbits, present only in males, and shed annually; rostral fenestrations nearly as wide as long....31 30* Frontal appendages horns, composed of bony core surrounded by sheath of fused hair, present in both sexes, bony core not shed; rostral fenestrations absent, or if present long and narrow...32 36 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 31 Tail tipped with black, white or buff above; antlers dichotomously branched; ears large (about two-thirds length of head); preorbital pit deep ...... Odocoileus hemionus 31' Tail brown above, white below, with sides fringed in white; antlers one main beam from which single, unbranched tines arise; ears smaller (about half the length of head); preorbital pit shallow... Odocoileus virginianus 32 Two white bands across throat area; horn core with sharp anterior edge; sheath forked with small anterior projection (in males only), and shed annually; rostral fenestrations present; lacrimal not articulating with nasal... Antilocapra americana 32' White bands across throat area absent; horn core with rounded anterior edge; sheath never forked, and not shed; rostral fenestrations absent; lacrimal articulating with nasal...........33 33 Size large (total length greater than 1800 mm); horns sweeping laterally and anteriorly......... Bos taurus 33' Size small to medium (total length less than 1800 mm); horns curling posteriorly and downward.............34 34 Beard present on chin (at least in males). 35 34' Ventral mane may be present, but beard is absent......36 35 Color reddish-tan to brown, often with whitish patches; horns with prominent transverse ridges..... Capra ibex 35' Color variable; horns relatively smooth, not broken with transverse ridges.. ...... Capra hircus 36 Conspicuous white patch on rump; long, ventral mane absent; canines 0/1 . Ovis canadensis 36 1 White rump patch absent; long, ventral mane present; canines 0/0. .Ammotragus lervia 37 Canines present; no diastema between incisors and cheek teeth... 38 37 Canines absent; conspicuous diastema between incisors and cheek teeth . 59 38 Tail prehensile; incisors 5/4; hallux opposable and without claw; abdominal pouch in females; medially inflected angular process of dentary... Didelphis virginiana 38’ Tail not prehensile; incisors 3/3 or less; hallux not opposable; all toes with claws; abdominal pouch absent; angular process of dentaiy not inflected......39 39 Size small (total length less than 200 mm); snout highly flexible; eyes proportionately small; canines proportionately small.40 39 Size larger (total length greater than 200 mm); snout usually not highly flexible; eyes proportionately large; canines proportionately large.41 40 Size rather small (total length less than 125 mm); front feet small and normal-shaped; first upper incisor large and procumbent with small accessory' cusp behind primary cusp; zygomatic arch absent... Notiosorex crawfordi 40’ Size larger (total length greater than 125 mm); front feet enlarged and paddle-shaped; first upper incisor not large and procumbent, and without small accessory cusp behind primary' cusp; zygomatic arch present... Scalopus aquaticus YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 37 41 Body cat-like; claws retractile; molars 1/1.. 42 41* Body not cat-like; claws usually not retractile; molars greater than 1/1. 45 42 Size large (total length greater than 1500 mm); color uniform light brown or grayish............. Felts concolor 42 1 Size smaller (total length less than 1500 mm); color and pattern variable... 43 43 Dorsal pattern spotted; tail short; premolars 2/2.... Lynx rufus 43' Dorsal pattern may be spotted or not; tail usually long; premolars 3/2. 44 44 Size small (greatest length of skull less than 105 mm); dorsal pattern highly variable, but usually not spotted; tail usually long, but may be short.... Felts catus 44’ Size medium (greatest length of skull greater than 105 mm); dorsal pattern heavily spotted, tail always long........ Felispardalis 45 Body dog-like; hind foot with four toes; total number of teeth 42. 46 45' Body not dog-like; hind foot with five toes; total number of teeth greater than 42, or if 42, cheek teeth flattened and without sharp cusps.... 50 46 Fur may be short or long; lateral view of dorsal profile of skull presents a bulging forehead. .Canis familiaris 46' Fur long; lateral view of dorsal profile of skull relatively straight.47 47 Size medium to large (weight greater than 9000 g, hind foot greater than 170 mm, greatest length of skull greater than 200 mm).....48 47' Size smaller (weight less than 9000 g, hind foot less than 170 mm, greatest length of skull less than 200 mm)........49 48 Size large (weight greater than 18,000 g, hind foot greater than 200 nun), greatest diameter of upper canine greater than 11 mm..... Canis lupus 48' Size medium (weight less than 18,000 g, hind foot less than 200 nun), greatest diameter of upper canine less than 11 nun... Canis lairans 49 Color dark gray with white throat and rusty sides; black stripe present along dorsum of tail; ears normal; temporal ridge lyre-shaped; lower margin of dentary anterior to angular process with truncated indentation or “step” .... Urocyon anereoargenteus 49' Color bufly gray with clear buff at sides, midbelly, and under tail; tail tipped in black but lacks dorsal stripe; ears large, temporal ridge not lyre-shaped; lower margin of dentary smooth. . Vulpes velox 50 Size large (weight greater than 50,000 g), tail short (shorter than hind foot); total teeth 42.... Ursus americanus 50’ Size smaller (weight less than 50,000 g), tail long (longer than hind foot), total teeth less than 42...... 51 51 Tail with alternating dark and light rings; molars 2/2; total number of teeth 40...-. 52 51' Tail without alternating dark and light rings; molars 1/2, total number of teeth 38 or less.- 54 38 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 52 52' 53 53' 54 54* 55 55' 56 56' 57 57 58 58' 59 59’ Tail long (as long or longer than head and body), and with 14-16 alternating black and white rings and a back tip; hind foot less than 80 mm, bony template terminating just posterior to last upper molar.. Tail shorter (shorter than head and body), and with 6-7 alternating dark and light rings; hind foot greater than 85 mm; bony template terminating far posterior to last upper molar.■ Flexible snout extending far beyond mouth; rings on tail inconspicuous, rostrum noticeably elongated; conspicuous diastema between canine and first upper premolar... Snout not as above; rings on tail conspicuous; rostrum only slightly elongated; diastema between canine and first upper premolar absent.. Bassariscus astutus 53 . Nasua narica Procyon lolor Body thick; tail short (about as long as hind foot); braincase triangular in shape; upper molar triangular in shape. Body not thick; tail long (conspicuously longer than hind foot); braincase not triangular in shape; upper molar quadrate or transversely elongate Taxidea taxus .55 Color light brown; upper molar transversely placed and dumbbell-shaped; bony palate extending far beyond molar..* -. Mustela frenata Color black and white; upper molar quadrate or subquadrate; bony palate extending only slightly beyond molar.■-.-.*""" Dorsum with single broad white stripe from head to tail; no white on forehead; large flexible nose pad present; premolars 2/3; total teeth 32. Conepatus mesoleucus Dorsum usually with two or more (rarely one) white stripes; small white stripe or spot on forehead; large flexible nose pad absent; premolars 3/3; total teeth 34.......*. Dorsum with six distinct continuous or broken white stripes; white spot on forehead; greatest length of skull less than 65 mm; small postorbital process present.....*. Spilogale gracilis Dorsum not as above; white line on forehead; greatest length of skull greater than 65 mm; postorbital process absent...-...*.^ Dorsal stripe bifurcated; sides black; long hairs on neck and back of head absent; small tympanic bulla... Mephitis mephitis Dorsal stripe pattern variable, either two narrow lateral stripes, a single solid central stripe, or a combination of the two; long hairs on neck and back forming hood; larger tympanic bulla.... Mephitis macroura Size larger; incisors 2/1; maxillary fenestrations present. Size smaller; incisors 1/1; maxillary fenestrations absent 60 Ears large (greater than 100 nun); tail with black dorsal stripe; supraorbital process broad, triangular in shape; interparietal indistinct, fused to parietal. Lepus calif ornicus 60’ Ears shorter (less than 100 nun); tail entirely white; supraorbital process narrow, strap-like, often fused to parietal posteriorly; interparietal distinct, not fused to parietal ............^1 YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 39 61 Ears greater than 58 mm; hind foot less than 90 mm; auditory bulla large, with rough surface........ Sylvilagus audubonii 61' Ears less than 58 mm; hind foot greater than 90 mm; auditory bulla small, with smooth surface. Sylvilagus floridanus 62 Dorsal hairs modified as sharp quills; infraorbital foramen larger than foramen magnum...... Erethizon dorsatum 62' Dorsal hairs normal, not modified as quills; infraorbital foramen smaller than foramen magnum.......63 63 Tail dorsal-ventrally compressed and paddle-shaped; hind foot completely webbed; skull with distinct basioccipital pit...-. Castor canadensis 63' Tail normal, not flattened or paddle-shaped; hind foot not webbed, or if webbed, only partially so; basioccipital pit absent. 64 64 External fur-lined cheek pouches present; infraorbital foramen on lateral surface of rostrum..........65 64 1 External fur-lined cheek pouches absent; infraorbital foramen at junction of rostrum and zygomatic plate... 74 65 Front foot much larger than hind foot; ears inconspicuous; tail short, less than half the length of body; infraorbital foramen not perforate.... 66 65 1 Front foot smaller than hind foot; ears conspicuous; tail longer, greater than half the length of body; infraorbital foramen perforate....67 66 Size smaller; feet light in color; claws on front foot small and slender, anterior surface of upper incisor smooth, lacking longitudinal groove.. Thomomys bottae 66* Size larger; feet dark in color; claws on front foot large and long; anterior surface of upper incisor with a single deep groove.. ........ Cratogeomys castanops 67 Hind foot relatively large (greater than twice as long as front foot); mastoid bulla markedly inflated; interparietal reduced, much longer than broad.... ..68 67' Hind foot relatively small (less than twice as long as front foot); mastoid bulla only moderately inflated; interparietal not markedly reduced, at least as broad as long .... 70 68 Size large (total length greater than 300 mm); prominent white tip at end of tail. • Dipodomys spectabilis 68' Size smaller (total length less than 300 mm); prominent white tip at end of tail absent... ... ■ 69 69 Hind foot with five toes.■■■■*■.■ ■ Dipodomys ordii 69' Hind foot with four toes.. Dipodomys mem amt 70 Size small (total length less than 135 mm); pelage silky'; mastoid bulla inflated so that it encroaches dorsal surface of skull and extends posterior beyond occiput. Penognathus flavus 70' Size larger (total length greater than 135 mm); pelage not silky, oflcn with bristles; mastoid bulla less inflated mostly' restricted to lateral surface of skull, not extending posterior bey ond occiput 1\ 40 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 71 Weight greater than 30 g; tail relatively short (less than length of head and body), and without terminal tuft; greatest length of skull greater than 28 mm ..... Chaetodipus hispidus 71' Weight less than 30 g; tail relatively long (greater than length of head and body), and with terminal tuft; greatest length of skull less than 28 mm.......72 72 Rump with numerous conspicuous spines projecting beyond normal guard hairs; small white patch present at base of ear;... Chaetodipus nelsoni 72* Rump spines absent, or if present, fewer and less conspicuous; small white patch at base of ear absent;.......73 73 Rump spines absent; interparietal separated from mastoid bulla by thin projections of the parietal and supraoccipital.. Chaetodipus eremicus 73' Weak rump spines present; interparietal in contact with mastoid bulla, or nearly so. Chaetodipus intermedius 74 Body squirrel-like; prominent postorbital process present; four cheek teeth on dentary; infraorbital foramen a small hole, positioned above midline of rostrum...75 74' Body rat- or mouse-like; postorbital process absent; three check teeth on dentary; infraorbital foramen slit-like, positioned above midline of rostrum .. 78 75 Upper parts mottled grayish brown with head and upper back blackish, not spotted or striped... Spermophilus vanegatus IS' Upper parts spotted or stnped......76 76 Upper parts grayish with a single white stripe on each side; auditory bulla large; premolar reduced........ Ammospermophilus interpres 1C Upper parts wdth spots; auditory bulla normal in size; premolar well-developed..... „ . . . .. 77 77 Spots in 10 or more distinct rows; tail relatively long (about three times the length of hind foot) and moderately bushy. Spermophilus mexicanus 77 Spots randomly scattered, never in distinct rows; tail relatively short (about twice the length of hind foot) and not bushy..... Spermophilus spilosoma 78 Tail always naked and scaly; cheek teeth cuspidate, w ith cusps of first two molars situated in three longitudinal rows.. .79 78* Tail naked, lightly haired, or heavily haired; cheek teeth prismatic, semipnsmatic, or cuspidate with cusps of first two molars situated in two longitudinal rows. . 81 79 Body small (total length less than 250 nun) and mouse-like, upper incisors notched on occlusal surface. Mus musculus 79' Body larger (total length greater than 250 mm) and rat-like; upper incisors not notched on occlusal surface. ... 80 YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 41 80 Tail usually longer than head and body; first upper molar with distinct outer notches on first row of cusps....... Rattus rattus 80’ Tail shorter than head and body; first upper molar without distinct outer notches on first row of cusps..... ...Rattus norvegicus 81 Tail laterally compressed; hind foot partially webbed; zygomatic plate not extending anteriorly from zygomatic process of maxilla; cheek teeth prismatic....... Ondatra zihethicus 8T Tail round, not laterally compressed; hind foot not webbed at all; zygomatic plate extending anteriorly from zy gomatic process of maxilla; cheek teeth semiprismatic or cuspidate.82 82 Body rat-like; size large (greatest length of skull greater than 38 mm); cheek teeth semiprismatic with deep re-entrant angles..... 83 82' Body mouse-like or rat-like; size smaller (greatest length of skull less than 38 mm); cheek teeth cuspidate.......85 83 Dorsum steel gray......... Neotoma micropus 83’ Dorsum brownish or tan............. 84 84 Throat hairs white to base; anterointemal re-entrant angle of first upper molar shallow, not extending greater than half way across crown....., Neotoma albigula 84* Hairs on throat often, but not always, gray at base; anterointemal re-entrant angle of first upper molar deep, extending greater than halfway across crown. . Neotoma mexicana 85 Body large, rat-like (total length greater than 220 mm); temporal ridge strongly developed; zygomatic notch deep .... ...86 85' Body small, mouse-like (total length less than 220 mm); temporal ridge absent; zygomatic notch shallow...88 86 Under parts huffy to ochraceous; tail entirely black; top of feet buffy. . Sigmodon fulviventer 86' Under parts whitish; tail bicolored, dark above and light below; top of feet whitish.............87 87 Size smaller (total length less than 260 mm); area around nose yellowish or orange... Sigmodon ochmgnathus 87 Size larger (total length greater than 260 mm); area around nose similar in color to rest of dorsum. .. Sigmodon hispidus 88 Upper incisor with distinct median groove on anterior surface... 89 88* Upper incisor smooth, without distinct median groove on anterior surface..... 91 42 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 89 Bright fulvous coloration on sides; tail relatively long (greater than 80 mm and much longer than head and body), naked and scaly, and not bicolored; last lower molar with S-shaped dentine...... Reithrodontomys fulvescens 89' Sides buffy to brown; tail shorter (less than 80 mm and usually shorter or about the same length as head and body), with short hairs, often bicolored; last lower molar with C-shaped dentine.90 90 Tail usually about equal length to head and body, not sharply bicolored; breadth of braincase greater than 9.6 mm.. Reithrodontomys megalotis 90* Tail shorter than length of head and body, and sharply bicolored; breadth of braincase less than 9.6 mm......... ..Reithrodontomys montanus 91 Tail relatively short (less than 60 percent head and body length); coronoid process extending w'ell above condyloid process; soles of feet well-furred.. Onychomys arenicola 91* Tail relatively long (greater than 60 percent head and body length); coronoid process not extending well above condyloid process; soles of feet only sparsely furred.........92 92 Tail conspicuously shorter than head and body......93 92’ Tail as long or longer than head and body.............. 94 93 Total length usually greater than 170 mm (mean about 175 mm); tail usually greater than 75 nun , and not sharply bicolored... Peromyscus leucopus 93 1 Total length usually less than 170 mm (mean about 160 mm); tail usually less than 75 mm, and sharply bicolored..... Peromyscus maniculatus 94 Tail scaly, almost naked, heel naked; only four mammae present in females (pectoral mammae absent); in males, glans penis broad, vase-shaped, and strongly flared distally; posterior extensions of premaxilla extending far beyond posterior end of nasal... Peromyscus eremicus 94 Tail heavily or scantly haired; heel furred; six mammae present in females; in males, glans penis elongate and rod-shaped; posterior extensions of premaxilla not extending far beyond posterior end of nasal............. 95 95 Tarsal joint of ankle white, ears small (usually less than 18 mm); baculum of males with long, cartilaginous spine at tip; tail only scantly haired with short tuft..... Peromyscus pectoralis 95’ Dusky color of hind leg extending to tarsal joint; ears larger (greater than 18 mm); baculum of males with short, cartilaginous spine at tip; tail more heavily haired with short longer tuft...... 96 96 Dorsal color bright yellow-brown; ears medium (usually less than 20 mm); greatest length of skull usually less than 28 mm .. .. .. Peromyscus boylii 96’ Dorsal color grayish; ears large (greater than 20 mm); greatest length of skull usually greater than 28 mm. .. Peromyscus nosutus ACCOUNTS OF SPECIES In the following accounts of species, detailed ac¬ counts of the native species of mammals are presented, followed by brief accounts of nondomestic introduced species, domestic species, and species of postulated oc¬ currence. In addition, a fourth section on extirpated species provides general information on two species of mammals that once inhabited the BBRSP area, but now are absent from the area. Within each section, accounts are presented in currently accepted phylogenetic order through genera (Jones and Jones, 1992; Jones et al., 1992). Species are arranged alphabetically within each genus. Unless noted, scientific and vernacular names follow those of Jones and Jones (1992), and Jones et al. (1992). All linear measurements presented are in millimeters. Weights are in grams unless noted, in which case they are in kg. Native Species For each of the 59 species of native mammals known to occur in BBRSP, the following are included: a description of the species, including key characteris¬ tics that help differentiate it from similar species; the overall distribution of the species, as well as locations within BBRSP from which it has been recorded; infor¬ mation regarding various aspects of the ecology and natural history of the species; additional comments per¬ taining to the taxonomy and nomenclature of taxa from BBRSP; and a list of specimens examined. The major¬ ity of the specimens examined are deposited in the Col¬ lection of Recent Mammals at the Museum of Texas Tech University and are not denoted with an acronym. A small number are housed in the mammal collection at SuJ Ross State University and are indicated by the acronym SRSU. Unless noted otherwise, all linear measurements refer to adults without regard to sex, and weights pre¬ sented were taken from non-gravid adults Refer to the Methods section for an explanation of relative abun¬ dance indices. ORDER CHIROPTERA—BATS Family Mormoopidae (Mormoopid Bats) Mormoops megalophylla (Peters, 18o4) Ghost-faced Bat Description.—Mormoops megalophylla is a me¬ dium-sized bat with dorsal pelage that ranges from pale brown to reddish-brown. Constantine (1958) attrib¬ uted this variation to the fading of adult pelage. A red¬ dish tinge in the hairs indicates an older pelage (Smith, 1972). The ears of the ghost-faced bat are round and fused across the rostrum. The tragus is complex and folded. A distinct leaf-like structure is present on the chin, and the tail protrudes dorsallv from the middle of the uropatagium. The skull of M. megalophylla is unique in that the braincase is grossly vaulted, rising abruptly above an upturned rostrum. The dental for¬ mula for this species is: i 2/2, c 1/1, p 2/3, m 3/3, total 34 Means of external and cranial measuremen ts ( with sample size, extremes, and standard deviation in pa¬ rentheses) of adult female specimens from BBRSP are: total length, 89 3 (119, 79-108,3.9); length of tail ver¬ tebrae, 28.8 (113,24-32, 1.5); length of hind foot, 10.0 (120, 8-13, 0.8); length of car from notch, 13.9 (120, 13-17,0.9); weight, 15.1 (90, 11.5-18.0, 1.4); greatest length of skull, 14.12(20, 13.86-14.80,0.23). Females average slightly larger than males (Rczsutck and Cameron, 1993). Ghost-faced bats are easily distinguished from all other species of bats that occur in BBRSP No other species in the park possesses a chin leaf or a tail that protrudes dorsallv from the tail membrane. Distribution .— M megalophylla ranges from parts of northern South America, northward through Central America, on up to northern Mexico and the southern United States In the United States, it is known only from southern Arizona and Texas (Rczsutck and 43 44 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY kilometers Figure 10. Localities of known specimens of Mormoops megatophylla from Big Bend Ranch State Park, Texas. Cameron, 1993). At BBRSP, the ghost-faced bat was recorded throughout the park (Fig. 10), but was most often found in the Los Alamos, Arroyo Segundo, and Las Quevas areas. Natural History ■ — With a relative abundance in¬ dex of 0.389, M. megalophylla was the second most frequently encountered bat at BBRSP. This species ac¬ counted for 23 percent of all bats collected. Only west¬ ern pipistrelles (Pipistrellus hesperus) were more com¬ mon. Scudday (1976Z?) reported ghost-face bats as rare from the area. This discrepancy indicates the possible existence of temporal variations in the population size of this species at BBRSP. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 45 All specimens ofAT. megalophylla were acquired from water-associated habitats. This species occasion¬ ally was taken in riparian areas with dense vegetation that formed a closed canopy, but was acquired more often from areas near streams and springs that were not enclosed by thick vegetation. Individuals were taken from both deep and shallow canyons, as well as areas of level topography, but the species seemed to favor can¬ yons to flatlands. This bat is known to roost in caves (Schmidly, 1991), and the abundance of these structures on the sides of canyon walls probably accounts for this bat’s affinity for canyons. Ghost-faced bats are known to reside in Trans- Pecos Texas only during the spring and summer (Schmidly, 1991). I found this to be the situation at BBRSP, as this bat was taken only between 29 April and 18 September. Of 130 adult individuals captured, all were females. Interestingly, this species winters on the Edwards Plateau just to the east. No seasonal mi¬ gration between the two regions has been documented (Schmidly, 1991). Information available on the reproductive biol¬ ogy ofAT. megalophylla is scant. In Big Bend National Park, Easterla (1973) discovered two gravid females on 15 June, each of which possessed one embryo, I examined 30 pregnant females taken from 29 April to 9 June, all of which contained only a single embryo as well. Pregnant females (corresponding crown-rump length of embryos in parentheses) were examined on the following dates: 29 April (17, 20, 21), 30 April (18, 20 21, 22), 2 May (19, 22), 14 May (22, 23, 24), 15 May (28), 16 May (22), 20 May (25, 26), 24 May (19, 24, 27), 28 May (26), 29 May (26, 28), 30 May (21), 6 June (27), and 9 June (26). Lactating females were noted from 21 June to 18 September. One volant juvenile individual, a male, was captured on 3 Septem¬ ber. The aforementioned reproductive data suggest that female ghost-faced bats migrate to BBRSP in the spring to set up nursery colonies. They are well into their preg¬ nancy upon arrival, and give birth to a single young probably in early to mid-June. Nursing appears to con¬ tinue for at least three months, a duration among the highest known in bats (Hill and Smith, 1984). Young continue to suckle well after the ability' of flight is ob¬ tained, and possibly into the onset of fall migration AT. megalophylla was active from just after dusk (2154 h) to just afrer sunrise (0700 h), but was observed most often between 2200 h and midnight. Foraging oc¬ curred above standing or slowly moving water. This bat previously has been reported to feed strictly on lepi- dopterans, however this conclusion was based on the evaluation of gastrointestinal contents of only four in¬ dividuals (Easterla and Whitaker, 1972). I examined the contents of 45 stomachs, and found that AT. megalophylla favors lepidopterans (100 percent occur¬ rence), but occasionally feeds on coleopterans (4.4 per¬ cent occurrence), homopterans (2.2 percent occurrence), hemipterans (2.2 percent occurrence), and neuropter- ans (2.2 percent occurrence). Other species of bats taken from the same locali¬ ties at BBRSP as AT. megalophylla included Myotis califormcus,M. Ihysanodes, AT. velifer,M. yumanensis, Pipistrellus hesperus , Eptesicus fuscus , Plecotus townsendii , Antrozouspallidus , Tadarida brasiliensis , and Nyctinomops macrotis. Ectoparasites found on ghost-faced bats from BBRSP included ticks and streblid flies. Ectoparasites previously reported from this bat include two species of streblid flies (Whitaker and Easterla, 1975; Whitaker etal., 1987), chiggers (Jameson, 1959; Loomis, 1969), and wing nutes (Jameson, 1959). Internal parasites col¬ lected included two unidentified ccstodcs and an unde¬ termined species of nematode. In addition, Jameson (1959) documented the presence of trcmatodcs in the small intestine of AT megalophylla. In Mexico, popu¬ lations of this bat are known to be afflicted by large- scale outbreaks of rabies (Jimenez Guzman, 1982). However, 42 specimens from BBRSP were tested for the rabies virus, and all proved to be negative (Yancey et al., 1997). Comments. —The subspecies of AT. megalophylla at BBRSP is AT. m. megalophylla (Peters, 1864) The generic name Mormoops is derived from the Greek “mormon” and “ops,” which translate to she-moustcr and face, respectively The specific epithet megalophylla is from the Greek “megas” and “phyllon,” meaning big and leaf, respectively (Stangl ct al., 1993) 46 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Specimens Examined (126).— Presidio Co.: BBRSP, UTM coordinates: 13 576699E 3296276N, 1; BBRSP, UTM coordinates: 13 580196E3264339N, 2; BBRSP, UTM coordinates: 13 586937E 3262923N, 26; BBRSP, UTM coordinates: 13 586938E 3262910N, 4; BBRSP, UTM coordinates: 13 599794 E 3261524N, 1; BBRSP, UTM coordinates: 13 600689E 3259514N, 1; BBRSP, UTM coordinates: 13 601325E3260789N, 4; BBRSP, UTM coordinates: 13 601335E 3260787N, 2; BBRSP, UTM coordinates: 13 608608E3253227N, 7; BBRSP, UTM coordinates: 13 608870E 3253520N, 2; BBRSP, UTM coordinates: 13 608955E3253483N, 3; BBRSP, UTM coordinates: 13 615458E 3268807N, 1; BBRSP, UTM coordinates: 13 615525E 3268958N, 18; BBRSP, UTM coordinates: 13 615559E3268762N, 1; BBRSP, UTM coordinates: 13 615565E 3268878N, 21; BBRSP, UTM coordinates: 13 615599E3268863N, 29; Fresno Canyon, Smith Ranch, 2 (SRSU). Brewster Co.: El Solitario, Tres Papalotes, 1 (SRSU). Family Vespertilionidae (Vespertilionid Bats) Myotis californicus (Audubon and Bachman, 1842) California Myotis Description.—Myotis californicus is a small bat with pale brown to reddish-brown dorsal pelage. It pos¬ sesses a dark facial mask that extends from ear to ear. The calcar of this bat is keeled, and its feet are small. The dental formula for M. californicus is: i 2/3, c 1/1, p 3/3, m 3/3, total 38. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of specimens from BBRSP are: total length, 82.5 (20,77-90,3.8); length of tail vertebrae, 40.0 (20, 30-43,3.0); length of hind foot, 6.1 (20,5-7,0.6); length of ear from notch, 13.6 (20, 12-15, 0.7); weight, 3.9 (17, 3.0-5.6, 0.6); greatest length of skull, 13.63 (20, 13.28-13.90, 0.18). No significant sexual dimorphism is apparent inM californicus (Bogan, 1974). M. californicus is confused easily with M. ciliolabrum . The former often takes on a more reddish color, whereas the latter usually is buff-brown in color. However, distinctions based solely on pelage color are unreliable. Only by close examination of the skull can these two species be separated. M. californicus has a braincase that rises abruptly above the rostrum, whereas that of M. ciliolabrum has a more flattened profile. Bi¬ variate plots of depth of cranium versus rostral breadth may distinguish the two species (Bogan, 1974). M. californicus can be differentiated from other species of Myotis known from BBRSP and from Pipistrellus subflavus by the presence of the well-developed keel on its calcar. The only other bat at BBRSP that M. californicus might be mistaken for is Pipistrellus hesperus. However, these tw o species are distinguished easily based on tragus morphology. M. californicus has a long, straight, pointed tragus, whereas the tragus of P. hesperus is short, curved, and blunt. Distribution ,— M. californicus ranges from southern Mexico, northward through the southwestern United States and California, on up through the Pacific Northwest to the Alaskan Panhandle (Simpson, 1993). In BBRSP, it is known from the Las Quevas, Sauceda, Los Alamos, and Arroyo Segundo areas (Fig. 11). Natural History. — With a relative abundance in¬ dex of 0.062, M. californicus ranked sixth in captures among bats at BBRSP. It accounted for 3.7 percent of all bats netted. These figures suggest that this bat is neither common nor rare in the park. All specimens ofA/. californicus taken during this study were acquired from riparian areas associated with creeks or springs. This species was taken in both dense, closed canopy vegetation, and open, sparsely vegetated areas. In the Trans-Pecos, M. californicus also has been recorded from desert scrub and grassland (Schmidly, 1991), and should be considered a potential resident of these habitats in BBRSP. This bat roosts alone or in small groups in rocky crevices, under tree bark, among small desert shrubs, on the ground, or in human struc¬ tures (Krutzsch, 1954; Hirshfeld et aL, 1977), all of w'hich are abundant in BBRSP. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 47 KILOMETERS Figure 1L Localities of known specimens of Myotis californicus from Big Bend Ranch State Park, Texas. M. californicus was recorded at BBRSP only from May to August. However, Schmidly (1991) suggests that this species overwinters in the Trans-Pecos, at which time it is known to be active. Furthermore, at Big Bend National Park this species was acquired on 3 March and 7 December (Easterla, 1973). Therefore, it should be considered a potential year round resident of BBRSP Over most of its range, the California myotis breeds in late autumn, at which time fertilization is de¬ layed (Krutzsch, 1954) Of tire 20 adult individuals of this species captured in BBRSP, 17 were females This discrepancy probably is in response to the formation of maternity colonics in the area as reported for the spe¬ cies by Krutzsch (1954). Three gravid females, each of which contained a single embryo (corresponding 48 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY crown-rump length of embryos in parentheses), were noted on 29 May (11, 16) and 4 June (17). Lactating females were examined on 6, 7, and 9 June; 15 and 25 July; and 2 and 3 August. A single, volant juvenile was taken on 3 August. These data support a parturition period of late May to early June as reported by Schmidly (1991). Af. califormcus often forages among trees and over water (Woodsworth, 1981). It is known to feed primarily on lepidopterans, dipterans (Whitaker et al., 1981), and trichopterans (Woodsworth, 1981), but also, to a lesser degree, on coleopterans and hemipterans (Woodsworth, 1981; Whitaker et al, 1981). Other species of bats taken from the same locali¬ ties at BBRSP as Af. californicus w r ere Mormoops megalophylla , Myotis thysanodes , Af. velifer; Pipistrellus hesperus, Eptesicus fits cus, Plecolus townsendii , Antrozous pallidus , and Tadarida brasiliensis. No parasites were noted in association with speci¬ mens ofAf. californicus from BBRSP. This bat is known to harbor various mites (Krutzsch, 1954; Dooley et al., 1976). The California myotis has been known to be afflicted with rabies (Constantine, 1986; 1988), but of eight individuals from BBRSP examined for the virus, all tested negative (Yancey et al., 1997). Comments. — The subspecies of A/, californicus at BBRSP is Af. c. californicus (Audubon and Bachman, 1842). The generic name Myotis is derived from the Greek “mys ?? and "ous,” which translate to mouse and ear, respectively. The specific epithet californicus re¬ fers to of California (Stangl et al., 1993). Specimens Examined (21).— Presidio Co.: BBRSP, UTM coordinates: 13 586937E 3262923N, 1; BBRSP, UTM coordinates: 13 587263E3263005N, 1; BBRSP, UTM coordinates: 13 600689E 3259514N, 1; BBRSP’ UTM coordinates: 13 601325E 3260789N, 6; BBRSP, UTM coordinates: 13 608477E3253180N, 1; BBRSP, UTM coordinates: 13 615458E 3268807N, 2; BBRSP, UTM coordinates: 13 615525E 3268958N, 1; BBRSP, UTM coordinates: 13 615559E 3268762N^ 6; BBRSP, UTM coordinates: 13 615599E 3268863N, 2 . Myotis clUolabrum (Merriam, 1886) Western Small-footed Myotis Description.—Myotis ciliolabrum is a small bat with pale brown pelage. A dark facial mask about the eyes and rostrum is present. This bat has a keeled cal¬ car and relatively small feet. The dental formula for Af. ciliolabrum is: i 2/3, c 1/1, p 3/3, m 3/3, total 38. External and cranial measurements of a single adult female from BBRSP are: total length, 83; length of tail vertebrae, 42; length of hind foot, 6; length of ear from notch, 14; weight, 4.4; greatest length of skull, 13.82. No marked sexual dimorphism is evident inM ciliolabrum (Bogan, 1974). Af. ciliolabrum often is confused with Af. californicus . See the previous account for discriminat¬ ing characters. Af. ciliolabrum is distinguished easily from other species of Myotis known from BBRSP and from Pipistrellus sub fleams by its keeled calcar. Su¬ perficially, Af. ciliolabrum might be confused with Pipistrellus hesperus. However, the two can be readily distinguished based on the appearance of the tragus. M. ciliolabrum has a long, straight, pointed tragus, whereas the tragus of P. hesperus is short, curved, and blunt. Distribution. —Af. ciliolabrum ranges from cen¬ tral Mexico, northward throughout the western half of the United States, and into southwestern Canada (Jones and Bimey, 1988). In BBRSP, it is known from only a single specimen taken from Lava Canyon (Fig. 12). Natural History. — With a relative abundance in¬ dex of 0.003, Af. ciliolabrum was among the rarest of bats encountered at BBRSP. This species accounted for only 0.2 percent of all bats captured. Af. ciliolabrum also was reported as rare in neighboring Big Bend Na¬ tional Park (Easterla, 1973). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 49 KILOMETERS Figure 12, Localities of known specimens ofMyotis ciliolabrum from Big Bend Ranch State Park, Texas. The individual taken in BBRSP was netted over a small pool in a shallow canyon. Vegetation at the site was sparse. Although occasionally recorded from desert areas in the Trans-Pecos, A/, ciliolabrum favors wooded, mountainous areas, which arc uncommon in BBRSP. Preferred roosting sites of M. ciliolabrum include rock crevices, under loose tree bark, and in man-made struc¬ tures (Sehmidly, 1991), all of which are abundant at BBRSP Therefore, it is probably this species’ ecologi¬ cal affinity for montane habitats that accounts for its scarcity in the park. The single western small-footed myotis collected during this study was taken in July. "Tire species has been documented to occur in the Trans-Pecos only from 50 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY March through July. However, in much of the remain¬ der of its range it is thought to hibernate within its sum¬ mer range (Schmidly, 1991). Therefore, M. ciliolabrum may occur in BBRSP throughout the year. Little is known regarding the reproductive biol¬ ogy ofM ciliolabrum. Schmidly (1991) reports that this species forms small maternity colonies, where birth is given to a single young from late May to early June. The one individual from BBRSP was a non-gravid, non- lactating, adult female taken on 21 July. M. ciliolabrum often forages near rocky bluffs or, in the absence of its close congener M. californicus , over water (Woodsworth, 1981). The specimen from BBRSP was taken while foraging near rocky bluffs and over w ater. The kinds of prey that M ciliolabrum for¬ ages upon are not documented, but Black (1974) sug¬ gests that it favors either lepidopterans or coleoptcrans. Other species of bats taken from the same local¬ ity at BBRSP as M. ciliolabrum included Pipislrellus hesperus and Antrozouspallidus. The one specimen ofM ciliolabrum from BBRSP tested negative for rabies (Yancey et al, 1997). How¬ ever, the species is known to harbor the virus (Constantine, 1988). Comments. — The subspecies ofM. ciliolabrum at BBRSP is M. c. ciliolabrum (Merriam, 1886). Pre¬ viously, M. ciliolabrum was considered a subspecies ofM. leibii, the eastern sinall-footcd myotis, until the former was elevated to specific status by Van Zvll dc Jong (1984). See the account on Myotis californicus for the etymology of the generic name. The specific epithet ciliolabrum is from the Latin “cilium” and “la¬ bium,” meaning eyelid and lip, respectively (Stangl ct al, 1993). Specimens Examined (1).— Presidio Co.: BBRSP, UTM coordinates: 13 598236E 3263889N, 1 . Myotis thysanodes G. S. Miller, 1897 Fringed Myotis Description .— Myotis thysanodes is a medium¬ sized bat with a buffy-brown dorsal pelage. An obvi¬ ous fringe of short, stiff hairs extends from the trailing edge of the uropatagium. Its calcar is without a keel, and relative to other species of Myotis at BBRSP, its feet and cars are large. The dental formula for M thysanodes is: i 2/3, c 1/1, p 3/3, m 3/3, total 38. External and cranial measurements of one adult male and one adult female, respectively, from BBRSP are: total length, 85, 90; length of tail vertebrae, 37, 35; length of hind foot, 9, 9; length of ear from notch, 17,17; weight, 6.7,10 (gravid); greatest length of skull, 16.61, 16.32. Females tend to be larger than males (Williams and Findley, 1979), Superficially, M thysanodes may appear similar to other species of bats at BBRSP. However, the pres¬ ence of the fringe of short hairs on the free edge of the uropatagium easily discriminates this bat from all oth¬ ers at the park. Distribution. —M thysanodes ranges from south¬ ern Mexico, through the southwestern United States to the Pacific Northwest, and into southern British Co¬ lumbia (Cf Farrell and Studier, 1980). In BBRSP, it is known only from the Sauccda area and Arroyo Segundo (Fig. 13). Natural History— During this study, only two specimens of M thysanodes were taken, which resulted in a relative abundance of0.006. This species accounted for only 0.4 percent of all bats taken, and therefore should be considered rare in BBRSP Easterla (1973) reported that, except for nursery colonies, the fringed myotis was uncommon at Big Bend National Park as well. Both specimens of M thysanodes taken during this study were captured while flying over small pools of water in deep or shallow canyons. In addition, this YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 51 KILOMETERS Figure 13. Localities of known specimens of Myotis thysanodes from Big Bend Ranch State Park, Texas. bat may be found in montane woodlands, desert scrub, and grassy areas. The fringed myotis utilizes caves, tunnels, rock crevices, and human structures as roosts (Schmidly, 1991). M. thysanodes was recorded in BBRSP only in June and July. It is a migratory bat that arrives in the area in May. Its winter grounds and behavior arc un¬ known (Schmidly, 1991). The reproductive biology ofM thysanodes is not well understood Upon arrival to the Trans-Pecos in May, females form nursery colonics (Schmidly, 1991) O’Farrell and Studicr (1973) report that females give 52 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY birth during the last week of June or the first week of July. However, a near-term pregnant female (crown- rump length, 21) that I examined on 9 June suggests that parturition at BBRSP may occur earlier. Nursery colonies at Big Bend National Park apparently disperse in October (Easterla, 1973). Black (1974) lists M thysanodes as a bat that forages between, within, or below r vegetative canopy. However, vegetation w'as sparse in both areas from which 1 collected this species. The fringed myotis is known to consume primarily coleopterans, but also feeds on lepidopterans to a lesser degree (Black, 1974). Other species of bats taken in sympatry with M. thysanodes included Mormoops megalophylla, Myotis californicus , Pipistrellus hesperus , Eptesicus fiuscus, Plecotus townsendii, Antrozouspallidus, and Tadarida brasiliensis. An unidentified species of tick was noted on M thysanodes from BBRSP In a summary of the ecto¬ parasites of M. thysanodes, O’Farrell and Studier (1980) list several species of mites and a wingless fly, Cestodes are the only endoparasites reported from M. thysanodes (Cain and Studier, 1974). Constantine (1988) reported this bat as a host of the rabies virus, A single individual from BBRSP was tested for rabies; it proved to be negative (Yancey ct al., 1997). Comments.— The subspecies of M. thysanodes that occurs at BBRSP isM t thysanodes Miller, 1897. See the account on Myotis californicus for the etymol¬ ogy of the generic name. The specific epithet thysanodes is from the Greek “thysanos” and “odes,” meaning tas¬ sel or fringe, and resemblance, respectively (Stangl et al., 1993). Specimens Examined (2).— Presidio Co.: BBRSP, UTM coordinates: 13 601325E 3260798N, 1; BBRSP, UTM coordinates: 13 608477E 3253180N, Myotis velifer (J. A. Allen, 1890) Cave Myotis Description.—Myotis velifer is a medium-sized bat with a dull, grayish-brown dorsal pelage. The cal¬ car of this species lacks a keel. Its feet are large, and its ears are intermediate in length. A bare patch in the pelage near the interscapular region frequently is present. A well-developed sagittal crest is present on the cranium. The dental formula forM velifer is: i 2/ 3, c 1/1, p 3/3, m 3/3, total 38. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of specimens from BBRSP are: total length, 96,8 (15, 89-115, 6.6); length of tail vertebrae, 40.3 (15,35-46, 3.4); length of hind foot, 9.1 (15, 8-10,0.7); length of ear from notch, 15.4 (15, 14-16,0.8); weight, 8.3(15,6.0-10, 1.2); greatest length of skull, 16.27 (7, 15.83-16.53, 0.26), Females are significantly larger than males for some measurements (Williams and Findley, 1979). M. velifer conceivably could be mistaken for M. thysanodes, but the former lacks the obvious fringe of hairs on the posterior margin of the uropatagium. M. velifer is easily distinguished from all other species of bats known to occur at BBRSP. Distribution .— M. velifer ranges from Central America, northw ard tlirough Mexico, and into the south¬ western United States. A disjunct population occurs on the southern High Plains of the United States (Fitch et al., 1981). At BBRSP, this bat was found along Cienega Creek and near Los Alamos (Fig. 14). Natural History. — M. velifer had a relative abun¬ dance index of 0.036, which ranked sixth among bats at BBRSP. This species represented 2.6 percent of all bats netted. These results suggest that the cave myotis is not extremely common in BBRSP. It was reported as uncommon at Big Bend National Park (Easterla, 1973). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 53 kilometers Figure 14, Localities of known specimens of Myotis velifer from Big Bend Ranch Stale Park, Texas. M. velifer was taken mostly along watercourses in areas of thick vegetation, but also near human dwell¬ ings. It tends to roost in caves and tunnels (Schmidly, 1991), often in colonics of 2000 to 5000 individuals (Fitch et al., 1981) The cave myotis is reported as a year round resi¬ dent of the Texas Panhandle and the Edwards Plateau, but, prior to this work at BBRSP, was unknown from the Trans-Pecos during the winter months. M velifer was taken at BBRSP from 29 May to 5 September, and a single individual was acquired on 26 February This specimen represents the first winter record of the cave myotis from Trans-Pecos Texas (Yancey and Jones, 1996). This w inter specimen indicates that at least part of the Trans-Pecos population of A/ velifer winters in the region. Most individuals of M velifer in the area 54 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY probably migrate from the region to winter hibemacula elsewhere. But a few individuals apparently hibernate in local caves over the winter, occasionally taking flight for short periods of time, as is the case with M. velifer from the Panhandle (Schmidly 1977#). Information on the reproductive biology of M. velifer in the Trans-Pecos is sparse (Schmidly, 1977#). Copulation probably occurs in the fall and winter (Fitch et al., 1981). Females are reported to give birth to a single young (Schmidly, 1991). I examined no preg¬ nant females during this study, and there are no prior records of gravid females from the Trans-Pecos (Schmidly, 1977#). In Kansas, Kunz (1973#) found that the cave myotis gives birth at the end of June or beginning of July. However, in central Texas, Raun and Baker (1958) noted near-term gravid females in May. The latter report led Easterla (1973) to speculate that parturition in M. velifer in the Big Bend region occurs in May. I examined lactating females on 5 July, and in Big Bend National Park, Easterla (1973) noted lactating females from 15 June to 26 July. During the summer, M. velifer usually forages two times during the night (Kunz, 1974). At BBRSP, this species frequently was observed feeding shortly after sunset. Kunz (1974) reports a second foraging period occurs just prior to sunrise This bat is an opportunistic inscctivore with a fluctuating diet (Fitch et al., 1981). It is known to prey heavily on small lepidopterans (Ross, 1967; Hayward, 1970) and coleopterans (Kunz, 1974). Other species of bats found in association with M. velifer at BBRSP included Mormoops megalophylla , Myotis californicus , M. yiimcmensis , Pipistrellus hesperus , Eptesicus fuscus , Lasiurus cine reus, Plecotus townsendii , Antrozous palliclus , and Tadarida brasihensis. No parasites were observed in association with specimens of M. velifer at BBRSP. Ectoparasites known to infest M velifer include mites (Fitch et al., 1981), true bugs (Bradshaw and Ross, 1961), fleas (Jameson, 1959; Bradshaw and Ross, 1961; Ubelaker, 1966; Reisenctal., 1976), and flies (Jameson, 1959; Ubelaker, 1966; Hayward, 1970; Reisen et al., 1976). Endopara- sites known from M. velifer include various species of trematodes, cestodes, and nematodes (Fitch et al., 1981). Rabies has been reported to infect the cave myotis (Constantine, 1988; Schmidly, 1991). Schmidly (1991) reports that only two of 82 (2.4 percent) specimens sub¬ mitted to the Texas Department of Health tested posi¬ tive. Four specimens from BBRSP were examine for rabies; all tested negative (Yancey et al., 1997). Comments .— The subspecies of M. velifer that occurs at BBRSP is M. v. incautus (J. A. Allen, 1896). See the account on Myotis californicus for the etymol¬ ogy of the generic name. The specific epithet velifer is from the Latin “velum” and “ferre,” meaning sail, and cany, respectively (Stangl et al., 1993). Specimens Examined (15).— Presidio Co.: BBRSP, UTM coordinates: 13 576060E 3288074N, 1; BBRSP, UTM coordinates: 13 576699E 3296276N, 1; BBRSP, UTM coordinates: 13 576783E 3296292N, 5; BBRSP, UTM coordinates: 13 576795E 3296125N, 3; BBRSP, UTM coordinates: 13 576823E3296177N, 2; BBRSP, UTM coordinates: 13 576842E 3296279N, 1; BBRSP, UTM coordinates: 13 615559E 3268762N, 1; BBRSP, UTM coordinates: 13 615599E3268863N, 1 . Myotisyumanensis (H. Allen, 1864) Yuma Myotis Description.—Myotis yumanensis is a small bat with pale to buff-browm dorsal pelage. Its calcar lacks a keel, its ears are small, and its feet are relatively mod¬ erate in size. Tire dental formula forM yumanensis is: i 2/3, c 1/1, p 3/3, m 3/3, total 38. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of specimens from BBRSP are: total length, 77 3 (4, 73-80, 3.1); length of tail vertebrae, 33.8 (4, 28-37,4.0); length of hind foot, 7.8 (4, 7-8,0.5); length of ear from notch, 13.8 (4, 13-14, 0.5); weight, 4.8 (4, 4,3-5.5, 0.6); greatest length of skull, 13.20 (4, 13.04- YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 55 13.37, 0.15). I know of no reports pertaining to sec¬ ondary sexual dimorphism in this species. Of the species of bats known from BBRSP, M. yumanensis is most easily confused with M. califomicus.M. ciliolabrum , and Pipistrellus hesperus. M. yumanensis is distinguished easily from all three of these bats by the absence of a keel on its calcar. In addition, the tragus of P. hesperus is short and blunt, whereas it is long and pointed in all members of the genus Myoiis . Distribution, — M. yumanensis ranges from cen¬ tral Mexico, northward through the southwestern United States, up through California and the Pacific Northwest, thence into British Columbia (Hall, 1981). In BBRSP, it is known from the Cienega Mountains area, Arroyo Segundo, the Whitroy Mine area, and along the Rio Grande (Fig. 15). Natural History. — With a relative abundance in¬ dex of 0.006, and composing only 0.4 percent of all bats netted, M. yumanensis appears to be rather rare at BBRSP. However, in addition to individuals netted, others were acquired from roost sites. Furthermore, sev¬ eral more individuals were taken or sighted in areas outside, but adjacent to, BBRSP. Therefore, this bat should be considered more common than mist net re¬ sults suggest, especially along the Rio Grande Corri¬ dor. M. yumanensis is known to occur in both upland and lowland situations, but seems to prefer the latter (Schmidly, 1977a). Only two specimens of M. yumanensis were netted during this study. Both were taken m riparian areas associated with cottonwood and willow trees. One was from a deep canyon in an area of sparse vegetation, whereas the other w as taken on level terrain in thick, closed-canopy vegetation. Addi¬ tional individuals were taken from their daytime roost, which was an abandoned building near Whitroy Mine This structure is situated in desert scrub domi¬ nated by creosote-bush. Outside BBRSP near Lajitas, M. yumanensis was netted above open water along the Rio Grande. Night roost structures of this bat included the undersides of the structures at Teepees Roadside Park, and Madera Creek Bridge on FM 170. In addi¬ tion to buildings and bridges, these bats also may roost in caves and mine tunnels (Schmidly, 1991). M yumanensis was detected in BBRSP between 23 June and 17 August, but the species is known to occur in the Trans-Pecos from April through Novem¬ ber. Furthermore, there is speculation that this bat may hibernate in the area over the winter (Schmidly, 1977a). Therefore, M. yumanensis should be considered a po¬ tential year round resident of BBRSP. Prior to parturition, females form large nursery colonies (Schmidly, 1991). No gravid or lactating fe¬ males were examined during this study, but in Big Bend National Park, a single young reportedly is bom in late May or early June, and lactating females were observed between 10 June and 12 July. Volant juveniles were noted in Big Bend National Park as early as 28 June (Easterla, 1973). M. yumanensis most often forages at low levels over streams and ponds (Schmidly, 1991). It is known to feed on a variety' of insects, but appears to favor lcpi- dopterans, diptcrans, and coleopterans (Easterla, 1973). Other species of bats found at the same localities as M. yumanensis at BBRSP included Mormoops megalophylla , Myotis velifer, Pipistrellus hesperus , Eptesicus fuscus , Plecotus townsendii, Antrozous pallidus , Tadaricia brasiliensis , and Nyctinomops macrotis. No parasites were observed in association with M yumanensis during tins study This bat is known to be afflicted by the rabies virus (Constantine, 1988) Only a single individual from BBRSP was tested for the virus and it was negative (Yancey' ct al, 1997) Comments ,— The subspecies of M yvmanensis that occurs at BBRSP is M y yumanensis (H Allen, 1864), See the account on Myotis californtcus for the 56 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Figure 15, Localities of known specimens of Myotis yumanensis from Big Bend Ranch State Park, Texas, etymology of the generic name. The specific epithet 1; BBRSP, UTM coordinates: 13 614933E3246380N, yumanensis refers to of (Old Fort) Yuma (Stangl et al, s 2; BBRSP, Colorado Canyon, 1 (SRSU); BBRSP, 12 1993). mi. W Lajitas, 1. Specimens Examined (6).— Presidio Co.: BBRSP, UTM coordinates: 13 576795E 3296125N, 1; BBRSP, UTM coordinates: 13 608608E3253227N, YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 57 Pipistrellus hesperus (H. Allen, 1864) Western Pipistrelle Description—Pipistrellus hesperus is the small¬ est bat that occurs at BBRSP. The dorsal pelage usu¬ ally is smoky gray in color. A dark facial mask extends between the ears about the rostrum and eyes. The cal¬ car of P. hesperus is keeled, and the tragus is short, curved, and blunt. The feet and ears are small. The dental formula for P hesperus is: i 2/3, c 1/1, p 2/2, m 3/3, total 34. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult western pipistrelles from BBRSP are: total length, 76.4 (98, 69-90, 4.4); length of tail verte¬ brae, 32.5 (98,26-39,2.6); length of hind foot, 5 4 (99, 4-6, 0.5); length of ear from notch, 12.1 (98, 10-14, 0.7); weight, 3.8 (82, 2.0-6.5, 0.8); greatest length of skull, 12.46 (20, 11.88-13.06, 0.29). Females tend to be larger than males (Schmidly, 1991). In BBRSP, P. hesperus might be mistaken for Myotis californicus and M. ciliolabrum. See the ac¬ counts of those two species for differentiation. P hesperus conceivably could be confused with its con¬ gener, P. subflavus. However, the two can be distin¬ guished easily based on coloration of pelage and tragus morphology. P hesperus is smoky gray with a short, curved, blunt tragus, whereas P. subjlavus has yellow- orange tricolored pelage, and a long, straight, pointed tragus. In addition, the calcar of P. hesperus is keeled, whereas that of P subjlavus lacks a keel. Distribution .— P hesperus ranges from central Mexico, northward throughout the southwestern United States, up to the Pacific Northwest (Hall, 1981). It oc¬ curs throughout BBRSP (Fig. 16), where it is the most widespread species of bat. Natural History .— At BBRSP, P. hesperus had a relative abundance index of 0.534, and accounted for 34.4 percent of all bats netted. Based on these figures, the western pipistrelle is the most abundant bat at BBRSP. Aside from being the most widespread and abun¬ dant bat at BBRSP, P hesperus may also be the most ubiquitous in terms of habitat utilization. This bat w as taken in most water-associated situations, whether in deep canyons, shallow canyons, or level conditions. It was found in both densely vegetated areas, as well as open areas with sparse or no vegetation. This bat also w'as taken frequently in desert scrub habitats that lacked any source of water. In addition, it often w as observ ed frying about human dwellings. This species tends to roost alone or in small groups in rock crevices, under rocks, in burrows, and in man-made structures (Schmidly, 1991). At BBRSP, P hesperus was present and active throughout the year, having been taken during every month except January. Schmidly (1991) reports this bat to be sporadically active during winter, at which time it may become aroused during warm spells This appears to be situation at BBRSP, as it was encoun¬ tered much less frequently during the cooler months. Prior to parturition, females form small maternity colonies of up to 12 individuals (Schmidly, 1991). I examined 17 grav id females taken from 29 April to 9 June, 12 of which were pregnant with twins, and five that contained a single embryo (mean, 1.7). Pregnant females (with number of embryos and corresponding crown-rump lengths in parentheses) were examined on the following dates: 29 April (2 embryos, crown-rump length, 5), 30 April (1 embryo, crown-rump length, 4), 3 May (2 embryos, crown-rump length, 8), 13 May (2 embry os, crown-rump length, 10), 14 May (1 embryo, crown-rump length, 9; 2 embryos, crown-rump length, 10), 15 May (1 embryo, crown-rump length, 14), 25 May (2 embryos, crown-rump length, 10), 28 May (2 embryos, crown-rump length, 11; 2 embryos, crown- rump length, 12), 29 May (2 embryos, crown-rump length, 9; 2 embryos, crown-rump length, 17; 2 em¬ bryos, crown-rump length, 18), and 9 June (1 embryo, crown-rump length, 16:2 embry os, crowm-rumo length, 15; 2 embryos, crown-rump length, 16) Lactating fe¬ males were noted from 21 June to 2 August Volant juveniles were observed from 8 July through 22 Au¬ gust. Schmidly (1991) reports P hesperus to give birth from June to July, and most of the data from this study concur. However, given a gestation period of about 40 58 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY KILOMETERS Figure 16 Localities of known specimens of Pipistrellus hesperus from Big Bend Ranch State Park, Texas. days (Schmidlv, 1991), it is conceivable that the females carry ing 4 and 5 mm embryos in late April may have given birth in late May. Thus, parturition in BBRSP may occur from late May to July. P. hesperus is known to exhibit two peaks in for¬ aging activity, the first in the early evening and the sec¬ ond around dawn (Fitzgerald et ah, 1994). At BBRSP, this bat was observed foraging very early in the evening, often as early as one hour before sunset. In the morn¬ ing, it was observed foraging as late as 0930 h. This species feeds on a wide variety of small insects, includ¬ ing lepidopterans, coleopterans, trichopterans, plecop- terans, homopterans, dipterans, and hymenopterans (Schmidly, 1991). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 59 Other species of bats found at the same localities as P. hesperus at BBRSP included Mormoops megalophylla, Myotis californicus 9 M. ciliolabrum,M. velifer, M. yumanensis, Eptesicus fuscus, Lasiurus cinereus, Plecotus townsendii, Antrozous pallidus , Tadarida brasiliensis , and Nyctinomops macrotis. In addition, Pipistrellus subflavus, was taken in the near vicinity of P. hesperus , and the two should be consid¬ ered to occur sympatrically in BBRSP. Undetermined species of mites and ticks were ob¬ served on P. hesperus from BBRSP. Also, one indi¬ vidual was infected with an unidentified nematode. P. hesperus has been known to harbor the rabies virus (Constantine, 1988), but 60 individuals from BBRSP were examined for the vims; all proved negative (Yancey etal, 1997). Comments .— The subspecies of P. hesperus at BBRSP is P h. maximus Hatfield, 1936. The generic name Pipistrellus is derived from the Italian “pipistrello,” which translates to bat. The specific epi¬ thet hesperus is from the Greek “hesperos,” meaning of evening (Stangl et al., 1993). Specimens Examined (123).— Presidio Co.: BBRSP, UTM coordinates: 13 576060E 3288074N, 2; BBRSP, UTM coordinates: 13 576609E3295115N, 3; BBRSP, UTM coordinates: 13 576783E 3296292N, 5; BBRSP, UTM coordinates: 13 576823E 3296177N, 3; BBRSP, UTM coordinates: 13 576839E3296085N, 1; BBRSP, UTM coordinates: 13 576842E3296279N, 1; BBRSP, UTM coordinates: 13 577553E3287272N, 4; BBRSP, UTM coordinates: 13 577563E 3287242N, 1; BBRSP, UTM coordinates: 13 579592E3269404N, 1; BBRSP, UTM coordinates: 13 580916E 3264339N, 3; BBRSP, UTM coordinates: 13 586937E3262923N, 24; BBRSP, UTM coordinates: 13 586938E 326291 ON, 5; BBRSP, UTM coordinates: 13 589354E 3246455N, 1; BBRSP, UTM coordinates: 13 590668E3261956N, 1; BBRSP, UTM coordinates: 13 592955E 3259156N, 3; BBRSP, UTM coordinates: 13 596232E 3258492N, 1; BBRSP, UTM coordinates. 13 598044E3263850N, 3; BBRSP, UTM coordinates: 13 598124E3263864N, 1; BBRSP, UTM coordinates. 13 598236E3263889N, I; BBRSP, UTM coordinates: 13 598326E3263912N, 1; BBRSP, UTM coordinates: 13 600689E 3259514N, 2; BBRSP, UTM coordinates: 13 601325E326G789N, 15; BBRSP, UTM coordinates: 13 607610E 326363ON, 1; BBRSP, UTM coordinates: 13 608477E 3253180N, 2; BBRSP, UTM coordinates: 13 608597E 3253243N, 2; BBRSP, UTM coordinates: 13 608608E3253227N, 3; BBRSP* UTM coordinates: 13 608870E 3253520N, 1; BBRSP, UTM coordinates: 13 608955E 3253483N, 1; BBRSP, UTM coordinates: 13 611283E 3249529N, 1; BBRSP, UTM coordinates: 13 611393E 3249399N, 3; BBRSP, UTM coordinates: 13 614303E3264882N, 1; BBRSP, UTM coordinates: 13 615525E 3268958N, 3; BBRSP, UTM coordinates: 13 615559E 3268762N, 1; BBRSP, UTM coordinates: 13 615565E 3268878N, 6; BBRSP, UTM coordinates: 13 615599E 3268863N, 9; BBRSP, UTM coordinates: 13 615650E 3268869N, 2; BBRSP, Colorado Canyon, 1 (SRSU); BBRSP, Smith Ranch, Fresno Canyon, 2 (SRSU), BBRSP, Burnt Camp, the Solitario, 1 (SRSU). Brewster Co.: BBRSP, Tres Papalotes, the Solitario, 1. Pipistrellus subflavus (F. Cuvier, 1832) Eastern Pipistrelle Description .— Pipistrellus subflavus is a small bat with a pale yellow-orange dorsal pelage. The most distinguishing feature of this bat is the tricolorcd ap¬ pearance of the fur. Each hair is dark at the base, paler in the middle, and dark at the tips. The feet and ears of this bat are relatively small in size. The calcar lacks a keel, and the tragus is straight and pointed. The dactylopatagium minus is distinctly paler than the rest of the wing membrane. The dental formula for P subflavus is: i 2/3, c 1/1, p 2/2, m 3/3, total 34 External and cranial measurements of a single adult male from BBRSP are: total length, 86; length of tail vertebrae, 38; length of hind foot, 8; length of ear from notch, 12; weight, 5.0; greatest length of skull, 12.67. Females typically arc larger than males (Fujita and Kunz, 1984). Other species of bats that occur at BBRSP that P subflavus might be mistaken for include Myotis californicus , M ciliolabrum , and P hesperus Sec the accounts of these species for distinguishing characters. 60 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Distribution ,— P. subflavus ranges from south¬ eastern Mexico, northward through the eastern half of the United States, and into southeastern Canada (Fujita and Kunz, 1984). In BBRSP, the eastern pipistrelle was taken from a single locality in the Cienega area (Fig. 17). This locality is the only site in Trans-Pecos Texas from which P. subflavus has been recorded, and represents one of the we stem-most localities for the species. Natural History. — A single specimen of P. subflavus was taken during this study, which resulted in a relative abundance index of 0.003. This species accounted for only 0.2 percent of all bats netted, and therefore should be considered very rare in BBRSP. Because the specimen of P. subflavus taken dur¬ ing this study is the first from the Trans-Pecos, virtu¬ ally nothing is known about the life history' of this spe¬ cies in the area. This individual was taken along Cienega Creek among dense vegetation primarily composed of large willow and cottonwood trees. In Coahuila, Mexico, this bat was found to be restricted to this type of riparian habitat. There is speculation that P. subflavus reached Coahuila from the east by following the water- associated habitat along the Rio Grande, rather than traversing the inhospitable habitat of central Texas. It is suggested that this bat is linked to large trees found in riparian habitats, relying on them for roosting struc¬ tures. In addition to trees, the eastern pipistrelle also may roost in caves, mines, rock crevices, and buildings (Schmidly, 1991). The eastern pipistrelle acquired at BBRSP was taken in July. Elsewhere in Texas, it is known to hiber¬ nate within its summer range (Schmidly, 1991). There¬ fore, this bat should be considered a potential year round resident of BBRSP. Female eastern pipistrelles form small nursery colonies, frequently at sites that are unsuitable for most other species of bats (Schmidly, 1991). No pregnant or Iactating females were observed at BBRSP. Females are reported to give birth, usually to twins, in late May to early July. Young bats typically obtain the ability to fly by the age of one month (Schmidly, 1991). P subflavus often forages for insects over water at treetop level (Schmidly, 1991). This bat has a varied diet, and is known to feed on coleopterans, homopter- ans, dipterans, hymenopterans, and lepidopterans (Sherman, 1939; Ross, 1967; Whitaker, 1972). Plecotus townsendii was the only other species of bat taken at the same locality as P. subflavus at BBRSP. However, several other species were taken in the same general area and habitat, and therefore should be considered to occur sympatrically with P subflavus. These species were Mormoops megalophylla , Myotis ve lifer\M. yumanensis , Pipistrellus hesperus , Eptesicus fuscus, Lasiurus cinereus , and Tadarida brasiliensis. No parasites were noted in association with the P subflavus specimen from BBRSP. Ectoparasites re¬ ported previously from P subflavus include numerous species of mites (Fujita and Kunz, 1984). Endopara- sites known to infect P subflavus include protozoans (Wheat, 1975) and trematodes (Macy, 1940; Jones, 1957). P. subflavus has been documented to harbor the rabies virus (Constantine, 1988; Schmidly, 1991), al¬ beit at low levels (Fujita and Kunz, 1984). The single individual from BBRSP tested negative for this virus (Yancey et al., 1997). Comments. — The single specimen of P. subflavus taken from BBRSP tentatively has been assigned to the subspecies P s. clarus Baker, 1954 (Yancey et al., 1995). However, the color of this specimen does not appear to be as pale as that described for other speci¬ mens of P s. clarus. Additional specimens of this bat are necessary in order to resolve the systematics of this taxon in BBRSP. See the account on Pipistrellus hesperus for the etymology of the generic name. The specific epithet subflavus is from the Latin “sub” and “flavus,” meaning under and yellow, respectively (Stangl et al., 1993). Specimens Examined (1).— Presidio Co.: BBRSP, UTM coordinates: 13 576658E 3296469N, 1 . YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 61 kilometers Figure 17. Localities of known specimens of Fipistrellus subflavus from Big Bend Ranch State Park, Texas. Eptesicus fuscus (Palisot de Beauvois, 1796) Big Brown Bat Description.— Eptesicus fuscus is a large bat with a pale to chocolate brown dorsal pelage. The tra¬ gus is short, broad, and curved, and its calcar is keeled The dental formula for E. fuscus is: i 2/3, c 1/1, p 1/2, m 3/3, total 32. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult big brown bats from BBRSP are total length, 116.4(44. 104-126,4 8), length of tail ver¬ tebrae, 51.2 (44, 43-59, 4.2), length of hind foot, 10 1 62 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY (44,9-11, 0.5); length of ear from notch, 17.9 (44, 16- 19,0.7); weight, 15.2 (41,9.5-19, 2,2); greatest length of skull, 19.36 (20, 18.29-20.02, 0.52). Females tend to be slightly larger than males (Schmidly, 1991). The color, size, and tragus morphology of E . fuscus make it difficult to confuse this bat with any other species of bat that occurs at BBRSP Distribution .— E. fuscus ranges from northern South America, northward through Central America, on into and across all of the United States and southern Canada. It also is present on several of the Caribbean Islands (Kurta and Baker, 1990). In BBRSP, E. fuscus was recorded from the Cienega, Las Quevas, Sauceda, Arroyo Segundo, and Los Alamos areas (Fig. 18). Natural History. — With a relative abundance in¬ dex of 0.163, E. fuscus was the fourth most frequently netted bat. It comprised 9.9 percent of all bats netted. These results indicate that the big brown bat is rela¬ tively common in the park. Most specimens of E. fuscus acquired at BBRSP were taken near small springs or streams associated with cottonwood and willow trees. One individual was taken near a human dwelling. However, this bat seems to be a habitat generalist (Furlonger et al., 1987), and there¬ fore, may occur in any of the habitats present at BBRSP. E. fuscus is known to roost in hollow trees, but also may utilize rock crevices, tunnels, and man-made struc¬ tures (Kurta and Baker, 1990). In Big Bend National Park, Easterla (1973) found evidence that the sexes seg¬ regate by elevation during the summer. He proposed that females set up nursery colonies at lower elevations, while the males spend the summer at cooler high eleva¬ tions. Although females outnumbered males almost two to one (29 to 16) in the low lands of BBRSP during the summer, segregation of the sexes does not appear to be the situation, as males and females wore taken together on numerous occasions. During this study, E. fuscus was taken from 11 April to 4 September. No winter records of this species exist from Trans-Pecos Texas, but it is believed to hi¬ bernate in the area over winter (Easterla, 1973), In BBRSP, it probably is a year round resident, probably being active only during the warmer months. Little is known on the reproductive biology of E. fuscus in the Trans-Pecos. In Texas in general, partu¬ rition occurs from late May to June. E. fuscus from the eastern part of the state typically gives birth to twins, whereas only a single young is produced in West Texas. Based on this information, it is assumed that E. fuscus in the Trans-Pecos gives birth to a single young in May or June (Schmidly, 1991). I examined a single gravid female taken on 5 May that was carrying one embryo with a crown-rump length of 9. Lactating females were noted on 23 June, and 5, 10, 15, and 16 July. Volant juveniles were observed among the population on 18, 24, 25, and 31 July, and 4 September. E. fuscus is known to forage throughout the night, but the majority of feeding activity occurs within two hours following sunset (Kunz, 1973Z>). At BBRSP, this bat was one of the first bats seen foraging in the evening. It frequently was observed flying about shortly after sunset. E. fuscus primarily feeds on small coleopterans (Freeman, 1981; Mumford and Whitaker, 1982). In addition, it is known to prey on isopterans, hemipter- ans, homoptcrans, and hymenopterans (Ross, 1967). Other species of bats taken in association with E. fuscus at BBRSP were Mormoops megalophylla , Myotis californicus , M. thysanodes, M. velifer, M. yumanensis , Pipistrellus hesperus , Lasiurus cine reus, Plecotus townsendii, Antrozous pallidus , Tadarida brasiliensis , and Nyctinomops macrotis . Mites and ticks were found on E. fuscus from BBRSP. Several insects also are known to infest E. fuscus (Kurta and Baker, 1990). Endoparasiies of E. fuscus include protozoans (Bower and Woo, 1981), trematodes, cestodes, and nematodes (Kurta and Baker, 1990). E. fuscus has been implicated as a reservoir for rabies on several occasions (Kurta and Baker, 1990), but of 12 specimens from BBRSP that were tested for the virus, none was positive (Yancey et al., 1997). E. fuscus also has been implicated as a host for St. Louis encephalitis virus and the fungus Histoplasma capsulatum (Kurta and Baker, 1990), the etiologic agent of histoplasmosis (Rippon, 1982). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 63 Figure 18 Localities of known specimens of Eptesicus fuscits from Big Bend Ranch State Park, Texas. Comments .— The subspecies of E. fuscus at Specimens Examined (50).— Presidio Co.: BBRSP is E.fpallidus Young, 1908. The generic name BBRSP, UTM coordinates 13 576699E 3296276N, Eptesicus is derived from the Greek “petesthai” and 3, BBRSP, UTM coordinates: 13 576783E 3296292N, “oikos,” which translate to fly and house, respectively. 5; BBRSP, UTM coordinates: 13 576795E 3296125N, The specific epithet fuscus is from the Latin “fuscus,” 2; BBRSP, UTM coordinates 13 576842E 3296279N, meaning dusky (Stangl et al., 1993). 1; BBRSP, UTM coordinates: 13 586937E 3262923N, 1; BBRSP, UTM coordinates 13 586938E 32629ION, 1; BBRSP, UTM coordinates 13 601325E 3260789N, 64 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 4; BBRSP, UTM coordinates: 13 604886E 3240689N, 1; BBRSP, UTM coordinates: 13 608477E3253180N, 1; BBRSP, UTM coordinates: 13 608597E 3253243N, I; BBRSP, UTM coordinates: 13 608608E 3253227N, 3; BBRSP, UTM coordinates: 13 608870E 3253520N, 4; BBRSP, UTM coordinates: 13 615525E3268958N, 3; BBRSP, UTM coordinates. 13 615559E3268762N, 1; BBRSP, UTM coordinates: 13 615565E3268878N, 2, BBRSP, UTM coordinates: 13 615599E3268863N, 16; BBRSP, UTM coordinates: 13 615650E3268869N, 1 . Lasiurus cinereus (Palisot de Beauvois, 1796) Hoary Bat Description .— Lasiurus cinereus is a large bat with heavy, dark brown dorsal pelage that is frosted w ith white. The face of this bat is yellowish. The feet are large, and the ears are relatively short and round. As with all members of the genus, the dorsal surface of the uropatagium is heavily furred. The dental formula for L. cinereus is: i 1/3, c 1/1, p 2/2, m 3/3, total 32. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult hoary bats from BBRSP are: total length, 133.5 (6, 120-143, 8.2); length of tail verte¬ brae, 59.1 (6, 51-66, 6.0); length of hind foot, 10.3 (6, 9-12, 1.0); length of ear from notch, 17.3 (6, 16-19, 1.2); weight, 21.3 (6, 16-29, 4.8); greatest length of skull, 16.72 (6, 14.85-17.51,0.98). Significant sexual dimorphism has been reported in L. cinereus , with fe¬ males averaging larger than males (Williams and Findley, 1979). Because of its size and distinct coloration, it is difficult to confuse the hoary bat with any other species of bat at BBRSP Distribution .— L. cinereus is the most w idespread bat in the New World. It ranges from southern South America, up through parts of western South America to northwestern South America. There is a hiatus in its distribution between northern South America and north¬ ern Central America. From northern Central America, it ranges on up through Mexico, northward throughout most of the United States and into much of Canada. In addition, it is known from several island localities, in¬ cluding the Hawaiian Islands (Shump and Shump, 1982). In BBRSP, L. cinereus is known from the Cienega area. Las Cuevas, and Chorro Canyon (Fig. 19). Natural History. — At BBRSP, L. cinereus had a relative abundance index of 0.018. This species repre¬ sented 1.1 percent of all bats netted during this study. These data indicate that the hoary bat is rather uncom¬ mon in the park. This bat was considered uncommon in Big Bend National Park as well (Easterla, 1973), Schmidly (1991) reported that in the Trans-Pecos, the hoary bat is restricted to montane woodlands. How¬ ever, all specimens of L. cinereus taken at BBRSP were acquired from lowland riparian woodlands. Vegetation at all sites was dominated by dense stands of cotton¬ wood and willow trees. L. cinereus is a tree-roosting bat (Shump and Shunip, 1982), and undoubtedly roosts among the foliage of these trees. L. cinereus w as recorded at BBRSP during April, May, and September This is a migratory species, and may occur in BBRSP only during the spring and fall while migrating through the area. Females are thought to begin migratory movements prior to males and the sexes are thought to segregate during the summer months. Females move to the northern, eastern, and central United States to give birth and raise their young. In contrast, males sununer in the mountains of the west (Findley and Jones, 1964). This appears to be the situ¬ ation at Big Bend National Park where only males are found in the Chisos Mountains during the summer, and only females or known from the park during the spring and fall (Easterla, 1973). Fall migration commences in August, and although not documented, sexual segrega¬ tion during this activity was suggested by Findley and Jones (1964). At BBRSP during early September, an adult male hoary bat was taken along with numerous female hoary bats at the same general time and locality. This discounts the possibility of complete segregation of the sexes during fall migration. Because of the ab¬ sence of sununer records, and the lack of suitable mon¬ tane habitat, such as that found in Big Bend National YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 65 kilometers Figure 19. Localities of known specimens of Lasiurus cinereus from Big Bend Ranch State Park, Texas. Park, L, cinereus probably occurs in BBRSP only as a spring-fall migrant. Little is known about the reproductive habits of hoary' bats in the Trans-Pecos. Females are thought to give birth from mid-May to early July (Schmidly, 1991). Litters typically consist of two young, but may range from one to four (Shump and Shump, 1982) A single female taken at BBRSP on 18 May was gravid with two embry os (crown-rump length, 14) Young usually obtain the ability to fly by 33 days of age. 1. cinereus typically begins to forage late in the evening (Shump and Shump, 1982) This bat seems to 66 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY favor lepidopterans (Ross, 1967; Black, 1972), but also may feed on coleopterans, dipterans, orthopterans, isopterans, odonatans, and hymenopterans (Shump and Shump, 1982). Several species of bats were taken at the same localities as L. cinereus , but at different times of the year. Tadarida brasiliensis was the only bat taken at the same place and time as L. cinereus. No parasites were noted in association with L. cinereus from BBRSP. Previously reported external parasites of L. cinereus include various species of mites. Protozoans and various helminths are known endopara- sites of hoary bats. L. cinereus has been reported as having a high incidence of rabies (Shump and Shump, 1982). Schmidly (1991) reported that 25 percent of hoary bats tested by the Texas Department of Health from 1984 to 1987 were positive; this was the highest frequency observed among Texas bats. However, this figure was based on a sample of only 40 specimens. No hoary bats obtained from BBRSP during this study were tested for rabies. Comments .— Tire subspecies of L. cinereus at BBRSP is L. c. cinereus (Palisot de Beauvois, 1796). The generic name Lasiurus is derived from the Greek “lasios” and “oura,” which translate to shaggy and tail, respectively. The specific epithet cinereus is from the Latin “cinereus,” meaning ashen (Stangl et al., 1993). Specimens Examined (6).— Presidio Co.: BBRSP, UTM coordinates: 13 576783E 3296292N, 2; BBRSP, UTM coordinates: 13 576823E 3296177N, 2; BBRSP, UTM coordinates: 13 576844E 3296174N, 1; BBRSP, UTM coordinates: 13 609585E 3249854N, 1 . Plecotus town sen dii Cooper, 1837 Townsend’s Big-cared Bat Description .-— Plecotus townsendii is a medium- sized bat w ith a pale brown dorsal pelage. The ears of this bat are distinctively large. An obvious lump-like facial gland is present on both sides of the nose. The dental formula for P. townsendii is: i 2/3, c 1/1, p 2/3, m 3/3, total 36. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 97.3 (10, 90-105, 5.4); length of tail vertebrae, 47.0 (10, 43-50, 2.3); length of hind foot, 9.1 (10, 8- 11,1.2); length of ear from notch, 35.0(10,34-37,0.8); w eight, 8.2 (10, 6.7-9.0, 0.6); greatest length of skull, 16.05 (9, 15.56-16.39, 0.26). Females may average slightly larger in size than males (Kunz and Martin, 1982). The only other bat known to occur in BBRSP that P. townsendii might be confused with is Antrozous pallidus. Both of these bats are pale in color, and both possess noticeably long ears. However, the two can be distinguished easily on the basis of color, length of ears, and presence or absence of conspicuous nose lumps. P. townsendii is pale brown, has ear measurements greater than 30, and possesses two distinct nose lumps. In con¬ trast, A. pallidus is pale yellow to cream, has ear mea¬ surements usually less than 30, and lacks distinct nose lumps. Distribution .— P. townsendii ranges from cen¬ tral Mexico, northward throughout the western United States, and into southern British Columbia (Kunz and Martin, 1982). In BBRSP, this bat is known from the Ciencga, Sauceda, Los Alamos, Arroyo Segundo, and Fresno Canyon areas (Fig. 20). Natural History .— At BBRSP, P. townsendii had a relative abundance index of0.027. This bat accounted for 2.0 percent of all bats netted. These figures suggest that P townsendii is rather uncommon in BBRSP. This bat was found to be somewhat more abundant in nearby Big Bend National Park (Easterla, 1973). In BBRSP, P townsendii w'as netted over small streams and springs, all of which were associated with riparian woodland habitat. In addition, specimens were acquired from inside Whitroy Mine. This mine is situ- YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 67 KILOMETERS Figure 20. Localities of known specimens of Plecotus townsendii from Big Bend Ranch State Park, Texas, ated among desert scrub dominated by creosote-bush. The distribution of this bat apparently is not a function of floral associations (Schmidly, 1991), Rather, its dis¬ tribution appears to be correlated with the abundance of preferred roost sites, especially caves and abandoned mines (Davis and Schmidly, 1994). Therefore, P townsendii potentially could occur almost anywhere in BBRSP where these structures exist. Townsend’s big-eared bat was recorded at BBRSP from 20 March to 3 September It is known to hiber- 68 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY nate in tight clusters in local caves rather than migrate (Schmidly, 1991), and should be considered a year round resident of the park. During summer, females form small to medium- sized maternity colonies consisting of 12 to 200 indi¬ viduals. Birth is given to a single young in late May or early June (Schmidly, 1991). Lactating females were observed at BBRSP on 5, 6, 8, and 9 July. Juveniles obtain the capability of flight by week three, and are weaned by six weeks of age (Kunz and Martin, 1982), P townsendii is considered a late-evening forager (Kunz and Martin, 1982), although during this study it was taken infrequently during the early evening. This bat is considered an aerial msectivore, but is known occasionally to glean prey from leaves of plants (Kunz and Marti, 1982). P. touwsendii primarily feeds on small lepidoptcrans, but also is known to consume neuroptcr- ans, coleopterans, dipterans, and hymenopterans (Hamilton, 1943; Ross, 1967; Whitaker et ah, 1977). Bats netted in sympatrv with P townsendii at BBRSP included Mormoops megalophylla , Myotis calijornicus,M. thysanodes, bA. ve lifer, M. yumanensis, Pipistrellus hesperus , Pipistrellus subflavus , Eptesicus fuscus , and Antrozous pallidus. Ectoparasites noted infesting P townsendii at BBRSP included ticks and a wingless bat fly (Nycteribiidae). P townsendii from Big Bend National Park is known to be infested with the nycteribiid Basilia corynorhini (Whitaker and Easterla, 1975), and it is likely that this was the species of wingless bat fly in¬ festing P. townsendii at BBRSP Other external para¬ sites reported from P townsendii include various spe¬ cies of mites and ticks, and a w inged bat fly (Strcblidae). Internal parasites documented to infect P townsendii include protozoans, ccstodes, and nematodes (Kunz and Martin, 1982). Townsend’s big-cared bat is known to be afflicted by rabies (Constantine, 1967; 1988). Four individuals from BBRSP were tested for the virus, but all proved negative (Yancey ct ah, 1997). Comments .— The subspecies of P. townsendii at BBRSP is P. t. pallescens (Miller, 1897). The generic name Plecotus is derived from the Greek “plekos” and “tous” which translate to twist or braid, and ear, re¬ spectively. The specific epithet townsendii refers to Townsend’s (Stangl et ah, 1993). Many workers (e.g., Menue, 1987; Tumlison and Douglas, 1992) consider New World members of the genus Plecotus as mem¬ bers of the genus Corynorhinus . If this view is fol¬ lowed, Townsend’s big-eared bat would be recognized as Corynorhinus townsendii. Specimens Examined (11).— Presidio Co.: BBRSP, UTM coordinates: 13 576658E 3296469N, 3; BBRSP, UTM coordinates: 13 576699E 3296276N, 1; BBRSP, UTM coordinates: 13 576795E3296125N, 2, BBRSP, UTM coordinates: 13 601325E3260789N, 1; BBRSP, UTM coordinates: 13 614672E3246532N, 2; BBRSP, UTM coordinates: 13 615559E 3268762N, 1; BBRSP, Smith Ranch, Fresno Canyon, 1 (SRSU). Antrozous pallidus (Le Conte, 1856) Pallid Bat Description .— Antrozous pallidus is a medium- sized bat with pale yellowish dorsal pelage, often with pale brown or gray blotches. The ears of this bat are moderately large. The dental formula for A . pallidus is: i 1/2, c 1/1, p 1/2, m 3/3, total 28. M eans of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 107.2 (35,92-115,4.6); length of tail vertebrae, 45.8 (35, 31-54, 4.5); length of hind foot, 10.7 (36, 9- 13,0.9); length of ear from notch, 28.9 (35,24-31,1.4); weight, 13.5(33, 10.5-19,1.9); greatest length of skull, 19.29(20,18.57-19.96,0.42). Males often are slightly smaller than females (Schmidly, 1991), The only other bat known to occur in BBRSP that A. pallidus might be confused with is Plecotus townsendii. See the account of the latter for differen¬ tiation. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 69 KILOMETER Figure 21. Localities of known specimens of A ntrozous pallidus from Big Bend Ranch State Park, Texas. Distribution .— A. pallidus ranges from central Mexico and Baja California, northward throughout the southwestern United States, up through the Pacific Northwest, and into southern British Columbia (Hermanson and O’Shea, 1983). At BBRSP, this bat was fairly widespread, being found at several localities scattered throughout the park (Fig. 21). Natural History .— With a relative abundance in¬ dex of 0 131,-4. pallidus was the fifth most frequently netted bat at BBRSP It accounted for 7.8 percent of all bats netted. Although these results suggest that the pal¬ lid bat is not uncommon in BBRSP, it is not as abun¬ dant as in Big Bend National Park, where it was re¬ ported as the most common bat in the park (Eastcrla, 1973). 70 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY A. pallidus frequently was taken along water courses in BBRSP. It was acquired from cottonwood- willow associations near small streams and pools, as w r ell as from tamarisk-mcsquite associations along the Rio Grande. In addition it was taken over water tanks in desert scrub dominated by creosote-bush. Pallid bats tend to roost in small colonies (12 to 100 individuals) within rock crevices, caves, tunnels, in buildings (Schmidly, 1991), and possibly hollow trees (Orr, 1954). A. pallidus was recorded at BBRSP from 19 March to 16 September. There are no records of this bat from Texas during any other time of year. This bat is not known to undergo long migrations, and therefore, is thought to hibernate within its summer range (Schmidly, 1991). Therefore,/!, pallidus should be con¬ sidered a probable year round resident of BBRSP Little information on the reproductive biology of the pallid bat in the Trans-Pecos has been documented. Distribution-wide, this bat is reported to give birth to one to four young (Manning et al., 1987) in May or June (Hermanson and O’Shea, 1983). However, a single pregnant female taken on 28 May near Boquillas, Coahuilla, Mexico (Bailey, 1905) led Easterla (1973) to speculate that parturition in the Big Bend area oc¬ curs earlier, probably in May only. I examined 5 gravid females taken between 27 May and 9 June, 2 of which w ere pregnant with twins, and tl\ree that carried a single embry o (mean, 1.4). Pregnant females (with number of embry os and corresponding crown-rump lengths in parentheses) were examined on the follow ing dates: 27 May (1 embryo, crown-rump length, 19; 1 embryo, crown-rump length, 21), 7 June (2 embry os, crown-rump length, 25), and 9 June (1 embry o, crown-rump length, 26; 2 embryos, crown-rump length, 28). Lactating fe¬ males were noted from 4 July to 21 July. Volant juve¬ niles were observed from 13 July through 29 July. These data indicate that the time of parturi tion in the Big Bend area is not restricted to May, but probably occurs from May to mid-June. The foraging behavior of A pallidus is somewhat unusual for a bat. This bat primarily is an insectivore that sometimes, like other insectivouous bats, pursues its prey in flight. However, it more often gleans its prey from the ground or vegetation surfaces. Its diet is highly variable, but seems to mostly consist of large insects 20 to 70 mm in length. Major insect prey items include orthopterans, coleopterans, homopterans, and lepidopterans. In addition to insect prey, A. pallidus also is reported to forage upon additional taxa of flight¬ less arthropods, most notably arachnids such as scorpi¬ ons and solpugids (Hermanson and O’Shea, 1983). On occasion, the muzzles of individuals taken at BBRSP were covered with plant pollen. These bats probably w ere not feeding on the pollen or nectar of the plant, but rather encountered the pollen while foraging on arthropods that feed on flower parts (Herrera M. et al., 1993). Other species of bats taken in association with/1. pallidus at BBRSP included Mormoops megalophylla, Myotis californicus , M. thysanodes, M velifer , M, yumanensis, Pipistrellus hesperus, Eptesicus fuscus. Pie coins townsendii, Tadarida brasiliensis , and Nyctinomops macroiis. Ectoparasites taken from A. pallidus at BBRSP included unidentified species of mites and ticks. Also, several individuals were infested with wingless bat flies of the Family Nycteribiidae. In addition to these para¬ sites, this bat is known to be infested with bedbugs and fleas. Internal parasites known to infect A. pallidus include protozoans (Hermanson and O’Shea, 1983). Pallid bats are known to be infected with the rabies vi¬ rus (Hermanson and O’Shea, 1983, Constantine, 1988), but of 27 specimens from BBRSP that were tested for rabies, all were negative (Yancey et al1997). Also of medical importance, pallid bats harbor bacteria of the Genus Borrelia (Hermanson and O’Shea, 1983), the genus of the etiologic agents of relapsing fever (Joklik et al., 1980) and Lyme disease (Tiemo, 1990). Comments .— The subspecies of A. pallidus at BBRSP is A. p. pallidus (Le Conte, 1856). The ge¬ neric name Antrozous is derived from the Greek “antron” and “zoos,” which translate to cave, and liv¬ ing, respectively. The specific epithet pallidus is from the Latin “pallidus” meaning pale (Stangl et al, 1993). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 71 Specimens Examined (48).— Presidio Co.: BBRSP, UTM coordinates: 13 576699E 3296276N, 1; BBRSP, UTM coordinates: 13 576795E3296125N, 2; BBRSP, UTM coordinates: 13 577000E3287710N, 1;BBRSP, UTM coordinates: 13 577553E3287272N, 1;BBRSP, UTM coordinates: 13 586937E3262923N, 1; BBRSP, UTM coordinates: 13 587490E 3262902N, 1; BBRSP, UTM coordinates: 13 596232E 3258492N, 2; BBRSP, UTM coordinates: 13 598236E 3263889N, 3; BBRSP, UTM coordinates: 13 601325E3260798N, 7; BBRSP, UTM coordinates: 13 601335E3260787N, 1; BBRSP, UTM coordinates: 13 601632E3241210N, 1; BBRSP, UTM coordinates: 13 604886E3240689N, 5; BBRSP, UTM coordinates: 13 608608E 3253227N, 3; BBRSP, UTM coordinates: 13 608776E3253333N, 1; BBRSP, UTM coordinates: 13 608870E 3253520N, 3; BBRSP, UTM coordinates: 13 611283E3249529N, 1; BBRSP, UTM coordinates: 13 611393E3249399N, 1; BBRSP, UTM coordinates: 13 615599E 3268863N, 7; BBRSP, Colorado Canyon, 2 (SRSU); BBRSP, Ar¬ royo Segundo, 1 (SRSU); BBRSP, Smith Ranch, Fresno Canyon, 1 (SRSU). Brewster Co.: BBRSP, the Solitario, Tres Papalotes, 2 (SRSU). Family Molossidae (Free-tailed Bats) Tadarida brasiliensis (I. Geof, St.-Hilaire, 1824) Brazilian Free-tailed Bat Description .— Tadarida brasiliensis is a me¬ dium-sized bat with uniform dark brown to dark gray dorsal pelage. The posterior third of the tail of this bat, as in all molossids, extends beyond the trailing edge of the uropatagium. The ears of T. brasiliensis are rela¬ tively broad and are not joined. Vertical folds are present on the lateral sides of the lips. The dental formula for T. brasiliensis is: i 1/2 or i 1/3, c 1/1, p 2/2, m 3/3, total 30 or 32. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 93.7 (53, 87-103, 3.6); length of tail vertebrae, 35.2 (53, 26-44, 3.1); length of hind foot, 8.2 (53, 7- 10,0.7); length of ear from notch, 17.8(53,15-19,1.0); weight, 10.7(46, 6.5-13, 1.1); greatest length of skull, 16.64 (20, 15.99-17.28,0 38). Males average slightly larger than females for most measurements (Wilkins, 1989). Two other species of free-tailed bats are known from BBRSP Both are similar in appearance, but can be distinguished easily from T. brasiliensis on the basis of size. Both Nyctinomops macrotis and Eumops perotis are considerably laiger than T. brasiliensis. Fur¬ thermore, the base of the ears of T. brasiliensis are not fused at the midline of the head, whereas they are in the other free-tails at BBRSP. Potential confusion may exist if Nyctinomops femorosaccus is encountered in BBRSP. Currently, this species is unknown from the park, but has been recorded from nearby Big Bend National Park. It is similar in appearance and size, but, as in the other non-tadarid free-tailed bats at BBRSP, its ears are joined at the mid-line of the head. Distribution. — The range of T brasiliensis ex¬ tends from southern and central South America, north¬ ward along the west coast of South America, through Central America and Mexico, across the southern half of the United States (Wilkins, 1989). In BBRSP, T. brasiliensis was recorded from scattered localities throughout the park (Fig. 22). Natural History. — With a relative abundance in¬ dex of 0.228, T. brasiliensis w r as the third most fre¬ quently encountered bat at BBRSP. It accounted for 13.7 percent of all bats netted. This bat is reported as the most common bat in lowland areas of the Trans- Pecos (Schmidiy, 1977a). My results indicate that T brasiliensis is common, but not extremely abundant in the park. At BBRSP, T. brasiliensis frequently was taken along water courses in both densely and sparsely veg¬ etated areas. This bat often was associated with rocky canyons A large colony uses the ceiling areas of Fort Leaton as a summer roost. This structure lies outside the boundaries of BBRSP, but serves as a visitor's cen¬ ter for the park An additional large colony roosts un¬ der the Fresno Creek Bridge year round This structure also lies outside the park Other than in buildings and 72 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY KILOMETERS Figure 22, Localities of known specimens of Tadarida brasiliensis from Big Bend Ranch State Park, Texas. under bridges, this bat also may roost in caves (Wilkins, 1989). In the Trans-Pecos, T brasiliensis is highly mi¬ gratory, arriving in the area in March and departing in November (Schmidly, 1977a). This bat was taken in BBRSP from 20 March through 9 November. There are rare winter records of T. brasiliensis hibernating in the Trans-Pecos (Schmidly, 1977a), including the Fresno Creek Bridge colony, therefore, this bat should be con¬ sidered a potential, year round resident in BBRSP. The reproductive activities of T brasiliensis in the Trans-Pecos are not well understood. Females are YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 73 thought to segregate themselves from males in early summer and form large maternity colonies outside the Trans-Pecos. Only males and nongravid females are thought to reside in the Trans-Pecos throughout the sum¬ mer (Schmidly, 1977a). There are rare records of preg¬ nant females in Big Bend National Park in June, but these were considered late migrants through the area (Easterla, 1973). The situation appears to be similar at BBRSP. I examined 7 gravid females taken between 30 April and 7 June, all of which were carrying a single embryo. Pregnant females (with crown-rump length of embryo in parentheses) were examined on the follow¬ ing dates: 30 April (3, 3), 14 May (6), 20 May (11, 12), and 7 June (20, 21). Lactating females were not observed. Both sexes were noted in the park from 20 March to 7 June. From the remainder of June to late July, only males were taken. Both sexes were observed again during the fall months. However, a single volant juvenile was observed on 2 August. This seems rather early for a migrant bat to be passing through, and sug¬ gests that possibly a few females give birth in the area. I brasiliensis is known to forage in small groups (Ross, 1967) at low to high altitudes over streams, ponds, and cattle watering tanks (Humphrey, 1982). Reported prey items in order of importance include lepi- dopterans, hymenopterans, coleopterans, homopterans, and hemipterans (Ross, 1967). Other species of bats taken in sympatry with T. brasiliensis at BBRSP included Mormoops megalophylla, Myotis californicus, M thysanodes, M velifer , M. yumanensis , Pipistrellus Hesperus, Eptesicus fuscus , Lasiurus cine reus. Pie cot us townsendii, Antrozous pallidus , and Nyctinomops macrotis. Undetermined species of mites and fleas were ob¬ served infesting T. brasiliensis from BBRSP: In addi¬ tion, to mites and fleas, other ectoparasites known from this bat include ticks (Wilkins, 1989) and nycteribiid bat flies (Whitaker and Easterla, 1974) Endoparasites recorded from Brazilian free-tailed bats include proto¬ zoans, trematodes, and nematodes. This bat frequently has been associated with rabies (Wilkins, 1989), and the incidence of infection in Texas has been reported as high as 24 percent (Schmidly, 1991). Nine specimens from BBRSP were tested for rabies, and all proved nega¬ tive (Yancey et al., 1997). Other human pathogens har¬ bored by T. brasiliensis include Rio Bravo, St. Louis encephalitis, eastern equine encephalitis, western equine encephalitis, and Japanese B encephalitis viruses (Wilkins, 1989). In addition. Trypanosoma cruzi, the protozoan that causes Chaga disease, has been recorded in I brasiliensis from the Trans-Pecos (UDelaker, 1970). T. brasiliensis also has been associated with the fungus Histoplasma capsulatum (Wilkins, 1989). Comments. — The subspecies of T. brasiliensis at BBRSP is T. b. mexicana (Saussure, 1860). The etymology of the generic name Tadarida is uncertain It possibly was derived from the Greek “ta darida,’' which translates to long ones. The specific epithet brasiliensis refers to of Brazil (Stangl et al, 1993). Specimens Examined (62).— Presidio Co.: BBRSP, UTM coordinates: 13 576060E 3288074N, 1, BBRSP, UTM coordinates: 13 576783E 3296292N, 2; BBRSP, UTM coordinates: 13 576808E 329621 IN, 1; BBRSP, UTM coordinates: 13 577000E 328771 ON, 2; BBRSP, UTM coordinates: 13 580196E 3264339N, 1; BBRSP, UTM coordinates: 13 586937E3262923N, 5; BBRSP, UTM coordinates: 13 587263E 3263005N, 2; BBRSP, UTM coordinates: 13 601335E 32G0787N, 1; BBRSP, UTM coordinates: 13 608477E 3253180N, 5; BBRSP, UTM coordinates: 13 608608E3253227N, 6; BBRSP, UTM coordinates: 13 608955E 3253483N, 7; BBRSP, UTM coordinates: 13 609027E 3253496N, 1; BBRSP, UTM coordinates: 13 611283E 3249529N, 1; BBRSP, UTM coordinates: 13 615525E 3268958N, 1; BBRSP, UTM coordinates: 13 615565E 3268878N, 3; BBRSP, UTM coordinates: 13 615599E 3268863N, 15; BBRSP, Arroyo Segundo, 6 (SRSU); BBRSP, Smith Ranch, Fresno Canyon, 2 (SRSU). Nyctinomops macrotis (Gray, 1839) Big Free-tailed Bat Description Nyctinomops macrotis is a large bat with dark brown to dark gray dorsal pelage As in all molossids, the posterior third of the tail of jV macrons extends beyond the trailing edge oflhc uropatagium 74 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY The base of the large, broad ears of this bat are joined near the midline of the head. Vertical folds are present on the lateral sides of the lips. The dental formula for N. macrotis is: i 1/2, c 1/1, p 2/2, m 3/3, total 30. External and cranial measurements of a single adult female from BBRSP are: total length, 130; length of tail vertebrae, 50; length of hind foot, 10; length of ear from notch, 31; weight, 28 (gravid); greatest length of skull, 23.56. Males seem to average slightly larger than females (Milner et al., 1990). N. macrotis might be confused with the other two species of free-tailed bats that occur at BBRSP. It can be differentiated from Tadarida brasiliensis as described m the account for that species. It can be distinguished from Eumops perotis by its smaller size, and the pres¬ ence of vertical folds on the lateral sides of the lips. Distribution.— N. macrotis ranges from the northern two thirds of South America, northward through Central America and Mexico, on into the south¬ western United States (Milner, et al., 1990). In BBRSP, N ' macrotis is known only from Arroyo Segundo (Fig, 23). Natural History .— Only a single specimen of N. macrotis was acquired during my field work at BBRSP This resulted in a relative abundance index of 0.003. This bat accounted for only 0.2 percent of all bats net¬ ted. These results suggest that A. macrotis is extremely rare in BBRSP. Interestingly, some 20 years earlier, Scudday (1976/7) found this bat to be fairly common in Arroyo Segundo. In a five-year study at Big Bend Na¬ tional Park, this bat w-as found to be rare in most areas, but yearly fluctuations in population numbers were noted. Elsewhere in the state, N. macrotis is consid¬ ered uncommon (Easterla, 1973). In BBRSP, N. macrotis is known only from Ar¬ royo Segundo. This is a deep canyon formed by sheer, rocky cliffs. A small stream and several pools of water occur at the bottom of the canyon. Associated vegeta¬ tion is dominated by willow and cottonwood, but, in most areas, the water is unobstructed by vegetation. In addition to rugged, rocky arroyos, N. macrotis also is known to inhabit desert shrublands and woodlands (Easterla, 1973). In Big Bend National Park, this bat is known to roost in rock crevices (Borell and Bryant, 1942), but also may roost in caves, tree holes, and build¬ ings (Milner et al., 1990). It may roost singly, or in small groups of up to 150 individuals (Milner et al., 1990). The one specimen acquired during this field work was taken in May. Other specimens have been taken from BBRSP in June. In Big Bend National Park, N. macrotis has been recorded from 10 June to 9 Septem¬ ber. Winter tendencies of this bat are unknown, but Easterla (1973) and Schmidly (1991) speculate that it may hibernate in the Trans-Pecos, and therefore should be considered a possible year round res ident of BBRSP. At the beginning of summer, the sexes segregate, and females form nursery colonies (Barbour and Davis, 1969; Schmidly, 1977tf). On 20 May, I examined a pregnant female carrying one embryo (crown-rump length, 12). Easterla (1973) observed gravid females in Big bend National Park from 10 June to 7 July, all of which carried one embry o. He noted lactating females between 27 June and 30 August, and volant juveniles as early as 8 August. These data indicate that in the Big Bend area, females give birth to one young in June or July, as suggested by Easterla (1973) and Schmidly (1991). The specimen taken during this study was netted late at night, and this was the norm for individuals cap¬ tured at Big Bend National Park. However, on rare occasions, this bat has been taken before dark. It tends to forage primarily on large lepidopterans, but ortho- pterans, hymenopterans, and hemipterans occasionally are taken (Easterla, 1973). Other species of bats taken at the same locality as N. macrotis at BBRSP included Mormoops megalophylla , Myotis yumanensis, Pipistrellus hesperus, Eptesicus fuscus , Antrozous pallidus, and Tadarida brasiliensis. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 75 KILOMETERS Figure 23. Localities of known specimens of Nyctinomops macrotis from Big Bend Ranch State Park, Texas. No parasites were observed in association with the specimen of N. macrotis taken during this study. Ectoparasites known to infest this bat include mites, ticks, and fleas (Milner et al., 1990). The only reported internal parasite of N. macrotis is a nematode (Silva Taboada, 1979). N. macrotis has been known to be infected with rabies, but no specimens from BBRSP were tested for this virus. Comments .— N. macrotis is a monotypic species The generic name Nyctinomops is derived from the Greek “nyktios,” “nomos,” and “ops,” which translate to night, custom of grazing, and face, respectively. The specific epithet macrotis is from the Greek makros and “ous” meaning long and car, respectively (Stangl et al., 1993). 76 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Specimens Examined (2).— Presidio Co.: BBRSP, UTM coordinates: 6086Q8E 3253227N, 1; BBRSP, Arroyo Segundo, 1 (SRSU). Eumops perotis (Schinz, 1821) Western Mastiff Bat Description — Eumops perotis is the largest bat that occurs at BBRSP. Its dorsal pelage is dark gray. As in other molossids, the posterior third of the tail of E. perotis extends beyond the trailing edge of the uropatagium. The ears of this bat are large and broad, and are joined at the base near the midline of the head. The lips lack vertical folds. The dental formula for E. perotis is: i 1/2, c 1/1, p 2/2, m 3/3, total 30. No measurements of E. perotis from BBRSP were obtained. Schmidly (1991) lists the following average external measurements for this species in general: total length, 171; length of tail vertebrae, 57; length of hind foot, 17; length of ear from notch, 40; weight, 65. Hall (1981) lists the range for greatest length of skull mea¬ surements as 30.0-32.9. I know of no reports pertain¬ ing to secondary sexual dimorphism in this bat. E. perotis can be distinguished easily from the other free-tailed bats that occur at BBRSP as described in the two previous accounts. Distribution — E. perotis ranges from Central Mexico, northward across extreme southwestern Texas, northwestward across the far southwestern United States, into central California (Hall, 1981). In BBRSP, E perotis is known only from Arrovo Segundo (Fig. 24). Natural History .— E. perotis was not taken dur¬ ing this study, and therefore no relative abundance in¬ dex was calculated. However, as with Nyctinomops macrotis, E. perotis was reported as fairly common in Arroyo Segundo about 20 years prior to this study (Scudday, 19766). Significant annual fluctuations in abundance of this bat were noted at Big Bend National Park, as no bats were acquired during one year, and 31 were taken the following year (Easterla, 1973). All specimens of E. perotis known from within the boundaries of BBRSP were acquired from Arroyo Segundo. See the previous account for a description of this area. In addition, there is a record of E. perotis taken from the Fresno Mine (Eads et al., 1957), which is situated to the east of Whitroy Mine, just outside the eastern park boundary. The habitat in this area is desert scrub dominated by creosote-bush. E. perotis is known from a third site in the vicinity of BBRSP based on a specimen housed in the mammal collection at Sul Ross State University. The locality on this specimen simply is “Casa Piedra Road.” This road traverses the south¬ west edge of the park, but the majority of the road lies outside park boundaries. The habitat along most of the road is creosote-bush scrub. E. perotis usually roosts in small colonies (2-100 individuals) within rock crev¬ ices situated high on cliffs. Roosts must be positioned to allow at least a three-meter unobstructed drop, which is required to initiate flight (Schmidly, 1991). Records of E perotis from BBRSP exist only from July. However, this bat was obsened near Candelaria, Presidio County, during January, February, May, June, July, August, September, and November (Ohlendorf, 1972), indicating that E. perotis is a year round resi¬ dent of the area. The reproductive biology of E. perotis from the Trans-Pecos is poorly known. Males and females con¬ tinue to use the same roosts w r hile young are bom and raised (Schmidly, 1991). In Big Bend National Park, pregnant females were noted between 10 and 27 June, and lactating females were observed from 22 June to 7 August. Volant juveniles were first recorded on 30 Au¬ gust (Easterla, 1973). Apparently a single young is bom during June or July. E. perotis begins foraging late in the night (Schmidly, 1991). It preys primarily upon large lepi- dopterans, but orthopterans, hymenopterans, coleopter- ans, odonatans, and homopterans also are consumed (Ross, 1967; Easterla and Whitaker, 1972; Schmidly, 1991). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 77 K«_OMETERS Figure 24. Localities of known specimens of Eumops perotis from Big Bend Ranch State Park, Texas. Because E. perotis was not captured during my field work, no comments on associated species can be made. However, the following species of bats were ac¬ quired from the same general area from which E. perotis was taken previously: Mormoops megalophylla , Myotis thysanodes , M. yumanensis , PipistreIIus hesperus , Eptesicus fuscus , Antrozous pallidus , Tadarida brasiliensis, and Nyctinomops mac rot is. E. perotis is known to harbor the rabies virus (Constantine, 1988), but no specimens from BBRSP have been tested. Comments. — The subspecies of E perotis at BBRSP is E p. californicus (Mcmam, 1890). The generic name Eumops is derived from the Greek vk cu” 78 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY and the Malay “mops,” which translate to good or true, and name of a bat, respectively. The specific epithet perotis is from the Greek “peros” and “ous” meaning maimed and ear, respectively (Stangl et al, 1993). Specimens Examined (3).— Presidio Co,: BBRSP, Arroyo Segundo, 3 (SRSU). ORDER LAGOMORPHA—LAGOMORPHS Family Leporidae (Rabbits and Hares) Sylvilagus audubonii (Baird, 1858) Desert Cottontail Description — Sylvilagus audubonii is a small to medium-sized rabbit with dark buSy-brown dorsal pelage that is frosted with black. The ears are moder¬ ately long, and the tail is bufly-gray above and white below. The dental formula for S. audubonii is: i 2/1, c 0/0, p 3/2, m 3/3, total 28. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 346.8 (8, 280-415, 45.2); length of tail verte¬ brae, 39.8 (8, 32-52, 7.1); length of hind foot, 87.5 (8, 78-101, 8.1); length of ear from notch, 69.4 (8, 62-79, 5.7); weight, 804 (5, 600-1210, 243.2); greatest length of skull, 66.18 (6, 61.86-74.95, 4.64). Females are slightly larger than males (Orr, 1940). The only other mammal known from BBRSP that S. audubonii might be mistaken for is Lepus californicus. Differences are as follows: S. audubonii is significantly smaller in size than L. californicus , the ears of S. audubonii are much shorter (less than 85) than those of L. californicus (greater than 115), and the underside of the tail of S. audubonii is pure white, whereas that of L californicus is mottled gray. Distribution .— S. audubonii ranges from central Mexico, northward throughout the western half of the United States, except for the Pacific Northwest (Chapman and Willner, 1978). In BBRSP, specimens of this rabbit are known from the Ciencga and Las Quevas areas, as well as from the Solitario and the Rio Grande Corridor (Fig. 25). Furthermore, desert cot¬ tontails were sighted throughout the entire park. Natural History. — During this study, eight speci¬ mens of S. audubonii were collected, and several other individuals were sighted throughout the park. This rab¬ bit should be considered both common and widespread in BBRSP. Desert cottontails favor desert scrub habitats (Schmidlv, 1977a). At BBRSP, it was taken in this type of habitat, but also was acquired from riparian wood¬ lands. In addition, it frequently was observed in grass¬ lands and occasionally in juniper woodlands. There¬ fore, S. audubonii should be considered an inhabitant of all major habitat types at BBRSP. The desert cottontail is active year round, but w f as taken in BBRSP only during April, June, and July. However, it was sighted throughout the year. The breeding season of S. audubonii varies throughout its range (Chapman et aL, 1982). In Texas, mating begins in February (Chapman and Morgan, 1974) and continues throughout most of the year (Davis and Schmidly, 1994). Females give birth to one to six (mean, 2.6) young, two or more times a year (Chapman and Morgan, 1974; Davis and Schmidly, 1994). Two gravid females were examined during this study. One carried three embryos (crown-rump length, 30) on 29 April, and the other was pregnant with two embryos (crown-rump length, 12) on 3 June. Measurements of testes of adult males were as follows: 5 June, 43 X 16; 1 July, 36 X 14; 3 July, 28 X 10; 27 July, 42 X 15. A juvenile that w as killed by a western diamondback rattle¬ snake ( Crotalus atrox) was collected on 22 July. Desert cottontails most often were observed for¬ aging during the evening or at night, but frequently were sighted during the daytime as well. This rabbit was seen foraging on grasses, and also is known to feed on YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 79 KILOMETERS Figure 25. Localities of known specimens of Sylvilagus audubonii from Big Bend Ranch State Park, Texas. the pods and leaves of mesquite, the woody parts of shrubs, and the pads of prickly pear cactus (Davis and Schmidly, 1994). Seasonal molt occurs twice a year in S. audubonii. The first molt begins in late spring or summer, and the second occurs in the fall (Jones et al., 1983). During this study, molting adults were observed in April, June, and July. No parasites were observed in association with S. audubonii at BBRSP Ectoparasites reported previ¬ ously include ticks, fleas, and botfly larvae (Chapman and Willncr, 1978; Jones et al., 1983). Internal para- 80 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY sites known to infect S. audubonii include protozoans (Fitch, 1947), cestodes, and nematodes (Chapman and Willner, 1978). Desert cottontails commonly are in¬ fected with Frcmcisella tularensis , the bacterium that causes tularemia (Gage et al., 1995). Other than hu¬ mans, S. audubonii is the only non-rodent mammal known to be infected with hantavirus (Stone, 1993). Comments .— The subspecies of S. audubonii at BBRSP is S. a. minor (Meams, 1896). The generic name Sylvilagus is derived from the Latin “silva” and Greek “lagos,” which translate to forest and hare, re¬ spectively. The specific epithet audubonii refers Audubon’s (Stangl et al, 1993). Specimens Examined (9).— Presidio Co.: BBRSP, UTM coordinates: 13 576329E 3296134N, 1; BBRSP, UTM coordinates: 13 576855E3295469N, 1; BBRSP, UTM coordinates: 13 576866E3295865N, 2; BBRSP, UTM coordinates: 13 587281E3262891N, 1; BBRSP, UTM coordinates: 13 599525E 3261240N, 1; BBRSP, UTM coordinates: 13 601203E 3260197N, 1; BBRSP, UTM coordinates: 13 608309E3239482N, 1; BBRSP, McGurk’s Tank, the Solitario, 1 (SRSU). Lepus californicus (Gray, 1837) Black-tailed Jackrabbit Description .— Lepus californicus is a large hare with dark bully-gray dorsal pelage that is washed with black. The ears are noticeably long, and the tail is topped with a mid-dorsal black stripe that extends onto the rump. The dental formula for L. californicus is: i 2/1, c 0/0, p 3/2, m 3/3, total 28. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 532.9 (10, 495-579, 24.5); length of tail verte¬ brae, 65.9 (10, 57-77, 7.5); length of hind foot, 124.7 (10, 115-130,4 5); length of ear from notch, 137.6(10, 128-148,5 1); weight, 2400 (9,2100-2700,200); great¬ est length of skull, 95.34 (9, 93.67-98.37, 1.55). Fe¬ male black-tailed jackrabbits are slightly larger than males (Nelson, 1909; Dunn et al., 1982), The only other mammal that occurs at BBRSP that L. californicus might be confused with is Sylvilagus audubonii. See the previous account for differentia¬ tion. Distribution .— The range of L. californicus ex¬ tends from central Mexico, northward throughout most of the western half of the United States (Hall, 1981). At BBRSP, specimens of L. californicus are known from the Cienega, Temeros Creek, and Sauceda areas, as well as from the north rim of the Solitario (Fig. 26). How¬ ever, this lagomorph was sighted in all areas of the park except along the Rio Grande. Natural History - Schmidly (1977a) considered L. californicus to be among the commonest of mam¬ mals occurring in the Trans-Pecos. Ten specimens of L. californicus were collected at BBRSP. In addition, there were countless sightings of this hare throughout this study. Based on these observations, L. californicus should be considered abundant in BBRSP. At BBRSP, black-tailed jackrabbits were taken in both desert scrub and grassland, their preferred habi¬ tats (Schmidly, 1977a). They were not recorded in ri¬ parian habitats. Apparently they avoid such w'ooded areas because their primary defense mechanisms of ex¬ ceptional eyesight and escape speed are rendered inef¬ fective (Jones et al., 1985). L. californicus is active year round, although its abundance may vary by season (Schmidly, 1977a). In BBRSP, it was taken during the spring, summer, and fall, and was observed throughout the year. Black-tailed jackrabbits breed throughout the year. Each year, females give birth to two to six litters, each consisting of one to six young (Davis and Schmidly, 1994). 1 examined one pregnant female carrying 2 em¬ bryos (crown-rump length, 30) on 3 July. Testicular measurements of adult males were as follows: 2 April, 28 X 10,56X21; 13 May, 50 X 15; 23 May, 42X23; 1 June, 37; 3 July, 48 X 20; 15 July, 32 X 17; 4 Sep¬ tember, 30 X 11; 8 November, 40 X 10. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 81 KILOMETERS Figure 26. Localities of known specimens of Lepus californicus from Big Bend Ranch State Park, Texas. L californicus typically forages at night, but oc¬ casionally was observed foraging during the daytime. This hare was seen feeding on various grasses and mes- quite leaves. In addition, several prickly pear cactus plants showed signs of jackrabbit browsing. Schmidly (1977a) reports that L. californicus in the Trans-Pecos also consumes sagebrush. Black-tailed jackrabbits have been reported to undergo one annual molt between August and October (Jones ct al, 1983). However, during this study, adults were observed molting in April, June, July, September, and November. These data suggest that at BBRSP, the molting period is longer than reported previously, or that L. californicus molts twice a year, once in the spring or summer, and once in the autumn. 82 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY External parasites noted on L. californicus from BBRSP were ticks and botfly larvae. Other ectopara¬ sites previously reported include mites, lice, and fleas (Jones et al., 1985). Internal parasites found in speci¬ mens from BBRSP were limited to tapeworm cysts re¬ sembling those of Taenia serialis. L. californicus has been implicated as a primary' reservoir for the patho¬ genic bacterium Francisella tularensis, the etiologic agent of tularemia (Joklik et al., 1980; Jones et al., 1985). Comments. — The subspecies of L. californicus at BBRSP is L. c. texianus Waterhouse, 1848. The generic name Lepus is Latin for hare. The specific epi¬ thet californicus refers to of California (Stangl et al., 1993). Specimens Examined (10).— Presidio Co.: BBRSP, UTM coordinates: 13 576730E 3295308N, 1; BBRSP, UTM coordinates; 13 576796E 3295418N, 1; BBRSP, UTM coordinates: 13 576836E 329625 IN, 1; BBRSP, UTM coordinates: 13 576842E3296279N, 1; BBRSP, UTM coordinates: 13 576872E3295728N, 1; BBRSP, UTM coordinates: 13 584337E3269447N, 1; BBRSP, UTM coordinates: 13 602473E 3260516N, 1; BBRSP, UTM coordinates: 13 605201E 3260431N, 1; BBRSP, UTM coordinates: 13 605895E 326101 IN, 1; BBRSP, UTM coordinates: 13 615947E3262894N, 1 . ORDER RODENTIA—RODENTS Family Sciuridae (Squirrels) Ammospermophilus interpres (Merriam, 1890) Texas Antelope Squirrel Description .— Ammospermophilus interpres is a small squirrel with dorsal pelage that is gravish-brown on top, and buff to buffy-brown on the sides. Two nar¬ row white lines that extend from the shoulder to the rump are present, one on each lateral side of the back. The tail hairs are distichous, banded with black and white above, and are creamy white below. The dental formula for A. interpres is: i 1/1, c 0/0, p 2/1, m 3/3, total 22. Means of external and cranial measurements (with sample size and extremes in parentheses) of adult speci¬ mens from BBRSP are: total length, 233.3 (3, 222- 255); length of tail vertebrae, 76.3 (3,74-80); length of hind foot, 35.7 (3, 35-37); length of ear from notch, 12.3 (3, 12-13); weight, 98 (3, 97-99); greatest length of skull, 38.85 (2, 37.69-40.00). I know of no reports pertaining to secondary sexual dimorphism in this squir¬ rel. The presence of two white stripes on the dorsum of A interpres easily distinguishes this squirrel from Spermophilus spilosoma and S. variegatus , the only other species of squirrels at BBRSP. Distribution — The distribution of A interpres extends from southern Coahuila and northeastern Durango, Mexico, northward through eastern Chihua¬ hua, Mexico, and southwestern Texas, and into central New' Mexico (Best et al., 1990). in BBRSP, specimens exist from the Bofecillos Mountains area and the Solitario (Fig. 27), but this squirrel also was observed at scattered sites throughout much of the park. Natural History .— Two specimens of A interpres were collected during this study, and occasionally indi¬ viduals were sighted. The w r ary and nervous disposi¬ tion of this squirrel (Best et al., 1990) hindered efforts to collect and observe them. Therefore, they' probably are more abundant than records indicate, but still should be considered uncommon at BBRSP. Both specimens of A. interpres acquired from BBRSP were taken in rocky- uplands. The associated vegetation of both sites was grassland with encroach¬ ing scrub species. Additional individuals were sighted in similar habitats, as well as in boulder fields and grav- YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 83 Figure 27. Localities of known specimens of Ammospermophilus interpres from Big Bend Ranch State Park, Texas. elly washes. This squirrel was not noted in level desert this squirrel docs not hibernate at low elevations (Davis scrub or in sandy places, but is known to occur in such and Schmidly, 1994); that appears to be the situation at areas (Davis and Schmidly, 1994). BBRSP. During this study, A. interpres was taken in Feb- Data on the reproductive habits of A interpres niary and June. Additional sightings occurred in Janu- are wanting. I examined a male taken on 28 February ary, May, June, July, and November. It is thought that that was in reproductive condition (testes, 17X8) This 84 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY apparently is about the time the breeding season be¬ gins. Typically, females give birth to one litter of five to 14 young per year. However, some females may pro¬ duce two litters during the same year (Davis and Schmidly, 1994). Like other squirrels at BBRSP, yl. interpres is di¬ urnal (Herman, 1950) and is active especially during the hottest part of the day (Blair and Miller, 1949; Baker et al., 1980). This squirrel feeds on a variety of plant material, including the fruits, seeds, and stems of cac¬ tus, mesquite beans, creosote-bush seeds, and juniper berries, but insects may be consumed as well (Best et al., 1990). A. interpres undergoes two annual molts. A spring molt occurs in May and a fall molt takes place in Sep¬ tember (Best et al., 1990). An undetermined species of flea was found in¬ festing A. interpres at BBRSP. The only parasite re¬ ported previously from tins squinel is a nematode (Baker and Greer, 1962). Comments — A . interpres is a monotypic spe¬ cies. The generic name Ammospermophilus is derived from the Greek "amnios,” "sperma,” and "philos,” which translate to sand, seed, and loving, respectively. The specific epithet interpres is Latin for intermediary (Stangl et al., 1993). Specimens Examined (3).— Presidio Co.: BBRSP, UTM coordinates: 13 591022E 3261963N, 1; BBRSP, UTM coordinates: 13 598198E3260782N, 1; BBRSP, Madrid Ranch, Chorro Canyon, 15 mi. N Lajitas, 1 (SRSU). Spermophilus spilosoma Bennett, 1833 Spotted Ground Squirrel Description .— Spermophilus spilosoma is a small squirrel with a dorsal pelage that is pale brown with numerous faint white spots scattered about. The dental formula for S. spilosoma is: i 1/1, c 0/0, p 2/1, m 3/3, total 22. Means of external and cranial measurements (with sample size and extremes in parentheses) of adult speci¬ mens from BBRSP are: total length, 236.0 (2, 233- 239); length of tail vertebrae, 77.0 (3,75-80); length of hind foot, 34.0 (4, 31-36); length of ear from notch, 11.0(3,11); weight, 112.3(3,100-125); greatest length of skull, 38.69 (2, 37.90-39.48). I know of no reports pertaining to secondary sexual dimorphism in this spe¬ cies. In BBRSP, S. spilosoma may be confused with S variegatus and Ammospermophilus interpres. S spilosoma is small and spotted, whereas S. variegatus is relatively large, lacks spots, and has a black head. See the previous account for differentiation from A. interpres . Distribution.— S. spilosoma ranges from north- central Mexico and South Texas, northward through Texas and the central Plains states and westward to Ari¬ zona and Utah (Streubel and Fitzgerald, 1978). In BBRSP, this squirrel is known only from near the west entrance of the park and the Solitario (Fig. 28). Natural History. — Three specimens of S. spilosoma were collected during this study, and one additional individual was sighted. This squirrel is known to be shy (Davis and Schmidly, 1994), which may ac¬ count, in part, for the infrequent encounters in the park. Nonetheless, given such few' observations, S. spilosoma should be regarded as uncommon in BBRSP. The spotted ground squirrel reportedly favors sparsely-vegetated areas with deep, sandy soils (Streubel and Fitzgerald, 1978). However, all individuals taken or observ ed during this study were in desert scrub domi¬ nated by creosote-bush. The substrate in each of these areas was gravelly. Desert scrub with hard substrata was reported as the preferred habitat at Big Bend Na¬ tional Park as w r ell (Schmidly, 1977a/ YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 85 KILOMETERS Figure 28. Localities of known specimens of Spermophiius spilosoma from Big Bend Ranch State Park, Texas. S, spilosoma hibernates, to some degree, over the cooler months, but the extent of its hibernating habits are not known (Schmidly, 1977a; Streubel and Fitzgerald, 1978; Davis and Schmidly, 1994). I col¬ lected a specimen in November, and individuals have been taken during December, January, and February elsewhere in the state (Davis and Schmidly, 1994) This suggests that in Texas, hibernation in S. spilosoma is not complete. The reproductive biology of S. spilosoma is poorly known. A male in reproductive condition (testes, 13 X 7) was examined on 14 May, and one in non-rcproduc- tivc condition (testes, 7X4) was noted on 8 Novcm- 86 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY ber, suggesting that this squirrel breeds during March, but not November. Litter sizes range from five to eight (Asdell, 1964), and it has been suggested that females are diestrous, producing two litters annually (Streubel and Fitzgerald, 1978). S. spilosoma is diurnal and, in an effort to avoid the mid-day heat, forages in the early morning and late afternoon. It feeds primarily on seeds and other plant material, but also may consume animal matter, includ¬ ing insects, lizards, and even small rodents (Streubel and Fitzgerald, 1978). Adult spotted ground squirrels molt twice a year. A spring molt occurs by late May, and a second molt, which is not conspicuous in adults, takes place some¬ time in the fall (Streubel and Fitzgerald, 1978). S . spilosoma was trapped in association with Dipodomys merriami and Chaetodipus eremicus. No parasites were observed in association with S. spilosoma from BBRSP. Ticks, biting lice, and fleas are known to infest S. spilosoma . Various nematodes are the only reported endoparasites of this squirrel (Streubel and Fitzgerald, 1978). Comments. — The subspecies of S. spilosoma at BBRSP is S. s. marginatus Bailey, 1890. The generic name Spermophilus is derived from the Greek “sperma” and “philos,” which translate to seed, and loving, re¬ spectively. The specific epithet spilosoma is from the Greek “spilos” and “soma,” meaning spot and body, respectively (Stangl et al., 1993). Specimens Examined (4).— Presidio Co.: BBRSP, UTM coordinates: 13 579684E 3269447N, 1, BBRSP, UTM coordinates: 13 579888E 3269478N, 1; BBRSP, UTM coordinates: 13 582900E 3268000N, 1; BBRSP, McGurk’s Tank, the Solitario, 1 (SRSU). Spermophilus variegatus (Erxleben, 1777) Rock Squirrel Description .— Spermophilus variegatus is a large squirrel with a dorsal pelage that is black about the head, neck, and upper back, and mottled grayish brown towards the rear. The tail is long and relatively bushy. The dental formula for S. variegatus is: i 1/1, c 0/0, p 2/1, m 3/3, total 22. External measurements of an adult male from BBRSP are: total length, 520; length of tail vertebrae, 248; length of hind foot, 62; length of ear from notch, 25; weight, 959. Males average larger in size than fe¬ males (Oaks et al., 1987). Distribution — S. variegatus ranges from cen¬ tral Mexico, northward throughout most of the south¬ western United States (Oaks et al., 1987). At BBRSP, this squirrel was collected only from the Rio Grande Corridor (Fig. 29). In addition, it was sighted in scat¬ tered localities throughout the park including the Cienega, Sauceda, Botilla, and Lava Canyon areas. Natural History.— During this study, one speci¬ men of S. variegatus was collected, and five additional individuals were sighted. As are the other squirrels in BBRSP, rock squirrels are wary, making them difficult to collect and observe (Oaks et al., 1987). Hence, they may be more common in BBRSP than the frequency of encounters indicates. All rock squirrels taken and observed at BBRSP w ere in areas of rock or boulder-associated cliffs, hills, canyons, stream washes, or slopes, its preferred habi¬ tats as suggested by its common name (Tomich, 1982; Oaks et al., 1987). In the absence of rocky areas, this squirrel may utilize human structures, such as build¬ ings, bridges, terraced roads, and stone walls (Oaks et al., 1987). Vegetation associated with the rocky areas where S. variegatus was observed at BBRSP included, mesquite, creosote scrub, and riparian woodland domi¬ nated by willow and cottomvood. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK Figure 29. Localities of known specimens of Spermophilus variegatus from Big Bend Ranch State Park, Texas. During this study, rock squirrels were encountered during May, June, July, and October. These squirrels hibernate throughout much of their range, and the ab¬ sence of observations during the winter months suggests that this might be the situation at BBRSP. However, they have been reported to be active throughout the year at low elevations in the Big Bend area (Davis and Schmidly, 1994). There is evidence that rock squirrels hibernate in response to food shortages, rather than cooler temperatures (Oaks ct al., 1987). They are known to store food for winter use (Davis and Schmidly, 1994), and the quantity of food in their winter caches may de¬ termine the degree to which this squirrel hibernates. There also is evidence that rock squirrels estivate in parts of their range (Oaks et al., 1987), but occasional summer observations discount this behavior at BBRSP 88 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY The breeding season for S . variegatus in the Trans-Pecos has been reported to last from April to June (Schmidly, 1977a). However, a male collected on 31 July possessed scrotal testes measuring 40 X 14. The testes of male rock squirrels are scrotal only during the breeding season, at which time their average length is 32. During non-breeding periods, they average only 11 (Oaks et al., 1987). This suggests that the breeding season of rock squirrels at BBRSP extends into late July or early August. Borell and Bryant (1942) sug¬ gested that females give birth to at least two litters per year at Big Bend National Park, and multiple litters seem likely at BBRSP given the potential length of the breed¬ ing season. Litter sizes range from two to nine (Oaks et al, 1987; Davis and Schmidly, 1994) with a mean of about five (Oaks et al., 1987). The rock squirrel is diurnal, but the time of peak activity varies by season. In the cooler months, it is most active at mid-day, whereas during the summer, it is more active in the morning and late afternoon. The majority of the daily activities of this squirrel is focused on foraging and feeding. Its diet is highly variable, and fluctuates seasonally (Oaks et al., 1987). The internal check pouches of the specimen collected at BBRSP were full of mesquite beans. Other foods consumed by rock squirrels include seeds, grains, fruits, roots, green veg¬ etation, cactus, invertebrates, small vertebrates, and dried meat (Oaks et al., 1987). Seasonal molting in adult rock squirrels occurs once a year. At BBRSP, this probably occurs around the middle of summer (Oaks et al, 1987). No parasites were noted in association with the rock squirrel specimen from BBRSP. Known external parasites of S', variegatus include mites, ticks, lice, fleas, and fly larv ae. Known internal parasites include proto¬ zoans, trematodes, cestodes, and several nematodes (Oaks et al., 1987). S. variegatus apparently is a res¬ ervoir for Yersinia pestis , the etiologic agent of plague (Quan et al, 1985). Furthermore, II of the 19 species of fleas reported to infest rock squirrels are known vec¬ tors of plague. Also, S. variegatus is known to harbor Rickettsia rickettsii , the causative agent of Rocky Moun¬ tain spotted fever. Several of the known ectoparasites of rock squirrels are vectors of tularemia, brucellosis, and Q-fever, however the infection of rock squirrels with these diseases has not been not documented (Oaks et al, 1987) Comments .—The subspecies of S. variegatus that occurs at BBRSP is S. v. grammurus (Say, 1823). See the account on Spermophilus spilosoma for the etymol¬ ogy of the generic name. The specific epithet variegatus is from the Latin “variegare,” meaning diversify (Stangl el al, 1993). Specimens Examined (1).— Presidio Co.: BBRSP, UTM coordinates: 13 587570E 3249037N, 1 . Family Geomyidae (Pocket Gophers) Thomomys bottae (Eydoux and Gervais* 1836) Botta’s Pocket Gopher Description — Thomomys bottae is a small to medium-sized gopher with pale brown dorsal pelage. The upper parts of the forefeet are whitish, and the an¬ terior surface of the upper incisors are smooth, lacking conspicuous grooves. The dental formula for T. bottae is: i 1/1, c 0/0, p 1/1, m 3/3, total 20. Means of external measurements (with sample size, extremes, and standard deviation in parentheses) of adult specimens from BBRSP are: total length, 205.2 (13, 177-225, 15.2); length of tail vertebrae, 57.9 (13, 48-64, 4.8); length of hind foot, 28.6 (12, 25-33, 2.3); length of ear from notch, 6.6 (11,5-8,1.1); weight, 105.8 (5, 92.5-133, 17.9). A single skull was examined, and its greatest length was 36.68. Males of this species tend to be considerably larger than females (Davis and Schmidly, 1994). T bottae can be distinguished easily from Cratogeomys castanops, the only other pocket gopher at BBRSP, by its small size, pale upper forefeet, and smooth upper incisors. C. castanops is considerably YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 89 KILOMETERS Figure 30. Localities of known specimens of Thomomys bottae from Big Bend Ranch State Park, Texas, larger, has dark upper forefeet, and has a large groove on the anterior surface of each upper incisor. Distribution .— T. bottae ranges from northern Mexico, northward throughout the western United States, excluding the far north (Hall, 1981). In BBRSP, specimens of this gopher are known from the Rio Grande Corridor, the Cienega area, and the Solitario (Fig. 30). In addition, mounds presumably made by T. bottae were noted throughout the park in suitable habitats Natural History .— Only two specimens of I bottae were acquired during this study However, nu¬ merous sightings of this gopher’s mounds indicate that this species is rather common in BBRSP 90 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY T bottae is very adaptable in terms of habitat re¬ quirements (Davis and Schmidly, 1994). During this study, this gopher was taken in water-associated habi¬ tat dominated by mesquite and short grass, and in desert grassland with large stands of lechuguilla. T. bottae mounds were observed in desert scrub associated with lechuguilla, in riparian areas dominated by willow and cottonwood, and in tamarisk-mesquite associations along the Rio Grande. The substrata where T. bottae was noted also were highly variable, ranging from loose sand, to sandy loam, to hard rocky soils. Botta’s pocket gopher is reported to be active year round (Davis and Schmidly, 1994). During this study, T. bottae was taken in February and November, and active burrows were noted in May, July, and Decem¬ ber. Museum specimens examined were acquired dur¬ ing January, February, and July. Adult Botta’s pocket gophers are solitary except while breeding (Davis and Schmidly, 1994). The breed¬ ing season lasts throughout the year, with peaks in re¬ productive activity in the spring, summer, and early win¬ ter. A male in breeding condition (testes, 17X12) was taken on 4 November. On average, females give birth to two litters of five young per year (Schmidly, 1977a). T bottae spends 90 percent of its life in its bur¬ row system. It feeds primarily on fleshy roots and tu¬ bers of most native plants. In addition, this gopher is known to clip off and feed on surface vegetation (Davis and Schmidly, 1994). At BBRSP, on several occasions the opening of burrows were filled with clipped lechuguilla stems. At BBRSP, an adult w f as observed with molt lines on 4 November. The presence of molt lines on T. bottae typically indicates a change from winter to summer pel- age. However, a molt line also could be a demarcation between parts of the pelage that molted at different times, a phenomenon not observed in most nonfossorial mam¬ mals (Chase et al., 1982). Other rodents taken from the same localities as T. bottae at BBRSP included Chaetodipus eremicus , Dipodomys merriami , Peromyscus eremicus, P. mamculatus , Neotoma albigula , and N. mexicana. In¬ terestingly, Cratogeomys castanops , the only other pocket gopher that occurs at BBRSP, was found to oc¬ cur both sympatrically and syntopically with T. bottae. Baker (1956), Reichman and Baker (1972), Schmidly (1977a), and Davis and Schmidly (1994) all discussed habitat segregation of T. bottae and G castanops where the two species are sympatric. Segregation was thought to be a function of substrate quality. Cratogeomys has been reported to exclude Thomomys from areas with deep sandy soils and displace it to areas with thin, rocky substrata (Hollander et al., 1987; Hollander, 1990). At BBRSP, sympatric and syntopic occurrence of the two pocket gophers was observed in an area adjacent to Cienega Creek. Vegetation was short grass with scat¬ tered mesquite, and the soil was a deep, moist, sandy loam. The site noticeably had been subjected to peri¬ odic flooding. At this locality, the two species of pocket gophers were taken within 25 m of one another. Where the two species reside in the same soil and vegetation, the burrow's of T. bottae are deeper than those of C. castanops , thus reducing interspecific encounters (Best, 1973). No parasites w r ere noted in association with T. bottae from BBRSP. Comments. — Specimens of T. bottae from BBRSP are tentatively assigned to T. b. limitaris Goldman, 1936. However, the systematic affinities of this gopher in BBRSP are questionable, and require fur¬ ther examination before specimens can be assigned de¬ finitively to a subspecies. The generic name Thomomys is derived from the Greek “thomos” and “mys,” which translate to heap and mouse, respectively. The specific epithet bottae refers to Botta’s (Stangl et al., 1993). Specimens Examined (16).— Presidio Co. BBRSP, UTM coordinates: 13 57732IE 3287548N, 1; BBRSP, Colorado Canyon, 9 (SRSU); BBRSP, 12 mi. W Lajitas, 5 (SRSU).Brewster Co.: BBRSP, UTM coordinates: 13 618185E 3257611N, 1. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 91 Cratogeomys castanops (Baird, 1852) Yellow-faced Pocket Gopher Description .— Cratogeomys castanops is a large pocket gopher with a pale to deep brown dorsal pelage. The top of its forefeet usually are dark, and a single, deep groove is present on the anterior surface of each upper incisor. The dental formula for T. hottae is: i 1/ 1, c 0/0, p 1/1, m 3/3, total 20. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 263.3 (4, 250-284, 16.1); length of tail verte¬ brae, 70.8 (4, 62-75, 6.1); length of hind foot, 33.8 (4, 32-36,2.1); length of ear from notch, 5.6 (4, 5-6, 0.5); weight, 250.5 (4, 168-400, 102.4); greatest length of skull, 50.68 (3, 46.55-57.71,6.12). Males are signifi¬ cantly larger than females (Hollander, 1990). C. castanops may be confused with Thomomys hottae , the only other pocket gopher known from BBRSP. The two can be distinguished easily as de¬ scribed in the previous account. Distribution .— C. castanops ranges from north- central and northeastern Mexico, northward through western Texas and eastern New Mexico, and into east¬ ern Colorado, the Oklahoma Panhandle, and western Kansas. Isolated populations occur in southern Texas (Davidow-Heiury et al., 1989). In BBRSP, this pocket gopher is known from the Cienega, Sauceda, and Las Quevas areas, as well as from the Barton Wamock Cen¬ ter (Fig. 31). Natural History Four specimens of C, castanops were collected during this study, and occa¬ sionally mounds of this species were noted. It should be considered widespread, but not common at BBRSP C. castanops reportedly favors habitats with deep, sandy soils that are relatively free of rocks, but is known to occur in rocky areas as well (Davidow-Henry et al, 1989; Hollander, 1990). At BBRSP, C. castanops was taken in a grassy area with scattered mesquite on a deep, sandy loam substrate, and in desert scrub dominated by creosote-bush, with a hard, gravelly substrate. In addi¬ tion, this gopher was taken in two artificial habitats; one being the garden at the Barton Wamock Center, and the other the lawn of the “Big House” at Sauceda. The substrate at the former site was hard and rocky, and that at the latter site was a deep, moist, sandy loam. Based on these data, C. castanops should be consid¬ ered somewhat of a habitat generalist at BBRSP During this study, C. castanops w as taken during March, May, and July, but this species is active all year long (Davidow-Henry et al., 1989). C. castanops is reproductively active throughout the year, with no obvious peaks in activity (Hollander, 1990). During this study, a reproductively active male (testes, 15 X 10) was observed on 17 March, and a lactating female was noted on 26 July. In Texas, gravid females have been taken during every month, with a mean litter size of 2.08 (Hollander, 1990). The yellow-faced pocket gopher mostly forages from within its burrow system. Plants are pulled into the burrow by their roots, or green vegetation is col¬ lected from the burrow opening (Davidow-Henry et al., 1989). Lechuguilla appears to be among the primary' plant species consumed (Hermann, 1950). Bimey et al. (1971) reported that adult yellow- faced pocket gophers molt twice a year, once in both spring and early autumn. In contrast, Ikenbcrry (1964) documented a single, continuous period of molt from August through March. I examined two adult speci¬ mens undergoing molt, one taken on 31 May, and the other captured on 26 July. These data appear more con¬ sistent with the single continuous molt strategy proposed by Ikenberry (1964). Other rodents taken in association with C. castanops at BBRSP included Thomomys bottae , Chaetodipus eremicus , and Peromyscus mamculatus See the previous account for a discussion on sympatric relations of C. castanops and T. bottae . No parasites were noted in association with vcl- lovv-faccd pocket gophers from BBRSP. Ectoparasites known to infest C castanops include mites, lice, and fleas (Davidow-Henry et al., 1989). Comments .— The subspecies of C castanops al BBRSP is C. c clarkii (Baird, 1855). The generic name 92 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY HILOUETEFtS Figure 31. Localities of known specimens of Cratogeomys castanops from Big Bend Ranch State Park, Texas, Cratogeomys is derived from the Greek “kratos,” “gaia,” and “mys,” which translate to strength, land, and mouse, respectively. The specific epithet castanops is from the Greek “kastanea,” and “ops,” meaning chest¬ nut, and face, respectively (Stangl et al., 1993). Specimens Examined (4).— Presidio Co.: BBRSP, UTM coordinates: 13 587062E 3262884N, 1;BBRSP,UTM coordinates: 13 577321E3287548N, 1; BBRSP, UTM coordinates: 13 601105E3260471N, 1. Brewster Co.: BBRSP, UTM coordinates: 13 620726E 3238321N, 1. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 93 Family Heteromyidae (Pocket Mice and Kangaroo Rats) Perognathus flavus (Baird, 1855) Silky Pocket Mouse Description ,— Perognathus flavus is a small pocket mouse with blonde-buff dorsal pelage inter¬ spersed with black. The fur is soft and silky in texture. As in all members of this family, external fur-lined cheek pouches are present. The tail of this mouse is short and sparsely haired. A conspicuous pale buff patch is present just posterior to the small ears. The dental formula for P.flavus is: i 1/1, c 0/0, p 1/1, m 3/3, total 20. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 119.9 (66, 107-130, 4.5); length of tail verte¬ brae, 60.3 (66, 51-66, 2.9); length of hind foot, 16.5 (69,15-18,0.8); length of ear from notch, 6.2 (69, 5-7, 0.4); weight, 6.7 (65, 4.9-8 4, 0.8); greatest length of skull, 20.79 (20, 19.93-21.58, 0.43). No significant sexual dimorphism has been noted in this species, al¬ though males may have slightly longer tails (Best, 1993; Best and Skupski, 1994a). P, flavus is distinguished easily from all other pocket mice at BBRSP by its small size, coloration, and silky fur. Distribution. — P. flavus ranges from central Mexico, northward through the western two thirds of Texas and onto the Great Plains, and westward to west¬ ern Utah and Arizona (Best and Skupski, 1994a; 19946). In BBRSP, this pocket mouse is known from throughout the park (Fig. 32). Natural History. — With a relative abundance in¬ dex of 0.647, P flavus was the fourth most abundant rodent at BBRSP. It accounted for 9.8 percent of all rodents trapped in the park. Schmidly (1 971a) reported this pocket mouse as one of the most common small mammals in the Trans-Pecos, and this appears to be the situation at BBRSP P flavus is a habitat generalist, and has been re¬ ported to occur in all the major habitat types found at BBRSP (Schmidly, 1977a; Best and Skupski, 1994a; 19946). However, during this study, the silky pocket mouse was taken only in desert scrub and desert grass¬ land habitats, neither to which it showed a significant preference (P=0.894). It is not known to have a prefer¬ ence for soil types (Best and Skupski, 19946), and dur¬ ing this study, it was taken on all types of substrata en¬ countered, including sand, sandy loam, gravel, rock, and boulder, but appeared to be more common on the latter three. P. flavus may hibernate in some areas, but remains active during winter throughout much of its range (Best and Skupski, 1994a). During this study, silky' pocket mice were taken only from April through November, despite extensive trapping during the winter months. These results suggest that the silky pocket mouse hi¬ bernates at BBRSP. In the Trans-Pecos, the breeding season lasts from April to November, and females may bear multiple lit¬ ters each year (Schmidly, 1977a). During this study, I examined 4 gravid females, three of w hich were cariy- ing four embryos, and one that was carrying two em¬ bryos, and one lactating female with seven placental scars. Thus, the mean litter size was 4.2, Prior to this study, the largest litter known for this species was six (Best and Skupski, 1994a; 19946). Pregnant females were examined on the following dates (number of em¬ bryos and corresponding crown-rump lengths in paren¬ theses): 5 June (2 embry os, crown-rump length, 11), 2 August (4 embry os, crown-rump length, 9), 5 August (4 embryos, crown-rump length, 10), 11 October (4 em¬ bryos, crown-rump length, 2). Previously, no pregnant females had been recorded from the Trans-Pecos dur¬ ing August (Schmidly, 1977a). A lactating female was observed on 29 October. Testicular measurements of males ranged as follows: April, 5 X 3; May, 4 X 3 to 7 X 4; June, 4 X 2 to 6 X 4, July 4 X 3 to 5 X 4, August, 5X3; October, 3X2. Juveniles were observed among the population on 28 May and 3 July. P fla\ms is nocturnal, but occasionally may be active outside its burrow' during the day. At night this 94 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY KILOMETERS Figure 32. Localities of known specimens of Perognathus flavus from Big Bend Ranch State Park, Texas. pocket mouse forages for seeds, which are collected and cached in its burrow for consumption the following day. In addition to seeds, P. flavus also will feed on green vegetation, juniper berries, and occasionally inverte¬ brates (Best and Skupski, 1994a; 19946). Adult silky pocket mice were reported to undergo a single annual molt. Winter pelage reportedly is re¬ tained through spring and summer. Then, in late July or August, the worn winter pelage gradually is replaced by summer pelage. By September, the process is com¬ plete (Best and Skupski, 1994a; 19946). This does not appear to be the situation at BBRSP, as adults undergo¬ ing seasonal molting were observed as early as 1 May, YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 95 and as late as 29 October. These data may indicate (1) early or late molt in some individuals, (2) a second an¬ nual molt, or (3) individuals molt at various times throughout the year. Other rodents taken at the same localities as P. flavus at BBRSP included Chaetodipus eremicus , C. hispidus , C. intermedius, C. nelsoni , Dipodomys merriami , Reithrodontomys megalotis , Peromyscus eremicus , P. leucopus , P maniculatus, Onychomys arenicola , and Neotoma micropus . Mites were the only parasites found in associa¬ tion with silky pocket mice at BBRSP. Additional ec¬ toparasites reported for this pocket mouse include ticks, lice, and fleas. Endoparasites known from P. flavus include protozoans and nematodes (Best and Skupski, 1994a; 19946). Comments .— The subspecies of P flavus at BBRSP probably is P f gilvus Osgood, 1900. The generic name Perognathus is derived from the Greek “pera” and “gnathos,” which translate to pouch and jaw, respectively. The specific epithet flavus is Latin for yellow (Stangl et al, 1993). Other workers (Lee and Engstrom, 1991) consider the taxon that Jones and Jones (1992) refer to as P. flavus to consist of two separate species, P flavus and P merriami . If the taxon regarded herein as P flavus actually is two species, both prob¬ ably occur in BBRSP (Davis and Schmidlv, 1994). Continued investigation is required to resolve the sys¬ tematic status of this taxon. Specimens Examined (77),— Presidio Co.: BBRSP, UTM coordinates: 13 575323E 3292088N, 3; BBRSP, UTM coordinates: 13 57631 IE 3271128N, 1; BBRSP, UTM coordinates: 13 576390E3296223N, 1; BBRSP, UTM coordinates: 13 576721E3296287N, 1; BBRSP, UTM coordinates: 13 576773E 3295277N, 2, BBRSP, UTM coordinates: 13 576796E 3295418N, i; BBRSP, UTM coordinates: 13 576836E 329625 IN, 3; BBRSP, UTM coordinates: 13 576931E 3296613N, 2; BBRSP, UTM coordinates: 13 576970E3296222N, 1; BBRSP, UTM coordinates: 13 576985E 3295102N, 1; BBRSP, UTM coordinates: 13 577120E 3295100N, 1; BBRSP, UTM coordinates: 13 578883E3292424N, 2; BBRSP, UTM coordinates: 13 579237E 3292359N, 4; BBRSP, UTM coordinates: 13 579410E 3289121N, 1; BBRSP, UTM coordinates: 13 579859E 3292474N, 2; BBRSP, UTM coordinates: 13 581659E3279903N, 1; BBRSP, UTM coordinates: 13 582110E3288790N, 1; BBRSP, UTM coordinates: 13 583205E 3282984N, 2; BBRSP, UTM coordinates: 13 583788E 3266885N, 2; BBRSP, UTM coordinates: 13 583846E 3290112N, 3; BBRSP, UTM coordinates: 13 586886E 3265832N, 1; BBRSP, UTM coordinates: 13 589824E 3265632N, 3; BBRSP, UTM coordinates: 13 592858E 3262597N, 1; BBRSP, UTM coordinates: 13 595478E 3262749N, 1; BBRSP, UTM coordinates: 13 597424E 3260494N, 1; BBRSP, UTM coordinates: 13 597543E3261182N, 2; BBRSP, UTM coordinates: 13 599607E 3261323N, 2; BBRSP, UTM coordinates: 13 599751E 3261864N, 1; BBRSP, UTM coordinates: 13 600868E 3256344N, 3; BBRSP, UTM coordinates: 13 601273E 3260059N, 3; BBRSP, UTM coordinates: 13 601508E 3260673N, 1; BBRSP, UTM coordinates: 13 601622E 3260685N, 1; BBRSP, UTM coordinates: 13 602666E 3260640N, 1; BBRSP, UTM coordinates: 13 605201E 326043 IN, 1; BBRSP, UTM coordinates: 13 605576E3257735N, 2; BBRSP, UTM coordinates: 13 606085E 3259112N, 1; BBRSP, UTM coordinates: 13 606207E 3256765N, 3; BBRSP, UTM coordinates: 13 614350E 3268071N, 4; BBRSP, UTM coordinates: 13 615747E 3255837N, 1; BBRSP, UTM coordinates: 13 616984E3256548N, 1; BBRSP, UTM coordinates: 13 619125E 3258986N, 3; BBRSP, Rancherias Springs, 1 (SRSU). Brewster Co.: BBRSP, UTM coordinates: 13 61908 IE 3260561N, 2; BBRSP, UTM coordinates: 13 621243E 3239655N, 2. Chaetodipus eremicus (Mearns, 1898) Chihuahuan Desert Pocket Mouse Description .— Chaetodipus eremicus is a me¬ dium-sized pocket mouse with a buff to pale brown dor¬ sal pelage. Vary ing degrees of black may be sprinkled about the dorsal pelage presenting an overall grayish- brown color. The pelage is coarse and lacks rump spines The tail is long and tufted, the cars arc short, and the soles of the hind feet are palc-flcshy in color The den¬ tal formula for C. eremicus is: i 1/1, c 0/0, p 1/1, m 3/ 3, total 20. 96 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 174.6 (82, 153-192, 7.7); length of tail verte¬ brae, 95.7 (82, 86-112, 4.7); length of hind foot, 22.5 (90,20-24, 1.0); length of ear from notch, 7.8 (90, 7-9, 0.5); weight, 14.6 (79, 9-20, 2.6); greatest length of skull, 25.57 (20, 24.78-26.40, 0.44). No sexual di¬ morphism is apparent in this species (Manning et al., 1996). C. eremicus can be confused with two other spe¬ cies of Chaetodipus that occur at BBRSP. It is fairly easy to differentiate C. eremicus from G nelsoni. The former usually is paler in color, lacks rump spines, and has pale colored soles on the hind feet. In contrast, the latter is darker, has prominent rump spines, and has dark soles on the hind feet. These two species of pocket mice also can be separated consistently based on cranial mor¬ phology as described by Manning et al. (1996). Dif¬ ferentiation between C. eremicus and C. intermedins poses more of a problem, as the appearance of the dor¬ sal pelage of these two mice is similar. However, upon close examination, weak rump spines can be noticed on C. intermedius , whereas they are completely absent from C. eremicus. Cranial morphology also can be used to assist in differentiating these two species. C. eremicus has been shown to have a significantly larger greatest length of skull than G intermedius (Wilkins and Schmidly, 1979). This observation appears to hold true for specimens from BBRSP as can be noted in the list of measurements in the respective accounts of these two species. Furthermore, the interparietal of G eremicus is not in contact with the mastoid bullae, being sepa¬ rated by narrow projections of the parietals and supraoccipitals. In contrast, the interparietal of G in¬ termedius is in contact, or nearly so, with the mastoid bullae (Davis and Schmidly, 1994). At BBRSP, the three species of Chaetodipus treated above were dis¬ tinguished easily based on karyology. G. eremicus had 2N=46 and FN=56, G intermedius had 2N=46 and FN=58, and G nelsoni had 2N=48 and FN=58. The kary otypes for G eremicus and G nelsoni were con¬ sistent with those reported by Lee et al. (1991), and the kary otype for G nelsoni was consistent with that re¬ ported by Patton (1970). Distribution .— Chaetodipus eremicus ranges from north-central Mexico, northward to southwestern Texas and southern New Mexico (Lee et al., 1996). In BBRSP, this pocket mouse was recorded throughout the park (Fig. 33). Natural History. — With a relative abundance in¬ dex of 1.294, G eremicus w as the most frequently en¬ countered rodent at BBRSP. It accounted for 19.5 per¬ cent of all rodents trapped. Trapping results indicate that this pocket mouse is both widespread and abun¬ dant in BBRSP. G eremicus has been reported to prefer desert scrub habitat (Schmidly, 1977 a). During this study, G eremicus was taken in desert scrubland, but also in desert grassland, and riparian habitats. However, this pocket mouse showed a significant preference for desert scrub over the latter two habitats (PcO.OOl). There was no preference shown between grassland and ripar¬ ian habitats (P=0.52). The majority of the specimens taken in riparian areas were acquired from along the Rio Grande. In addition to desert scrub vegetation, C eremicus reportedly favors sandy or silty soils, and is absent from areas w'ith gravelly or rocky' substrata (Davis and Schmidly, 1994). During this study, this pocket mouse was, in fact, taken most commonly on sandy or silty' soils (81 percent), but some were acquired on gravelly, rocky, or bouldery substrata (19 percent). Because G eremicus has been considered a sand dweller, whereas its similar appearing congeners, G intermedius and C. nelsoni , have been regarded as rock dwellers (Davis and Schmidly, 1994), the substrate quality from which specimens were collected often was considered in the identification process. However, con¬ sidering that 19 percent of G eremicus taken during this study were from gravelly or rocky' areas, this prac¬ tice should be regarded as unreliable. G eremicus is known to be less active during the winter months, and may enter a period of torpor during extremely cold w eather (Schmidly, 1977a). During this study, this pocket mouse was encountered from March to December. In nearby Big Bend National Park, Man¬ ning et al. (1996) found G eremicus to be active only during these months as well. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 97 i_»_ kilometers Figure 33. Localities of known specimens of Chaetodipus eremicus from Big Bend Ranch State Park, Texas. Apparently two annual periods of peak reproduc¬ tive activity occur in C. eremicus , one in the spring and the other in late summer (Schmidly, 1977 a). However, pregnant females are known from most months that this pocket mouse is active (Manning et al., 1996). Schmidly (1977a) reported a mean litter size of 3.6, with a range of two to five. However, Manning ct al. (1996) re¬ ported examining a female with 15 placental scars, sug¬ gesting a much greater range in litter size. During this study, I examined 11 gravid females taken between 4 and 27 July. The number of embryos ranged from three to five, with a mean of 3.8 Pregnant females (with number of embry os and corresponding crown-rump lengths in parentheses) were examined on the follow¬ ing dates 4 May (3 embry os, crown-rump length, 2; 3 embryos, crown-rump length, 3; 4 embryos, crown-rump 98 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY length, 3), 14 May (1 embryo, crown-rump length, 4), 3 May (2 embryos, crown-rump length, 8), 13 May (2 embryos, crown-rump length, 10), 14 May (3 embryos, crown-rump length, 5; 4 embryos, crown-rump length, 3), 26 May (5 embryos, crown-rump length, 18), 3 June (4 embryos, crown-rump length, 15), 21 June (4 em¬ bryos, crown-rump length, 5; 4 embryos, crown-rump length, 7), 27 July (5 embryos, crown-rump length, 6). Lactating females were noted on 5 and 27 July, 13 Sep¬ tember, and 8 and 10 December. Juveniles were ob¬ served in the population on 14 May, 5, 12, and 27 July, 22 August, 29 September, and 4 and 8 October. Sub- adults were noted on 11 June, 5 and 13 July, 22 August, 17 and 29 October, 4 November, and 8 December. Tes¬ ticular measurements of adult males ranged as follows: March, 6X4; April, 7 X 4 to 10 X 4; May, 6 X 3 to 15 X 5; June, 7 X 4 to 12 X 6; July, 10 X 4; September, 4 X 2 to 9 X 4; October, 3 X 1 to 7 X 4; November, 3 X 2 to 5 X 2; December, 3 X 1 to 5 X 3. G eremicus is nocturnal and forages primarily for seeds, especially those of mesquite, creosote-bush, and broomvveed (Schmidly, 1977a). Seasonal molting in C. eremicus previously has been documented as occurring from June through Oc¬ tober (Manning et al., 1996). During this study, molt¬ ing adults were taken during May, June, July, Septem¬ ber, November, and December. It is not known if these observations are due to a single annual molt that occurs at various times throughout the year, or two seasonal molts, one during spring, and the other during fall. Other rodents taken at the same localities as C. eremicus at BBRSP included Thomomys bottae , Spermophilus spilosoma , Perognathus flavus , Chaetodipus hispidus , C. intermedins , C. nelsoni , Dipodomys merriami , Reithrodontomys fulvescens , R. megalotis , Peromyscus eremicus, P. leucopus , P. maniculatus,P pectoral is, and Neotoma micropus. The s\mpatric occurrence of G eremicus , C. intermedins , and C. nelsoni is an interesting situation. Reportedly, C. eremicus is segregated from C. intermedius and C. nelsoni ecologically, with the former species restricted to sandy or silty substrata, and the latter two species limited to rocky or gravelly substrata (Schmidly, 1977a). The two rock-dwelling species, G intermedius and C. nelsoni , reportedly are separated geographically, with the former occurring in the western Trans-Pecos, and the latter occurring to the east. Previously, there were only two localities from which these two pocket mice were taken together (Wilkins and Schmidly, 1979). In¬ terestingly, G eremicus and C nelsoni were taken sym- patrically and syntopically on several occasions. More¬ over, at one locality, all three species of these pocket mice were taken. This is the first account of C eremicus , C. intermedius, and C. nelsoni occurring at the same locality. This site, which is at the west end of the park, is in creosote scrub habitat with a rocky, gravelly sub¬ strate. The ecologic and biogeographic relations of these pocket mice are deserving of further investigation. Various mites, especially on the tail, were ob¬ served on specimens of C. eremicus from BBRSP. In addition to mites, other ectoparasites previously reported from desert pocket mice include lice and fleas. En- doparasites known to infect desert pocket mice include protozoans and nematodes. C. eremicus is known to harbor the pathogenic fungus Coccidioides immitis , the etiologic agent of valley fever (Whittaker et al., 1993). Comments .— Chaetodipus eremicus is a mono- typic species. The generic name Chaetodipus is de¬ rived from the modem Latin “chaeta” and the Greek “dis” and “pous,” which translate to bristle, twice, and foot, respectively. The specific epithet eremicus is from the Greek “eremikos,” meaning solitary (Stangl et al., 1993). Previously, G eremicus was regarded as a sub¬ species of C. penicillatus until recent work based on mitochondrial DNA sequence data indicated that eremicus was worthy of specific status (Lee et al., 1996). Specimens Examined (114).— Presidio Co.: BBRSP UTM coordinates: 13 573986E 3270053N, 2; BBRSP UTM coordinates: 13 576206E 3268568N, 1; BBRSP UTM coordinates: 13 576311E 3271128N, 1; BBRSP UTM coordinates: 13 576390E 3296223N, 2; BBRSP UTM coordinates: 13 576646E 3296118N, 1; BBRSP UTM coordinates: 13 576699E 3296276N, 2; BBRSP UTM coordinates: 13 576721E3296287N,4; BBRSP UTM coordinates: 13 576757E3296109N,4; BBRSP UTM coordinates: 13 576808E 3295784N, 1; YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 99 BBRSPUTM coordinates: 13 576836E 329625 IN, 9; BBRSP UTM coordinates: 13 576842E 3296279N, 2; BBRSP UTM coordinates: 13 576846E 3296245N, 5; BBRSP UTM coordinates: 13 57693 IE 3296613N, 2; BBRSP UTM coordinates: 13 576970E 3296222N, 2; BBRSP UTM coordinates: 13 577002E 3296360N, 1; BBRSPUTM coordinates: 13 577321E 3287548N, 1; BBRSP UTM coordinates: 13 577472E 3287353N, 1; BBRSP UTM coordinates: 13 579684E 3269447N, 14; BBRSP UTM coordinates: 13 580342E 328893 IN, 1; BBRSP UTM coordinates: 13 581230E3264998N, 4; BBRSP UTM coordinates: 13 581659E 3279903N, 1; BBRSP UTM coordinates: 13 585434E3286791N, 1; BBRSP UTM coordinates: 13 586777E 324965 IN, 5; BBRSP UTM coordinates: 13 587184E 3262927N, 1; BBRSPUTM coordinates: 13 588746E 3247263N, 3; BBRSP UTM coordinates: 13 589348E 3246503N, 9; BBRSP UTM coordinates: 13 591851E 324549 IN, 3; BBRSP UTM coordinates: 13 592496E 3244969N, 1; BBRSPUTM coordinates: 13 599495E 3261227N, 1; BBRSP UTM coordinates: 13 600786E 3260060N, 8; BBRSP UTM coordinates: 13 600914E 3260458N, 1; BBRSP UTM coordinates: 13 601273E 3260059N, 3; BBRSP UTM coordinates: 13 601508E 3260673N, 2; BBRSP UTM coordinates: 13 604886E 3240689N, 1; BBRSP UTM coordinates: 13 606085E 3259112N, 1; BBRSP UTM coordinates: 13 606207E 3256765N, 1; BBRSPUTM coordinates: 13 608309E 3239482N, 3; BBRSP UTM coordinates: 13 609770E 3253645N, 1; BBRSP UTM coordinates: 13 615800E 3238476N, 3; BBRSP, Colorado Canyon, 1 (SRSU); BBRSP, Rancherias Springs, 1 (SRSU); BBRSP, Smith Ranch, Fresno Canyon, 1 (SRSU). Brewster Co.: BBRSP UTM coordinates: 13 617281E3261484N, 1; BBRSP UTM coordinates: 13 620927E 3238664N, 1. Chaetodipus hispidus (Baird, 1858) Hispid Pocket Mouse Description .— Chaetodipus hispidus is a large pocket mouse with a coarse dorsal pelage that is buffy- blonde mixed with black above, and with clear buff on the sides. The tail is relatively short (less than half the total length), bicolored, scantly haired, and lacks a ter¬ minal tuft. The dental formula for C hispidus is: i 1/1, c 0/0, p 1/1, m 3/3, total 20. Means of external and cranial measurements (with extremes in parentheses) of three adult specimens from BBRSP are: total length, 208.0 (196-215); length of tail vertebrae, 95.7 (85-104); length of hind foot, 24.0 (23-25); length of ear from notch, 12.0 (11-13); weight, 37.3 (33-46); greatest length of skull, 30.62 (29.78- 31.17). No sexual dimorphism is evident in C. hispidus (Best, 1993). The large size of C. hispidus , coupled with its relatively short, untufted tail, distinguishes this species from the other heteromyids at BBRSP. Distribution.— C hispidus ranges from central Mexico, northward through the central United States, to North Dakota (Paulson, 1988). In BBRSP, this pocket mouse is known only from a single locality in the Cienega area (Fig. 34). Natural History. — Three hispid pocket mice were taken during this study, which resulted in a relative abun¬ dance index of 0.024. This species accounted for 0.4 percent of rodents trapped. Schmidly (1977a:84) con¬ sidered C. hispidus as “one of the rarest pocket mice in the Trans-Pecos,” and apparently this is the situation at BBRSP. Prior to this report, tins species was known from Presidio County only on the basis of four speci¬ mens taken in the 19th century. C. hispidus reportedly prefers dry, grassland habi¬ tats with sandy or friable soils (Schmidly, 1977a; Paulson, 1988). The site at which this pocket mouse was taken at BBRSP was overgrazed grassland with scattered mesquite, false willow, and desert willow'. The soil was a hard, fine loam with patches of sand and gravel. During this study, C. hispidus was taken during April and July. This species is not known to hibernate, but may become torpid during periods of food shortage (Paulson, 1988). 100 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY KILOMETERS Figure 34. Localities of known specimens of Chaetodipus hispidus from Big Bend Ranch State Park, Texas. Little is known about the reproductive habits of C. hispidus in the Big Bend area. The breeding period of this mouse is nearly year round in south Texas (Davis and Schmidly, 1994), and that probably is the situation at BBRSP. A male taken on 5 July appeared to be in reproductive condition (testes, 18X5). Litter sizes typically range from two to nine, with a mean of six (Davis and Schmidly, 1994). Females may bear two or more litters annually (Jones et al., 1983). C hispidus is active at night, during which time it forages primarily for seeds, especially those of mes- quite, cactus, and sagebrush. Seeds most often are col¬ lected from the ground (Rcichman and Price, 1993), YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 101 bet occasionally this pocket mouse will climb vegeta¬ tion in an effort to gather food (Lemen and Freeman, 1995). Seeds gathered and stored during the warmer months allow individuals to subsist through winter. In addition to seeds, some green vegetation and insects may be consumed (Jones et al., 1983). Other rodents taken at the same locality as C. hispidus at BBRSP included Perognathus flavus, Chaetodipus eremicus , Dipodomys merriami, Reithrodontomys megalot is, Peromyscus eremicus, P leucopus, and P maniculatus. In addition, two lago- morphs, Sylvilagus audubonii and Lepus californicus, frequently were observed grazing at the site where C. hispidus was taken. Davis and Schmidly (1994) re¬ ported that C. hispidus usually avoids areas of dense grass, and it is conceivable that the extensive grazing activity by lagomorphs at this site is maintaining suit¬ able habitat for this pocket mouse. No parasites were observed in association with hispid pocket mice from BBRSP. Ectoparasites previ¬ ously documented to infest C. hispidus include mites, ticks, lice, and fleas (Turner, 1974; Paulson, 1988; Whitaker et al., 1993). Endoparasites reported to in¬ fect C. hispidus include protozoans. The hispid pocket mouse has been implicated as a reservoir for Trypano¬ soma cruzi, the etiologic agent of Chaga disease. In the lower Rio Grande Valley of Texas, 16 percent of hispid pocket mice examined tested positive for this protozoan (Burkholder et al., 1980). C. hispidus also has been known to carry 7 Borrelia-\ike spirochetes (Eads and Hightower, 1952). In addition, C. hispidus is known to harbor the flea Thrassis fotus , a vector of sylvatic plague (Rail et al., 1969). Comments ,— The subspecies of C. hispidus that occurs at BBRSP is C. h. paradoxus (Mcrriam, 1889). See the account on Chaetodipus eremicus for the ety¬ mology of the generic name. The specific epithet hispidus is Latin for shaggy 7 (Stangl et al., 1993). Specimens Examined (3).— Presidio Co.: BBRSP, UTM coordinates: 13 576836E 329625IN, 3. Chaetodipus intermedius Merriam, 1889 Rock Pocket Mouse Description .— Chaetodipus intermedius is a me¬ dium-sized pocket mouse with a bufly-brown dorsal pelage sprinkled with black. The pelage is rather coarse, with weak, sometimes inconspicuous spines on the rump. The tail is long and tufted, the ears are short, and the soles of the hind feet are pale in color. The dental for¬ mula for C. intermedius is: i 1/1, c 0/0, p 1/1, m 3/3, total 20, Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 172.9 (12, 164-185, 6.7); length of tail verte¬ brae, 97.1 (12, 86-107, 5.5); length of hind foot, 21.2 (13,20-22.5, 0.6); length of ear from notch, 7.9 (13, 7- 8,0.3); weight, 12.8(13, 11-14,1.1); greatest length of skull, 23.88 (13, 22.83-24.53, 0.48). Males may aver¬ age slightly larger than females (Best, 1993). C. intermedius is confused easily with C. eremicus , but the two can be distinguished as described in the account of the latter C. intermedius may also be mistaken for C. nelsoni , which frequently occupies the same habitat as C. intermedius. These two pocket mice usually can be separated on the basis of pelage appear¬ ance. C. intermedius is pale brown washed with black, and has weak rump spines. In contrast, C. nelsoni usu¬ ally is darker, almost black in color, and possesses heavy, black-tipped rump spines. However, coloration of C. nelsoni is variable, and pale-colored individuals arc known from BBRSP. Additional characters that can be used to separate these two pocket mice include dark foot pads and the presence of a small, w hite patch at the base of the ear in C. nelsoni , versus paler foot pads and no w hite patch at the base of the cars in C. intermedius. These two pocket mice can be distinguished easily by karyotypes as described in the account on C. eremicus. Distribution,— C. intermedius ranges from north¬ western Mexico, north and north-westward through Trans-Pecos Texas and the southern part of the south¬ western United States (Schmidly ct al , 1993). In BBRSP, C. intermedius is known only from the west- 102 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY era fourth of the park (Fig. 35). Davis and Schmidly (1994) report this pocket mouse as occurring through¬ out most of the Trans-Pecos, as well as from one county east of the Pecos River. Thus, the eastern limits of the range of this species were defined by specimens from Winkler, Reeves, and Brewster counties (Davis and Schmidly, 1994). However, specimens from these lo¬ calities apparently were misidentified; the record from Brewster County actually being C. nelsoni (Wilkins and Schmidly, 1979), and those from Winkler and Reeves counties being P. eremicus (Jones and Manning, 1991). This resulted in the eastern limit of the range of C. in¬ termedins being redefined by a record from 5 mi. E, 2 mi. S Presidio, Presidio County (Wilkins and Schmidly, 1979). The easternmost site from which C. interme¬ dins was taken at BBRSP during this study is approxi¬ mately 15 km east of this locality, and thus, redefines the eastern limit of the range of C. intermedins. Natural History. — During this study, C. inter¬ medins was found to have a relative abundance index of 0.105. This pocket mouse accounted for 1.6 percent of all rodents trapped. These figures indicate that C. intermedius is uncommon at BBRSP. This probably is do to the fact that the park is situated on the eastern boundary of this species’ distribution, rather than lack of suitable habitat. C. intermedius prefers desert scrub habitat domi¬ nated by creosote-bush (Schmidly, 1977a), and this was the only type of habitat from which this mouse was taken at BBRSP. It reportedly favors areas of boulders and rocks, but also is known to occur on gravelly substrata (Davis and Schmidly, 1994). All specimens acquired during this study were taken from the latter. During this study, C. intermedius was taken dur¬ ing March, May, and June.There is no documentation of this pocket mouse entering seasonal dormancy (French, 1993), and probably is active year round at BBRSP. C. intermedius apparently begins breeding in Feb¬ ruary or March, and continues to do so for several months. Pregnant females, which carry three to six young, are known from May, June, and July. Juvenile individuals have been observed during April, May, June, and August (Davis and Schmidly, 1994). Adult males examined during this study had testicular measurements as follows: 18 March, 12 X 6; 2 May, 6 X 4 and 7 X 4; 21 June, 7 X 4; 22 June, 7X4. The rock pocket mouse is strictly nocturnal, at which time it forages primarily for the seeds of herba¬ ceous plants (Davis and Schmidly, 1994). Seeds are cached for consumption during periods of environmen¬ tal stress. In addition, caching may help this pocket mouse maintain a diverse diet, and the growth of fungi on cached seeds may increase their nutritional value (Reichman and Price, 1993). Little is known about annual molting in C. inter¬ medius. Adult specimens undergoing seasonal molting at BBRSP w'ere observed on 21 and 22 June. Other species of rodents taken at the same locali¬ ties as C intermedius at BBRSP included Perognathus JIavus , Chaetodipus eremicus , C. nelsoni , Dipodomys merriami , and Peromyscus eremicus. See the account on C. eremicus for a discussion on the sympatry of C. eremicus , C. intermedius , and C. nelsoni. Mites noted on the tail were the only parasites observed in association with specimens of C. interme¬ dius from BBRSP Ectoparasites previously reported from C. intermedius are restricted to several species of mites. Endoparasites known from C. intermedius in¬ clude protozoans and nematodes. The pathogenic fun¬ gus Coccidioides immitis is known to infect C. inter¬ medius (Whitaker et al., 1993). Comments. — The subspecies of C. intermedius that occurs at BBRSP is C. i. intermedius (Merriam, 1889). See the account on Chaetodipus eremicus for the etymology of the generic name. The specific epi¬ thet intermedius is Latin for intermediate (Stangl et ak, 1993). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 103 KILOMETERS Figure 35. Localities of known specimens of Chaetodipus intermedins from Big Bend Ranch State Park, Texas. Specimens Examined (13).— Presidio Co,: BBRSP, UTM coordinates: 13 573986E 3270053N, 2; BBRSP, UTM coordinates: 13 576311E 3271128N, 1; BBRSP, UTM coordinates: 13 577526E3287386N, 1; BBRSP, UTM coordinates: 13 582906E3266716N, 3; BBRSP, UTM coordinates 13 583205E3282984N, 2; BBRSP, UTM coordinates: 13 584021E3269813N, 1; BBRSP, UTM coordinates: 13 584964E3273523N, 3. 104 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Chaetodipus nelsoni Me mam, 1894 Nelson’s Pocket Mouse Description .— Chaetodipus nelsoni is a medium¬ sized pocket mouse with grayish buff dorsal pelage that is washed heavily with black. The pelage is coarse with numerous, often back-tipped spines present on the rump. The tail is long and tufted, and the ears are short with a small white patch at the base. The soles of the hind feet are dark in color The dental formula for C nelsoni is: i 1/1, c 0/0, p 1/1, m 3/3, total 20. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 183.9 (47, 164-196, 6.5); length of tail verte¬ brae, 103.5 (47,90-110, 4.2); length of hind foot, 21.8 (59,20-24, 0.8); length of ear from notch, 8.2 (59, 6-9, 0.5); weight, 14.6 (56, 10-19, 1.8); greatest length of skull, 25.18 (20, 23.22-26.20, 0.66). No significant sexual dimorphism is apparent in this pocket mouse (Manning et al., 1996). C. nelsoni can be mistaken for C. eremicus and C. intermedins. See the accounts of these two species for distinguishing characters. Distribution. — C. nelsoni ranges from north-cen¬ tral Mexico northward to southwestern Texas and south¬ eastern New Mexico (Best, 1994). In BBRSP, it is known from scattered localities throughout most of the park (Fig. 36). Natural History.— During this study, C. nelsoni was found to have a relative abundance index of 0.615. It accounted for 9.3 percent of all rodents trapped, mak¬ ing it the fifth most abundant rodent in the park. Best (1994) reported that Nelson’s pocket mouse is among the most common pocket mice throughout its range, and this appears to be the situation at BBRSP. Schmidly (1977a) reported that in the Trans-Pecos m general, this pocket mouse has a strong preference for desert scrub and grassland vegetation. At BBRSP, C nelsoni was taken in these two habitats, as well as in riparian and juniper roughland habitats. Trap success indicated that this pocket mouse does, in fact, prefer both desert scrub, and grassland over riparian habitat (PcO.OOl and P=0.001, respectively). Capture rates were higher in both desert scrub and grassland than in juniper roughland, but the latter habitat was sparse, and therefore lacked adequate sampling for statistical com¬ parisons. There was no significant difference between capture rates in desert scrub and desert grassland (P=0.204). In addition to scrub and grassland vegeta¬ tion, C. nelsoni also is known to have a preference for rocky substrata, although it also may occur in sandy areas (Best, 1994). During this study, it most frequently was taken in rocky or gravelly situations (87 percent), but occasionally was taken on sandy substrata (13 per¬ cent). However, in all but one of the occasions where C. nelsoni was taken associated with sand, there were rocks scattered about the sand. Therefore, 99 percent of C. nelsoni specimens collected during this study were taken from substrata that were at least partially associ¬ ated with rocks. C. nelsoni does not hibernate and reportedly is active year round (Best, 1994). This appears to be the situation at BBRSP, as specimens w r ere taken during each month, excluding January and April. The breeding season of Nelson’s pocket mouse reportedly commences in February and continues through July (Schmidly, 1977a). Females are known to give birth to two to five (mean, 3.2) young per litter (Schmidly, 1977a; Best, 1994). At BBRSP, I exam¬ ined three gravid females carrying two to three (mean, 2.7) embry os. They were taken on 27 May (3 embryos, crown-rump length, 22), 30 May (3 embryos, crown- rump length, 8), and 3 June (2 embryos, crown-rump length, 15). Lactating females were noted on 22 June and 24 July. Juveniles were observed in the population on 30 and 31 May, 3 and 25 June, 3 July, and 22 Au¬ gust. Subadults were taken on 2, 3, and 26 July, and 4 September. Testicular measurements of adult males ranged as follow's: February', 8X4; March, 8X4; May, 4 X 8 to 10X 5; June, 7 X 4 to 8 X 4; July, 7X3 to 9 X 4; August, 7 X 3 to 8 X 4; October, 5X2; November, 4X2; December, 5X3. The above repro¬ ductive data are consistent w ith the reproductive period YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 105 kilometers Figure 36. Localities of known specimens of Chaetodipus nelsoni from Big Bend Ranch State Park, Texas. of February through July reported by Schmidly (1977a), with the exception of the size of testes observ ed in Au¬ gust. Enlarged testes measuring 7X3 and 8X4 were noted on 17 August, thus indicating that males are ac¬ tive reproductively at this time. This suggests that the breeding season of C. nelsoni at BBRSP extends well into August. C. nelsoni is strictly nocturnal, at which time it forages primarily for seeds (Best, 1994) Seeds gath¬ ered by Nelson's pocket mouse in the Big Bend area include those of mesquite, creosote-bush, and pnckl\ pear (Judd, 1967). In addition to seeds, C. nelsoni also may consume other plant parts and insects (Best, 1994). 106 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY A single annual molt is reported to occur in C. nelsoni between May and October (Best, 1994). How¬ ever, molting adults at BBRSP were observed on 24 February; 18 March; 21, 23, 29, and 30 May; 2, 8, 22, and 27 June; 1, 2, 3, 8, and 24 July, 17 August, 17 November, and 3 December. It is possible that these observations are due to a single annual molt that occurs at various times throughout the year, or two seasonal molts, one during spring and the other during fall Other species of rodents taken at the same locali¬ ties as C. nelsoni at BBRSP included Perognathus flavus , Chaetodipus eremicus, C. intermedins , Dipodomys merriami , Reithrodontomys fulvescens , Peromyscus eremicus , P. leucopus, P. pectoralis , and Neotoma micropus . See the account on C. eremicus for a discussion on the sympatry of C. eremicus, C. in¬ termedins , and C. nelsoni. Mites on the tail were the only parasites found in association with specimens of C. nelsoni from BBRSP Other ectoparasites previously reported from C. inter- medius include ticks and fleas. No endoparasites have been reported from C. nelsoni (Best, 1994). Comments .— The subspecies of C. nelsoni that occurs at BBRSP is C. n. canescens (Merriam, 1904). See the account on Chaetodipus eremicus for the ety¬ mology of the generic name. The specific epithet nelsoni refers to Nelson’s (Stangl et al., 1993). Specimens Examined (74).— Presidio Co. : BBRSP, UTM coordinates: 13 573986E 3270053N, 2; BBRSP, UTM coordinates: 13 575323E 3292088N, 3; BBRSP, UTM coordinates: 13 576206E3268568N, 1; BBRSP, UTM coordinates: 13 576947E 3295987N, 1; BBRSP, UTM coordinates: 13 576985E 3295102N, 3; BBRSP, UTM coordinates: 13 577120E 3295040N, 3; BBRSP, UTM coordinates: 13 577526E 3287386N, 1; BBRSP, UTM coordinates: 13 577690E 3290260N, 2; BBRSP, UTM coordinates: 13 579410E 328912IN, 2; BBRSP, UTM coordinates: 13 579859E 3292474N, 1; BBRSP, UTM coordinates: 13 583788E 3266885N, 1; BBRSP, UTM coordinates: 13 583846E 3290112N, 1; BBRSP, UTM coordinates: 13 584021E 3269813N, 2; BBRSP, UTM coordinates: 13 584964E 3273523N, 1; BBRSP, UTM coordinates: 13 586886E3265832N, 1; BBRSP, UTM coordinates: 13 586978E 3262992N, 4; BBRSP, UTM coordinates: 13 587302E 3262817N, 1; BBRSP, UTM coordinates: 13 589699E 3262276N, 3; BBRSP, UTM coordinates: 13 590643E 3262195N, 2; BBRSP, UTM coordinates: 13 592496E 3244969N, 6; BBRSP, UTM coordinates: 13 59285 8E3262597N, 3; BBRSP, UTM coordinates: 13 596255E 326205 IN, 1; BBRSP, UTM coordinates: 13 59975 IE 3261864N, 1; BBRSP, UTM coordinates: 13 600518E 3256679N, 4; BBRSP UTM coordinates: 13 601273E 3260059N, 3; BBRSP, UTM coordinates: 13 607355E 3255359N, 1; BBRSP, UTM coordinates: 13 608747E 3264582N, 1; BBRSP, UTM coordinates: 13 609405E3261495N, 1; BBRSP, UTM coordinates: 13 609611E3260698N, 1; BBRSP, UTM coordinates: 13 614094E3266037N, 1; BBRSP, UTM coordinates: 13 615504E 3263238N, 2; BBRSP UTM coordinates: 13 615747E3255837N, 4; BBRSP, UTM coordinates: 13 616984E3256548N, 2. Brewster Co.: BBRSP, UTM coordinates: 13 617281E3261484N, 1; BBRSP, UTM coordinates: 13 617505E 3256674N, 2; BBRSP, UTM coordinates: 13 619125E 3258986N, 2; BBRSP, UTM coordinates: 13 620694E 3240946N, 3. Dipodomys merriami Mearns, 1890 Merriam’s kangaroo Rat Description .— Dipodomys merriami is a large heteromyid that is buffy-brown with washed gray above, and white at the flanks and below. The face is white with dark markings. The tail is long and tufted, and the ears are short. Each hind foot of this kangaroo rat has only four toes. The dental formula for D . merriami is: i 1/1, c 0/0, p 1/1, m 3/3, total 20. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 248.0 (94, 226-279, 9.8); length of tail verte¬ brae, 144.9(94,129-165,7.5); length ofhind foot, 38.3 (112, 34-41, 1.2); length of ear from notch, 13.6(112, 11-15, 0.8); weight, 39.8 (99, 29-50, 4.5); greatest length of skull, 36.39 (20, 35.09-37.51, 0.58). Males are significantly larger than females (Best, 1993). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 107 D. merriami is similar in appearance to D. ordii, the only other kangaroo rat known from BBRSP. How¬ ever, the two can be differentiated easily on the basis of the number of toes present on each hind foot; D . merriami has four, whereas D. ordii has five. Distribution .— D. merriami ranges from central Mexico, northwestward through southwestern Texas, across the southern southwestern United States, and up into southern California and western Nevada (Schmidly et al., 1993). At BBRSP, this kangaroo rat is known from throughout most of the park, but apparently is ab¬ sent from areas along the Rio Grande (Fig. 37) Natural History. — With a relative abundance in¬ dex of 1.076, D. merriami was the second most fre¬ quently encountered rodent at BBRSP This kangaroo rat accounted for 16.2 percent of all rodents captured. It is reported as one of the most common rodents of the Trans-Pecos deserts (Schmidly, 1977a), and that un¬ doubtedly is the situation at BBRSP D. merriami is reported to be a habitat general¬ ist, but seems to prefer scrub habitats (Schmidly, 1977a). At BBRSP, this kangaroo rat was taken in all major habitat types, and trap success indicated that it did, in fact, prefer desert scrub over both grassland and ripar¬ ian habitats (P=0.006 and ^<0.001, respectively). Next to desert scrub, D. merriami preferred grassland over riparian habitats (P<0.001). In comparison to juniper roughlands, capture rates for this species were higher in both desert scrub and grassland habitats, but lower in riparian habitat. However, due to the small area of juniper roughlands, sample sizes from this habitat type were insufficient for statistical comparisons. In addi¬ tion to tolerating various vegetation-defined habitats, D. merriami also seems catholic regarding the substrate, were it resides. It is thought to succeed equally well on sand, clay, gravelly soils, and rocks. However, in places where D. merriami and D. ordii are sympatric, the former seems to restrict itself to hard, rocky, or grav¬ elly soils, whereas the latter is limited to sandy situa¬ tions (Davis and Schmidly, 1994). Even though both of these kangaroo rats are known from BBRSP, D merriami frequently was taken in both rocky and sandy situations. Apparently because D. ordii is so rare in the park (see the following account), this displacement effect has not occurred. D. merriami is not reported to enter seasonal tor¬ por (Reichman and Price, 1993). During this study, Merriam’s kangaroo rat was taken during every month, thus verifying that it is active throughout the year at BBRSP. In the Trans-Pecos, gravid females previously have been reported from August through March, with an average litter size varying from 2.3 to 2.8, depend¬ ing on the season (Schmidly, 1977a). During this study, 12 pregnant females carrying from one to three embry os (mean, 2.2) were examined from mid-April to mid-Oc¬ tober. Pregnant females (with number of embry os and corresponding crown-rump lengths in parentheses) were examined on the following dates: 11 April (2 embry os, crown-rump length, 9), 2 May (2 embryos, crown-rump length, 15), 14 May(l embry o, crown-rump length, 10), 23 May (2 embryos, crown-rump length, 10), 26 May (3 embryos, crown-rump length, 5), 22 June (2 embryos, crown-rump length, 9), 2 August (3 embryos, crown- rump length, 18), 5 August (2 embryos, crown-rump length, 20; 2 embryos, crown-rump length, 25), 11 Oc¬ tober (2 embry os, crown-rump length, 16), 12 October (2 embryos, crown-rump length, 9; 3 embry os, crown- rump length, 11). Juveniles were observed in the popu¬ lation on 11 April, 14 May, and 3 and 28 June. Sub¬ adults were noted on 11 April and 31 May Testicular measurements of adult males ranged as follows: Janu¬ ary', 11 X 6 to 12 X 6; February, 7 X 4 to 12 X 6, March, 9X5; April, 11 X 6 to 12 X 6; May, 10 X 5 to 14 X 7; June, 10 X 5 to 12 X 6; July, 9 X 5 to 12 X 6; August, 9 X 6 to 11 X 5; October, 10 X 5 to 12X6; November, 5 X 3 to 10X5; December, 7X3. These data from BBRSP, coupled with those reported by Schmidly (1977a), suggest that in the Big Bend area, D merriami breeds throughout the year. Being nocturnal, D. merriami forages at night pri¬ marily for seeds. Individuals tend to be more active throughout warm nights than on cold nights, and females are more active when pregnant (Reichman and Price, 1993) Merrianfs kangaroo rat mostly feeds on seeds, but will consume green vegetation and insects (Davis 108 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Figure 37. Localities of known specimens of Dipodomys merriami from Big Bend Ranch State Park, Texas. and Schnhdly, 1994). An individual taken at BBRSP Little is known about the molting process in D. during this study had cheek pouches full of creosote- merriami. During this study, adults undergoing sea- bush seeds. Food items most often are gathered from sonal molting were observed during all months exclud- the ground, but there is evidence to suggest that this ing April, suggesting that this species may molt more kangaroo rat occasionally may climb vegetation while than once a year, foraging (Reichman and Price, 1993). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 109 Other species of rodents taken at the same locali¬ ties as D. merriami at BBRSP included Spermophilus spilosoma , Thomomys bottae , Perognathus flavus, Chaetodipus eremicus, C. hispidus, C. intermedius , C nelsoni, Reithrodontomys fulvescens, R. megalotis , Peromyscus eremicus, P leucopus , P maniculatus , pectoralis , Onychomys are ni cola, Neotoma albigula, N. mexicana, and jV. micropus. Ectoparasites found on specimens ofZ). merriami from BBRSP included ticks and fleas. In addition, this kangaroo rat is known to be infested with several spe¬ cies of mites. The small intestine of one individual taken from BBRSP was loaded with an undetermined species of cestode. Other endoparasites reported from D. merriami include protozoans and nematodes. The pathogenic fungus Coccidioides immitis is known to infect D. merriami (Whitaker et al., 1993). Comments .— The subspecies of D. merriami at BBRSP is D. m. ambiguus Merriam, 1890. The ge¬ neric name Dipodomys is derived from the Greek “dis,” “pous,” and “mys,” which translate to twice, foot, and mouse, respectively. The specific epithet merriami re¬ fers to Merriam’s (Stangl et al., 1993). Specimens Examined BBRSP, UTM coordinates; 1; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 2; BBRSP, UTM coordinates 3; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 3; BBRSP, UTM coordinates 2; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 2; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 1; BBRSP, UTM coordinates 4; BBRSP, UTM coordinates (123).— Presidio Co.: 13 573986E 3270053N, 13 575323E3292088N, 13 576206E3268568N, 13 576311E3271128N, 13 576390E3296223N, 13 576773E3295277N, 13 576796E 3295418N, 13 576836E 329625 IN, 13 576846E3296245N, 13 57693IE3296613N, 13 576969E3296359N, 13 576970E 3296222N, 13 577066E3296038N, 13 577106E3291796N, 13 577120E 3295100N, 13 577690E 3290260N, 13 579410E 328912IN, 13 579684E 3269447N, 13 58123QE3264998N, 1; BBRSP, UTM coordinates: 13 581288E3268847N, 1; BBRSP, UTM coordinates: 13 581659E 3279903N, 1; BBRSP, UTM coordinates: 13 583096E3272189N, 1; BBRSP, UTM coordinates: 13 583205E 3282984N, 1; BBRSP, UTM coordinates: 13 583788E3266885N, 1; BBRSP, UTM coordinates: 13 583846E3290112N, 1; BBRSP, UTM coordinates: 13 584531E3266930N, 1; BBRSP, UTM coordinates: 13 584964E3273523N, 1; BBRSP, UTM coordinates: 13 585434E3286791N, 1; BBRSP, UTM coordinates: 13 595478E 3262749N, 1; BBRSP, UTM coordinates: 13 595848E 3258744N, 1; BBRSP, UTM coordinates: 13 596232E3258492N, 1; BBRSP, UTM coordinates: 13 597424E 3260494N, 1; BBRSP, UTM coordinates: 13 598125E 3260852N, l; BBRSP, UTM coordinates: 13 599495E 3261227N, 6; BBRSP, UTM coordinates: 13 599607E 3261323N, 1; BBRSP, UTM coordinates: 13 599992E 3265848N, 2; BBRSP, UTM coordinates: 13 600515E 3252408N, 1; BBRSP, UTM coordinates: 13 600634E 326370IN, 1; BBRSP, UTM coordinates: 13 600684E3259365N, 1; BBRSP, UTM coordinates: 13 600694E 325975 IN, 1; BBRSP, UTM coordinates: 13 600868E 3256344N, 7; BBRSP, UTM coordinates: 13 601154E 3260197N, 2; BBRSP, UTM coordinates: 13 601221E 3260400N, 1; BBRSP, UTM coordinates: 13 601508E 3260673N, 3; BBRSP, UTM coordinates: 13 601560E3260590N, 5; BBRSP, UTM coordinates: 13 601622E 3260685N, 1; BBRSP, UTM coordinates: 13 601973E 3253265N, 1; BBRSP, UTM coordinates: 13 6021 IE 3256243N, 2; BBRSP, UTM coordinates: 13 602666E 3260640N, 3; BBRSP, UTM coordinates: 13 605576E 3257735N, 1; BBRSP, UTM coordinates: 13 606085E 3259112N, 1; BBRSP, UTM coordinates: 13 608747E 3264582N, 2; BBRSP, UTM coordinates: 13 60961 IE 3260698N, 1; BBRSP, UTM coordinates: 13 612321E 3268161N, 3; BBRSP, UTM coordinates: 13 612683E 3265440N, 1; BBRSP, UTM coordinates: 13 614094E 3266037N, 4; BBRSP, UTM coordinates; 13 614933E32b7912N, 5; BBRSP, UTM coordinates: 13 615063E 3261184N, 1; BBRSP, UTM coordinates: 13 615371E3261358N, 2; BBRSP, UTM coordinates: 13 61595IE 3263099N, 2; BBRSP, UTM coordinates: 13 616984E 3256548N, 1; BBRSP, 0.75 mi SW Aqua Adcntro, 2 (SRSU); BBRSP, Rancherias Springs, 1 (SRSU); BBRSP, Madrid Ranch, Chorro Canyon, 15 mi. N Lajitas, 1 (SRSU); BBRSP, 15 mi NW Lajitas, 1 (SRSU) BrewsterCo. BBRSP, UTM coordinates 13 617223E 3256581N, 2; BBRSP, UTM coordinates: 13 617281E 3261484N, 4; BBRSP, UTM coordinates: 13 618185E no SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 3257611N, 2; BBRSP, UTM coordinates: 13 61908IE 3260561N, 1;BBRSP,UTM coordinates: 13 619125E 3258986N, 1; BBRSP, UTM coordinates: 13 619408E 3260416N, 1; BBRSP, UTM coordinates: 13 620927E 3238664N, 2. Dipodomys ordii Woodhouse, 1853 Ord’s Kangaroo Rat Description ,— Dipodomys ordii is a large heteromyid that is pale buff with washed gray above, and white at the flanks and below. The face is white with dark markings. The tail is long and tufted, and the ears are short. The hind feet of this kangaroo rat have five toes. The dental formula for D. ordii is: i 1/1, c 0/ 0,p 1/1, m 3/3, total 20. The external measurements of an adult specimen from BBRSP are: total length, 230; length of tail ver¬ tebrae, 138; length of hind foot, 37; length of ear from notch, 13; weight, 43.4. Garrison and Best (1990) list the mean greatest length of skull measurement for male D. ordii throughout its range as 39.4. Males are sig¬ nificantly larger than females (Garrison and Best, 1990). D. ordii closely resembles D. merriami , but can be distinguished easily as described in the account of the latter. Distribution .— D . ordii ranges from central Mexico, northward throughout much of the western United States, and into southern Alberta and Saskatchewan (Garrison and Best, 1990). At BBRSP, it is known only from a single locality in the Fresno Canyon area (Fig. 38). Natural History. —No specimens of D. ordii were acquired during this study, and this kangaroo rat is known from BBRSP on the basis of only a single speci¬ men. Therefore, D. ordii should be considered a rare inhabitant of BBRSP. Apparently, the reproductive rate of D. ordii decreases in response to prolonged drought (Schmidly, 1977a), as was the condition at BBRSP dur¬ ing the duration of this study. Reproductive activity is then thought to rebound following periods of favorable precipitation and subsequent increase in food supply (Schmidly, 1977a). Although Ord’s kangaroo rat is not common in much of the Trans-Pecos (Schmidly, 1977a), it has been reported as common in parts of Big Bend National Park (Jones et al., 1993), and I expect num¬ bers of this rodent at BBRSP to increase following the drought. The habitat type from which the specimen of D. ordii from BBRSP was taken is unknown. Of the habi¬ tat types that occur in the park, this kangaroo rat is known to occur in scrubland, grassland, and juniper- associated areas (Garrison and Best, 1990). However, it seems that the type of vegetative community in which D. ordii resides is less important than the substrate. It shows a strong preference for fine, sandy soils (Gam- son and Best, 1990), and at BBRSP is a potential in¬ habitant wherever these substrata exist. The single specimen of D. ordii known from BBRSP w r as collected in November. This kangaroo rat does not hibernate (Garrison and Best, 1990) and un¬ doubtedly is active throughout the year in the park. Most male Ord’s kangaroo rats are capable of breeding year round (Garrison and Best, 1990), but the breeding period of D. ordii in the Big Bend area appar¬ ently is restricted to August through February. Schmidly (1977a) reported that females give birth to litters of one to five young (mean, 2.75), and Alcorn (1941) sug¬ gested that more than one litter a year might be pro¬ duced. D . ordii is a nocturnal granivore, foraging at night primarily for seeds of grasses and forbs (Garrison and Best, 1990). Most seeds are gathered from the ground (Reichman and Price, 1993), but this kangaroo rat has been documented to climb a sunflower plant (Helianthus sp.) as high as one meter, clip off the flowering head, and return to the ground to feed on it (Lemen and Free¬ man, 1985). In addition to seeds, D. ordii also con¬ sumes other plant parts, as well as various arthropods (Flake, 1973). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 111 Figure 38, Localities of known specimens of Dipodomys ordii from Big Bend Ranch State Park, Texas. Nothing is known regarding annual molting in D. and nematodes. The bacteria that cause plague (Yersinia ordii. pestis) and tularemia ( Francisella tularensis ), and the rickettsia responsible for Rocky Mountain Spotted Fe¬ ver ( Rickettsia rickettsii) and Q-fcvcr ( Coxiella Ectoparasites documented to infest D. ordii in- burnetii) arc known to infect D ordii (Whitaker ct al., dude mites, ticks, sucking lice, and fleas. Internal para- 1993). sites known from D. ordii include protozoans, cestodes, 112 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Comments. — The subspecies of D. ordii that oc¬ curs at BBRSP probably is D. o. obscurus (J. A. Allen, 1903). See the account on Dipodomys merriami for the etymology of the generic name. The specific epi¬ thet ordii refers to Ord’s (Stangl et al., 1993). Specimens Examined (1).— Presidio Co.: BBRSP, 15 mi. NW fajitas, 1 (SRSU). Family Castoridae (Beavers) Castor canadensis KuhJ, 1820 American Beaver Description .— Castor canadensis is a large ro¬ dent with long, coarse dorsal pelage that is dark to red¬ dish brown in color. The hind feet of this semi-aquatic mammal are webbed, and its tail is naked, scaly, and flattened dorsoventrally. The dental formula for C. canadensis is: i 1/1, c 0/0, p 1/1, m 3/3, total 20. No measurements of C. canadensis from BBRSP were obtained. Schmidly (1977a) lists the following average external measurements for specimens from the Trans-Pecos: total length, 1070; length of tail verte¬ brae, 400; length of hind foot, 174; weight, 20 kg. Jenkins and Busher (1979) list the range for ear length and greatest length of skull measurements for the spe¬ cies in general as 23 to 29, and 121 to 146, respec¬ tively. C. canadensis is not sexually dimorphic (Jenkins and Busher, 1979). C. canadensis is distinguished easily from all other mammals that occur at BBRSP on the basis of its size, webbed hind feet, unique tail, and aquatic habits. Distribution.- — The range of C canadensis ex¬ tends from northern Mexico, northward throughout most of North America (Jenkins and Busher, 1979). There are no specimens from BBRSP, however beavers have been observed at sites along the Rio Grande, including Arenosa (this study), Colorado Canyon (Scudday, 1976c), and the Lajitas area (Schmidly, 1977a). Natural History. — No beavers were collected during this study, and only a single individual was ob¬ served. However, both Scudday (1976c) and Schmidly (1977a) suggest that this rodent is rather common at some places in the Big Bend area. At BBRSP, the beaver is restricted to water-asso¬ ciated habitats along the Rio Grande. Vegetation in these areas typically consists of salt cedar, giant reed, tree tobacco, mesquite, willow, and various grasses. Somewhat uncharacteristic of beavers, the subspecies of C. canadensis that occurs at BBRSP does not build elaborate dams. Instead, it digs burrows into the banks of the Rio Grande at about the level of the water (Schmidly, 1977a). The single beaver observed during this study was sighted in December. C. canadensis does not hiber¬ nate, and should be considered active throughout the year at BBRSP. Little is known regarding the reproductive biol¬ ogy of beavers in the Big Bend area. Juveniles that appeared to be a few weeks old have been sighted as early as March (Schmidly, 1977a). Given a gestation period of about 107 days (Wilsson, 1971), these indi¬ viduals probably were conceived in October or Novem¬ ber. C. canadensis in general usually breeds in Janu¬ ary or February, with parturition occurring in May or June. However, this species has been documented to breed as late as November. Females give birth usually to three or four young once a year (Jenkins and Busher, 1979). C. canadensis mainly is crepuscular and noctur¬ nal, but may be active during the day as well (Jones and Birney, 1988). It is an obligate vegetarian , feed¬ ing on the lea ves, twigs, and bark of a variety of plants (Jenkins and Busher, 1979). Along the Rio Grande, beavers seem to prefer willow, although desert willow, mesquite, and tree tobacco also are consumed (Schmidly, 1977a). The digestion of these woody materials is en¬ hanced by a prominent cardiogastric gland in the stom¬ ach, glandular digestive areas elsewhere, and a large YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 113 cecum containing cellulose-degrading microbes (Hill, 1982). No data regarding the process of seasonal molt¬ ing are available. Ectoparasites known from C. canadensis include ticks. Endoparasites of beavers include protozoans, trematodes, and nematodes. Epidemics of tularemia due to infection with the bacterium Francisella tularensis have been documented in beavers (Jenkins and Busher, 1979). Comments .— The subspecies of C. canadensis at BBRSP is C. c. mexicanus Bailey, 1913. The ge¬ neric name Castor is derived from the Greek “kastor,” which translates to beaver. The specific epithet canadensis refers to of Canada (Stangl et al., 1993). Specimens Examined (0). Family Muridae (Mice and Rats) Reithrodontomys fulvescens J. A. Allen, 1894 Fulvous Harvest Mouse Description .— Reithrodontomys fulvescens is a small mouse with a dorsal pelage that is ochraceous buff washed with dark brown above, and golden buff on the sides. The tail of this mouse is longer than the head and body, scaly, and not bicolored The ears are short, each with reddish-orange hairs on the inside, As in all members of the genus, the anterior surface of each upper incisor is grooved. The dental formula for R. fulvescens is: i 1 / 1 , c 0/0, p 0/0, nt 3/3, total 16. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP arc: total length, 159.3 (8, 147-178, 10.7); length of tail verte¬ brae, 91.0 (8, 86-98,3.9); length of hind foot, 19.0 (8, 18-20, 7.6); length of ear from notch, 13.8 (8, 12-16, 12); weight, 10.2 (7, 8.0-12, 1.3); greatest length of skull, 21.21 (8, 20.62-21.83, 0.43). I know of no re¬ ports pertaining to secondary sexual dimorphism in the fulvous harvest mouse. R. fulvescens can be confused easily with R megalotis. The two, however, can be separated on the basis of color, tail characteristics, and dentition. R. fulvescens has bright, fulvous coloration on the sides; the tail is relatively naked and scaly, not bicolored, and much longer than the head and body; and the last lower molar typically has an S-shaped dentine. In contrast, R. megalotis is buffy brown on the sides; the tail is cov¬ ered with short hairs, indistinctly bicolored, and about the same length or shorter than the head and body, and the last lower molar has C-shapcd dentine. R. fulvescens is distinguished easily from all other murids at the park, by the grooved upper incisors. Distribution .— R. fulvescens ranges from Cen¬ tral America, northward throughout most of Mexico, and into parts of the southwestern and south-central United States (Spencer and Cameron, 1982). At BBRSP, it is known from the Las Qucvas and Sauceda areas, as well as front the Solitario (Fig. 39). Speci¬ mens taken from Las Qucvas define the southwestern limits of the range of this species in the Trans-Pecos. Natural History .— The relative abundance index of R. fulvescens at BBRSP was 0.065. This harvest mouse accounted for 1.0 percent of all rodents taken. These data indicate that R. fulvescens is uncommon at BBRSP The park is situated near the western limits of the distribution of this species in the Trans-Pecos (Schmidly, 1977a), which may account for its rarity. R. fulvescens has been documented to favor rough grasslands often associated w ith shrubs (Hooper, 1952; Packard, 1968; Schmidly, 1977a). However, at BBRSP, this species was taken only in riparian habitat domi¬ nated by willow, cottonwood, false willow; and deer grass, and in desert scrub dominated by mcsquitc. Of these two habitats, R fulvescens significantly favored the riparian woodland over desert scrub (/ > =0 001) Blair (1940) trapped fulvous harvest mice in mesquite- associalcd habitat, but 1 know of no previous report of this species having an affinity for riparian woodlands. 114 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY i_ i _—i kilometers Figure 39. Localities of known specimens of Reithrodontomys fulvescens from Big Bend Ranch State Park, Texas. During this study, R. fulvescens was taken only during January, February, and November. However, this harvest mouse is not known to enter seasonal tor¬ por (Davis and Schmidly, 1994) and is assumed to be active throughout the year at BBRSP. Virtually nothing is known of the reproductive habits of R. fulvescens in the Big Bend area. In Texas in general, this harvest mouse reportedly breeds from February through October (Davis and Schmidly, 1994). I examined a single gravid female (3 embryos, crown- rump length, 14) on 10 November. Testicular measure¬ ments of males taken on 13 February and 10 November were 4X2 and 10X5, respectively. Given a gestation period of about 21 days (Davis and Schmidly, 1994), these data suggest that the breeding period in BBRSP may extend well into November (Yancey et al., 1995). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 115 Litter sizes are known to range from two to six (mean, 3-4; Spencer and Cameron, 1982; Davis and Schmidly, 1994). Females may produce two or more litters a year (Packard, 1968). R. fulvescens is strictly nocturnal at which time it forages for a variety of foods. Seeds and invertebrates seem to constitute the majority of the diet. Fulvous har¬ vest mice are known to forage on the ground as well as up to one meter high in vegetation (Spencer and Cameron, 1982), Little has been documented on the molting pro¬ cess of adult fulvous harvest mice. During this study, adults undergoing seasonal molting were noted on 10 and 17 November. Hooper (1952) reported evidence of at least one and perhaps two annual molts. Other species of rodents taken at the same locali¬ ties as R. fidvescens at BBRSP included Chaetodipus eremicus, C. nelsoni , Dipodomys merriami , Reithrodontomys megalotis, Peromyscus leucopus , P. maniculatus, P. pectoralis, Sigmodon hispidus , and S. ochrognathus . The sympatric and syntopic occurrence of R. fulvescens and R. megalotis is an interesting situ¬ ation. Such a close ecological association of these two species of harvest mice has not been documented else¬ where in the Big Bend area (Yancey et al., 1995). No parasites were observed in association with fulvous harvest mice taken at BBRSP. The only para¬ sites previously reported from this mouse are fleas (Spencer and Cameron, 1982). Comments. — The subspecies of R. fulvescens at BBRSP is R.f canus Benson, 1939. The generic name Reithrodontomys is derived from the Greek “rheithron,” “©dous,” and ‘"mys,” which translate to stream or chan¬ nel, tooth, and mouse, respectively. The specific epi¬ thet fulvescens is from the Latin “fulvus,” meaning brown (Stangl ct al., 1993). Specimens Examined (8).— Presidio Co.: BBRSP, UTM coordinates: 13 586937E 3262923N, 1; BBRSP, UTM coordinates: 13 587250E 3262918N, 5; BBRSP, UTM coordinates: 13 601619E 3260741N, 1; BBRSP. Brewster Co.: BBRSP, UTM coordinates: 13 617281E 3261418N, 1. Reithrodontomys megalotis (Baird, 1858) Western Harvest Mouse Description .— Reithrodontomys megalotis is a small mouse with a pale brown dorsal pelage. The tail is moderate in length (about as long as the head and body), covered with short hairs, and indistinctly bicol¬ ored, and the ears are short. The anterior surface of each upper incisor is grooved. The dental formula for /?. megalotis is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 137.4 (11, 125-152, 10.1); length of tail verte¬ brae, 71.0 (11, 64-79, 4.6); length of hind foot, 17.5 (11,16-18,4.6); length of ear from notch, 13.7 (11, 12- 15, 0.7); weight, 8.3 (10, 6.5-10, 1.3); greatest length of skull, 20.18 (11, 19.65-20.99, 0.42). There is no evidence of significant sexual dimorphism among west¬ ern harvest mice (Jones and Mursaloglu, 1961). R. megalotis is similar in appearance to R. fulvescens, but the two can be distinguished as described in the previous account. R. megalotis is differentiated from all other murids at BBRSP by the grooved upper incisors. Distribution. —The range of R megalotis extends from southern Mexico, northward throughout the west¬ ern and north-central United States (Webster and Jones, 1982). At BBRSP, this mouse is known from the Cienega, Las Qucvas, and Sauccda areas, as well as from the Bofccillos Mountains (Fig. 40). Natural History. — The relative abundance index of R megalotis at BBRSP was determined to be 0.089. It comprised 1.3 percent of all rodents trapped, and there¬ fore, should be regarded as uncommon in the park. This harvest mouse was reported as rather sporadic in north¬ ern Big Bend National Park (Jones ct al., 1993). 116 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Figure 40, Localities of known specimens of Reithrodontomys megalotis from Big Bend Ranch State Park, Texas. R. megabits is reported to favor grassland and versus riparian; P=0.31 for desert grassland versus ri- riparian situations (Webster and Jones, 1982), as well parian). as desert scrub (Jones et al., 1993). At BBRSP, this harvest mouse was acquired from all three of these habi¬ tats. There was a significant difference noted among R. megabits is known to hibernate in some parts trap success in the three habitats when examined col- of its range (Webster and Jones, 1982). However, this lectively (P=0.043). However their were no differences is not the situation at BBRSP as this mouse was taken detected between any two habitats (P= 0.37 for desert dining each season of the year, scrub versus desert grassland; P^0.029 for desert scrub YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 117 Most breeding activity of western harvest mice occurs from early spring to late fall (Webster and Jones, 1982), but in the Trans-Pecos, mating may occur throughout the year (Schmidly, 1977a). Throughout its range, litter sizes vary from one to nine (Long, 1962), but in the Trans-Pecos, reported extremes are two and five (mean, 3.8). Multiple litters are produced each year (Schmidly, 1977a). During this study, a gravid female was observed on 1 April (3 embryos, crown- rump length, 8). Testicular measurements of adult males ranged as follows: January, 5X3; February, 3 X 2 to 6 X4; July, 8 X 5. R. megalotis is a nocturnal granivore. It forages primarily for seeds, but also will consume other plant material and insects (Webster and Jones, 1982). Two annual molts are reported to occur in west¬ ern harvest mice, one in spring, the other in autumn (Jones and Mursaloglu, 1961). During this study, molt¬ ing adults were taken on 3 and 14 February, and 26 November, indicating that, at BBRSP, the first molt of the year begins in late winter, rather than spring. Other species of rodents taken at the same locali¬ ties as R. megalotis at BBRSP included Perognaihus jlavus, Chaetodipus eremicus , C. hispidus , Dipodomys merriami , Reithrodontomys fulvescens , Peromyscus eremicus , P leucopus , P maniculatus, P pectoralis , Onychomys arenicola , Sigmodon hispidus , S. ochrognathus , and Neotoma micropus. See the previ¬ ous account for a discussion on the sympatry of R. megalotis and R. fulvescens. Ticks and fleas were observed infesting R. megalotis at BBRSP. Additional ectoparasites known from this mouse include numerous species of mites. Endoparasites previously reported from R megalotis include protozoans, cestodes, and nematodes (Webster and Jones, 1982). R. megalotis has been shown to har¬ bor hantavirus (Childs et al., 1995). Comments. — The subspecies of R. megalotis at BBRSP is R. m . megalotis (Baird, 1858). See the ac¬ count on Reithrodontomys fulvescens for the etymol¬ ogy of the generic name. The specific epithet megalotis is from the Greek “megas” and “ous,” meaning big and ear, respectively (Stangl et al., 1993). Specimens Examined (11).— Presidio Co.: BBRSP, UTM coordinates: 13 576836E 329625 IN, 1; BBRSP, UTM coordinates: 13 576970E3296222N, 1; BBRSP, UTM coordinates: 13 587250E3262918N, 2; BBRSP, UTM coordinates: 13 595150E 3252057N, 1; BBRSP, UTM coordinates: 13 600694E 325975 IN, 1; BBRSP, UTM coordinates: 13 601619E 326074IN, 2; BBRSP, UTM coordinates: 13 6G1973E 3253265N, i; BBRSP, UTM coordinates: 13 605746E 3261330N, 2 . Peromyscus boy Hi (Baird, 1855) Brush Mouse Description .— Peromyscus boylii is a medium¬ sized mouse with a pale to moderately brown dorsal pelage. The tail of this mouse is longer than the head and body, heavily haired, indistinctly bicolored, and tufted at the tip. The ears are intermediate in length. The ankles are dusky gray, and the soles of the hind feet are furred at the heels. The dental formula for P boylii is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. No measurements of P boylii from BBRSP were obtained. Comely etal. (1981) list the following means of external and cranial measurements (with sample size, extremes, and 95% confidence interv al in parentheses) of adult specimens taken elsew here in the Trans-Pecos: total length, 194.0 (6, 183-201, 187 9-200 1); length of tail vertebrae, 100.5 (6, 82-108,92.6-108.4); length of hind foot, 21.2 (6, 19-22, 20.2-22.1); length of car from notch, 19.5 (6, 18-22, 18 2-20.8); greatest length of skull, 27.62 (6,27.15-28.00,27.36-27.88). Weights of the brush mouse range from 22-36 (Davis and SchmidIv, 1994). I know of no reports of marked sec¬ ondary sexual dimorphism in P boylii. P boylii is confused most easily with the other long-tailed Peromyscus at BBRSP, P eremicus and P pectoralis. P. boylii can be distinguished from P 118 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY eremicus by the densely haired and tufted tail, and haired heels, as opposed to the sparsely haired and nontufted tail, and naked heels of P. eremicus. In addition, there are three pairs of mammae in female P. boylii , whereas there are only two in female P. eremicus (the pectoral mammae are lacking). In male P. boylii , the glans pe¬ nis is elongate and rod-shaped, whereas it is vase-shaped in P. eremicus. Furthermore, cranial morphology can be used to easily distinguish these two species. In P. boylii , the posterior ends of the premaxillae terminate at about the level of the nasals, whereas they extend well beyond the nasals in P. eremicus. P. boylii can be distinguished from P pectoralis by its densely haired and tufted tail, rather than sparsely haired and nontufted, and by its dusky-colored, rather than white, ankles. In males, baculum morphology' can be used to easily sepa¬ rate these two species. The cartilaginous tip of the bacu¬ lum of P boylii is short and blunt, whereas it is long and pointed in P. pectoralis. In addition, cranial mor¬ phology varies between these two species. In P boylii , the posterior ends of the nasals terminate in a V-shape, whereas they arc relatively blunt in P. pectoralis. P. boylii is differentiated easily from the other species of Peromyscus at BBRSP by having a tail that is longer than the head and body. Distribution .— P boylii ranges from Central America, northward throughout much of Mexico and across the southwestern United States (Hall, 1981). At BBRSP, this mouse is known only from one locality along the Rio Grande (Fig. 41). Natural History. —No specimens of P boylii were acquired during this study. Scudday (1976c) reported this mouse as fairly common along the Rio Grande in Colorado Canyon. However, I examined these speci¬ mens, and all appeared to be either P. eremicus or R pectoralis. Only a single verified specimen of the brush mouse taken in 1966 exists from BBRSP. Based on this information, P boylii should be considered among the rarest of rodents at BBRSP. The specimen of/ 5 boylii taken from BBRSP was acquired from a rocky hillside above the Rio Grande. This mouse is reported to favor rocky, montane areas with oak, pinion, juniper, and brush (Borcll and Bryant, 1942, Schmidly, 1977a). In Big Bend National park, it is most common above 1800 m (Schmidly, 1977a), The lack of this type of habitat from BBRSP probably ac¬ counts for its scarcity there. The specimen of R boylii from BBRSP was taken in May. This mouse does not enter seasonal torpor and is active throughout the year (Davis and Schmidly, 1994). No reproductive data are available for P. boylii from BBRSP, Elsewhere in the Trans-Pecos, the breed¬ ing period of brush mice is thought to extend from March through August (Comely et al., 1981). Females give birth to litters of three to five (mean, 4) young, prob¬ ably two or more times a year (Schmidly, 1977a). P boylii is active at night, during which time it forages primarily for plant material. Hackberries, ju¬ niper berries, cactus fruits, and acoms are among its favorite foods (Schmidly, 1977a). Little is known of the molting process in P boylii. Comely et al. (1981) observed adult brush mice molt¬ ing in June and August. Ectoparasites known from P. boylii include mites, ticks, lice, fleas, and botfly larvae. Endoparasites re¬ ported from brush mice include cestodes and nematodes (Whitaker, 1968). P. boylii has been implicated as a carrier of pulmonary' syndrome hantavirus (Stone, 1993). Comments .— The subspecies of P. boylii at BBRSP is P b , rowleyi (J. A, Allen, 1893). The ge¬ neric name Peromyscus is derived from the Greek “pera” and “myskos,” which translate to pouch, and little mouse, respectively. The specific epithet boylii refers to Boyle’s (Stangl et al., 1993). Specimens Examined (1),— Presidio Co.: BBRSP, 12 mi. S Redford, 1 (SRSU). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 119 KILOMETERS Figure 41. Localities of known specimens of Peromyscus boylii from Big Bend Ranch State Park, Texas, Peromyscus eremicus (Baird, 1858) Cactus Mouse Description .— Peromyscus eremicus is a me¬ dium-sized mouse with an ochraceous buff dorsal pel- age, but the head often is grayish. The tail is longer than the head and body, scantly haired, and not sharply bicolored, but the top may appear slightly darker than the bottom. The ears are short to intermediate in length. The ankles are dusky gray, and the soles of the hind feet are naked at the heels. The dental formula for P eremicus is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total no SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY length, 184.7 (79, 165-201, 7.7); length of tail verte¬ brae, 96.5 (79, 86-115, 4.7); length of hind foot, 20.0 (84, 19-21, 0.5); length of ear from notch, 18.3 (84, 17-20, 0.7); weight, 18.0 (74, 13-24, 2.3); greatest length of skull, 25.01 (20,23.60-26.42,0.73). Females tend to be larger than males (Veal and Caire, 1979). Of the other mammals at BBRSP, P. eremicus is mistaken most often for the other species of long-tailed Peromyscus. It can be differentiated from P boylii as described in the account on that species. It can be dis¬ tinguished from P. pectoralis on the basis of its naked, rather than haired heel; its dusky, rather than white ankles; and by having premaxillae that extend posteri¬ orly well beyond the posterior ends of the nasals, rather than premaxillae that terminate at about the level of the nasals. In addition, the glans penis of male P eremicus is vase-shaped, rather than elongate and rod-shaped, as in P pectoralis. P. eremicus is distinguished from the other species of Peromyscus at BBRSP by having a tail that is longer than the head and body. Distribution — P eremicus ranges from north- central Mexico, northward throughout the southwest¬ ern United States and Baja California (Veal and Caire, 1979). At BBRSP, this mouse is known from several localities throughout the park (Fig. 42). Natural History. — With a relative abundance in¬ dex of 0.922, P. eremicus was the third most frequently trapped rodent at BBRSP. It accounted for 13.9 per¬ cent of all rodents captured in the park. These figures indicate that the cactus mouse is abundant at BBRSP. Throughout the Trans-Pecos, this mouse has been re¬ ported as common at lower elevations and rare in mon¬ tane areas (Schmidly, 1977a). The cactus mouse is known to occur in several vegetation associations, including desert scrub, grassy areas, riparian habitat, and among juniper (Schmidly, 1977a; Veal and Caire, 1979). At BBRSP, this mouse was taken in each of these situations. Desert scrub and desert grassland were significantly favored over ripar¬ ian areas (P<0.OO1 and P=0.001, respectively). There was no preference shown between the former two habi¬ tats (P=0.587). In comparison to juniper roughlands, capture rates for this species were higher in both desert scrub and grassland habitats, but lower in riparian habi¬ tat. But because of the small amount of juniper roughlands at BBRSP, a sample size adequate for sta¬ tistical analyses was not obtained. P eremicus has been reported as a soil generalist, inhabiting rocky, sandy, and loamy situations (Veal and Caire, 1979). At BBRSP, this mouse was taken from all three of these general substrata, but seemed to prefer rocky areas. P. eremicus also w'as taken commonly in association with man-made structures, P. eremicus has been reported to estivate during summer as a means to conserve water and food (MacMiilen, 1964; 1965). During this study, P. eremicus w'as taken during every month of the year, thus indicating that this mouse does not invariably en¬ ter prolonged summer torpor at BBRSP However, trends in trap success of this mouse indicate that it is much less active during the summer months than other times of the year. Davis and Schmidly (1994) reported the breed¬ ing season of P. eremicus to last at least from January through October, and possibly throughout the year. Two or more litters of one to four young are bom per year. During this study, I examined 11 pregnant females car¬ rying from one to three embryos (mean, 2.2) from early- February to late November. Pregnant females (with number of embryos and corresponding crown-rump lengths in parentheses) were examined on the follow¬ ing dates: 1 February' (3 embryos, crown-rump length, 23), 5 February (1 embryo, crown-rump length, 17), 5 February (2 embryos, crown-rump length, 4), 28 Feb¬ ruary (2 embryos, crown-rump length, 6), 15 March (2 embryos, crown-rump length, 10), 2 April (2 embryos, crown-rump length, 18), 1 May (2 embryos, crown-rump length, 12), 4 May (3 embryos, crown-rump length, 23), 13 July (3 embryos, crown-rump length, 8), 9 Novem¬ ber (2 embryos, crown-rump length, 5), and 28 Novem¬ ber (2 embryos, crown-rump length, 4). Lactating fe¬ males were examined on 1 and 26 February, 16 and 18 March, 1 and 2 May, 4 and 13 September, and 28 Octo¬ ber. Juveniles were observed in the population on 1 February, 1, 4, 27, and 31 May, 3 July, 25 November, and 8 December. Subadults were noted on 1 February, YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 121 Figure 42. Localities of known specimens of Peromyscus eremicus from Big Bend Ranch State Park, Texas. 1,2, and 26 May, 10 and 28 June, 13 and 18 July, 9 and P. eremicus is nocturnal and mostly feeds on the 16 November, and 1, 2, 5, and 7 December. Testicular seeds of desert annuals Other parts of plants, as well measurements of adult males ranged as follows: Janu- as insects, also are consumed (Veal and Cairc, 1979) ary, 6 X 3 to 7 X 4; February, 5 X 3 to 10 X 7; March, This mouse is scansorial to some extent, and has been 10 X 6 to 11 X 6; May, 9 X 5 to 9 X 6; June, 10 X 6 to known to forage up to two meters high in mcsquitc trees 12 X 5; July, 9X5; November, 4 X 2 to 12 X 6; De- (Davis and Schmidly, 1994). Cactus mice apparently cember, 4 X 2 to 11 X 7. These data strongly support arc prone to food hoarding (Barrs', 1976) the notion of a year round breeding season at BBRSP. 122 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Nothing previously has been reported regarding annual molt in P eremicus. During this study, I exam¬ ined adults in the process of molting during all months of the year, except April. These data suggest that R eremicus may undergo two annual molts. Other species of rodents taken at the same locali¬ ties as P. eremicus at BBRSP included Perognathus Jlavus, Chaetodipus eremicus, C. hispidus, C. inter- medius , C. nelsoni , Dipodomys merriami, Reiihrodontomys megalotis , Peromyscus leucopus , P maniculatus , P. pectoralis , Onychomys arenicola , Neotoma albigula , N. mexicanci, and N. micropus. Ectoparasites taken from P. eremicus at BBRSP include mites, ticks, and botfly larvae. Additional ex¬ ternal parasites known from cactus mice are several spe¬ cies of fleas and lice. Endoparasites documented from P, eremicus include nematodes (Veal and Caire, 1979). Comments .— The subspecies of P. eremicus at BBRSP is P. e. eremicus (Baird, 1858). Sec the ac¬ count on Peromyscus boylii for the etymology of the generic name. The specific epithet eremicus is from the Greek “eremikos,” meaning solitary (Stangl et ah, 1993). Specimens Examined (130).— Presidio Co.: BBRSP, UTM coordinates: 13 575323E 3292088N, 1; BBRSP, UTM coordinates: 13 576564E 3295022N, 2; BBRSP, UTM coordinates: 13 576721E 3296287N, 3; BBRSP, UTM coordinates: 13 576760E 3295806N, 1; BBRSP, UTM coordinates: 13 576808E 3295784N, 1; BBRSP, UTM coordinates: 13 576836E 329625IN, 2; BBRSP, UTM coordinates: 13 576842E 3296279N, 1; BBRSP, UTM coordinates: 13 576846E 3296245N, 2; BBRSP, UTM coordinates: 13 576931E3296613N, 3; BBRSP, UTM coordinates: 13 576970E3296222N, 3; BBRSP, UTM coordinates: 13 577066E 3296038N, 6; BBRSP, UTM coordinates: 13 577192E3295041N, 1; BBRSP, UTM coordinates: 13 577436E3293201N, 1; BBRSP, UTM coordinates: 13 577526E 3287386N, 1; BBRSP, UTM coordinates: 13 578146E 3288978N, 1; BBRSP, UTM coordinates: 13 581230E 3264998N, 1; BBRSP, UTM coordinates: 13 582656E 3265713N, 1; BBRSP, UTM coordinates: 13 584531E 3266930N, 1; BBRSP, UTM coordinates: 13 588746E 3247263N, 1; BBRSP, UTM coordinates: 13 589348E 3246503N, 11; BBRSP, UTM coordinates: 13 59185 IE 3245491N, 4; BBRSP, UTM coordinates: 13 592496E 3244969N, 4; BBRSP, UTM coordinates: 13 595478E 3262749N, 1; BBRSP, UTM coordinates: 13 595848E3258744N, 3; BBRSP, UTM coordinates: 13 596255E 326205 IN, 2; BBRSP, UTM coordinates: 13 597424E 3260494N, 8; BBRSP, UTM coordinates: 13 597543E 3261182N, 2; BBRSP, UTM coordinates: 13 598125E 3260852N, 1; BBRSP, UTM coordinates: 13 599495E3261227N, 4; BBRSP, UTM coordinates: 13 599992E 3265848N, 2; BBRSP, UTM coordinates: 13 600515E3252408N, 6; BBRSP, UTM coordinates: 13 600634E 3263701N, 1; BBRSP, UTM coordinates: 13 600694E 325975 IN, 1; BBRSP, UTM coordinates: 13 60103 IE 3260217N, 6; BBRSP, UTM coordinates: 13 601059E3260130N, 2; BBRSP, UTM coordinates: 13 601154E3260197N, 2; BBRSP, UTM coordinates: 13 601335E3260787N, 1; BBRSP’ UTM coordinates: 13 601560E 3260590N, 3; BBRSP, UTM coordinates: 13 601622E3260685N, 1; BBRSP, UTM coordinates: 13 601973E3253265N, 1; BBRSP, UTM coordinates: 13 602211E3256243N, 2; BBRSP, UTM coordinates: 13 602487E3241236N, 1; BBRSP, UTM coordinates: 13 603273E3263098N, 1; BBRSP, UTM coordinates: 13 614094E 3266037N, 2; BBRSP, UTM coordinates: 13 615033E3263895N, 1; BBRSP, UTM coordinates: 13 615063E 3261184N, 1; BBRSP, UTM coordinates: 13 615747E3255837N, 1; BBRSP, UTM coordinates: 13 61595 IE 3263099N, 1; BBRSP, UTM coordinates: 13 616012E 3263115N, 2; BBRSP, Colorado Canyon, 6 (SRSU); BBRSP, 0.75 mi. SW Aqua Adentro, 5 (SRSU); BBRSP, Chorro Can¬ yon, 1 (SRSU); BBRSP, 15 mi. NW Lajitas, 4 (SRSU); BBRSP, Arroyo Primero, 1 (SRSU). Brewster Co.: BBRSP, UTM coordinates: 13 618185E 3257611N, 2 . Peromyscus leucopus (Rafinesque, 1818) White-footed Mouse Description .— Peromyscus leucopus is a me¬ dium-sized mouse with a pale brown dorsal pelage that often is mixed with grayish. The tail of this mouse is relatively short (shorter than head and body), lightly haired, and indistinctly bicolored, and its ears are short. The dental formula for P. leucopus is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 123 Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 175.4 (46 160-190, 7.6); length of tail verte¬ brae, 80.6 (46, 71-91, 4.8); length of hind foot, 21.6 (47, 21-23, 0.6); length of ear from notch, 16.9 (47, 15-19, 0.7); weight, 21.2 (41, 17-26, 2.3); greatest length of skull, 26.83 (20, 25.42-27.88, 0.60). I know of no documentation of significant secondary sexua l di¬ morphism in P leucopus. At BBRSP, P. leucopus is distinguished from P maniculatus only with great difficulty, Typically, the tail of P. leucopus is bicolored, but not distinctly so, whereas it usually is distinctly bicolored in P. maniculatus. In addition, P. leucopus typically has a larger total length (mean, 175.4) and a longer tail (mean, 80.6), and greater length of skull (mean, 26.83), than those of P. maniculatus (means, 159.3,73.5, and 25.61, respectively). P leucopus is distinguished easily from other Peromyscus at BBRSP by having a tail that is shorter than its head and body. Distribution .— P leucopus ranges from eastern and north-central Mexico, northward throughout the eastern two thirds of the United States and parts of south¬ ern Canada (Carleton, 1989). At BBRSP, P leucopus is known from scattered localities throughout the park (Fig. 43). Natural History .— P. leucopus was found to have a relative abundance index of 0.574. It accounted for 8.7 percent of all rodents trapped at BBRSP, and ranked eighth among rodents. These figures, which suggest that P. leucopus is neither abundant nor rare at BBRSP, are somewhat misleading. This mouse was found to be fairly abundant in areas of suitable habitat and rare or absent from unpreferred habitat. Schmidly (1977a) reported P leucopus as com¬ mon in riparian woodlands, and lacking from desert situ¬ ations in the Trans-Pecos region. At BBRSP, I collected white-footed mice from riparian woodland, as well as from desert scrub and desert grassland This mouse did, in fact, show a significant preference for riparian woodland over both desert scrub (/^O.GOl) and desert grassland (PO.QQl). Moreover, it was the most fre¬ quently trapped rodent in riparian woodland. There was no significant difference noted between desert scrub and desert grassland affinities (P=0.024). P. leucopus is known to be active throughout the year (Jones et ah, 1985). At BBRSP this mouse was taken during every month of the year. In some parts of its range, P. leucopus is known to breed throughout the year (Choate et al., 1994; Davis and Schmidly, 1994), whereas at other places it repro¬ duces only during the warmer months (Jones et al., 1985). Gravid females previously' have been recorded from the Trans-Pecos only during March, April, June, and August (Schmidly, 1977a). At BBRSP, 1 exam¬ ined 7 pregnant females carrying from three to four embryos (mean, 3.7) on the following dates (with num¬ ber of embryos and corresponding crown-rump lengths in parentheses): 9 January (4 embryos, crown-rump length, 17), 18 March (4 embryos, crown-rump length, 2), 1 April (3 embryos, crown-rump length, 16), 7 July (4 embryos, crown-rump length, 11; 4 embryos, crown- rump length, 15), 8 July (3 embryos, crown-rump length, 9), and 10 December (4 embryos, crown-rump length, 6). A lactating female was noted on 27 July. Juveniles were observed in the population on 9 January', 3 and 4 April, 7 July, and 13 and 18 September. Subadults were taken on 15 March, 2 April, 17, 18, and 27 July, 24 August, 19 September, 13 October, 27 November, and 8 and 10 December. Testicular measurements of adult males ranged as follows: January, 8 X 5 to 13 X 8; February, 10 X 5; March, 6 X 4 to 20 X 10, April, 10 X 4 to 20 X 10; July, 13 X 7; September, 13 X 7, No¬ vember, 10X6; December, 9X5. These data indicate that P leucopus breeds year round at BBRSP, and that females probably bear multiple litters each year. P leucopus mostly is nocturnal, at which time it forages primarily for seeds, mesquite beans, berries, fruits, nuts, and insects (Schmidly, 1977a; Jones ct al , 1985). In addition, carrion sometimes is consumed A considerable amount of the foraging activities of the white-footed mouse occurs in brushy vegetation (Jones et al., 1985). 124 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY -L_ - _J KILOMETERS Figure 43. Localities of known specimens of Peromyscus leucopus from Big Bend Ranch State Park, Texas. Adult white-footed mice reportedly undergo a single annual molt beginning in spring or early summer (Choate et al., 1994). I examined molting adults dur¬ ing January, July, and November. This suggests that at BBRSP, P leucopus may molt twice a year or at vari¬ ous times during the year Other species of rodents taken at the same locali¬ ties as P leucopus at BBRSP included Perognathus Jlavus, Chaelodipus eremicus, C. hispidus , C. nelsoni , Dipodomys merriami , Reithrodontomys fulvescens, R. mega lot is, Peromyscus eremicus, P maniculatus , P pectoralis , Sigmodon hispidus , and S. ochrognathus. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 125 Fleas were the only parasites noted in association with specimens of P leucopus from BBRSP. Additional external parasites known from white-footed mice in¬ clude mites, ticks, lice, and botfly larvae. Endopara- sites known from P. leucopus include trematodes, ces- todes, and nematodes (Whitaker, 1968). The white- footed mouse has been implicated as the primary reser¬ voir for the bacterium Borrelia burgdorferi , the etio- logic agent of Lyme disease (Benach et ah, 1990). Comments .— The subspecies of P leucopus at BBRSP is P l. tornillo Meams, 1896. See the account on Peromyscus boylii for the etymology of the generic name. The specific epithet leucopus is from the Greek “leukos” and “pous,” meaning white and foot, respec¬ tively (Stangl et al., 1993). Specimens Examined (69).— Presidio Co. : BBRSP, UTM coordinates: 13 576390E 3296223N, 1; BBRSP, UTM coordinates: 13 576708E 3296384N, 1; BBRSP, UTM coordinates: 13 576760E3295806N, 2; BBRSP, UTM coordinates: 13 576785E3296105N, 2; BBRSP, UTM coordinates: 13 576790E 329621 IN, 2; BBRSP, UTM coordinates: 13 576804E 3296151N, 5; BBRSP, UTM coordinates: 13 576836E 329625 IN, 8; BBRSP, UTM coordinates: 13 576842E 3296279N, 1; BBRSP, UTM coordinates: 13 576846E 3296245N, 1; BBRSP, UTM coordinates: 13 577099E 3296389N, 1; BBRSP, UTM coordinates: 13 577472E 3287353N, 1; BBRSP, UTM coordinates: 13 577589E3287154N, 4; BBRSP, UTM coordinates: 13 586809E3262961N, 2; BBRSP, UTM coordinates: 13 586937E 3262923N, 4; BBRSP, UTM coordinates: 13 587250E 3262918N, 5; BBRSP, UTM coordinates: 13 590728E 3245948N, 2; BBRSP, UTM coordinates: 13 590980E 3262597N, 5; BBRSP, UTM coordinates: 13 595150E 3252057N, 3; BBRSP, UTM coordinates: 13 600914E 3260458N, 2; BBRSP, UTM coordinates: 13 601031E 3260217N, 2; BBRSP, UTM coordinates: 13 60I221E 3260400N, 1; BBRSP, UTM coordinates: 13 601335E 3260787N, 1; BBRSP, UTM coordinates: 13 601619E 3260741N, 3; BBRSP, UTM coordinates: 13 607355E 3255359N, 1; BBRSP, UTM coordinates: 13 608309E 3239482N, 4; BBRSP, UTM coordinates: 13 614935E 3268144N, 2; BBRSP, UTM coordinates: 13 615800E 3238476N, 2. Brewster Co.: BBRSP, UTM coordinates: 13 619125E 3258986N, 1. Peromyscus maniculatus (Wagner, 1845) Deer Mouse Description .— Peromyscus maniculatus is a small to medium-sized mouse with a dorsal pelage that ranges from pale ochraceous to dull gray in color. The tail is short (decidedly shorter than head and body), scantly haired, and distinctly bicolored, and its ears are short. The dental formula for P maniculatus is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 159.3 (47, 144-171, 7.0); length of tail verte¬ brae, 73.5 (47, 65-79, 3.4); length of hind foot, 21.2 (47, 20-23, 0.6); length of ear from notch, 16.9 (47, 16-19, 0.8); weight, 17.8 (45, 14-25, 2.8); greatest length of skull, 25.61 (20, 24.04-27.85, 0.81). I know of no reports of significant secondary' sexual dimorphism in P. maniculatus. At BBRSP, P maniculatus is confused most eas¬ ily with P. leucopus. See the previous account for dif¬ ferentiating characters. P maniculatus is distinguished easily from other species of Peromyscus at BBRSP by having a tail that is shorter than its head and body. Distribution .— The range of P maniculatus ex¬ tends from southern Mexico, northward throughout cen¬ tral Mexico, thence throughout most of the United States and Canada (Carlton, 1989). At BBRSP, the deer mouse is known from scattered localities throughout the park (Fig. 44). Natural History .— With a relative abundance in¬ dex of 0.477, P maniculatus accounted for 7.2 percent of all rodents trapped at BBRSP Based on these fig¬ ures, deer mice apparently occur at BBRSP in moder¬ ate numbers, being neither extremely abundant nor un¬ common Throughout the Trans-Pecos, P maniculatus is re¬ ported as partial to desert scrub and grasslands, and 126 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY KILOMETERS Figure 44. Localities of known specimens of Peromyscus maniculatus from Big Bend Ranch Slate Park, Texas. rare in woodlands (Schmidly, 1977a). During this study, this mouse was taken in all three of these habitats. It showed a significant preference for riparian woodland over both desert scrub (PO.OOl) and desert grassland (P<0.001). Grassland was second in order of habitat preference, as the capture rate of P. maniculatus in this habitat was significantly higher than that in desert scrub (/>=0.015). P. maniculatus is not known to hibernate (Davis and Schmidly, 1994). During this study, deer mice were taken during each season of the year, confirming that they are active year round at BBRSP. The breeding season of P. maniculatus is known to extend throughout the year (Davis and Schmidly, YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 127 1994). Multiple litters of about four young are pro¬ duced annually (Schmidly, 1977a; Millar, 1989). At BBRSP, I examined two pregnant females, one carry¬ ing four embryos (crown-rump length, 2) and the other with two embryos (crown-rump length, 10) on 27 May and 30 November, respectively. Juveniles were ob¬ served in the population on 1 April and 10 November. Subadults were noted on 27 February, 5 July, and 10 and 30 November. Testicular measurements of adult males ranged as follows: January, 6X3; February, 6 X3 to 14 X 8; March, 3 X 2 to 5 X 3; April, 9 X 4 to 15 X 4; September, 10X6, November, 3 X 2 to 7 X 3. P maniculatus primarily is nocturnal, foraging primarily for seeds. In addition, grains, fruits, bark, roots, green vegetation, and insects may be consumed (Schmidly, 1977a; Davis and Schmidly, 1994). This mouse occasionally may climb vegetation in an attempt to gather food (Davis and Schmidly, 1994). Little is known regarding annual molting in P maniculatus. During this study, molting adults were examined during February, March, May, September, and November. These data suggest two possible seasonal molts, one during spring (or late winter), the other in autumn. Other species of rodents taken at the same locali¬ ties as P. maniculatus at BBRSP included Thomotnys bottae , Cratogeomys castanops , Perognathus fleams, Chaetodipus eremicus, C. hispidus, Dipodomys merriami , Reithrodontomys fulvescens , R megalotis , Peromyscus eremicus , P leucopus , P. pectoralis, Onychomys arenicola , Sigmodon hispidus , S. ochrognathus , and Neotom a Micropus. Fleas and ticks wore the only parasites found in association with specimens of P. maniculatus from BBRSP. Additional ectoparasites known from white¬ footed mice include mites, lice, and botfly larvae. En- doparasites known to infect P. maniculatus include sev¬ eral species of trematodes, cestodes, and nematodes (Whitaker, 1968). The deer mouse has been implicated as the primary reservoir for Sin Nombrc virus, a strain of hantavirus responsible for hantavirus pulmonary syn¬ drome (Hughes et al, 1990; Mills et al, 1995). Comments. — The subspecies of P. maniculatus at BBRSP is P. m. blandus Osgood, 1904. See the ac¬ count on Peromyscus boylii for the etymology of the generic name. The specific epithet maniculatus is from the Latin “manicula,” meaning small hand (Stangl et al., 1993). Specimens Examined (57).— Presidio Co.: BBRSP, UTM coordinates: 13 576699E 3296276N, 1; BBRSP, UTM coordinates: 13 576757E 3296109N, 1; BBRSP, UTM coordinates: 13 576785E 3296105N, 3; BBRSP, UTM coordinates: 13 576836E 329625 IN, 5; BBRSP, UTM coordinates: 13 577321E 3287548N, 3; BBRSP, UTM coordinates: 13 577472E 3287353N, 3; BBRSP, UTM coordinates: 13 586937E 3262923N, 3; BBRSP, UTM coordinates: 13 587250E3262918N, 6; BBRSP, UTM coordinates: 13 590980E 3262597N, 12; BBRSP, UTM coordinates: 13 600684E3259365N, 2; BBRSP, UTM coordinates: 13 60O694E 325975 IN, 2; BBRSP, UTM coordinates: 13 601335E3260787N, 1; BBRSP, UTM coordinates: 13 601619E 3260741N, 4; BBRSP, UTM coordinates: 13 60221 IE 3256243N, 2; BBRSP, UTM coordinates: 13 605746E3261330N, 4; BBRSP, UTM coordinates: 13 614935E3268144N, 5. Peromyscus pectoralis Osgood, 1904 White-ankled Mouse Description .— Peromyscus pectoralis is a me¬ dium-sized mouse with a grayish brown dorsal pelage that is washed with black. The tail is longer than the head and body, scantly haired, and not sharply bicol¬ ored. The cars arc short. The ankles arc white, and the soles of the hind feet are haired at the heels The dental formula for P pectoralis is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP arc: total length, 191.5 (35, 168-223, 11.2); length of tail verte¬ brae, 102.5 (35,91-114, 6.3); length of hind foot, 21 2 (37, 20-22, 0.7), length of car from notch, 17,6 (37, 128 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 17-19, 0.6); weight, 17.2 (35, 13-21, 2.2); greatest length of skull, 26.84 (20, 25.83-27.84, 0.68). Over¬ all, males and females are approximately the same size (Schmidly, 1972). At BBRSP, P. pectoralis is mistaken most often for P. boylii and P. eremicus. See the accounts of these species for differentiation. Distribution .— The range of P. pectoralis extends from central Mexico, northward to the United States, where it occurs in southwestern New Mexico, south¬ western and central Texas, an southern Oklahoma (Schmidly, 1974). At BBRSP, P. pectoralis is known from scattered localities throughout the southern part of the park (Fig. 45). Natural History .— At BBRSP, P pectoralis was found to have a relative abundance index of 0.453. This species comprised 6.8 percent of all rodents trapped. White-ankled mice apparently are common, yet not over¬ whelmingly abundant at BBRSP. P. pectoralis has been reported to inhabit a vari¬ ety of vegctational conditions, including desert scrub, grassland, and juniper woodland (Blair, 1940; Schmidly, 1974; 1977#). During this study, P. pectoralis was taken in all four major habitat types, albeit not in equal num¬ bers (PO.OOl), Interestingly, this mouse was more common in riparian woodland than either desert scrub or grassland (P0.001 and P=0.001, respectively). It was found to favor desert grassland over desert scrub (P=0.001). The greatest capture rate for this species w as in juniper roughlands, but due to the small amount of this habitat in the park, sample sizes were insuffi¬ cient for statistical comparisons. All individuals en¬ countered were in or near rocky areas. P. pectoralis is a saxicolous mouse (Schmidly, 1974); the presence of rocks, rather than vegetation type, seems to be the pri¬ mary requirement for suitable habitat. During this study, white-ankled mice were taken during each season of the year, thus indicating that this species is active throughout the year at BBRSP Little is known regarding the reproductive biol¬ ogy of P. pectoralis in the Trans-Pecos. Pregnant fe¬ males from dais area are known from March, April, July, and August (Schmidly, 1977a). In nearby Coahuila, Mexico, gravid females were taken during March, April, May, June, September, October, and December (Baker, 1956). At BBRSP, I examined two pregnant females, one carrying four embryos (crown-rump length, 19) and the other with two embryos (crown-rump length, 10) on 13 and 14 March, respectively. Juveniles were ob¬ served in the population on 10 January and 8 Novem¬ ber. Subadults were noted on 10 January, 24, 26, and 28 February, 8 November, and 1 December. Testicular measurements of adult males ranged as follows: Janu¬ ary; 4 X 2 to 9 X 5; February; 3 X 2 to 12 X 7; March, 3 X 2 to 11 X 5; July, 9X6; November, 9X6, Decem¬ ber, 3 X 2 to 10X5. The data from this study; along with those of Baker (1956) and Schmidly (1977#) col¬ lectively suggest that P pectoralis breeds throughout the year, and that two or more litters may be produced. Litter sizes are known to range from two to seven (Schmidly, 1974). P. pectoralis is nocturnal, at which time it for¬ ages primarily for seeds, juniper berries, acorns, cactus fruits, and hackberries. Other fruits and insects prob¬ ably are eaten as well (Schmidly, 1974; Davis and Schmidly, 1994). Little is known about the annual molting process in P. pectoralis. During this study, molting adults were examined during February; May, July, November, and December. These data suggest that either a single molt occurs at various times, or that this mouse possibly ex¬ hibits two seasonal molts. Other species of rodents taken at the same locali¬ ties as P. pectoralis at BBRSP included Chaetodipus eremicus , C. nelsoni , Dipodomys merriami , Reilhrodontomysfulvescens , R. mega lot is, Peromyscus eremicus, P. leucopus , P maniculatus , Sigmodon hispidus, and Neotoma albigula. Ectoparasites observed infesting P. pectoralis specimens from BBRSP included mites and fleas. An unidentified tapeworm was collected from the gut of a white-ankled mouse from BBRSP. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 129 Figure 45. Localities of known specimens of Peromyscus pectoralis from Big Bcrid Ranch State Park, Texas. Comments.— The subspecies of P. pectoralis at 6, BBRSP, UTM coordinates: 13 590980E 3262597N, BBRSP is P p . laceianus Bailey, 1906. See the ac- 4; BBRSP, UTM coordinates: 13 592898E 3261518N, count on Peromyscus boylii for the etymology of the 1; BBRSP, UTM coordinates: 13 596699E3259093N, generic name. The specific epithet pectoralis is Latin 3; BBRSP, UTM coordinates: 13 601031E 3260217N, for of the breast (Stangl ct al., 1993). 1, BBRSP, UTM coordinates: 13 608629E 3262171N, 3, BBRSP, UTM coordinates: 13 609405E 3261495N, 1; BBRSP, UTM coordinates: 13 609770E 3253645N, Specimens Examined (67).— Presidio Co.: 2; BBRSP, UTM coordinates 13 611393E3249399N, BBRSP, UTM coordinates: 13 587250E 3262918N, 2; BBRSP, UTM coordinates: 13 614458E 3265716N, 130 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 10; BBRSP, UTM coordinates: 13 615409E3268594N, 1; BBRSP, UTM coordinates: 13 615525E 3268958N, 5; BBRSP, UTM coordinates: 13 615559E 3268762N, 9;BBRSP,UTMcoordinates: 13 61595IE3263099N, 4; BBRSP, UTM coordinates: 13 616012E 3263115N, 1; BBRSP, Ojito Adentro, 2 (SRSU); BBRSP, Colo¬ rado Canyon, 1 (SRSU); BBRSP, Rancherias Springs, 1 (SRSU); BBRSP, 15 mi. NW Lajitas, 1 (SRSU); BBRSP, Chorro Canyon, 5 (SRSU); BBRSP, Smith Ranch, Fresno Canyon, 1 (SRSU); BBRSP, 15 mi. N Lajitas, 1 (SRSU). Brewster Co.: BBRSP, UTM coor¬ dinates: 13 618322E 3258007N, 2. Onychomys arenicola Mearns, 1896 Meams’ Grasshopper Mouse Description .— Onychomys arenicola is a me¬ dium-sized mouse with a pale brown to buffy gray dor¬ sal pelage. The tail is short (less than 60 percent of head and body length), lightly haired, indistinctly bi- colored, and often tipped in white. The ears are short, and each has a whitish gray patch at the anterior base. The dental formula for O. arenicola is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 146,9 (9, 129-156, 8.4); length of tail verte¬ brae, 54.1 (9, 48-60, 4.7); length of hind foot, 20.7 (9, 19-22, 0.9); length of ear from notch, 17.1 (9, 17-18, 0.3); weight, 18.7 (9, 15-22, 2.0); greatest length of skull, 25.60 (7, 25.25-26.21, 0.32). I know of no re¬ ports of sexual dimorphism in O. arenicola . O. arenicola possibly could be confused with members of the genus Peromyscus , but can be identi¬ fied easily by the short tail. In addition, the coronoid process extends well above the condyloid process, which it does not in members of the genus Peromyscus. Distribution .— O. arenicola ranges from central Mexico, northward to the United States where it occurs in southeastern Arizona, southern New Mexico, and West Texas (Musser and Carlton, 1993). At BBRSP, this mouse is known from the Cienega Mountains, the Sauceda area, various sites in the Bofecillos Mountains, and the north rim of the Solitario (Fig. 46). Natural History During this study, O. arenicola was found to have a relative abundance in¬ dex of 0.081. It accounted for 1.2 percent of rodents trapped at BBRSP. Based on these figures, O . arenicola should be regarded as uncommon at the park. Schmidly (1977a) reported this mouse as extremely rare in the Big Bend Region. O. arenicola has been reported to favor lowland desert scrub. At BBRSP, it was found in this type of habitat, but also in upland desert grassland and juniper woodland habitats. There was no significant difference detected between capture rates in desert scrub and grass¬ land (P=0.677). The capture rate in juniper roughlands was the highest of all habitats for this species, but due to the small amount of this habitat in the park, sample sizes were insufficient for statistical comparisons. This grasshopper mouse was taken on sandy, gravelly, and rocky substrata. During this study, Mearns’ grasshopper mouse was taken in the months of February, April, May, June, and November. In Big Bend National Park, this mouse was trapped during March, May, July, August, Septem¬ ber, and November (Jones et al, 1993). These data indicate that O. arenicola is active year round in the Big Bend region. The breeding period of O. arenicola reportedly extends from late January or early February to Septem¬ ber. Females give birth to litters of two to seven (mean, 4.2) young, two or three times a year (Davis and Schmidly, 1994). During this study, a subadult indi¬ vidual w as observed on 31 May. Adult males had tes¬ tes that measured as follows: February, 8X5 and 12 X 7; April, 15X9; June, 14 X 8; November, 6 X 3. O. arenicola is active at night during which time it forages mostly for insects. Additional food items in¬ clude other arthropods, especially scorpions, and small YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 131 KILOMETERS Figure 46. Localities of known specimens of Onychomys arenicola from Big Bend Ranch State Park, Texas. mammals (Genoways et af, 1979). At BBRSP, a cap¬ tive Mcams’ grasshopper mouse that was presented with a small scorpion (Centruroides sp.) consumed the en¬ tire arthropod within minutes, and I have witnessed a grasshopper mouse killing and feeding on a medium¬ sized kangaroo rat. In addition to animal matter, a small amount of plant material also may be consumed (Davis and Schmidly, 1994). Little is known about patterns of annual molt in O arenicola. I examined molting adults from BBRSP during February and November. Other species of rodents taken at the same locali¬ ties as 0. arenicola at BBRSP included Perognathus flavus t Dipodomys merriami , Reiihrodontomys 132 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY megalotis , Peromyscus eremicus, and P maniculatus. O. arenicola often is found in association with D. merriami (Schmidly, 1977 a). During this study, D. merriami was taken at four of the seven traplines from which O. arenicola was captured. Little is known of the parasites harbored by O. arenicola. At BBRSP, ectoparasites found on this mouse were mites and fleas. An undetermined species of nema¬ tode was the only endoparasite noted. Comments. — The subspecies of O. arenicola at BBRSP is O. a. arenicola Meams, 1896. The generic name Onychomys is derived from the Greek “onyx” and “mys,” which translate to claw, and mouse, respec¬ tively. The specific epithet arenicola is from the Latin “harena” and “colere,” meaning sand, and inhabit, re¬ spectively (Stangl et al., 1993). Individuals of this spe¬ cies in the Big Bend area previously were referred to as O. torridus (Schniidly, 1977a). However, subsequent examination of morphologic and chromosomal data in¬ dicated these mice to be a separate species (Hineslcy, 1979). Specimens Examined (10).— Presidio Co.: BBRSP, UTM coordinates: 13 578883E 3292424N, 1; BBRSP, UTM coordinates: 13 581288E 3268847N, 2; BBRSP, UTM coordinates: 13 596232E 3258492N, 1; BBRSP, UTM coordinates: 13 600868E 3256344N, 1; BBRSP, UTM coordinates: 13 602211E 3256243N, 1; BBRSP, UTM coordinates: 13 605746E 3261330N, 1; BBRSP, UTM coordinates: 13 615033E 3263895N, 3. Sigma don hispidus Say and Ord, 1825 Hispid Cotton Rat Description .— Sigmodon hispidus is a large rat with a dorsal pelage formed of coarse, black, guard hairs tipped with golden brown, thus appearing grizzled brown in color. The tail is relatively short, sparsely haired, and scaly. The cars are short. The dental for¬ mula for S. hispidus is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. The total length and length of tail vertebrae mea¬ surements of a single specimen from BBRSP are 276 and 111, respectively. Means of the other standard ex¬ ternal and cranial measurements (with sample size, ex¬ tremes, and standard deviation in parentheses) of adult specimens from BBRSP are: length of hind foot, 31.7 (3, 29-34, 2.5); length of ear from notch, 19.3 (3, 19- 20,0.6); weight, 95.7 (3,77-114, 18.5); greatest length of skull, 34.77 (3,34.67-34.89,0.11). Males are slightly larger than females (Cameron and Spencer, 1981). S. ochrognathus is the only mammal at BBRSP for which S. hispidus might be mistaken. However, S. hispidus is identified easily by the lack of a yellow- orange nose, which is present and obvious in S. ochrognathus. Distribution .— S. hispidus ranges from northern South America, northward tliroughout Central America and Mexico and into the south-central and southeastern United States. An isolated population occurs in south¬ western Arizona, southeastern California, and western Mexico (Cameron and Spencer, 1981). At BBRSP, S. hispidus is known from Las Quevas and Rancherias Springs (Fig. 47). Natural History. — With a relative abundance in¬ dex of 0.032, S. hispidus accounted for 0.5 percent of the rodents trapped at BBRSP. That this rat w'as found to be rare in the park w as somewhat of a surprise, as in nearby areas of Big Bend National Park, S. hispidus was reported as common (Jones et al., 1993). Popula¬ tion sizes of this species are known to decline in re¬ sponse to drought conditions such as those encountered during this study. Numbers reportedly increase in re¬ sponse to the return of normal precipitation levels (Schmidly, 1977a). S. hispidus reportedly prefers grassy situations, especially those near sources of water (Cameron and Spencer, 1981; Jones et al., 1993). However, this cot¬ ton rat also may inhabit creosote scrub (Jones et al., 1993). At BBRSP, S. hispidus was taken only in dense riparian woodland with thick grass. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 133 KILOMETERS Figure 47. Localities of known specimens of Sigmodon hispidus from Big Bend Ranch State Park, Texas During this study, S. hispidus was acquired in May, July, and November; however, this rat is active year round throughout its range (Cameron and Spen¬ cer, 1981). The breeding habits of .S', hispidus apparently van in response to levels of precipitation. During wet years, this rat breeds throughout the year, whereas during pe¬ riods of drought, reproductive activity declines signifi¬ cantly (Schmidly, 1977a). Litter sizes for hispid cotton rats range from one to 15, but arc known to vary geo¬ graphically (Cameron and Spencer, 1981). I did not observe any gravid females from BBRSP, however, three pregnant females from Big Bond National Park carried from six to eight embry os (mean, 7; Jones ct al.. 134 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 1993). I examined a lactating female on 10 November, and an adult male with testes measuring 18 X 10 on 7 July. S ' hispidus primarily is nocturnal, but may be ac¬ tive throughout the day. It mostly forages for grasses and seeds (Fleharty and Olson, 1969; Schmidly, 1977a), but also may feed on insects (Cameron and Spencer, 1981) and eggs of ground nesting-birds (Davis and Schmidly, 1994). Food gathered during the warmer months is not stored for winter consumption (Davis and Schmidly, 1994). Rather, fat storage accumulated dur¬ ing spring, summer, and autumn aids in sustaining indi¬ viduals over winter (Cameron and Spencer, 1981). Nothing has been reported on the characteristics of seasonal molting in S. hispidus ; no molting individu¬ als were noted during this study. Other species of rodents taken at the same locali¬ ties as S. hispidus at BBRSP included Reithradontomys fulvescens , R. megalotis , Peromyscus leucopus , P mcmiculatus , and P pectorolis . Fleas were the only parasites noted on specimens of 5. hispidus from BBRSP, and are the only ectopara¬ sites previously reported from this cotton rat. Endopara- sites known from S. hispidus include trcmatodcs, ces- todcs, and nematodes. The hispid cotton rat reportedly harbors the following human pathogens: Trypanosoma cruzi , the rabies virus, the Venezuelan equine encepha¬ lomyelitis virus (Cameron and Spencer, 1981), and a strain of hantavirus (Childs ct al., 1995). Comments.—- The subspecies of S. hispidus at BBRSP is S. h. berlandieri Baird, 1855. The generic name Sigmodon is derived from the Greek “’sigma” and “odous,” which translate to S-shaped and tooth, respec¬ tively. The specific epithet hispidus is Latin for shaggy (Stangl ct al., 1993). Specimens Examined (3).— Presidio Co.: BBRSP, UTM coordinates: 13 586937E 3262923N, 2; BBRSP, UTM coordinates: 13 595150E 3252057N, 1 . Sigmodon ochrognathus Bailey, 1902 Yellow-nosed Cotton Rat Description .— Sigmodon ochrognathus is a small to medium-sized rat with a dorsal pelage similar to that describe for S. hispidus , but paler. The short hairs about the snout are distinctly orange. The tail is relatively short, lightly haired, and bicolored, being black above and rusty gray below. The dental formula for S. ochrognathus is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. External and cranial measurements of a single adult female from BBRSP are: total length, 229; length of tail vertebrae, 99; length of hind foot, 27; length of ear from notch, 18; weight, 58 (gravid); greatest length of skull, 30.14. Males and females do not vary in size (Baker and Shump, 1978). S. ochrognathus could be mistaken for S. hispidus , but the two can be distinguished easily as described in the previous account. Distribution .— The range of S', ochrognathus ex¬ tends from north-central Mexico, northward into south¬ western Texas, southwestern New Mexico, and south¬ eastern Arizona (Baker and Shump, 1978). At BBRSP, S ochrognathus is known from a single locality near Sauceda (Fig. 48). Natural History .— During this study, one speci¬ men of S’, ochrognathus was taken, thus resulting in a relative abundance index of 0.008. This cotton rat com¬ prised 0.1 percent of all rodents trapped at BBRSP. The specimen from BBRSP is the second documented from Presidio County (Yancey and Jones, 1996). These figures imply that S. ochrognathus is extremely rare in the park. At Big Bend National Park, this cotton rat w r as reported as common, but at high elevations, which are lacking at BBRSP (Borrell and Bryant, 1942; Schmidly, 1977a). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 135 KILOMETERS Figure 48. Localities of known specimens of Sigmodon ochrognathus from Big Bend Ranch State Park, Texas. Throughout its range, S. ochrognathus reportedly favors high-elevation grasslands, as well as rocky up¬ land slopes with scattered bunches of grasses (Baker, 1956; Findley and Jones, 1960; Baker, 1969; Ander¬ son, 1972; Baker and Shuinp, 1978). The one yellow- nosed cotton rat taken at BBRSP was acquired from a lowland seasonal stream bed near a permanent spring. Associated vegetation included willow, false willow, and deergrass. The habitat surrounding the stream bed was desert scrub on a rugged, rocky substrate This appar¬ ently is the first documented occurrence of S ochrognathus from non-montanc riparian habitat (Yancey and Jones, 1996). 136 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY The one yellow-nosed cotton rat taken during this study was acquired in August. This species is active year round (Schmidly, 1977a). S ’ ochrognathus is reported to breed lliroughout the year. Female yellow-nosed cotton rats give birth to litters of three to five (mean, 3.6; Schmidly, 1977), pos¬ sibly several times a year (Davis and Schmidly, 1994). A specimen obtained on 5 August was a gravid female earn ing four embryos (crown-rump length, 9). S. ochrognathus may be nocturnal or diurnal, but evidence suggests that it may be more active during the day (Davis and Schmidly, 1994). This cotton rat pri¬ marily feeds on grasses, but also consumes the fruits of prickly pear cactus (Schmidly, 1977a). Gathered grasses may be cached in burrows for future consump¬ tion (Baker and Shump, 1978). I know of no data regarding annual molting in S. ochrognathus. Other species of rodents taken at the same local¬ ity as S. ochrognathus at BBRSP included Reithrodontomysfulvescens, R. mega lot is, Peromyscus leucopus , and P. maniculatus. No parasites were observed in association with the specimen of S. ochrognathus from BBRSP. Fleas are the only parasites previously documented from yel¬ low-nosed cotton rats (Baker, 1969). Comments ,— S. ochrognathus is a monotypic species. See the account on Sigmodon hispidus for the etymology of the generic name. The specific epithet ochrognathus is from the Greek “ochros” and “gnathos,'’ meaning pale, and jaw, respectively (Stangl et al., 1993). Specimens Examined (1).— Presidio Co.: BBRSP, UTM coordinates: 13 601619E 3260741N, 1 . Neotoma albigula Hartley, 1894 White-throated Woodrat Description.—Neotoma albigula is a moderate to large woodrat with a bufly brown dorsal pelage that is lightly washed with black and gray. Hairs about the throat and chin are white entirely. The tail is moderate in length, densely furred with short hairs, and distinctly bicolored, and the ears are large. The dental formula for N. albigula is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 301.8 (5, 268-327, 22.4); length of tail verte¬ brae, 131.4(5,110-149,14.3); length ofhindfoot,32.8 (6, 32-34, 0.8); length of ear from notch, 28.8 (6, 26- 32, 2.1); weight, 164.6 (5, 128-182, 22.1); greatest length of skull, 42.01 (5, 39.01-44.05, 2.22). Males are larger than females (Macedo and Mares, 1988), N. albigula is confused most easily with N, mexicana . Typically, the two can be identified on the basis of throat hair color. The throat hairs in N. albigula are white entirely; whereas, those of N. mexicana usu¬ ally are white above, but grayish at the base. However, this characteristic is not absolute in N. mexicana , as throat hairs occasionally may be white to the base. More reliably, these two woodrats can be differentiated on the basis of tooth morphology. In N albigula , each first upper premolar has a shallow anterointemal re¬ entrant angle that does not extend more than half-way across the crown. In contrast, the anterointemal re¬ entrant angle of M1 in N. mexicana is deep, extending more than half-way across the crown, N. albigula can be distinguished from the other species of woodrat at BBRSP, N. micropus , by its buffy brown, rather than steel gray, dorsal pelage. Distribution .— N. albigula ranges from central Mexico, northward throughout much of the southwest¬ ern United States (Macedo and Mares, 1988). At BBRSP, this woodrat was recorded from sites in the Bofecillos Mountains, Chorro Canyon, and the Solitario (Fig, 49). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 137 I_L—__J KILOMETERS Figure 49. Localities of known specimens of Neotoma albigula from Big Bend Ranch State Park, Texas. Natural History. — During this study, N. albigula was found to have a relative abundance index of 0.057. It accounted for 0.9 percent of all rodents taken at BBRSP. These results suggest that this woodrat is un¬ common at the park. N. albigula has been reported to inhabit a variety of plant associations, including desert scrub and grass¬ land (Schmidly, 1977a), as long as prickly pear cactus is present (Maccdo and Mares, 1988). This woodrat is known to reside at intermediate elevations primarily 138 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY among rocks, within which it often constructs nests of sticks, cactus pads, and other materials (Finley, 1958; Schmidly, 1977a; Macedo and Mares, 1988). During this study, A. albigula was taken in desert scrub and desert grassland, although it showed a significant pref¬ erence for the latter (P=0.0Q2). All individuals were acquired among rocks or boulders. At BBRSP, A albigula was taken only during January and February, but this species is active through¬ out the year (Macedo and Mares, 1988). Schmidly (1977a) reported the breeding season of A albigula in the Trans-Pecos to last from early spring to the end of summer. In contrast, Baker (1956) concluded that this woodrat breeds year round in nearby Coahuila, Mexico. I examined a single gravid female on 5 February that was carrying one embryo with a crown-rump length of 41. Adult males had testes that measured 13 X 8 and 17 X 10 on 6 and 26 February, respectively. Given a gestation length of at least 37 days and perhaps more (Richardson, 1943), the breed¬ ing season of A. albigula at BBRSP begins as early as late December. Females produce two or possibly three litters of one to three young per year (Macedo and Mares, 1988; Davis and Schmidly, 1994). A. albigula primarily is nocturnal, although there is some evidence of diurnal activity (Macedo and Mares, 1988). Succulent parts of prickly pear cactus are the primary material consumed by A albigula. This item serves as both a food and water source for this woodrat (Finley, 1958). Additional foods include grasses, shrubs, and fruits (Macedo and Mares, 1988). Small supplies of food may be found within dens, but food seldom is stored in large quantities, even in anticipation of winter (Finley, 1958). In Colorado, A albigula was reported to undergo a single annual molt that occurs from May to Septem¬ ber (Finley, 1958). However, during this study, adult white-throated woodrats were observed molting in Janu¬ ary and February 7 . Because of its more southerly loca¬ tion, individuals at BBRSP may begin molting earlier. Other species of rodents taken at the same locali¬ ties as A. albigula at BBRSP included Thomomys bottae , Dipodomys merriami , Peromyscus eremicus , P. pectoralis , and A. mexicana. The sympatric and syntopic occurrence of A albigula and A mexicana is an interesting situation. Schmidly (1977a) suggests an elevational segregation of the two species, with A albigula occurring at intermediate elevations and A mexicana preferring high elevations above 1400 m. On the other hand, Macedo and Mares (1988) imply a to¬ pographical separation, with A. albigula inhabiting moderately rocky 7 slopes and A mexicana residing among steep, rocky cliffs. At BBRSP, the site at which these two species were taken together was more typical of that preferred by A. albigula. It was in a moderately level area among small rocks at about 1300 m in eleva¬ tion. Finley (1958) reported these two species, on a rare occasion, to nest under the same rock. Ectoparasites detected on specimens of A. albigula from BBRSP were limited to mites and ticks. Other ectoparasites known from this woodrat include sucking lice and fleas. Endoparasites reported to infect A albigula include cestodes (Finley, 1958). White- throated w'oodrats are known to harbor hantavirus (Stone, 1993). Comments .— The subspecies of A. albigula at BBRSP is A. a. robusta Blair, 1939. The generic name Neotoma is derived from the Greek “neos” and “tomos,” which translate to new and cutting, respectively. The specific epithet albigula is from the Latin “albus” and “gula,” meaning white and throat, respectively (Stangl et ah, 1993). Specimens Examined (8).— Presidio Co.: BBRSP, UTM coordinates: 13 592898E 3261518N, 1; BBRSP, UTM coordinates: 13 602357E3260937N, 1; BBRSP, UTM coordinates: 13 603273E 3263098N, 1; BBRSP, UTM coordinates: 13 615786E3263185N, 2; BBRSP, South of Madrid Ranch, Chorro Canyon area, 1. Brewster Co.: BBRSP, UTM coordinates: 13 617223E3256581N, 1; BBRSP, UTM coordinates: 13 618185E 3257611N, 1. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 139 Neotoma mexicana Baird, 1855 Mexican Woodrat Description .— Neotoma mexicana is a moder¬ ate to large woodrat with a huffy brown dorsal pelage that is moderately washed with black. Hairs about the throat and chin are white at the tips, and often gray at the base The tail is short to moderate in length, densely furred with short hairs, and distinctly bicolored, and the ears are moderately large. The dental formula for N. mexicana is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. External and cranial measurements of an adult fe¬ male from BBRSP are: total length, 315; length of tail vertebrae, 153; length of hind foot, 34; length of ear from notch, 29; weight, 141; greatest length of skull, 43.95. Males average larger than females (Finley, 1958). N. mexicana is confused easily with N. albigula , but these two woodrats can be identified correctly as described in the previous account. N. mexicana can be distinguished from N. micropus, by its buffy brown, as opposed to steel gray, dorsal pelage. Distribution .— N. mexicana ranges from Cen¬ tral America, northward throughout western and inte¬ rior Mexico, into the United States where it occurs in Trans-Pecos Texas, New Mexico, Colorado, western Oklahoma, eastern Arizona, and southeastern Utah (Hall, 1981). At BBRSP, this woodrat has been docu¬ mented only from one site in the Solitario (Fig. 50). Natural History. — During this study, one Mexi¬ can woodrat was taken, which resulted in a relative abundance index of 0.001. This species accounted for only 0.1 percent of all rodents trapped. These figures indicate that N. mexicana is extremely rare at BBRSP. N. mexicana is known to favor high-elevation (up to 2500 m) areas among rocky slopes and boulders (Finley, 1958; Schmidly, 1977a). Associated plant com¬ munities usually are shrub land or wooded areas (Finley, 1958). The specimen from BBRSP was taken in desert grassland with scattered lechuguilla and sotol. The site was relatively level with a rocky substrate. This woodrat, unlike other woodrats, usually does not build an elaborate nest of sticks and other debris. Instead, it dens in the crevices among large rocks and boulders (Finley, 1958). However, large rocks and boulders were lacking at the site where this woodrat was taken in BBRSP. Apparently, N. mexicana will build a nest of sticks and other material if a natural rock shelter is ab¬ sent from the area (Finley, 1958). In the Trans-Pecos, the breedmg season of N. mexicana reportedly extends from early spring to the end of summer (Schmidly, 1977a; Davis and Schmidly, 1994). However, I examined a lactating female on 26 February, thus indicating that breeding may begin in winter at BBRSP. Litter sizes range from two to five with an average of about 3.5 (Schmidly, 1977a). Based on the length of the breeding season, Finley (1958) speculated that females may produce two litters a year Like other woodrats, N. mexicana forages at night and stores food in its den for daytime feeding. This woodrat feeds primarily on the leaves of forbs and shrubs, but also may consume fruits, flowers, and woody vegetation. In contrast to N. albigula , N. mexicana exhibits a strong distaste for cactus. Also unlike N. albigula, N. mexicana readily stores large quantities of food, presumably for consumption over win ter. Mexi¬ can woodrats typically reside at higher elevations than do white-throated w oodrats, and thus face longer, colder winters, and possible food shortages during that time (Finley, 1958). Annual molting in N. mexicana has been docu¬ mented to occur from April through December (Finley, 1958), but males and females may molt at different times. The single adult taken during this study was molting on 26 January, thus extending the period of which this woodrat is known to molt. Other species of rodents taken at the same local¬ ity as N. mexicana at BBRSP included Thomomys bottae , Dipodomys merriami , Pern my sc us eremicus , and N. albigula. See the previous account for a discus¬ sion on the sympatric occurrence of N. mexicana and N. albigula. 140 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY KILOMETERS Figure 50. Localities of known specimens of Neotoma mexicana from Big Bend Ranch State Park, Texas. Mites were noted infesting the specimen of N. mexicana from BBRSP Other ectoparasites previously reported from N. mexicana include ticks, fleas, and lice. Cestodes are the only documented internal parasites of Mexican vvoodrats (Finley, 1958). Comments .— The subspecies of N. mexicana at BBRSP is N. m. mexicana Baird, 1855. See the ac¬ count on Neotoma albigula for the etymology of the generic name. The specific epithet mexicana refers to of Mexico (Stangl et al., 1993). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 141 Specimens Examined (1).— Brewster Co.: BBRSP, UTM coordinates: 13 618185E 325761 IN, i. Neotoma micropus Baird, 1855 Southern Plains Woodrat Description,—Neotoma micropus is a moderate to large woodrat with a fairly uniform steel gray dorsal pelage. The tail is short to moderate in length, lightly furred with short hairs, and distinctly bicolored, and the ears are medium to large. The dental formula for N. micropus is: i 1/1, c 0/0, p 0/0, m 3/3, total 16. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 298.7 (10, 265-332, 19.7); length of tail verte¬ brae, 122.7 (10,105-134, 8.3); length of hind foot, 34.4 (10, 32-36, 1.3); length of ear from notch, 26.1 (10, 24-28, 1.1); weight, 143.8 (8, 91-225, 43.3); greatest length of skull, 41.90 (9, 39.15-45.67, 1.97). Males are larger than females (Finley, 1958). N. micropus conceivably could be confused with N. albigula and N. mexicana. See the accounts of these two species for differentiation. Distribution ,— N micro pus ranges from north¬ eastern and north-central Mexico, northward into the United States where it occurs in the western two thirds of Texas, much of New Mexico, western Oklahoma and Kansas, and southeastern Colorado (Braun and Mares, 1989). This woodrat is known from scattered localities in BBRSP (Fig. 51). Natural History .— With a relative abundance in¬ dex of 0.097, N. micropus accounted for 1.5 percent of all rodents trapped at BBRSP. Considering rodents in general, these figures suggest that N. micropus is un¬ common in the park. However, this was the most com¬ monly trapped large murid, and frequent sightings of its nests suggest that N. micropus is more abundant than trapping results indicate. Throughout its range, N. micropus is known to inhabit a variety of habitats (Braun and Mares, 1989). In Trans-Pecos Texas, this woodrat apparently favors lowland desert scrub and grasslands where cactus or thorny desert shrubs occur, and tends to avoid rocky cliffs (Schmidly, 1977a). During this study, N. micropus was taken only from lowland desert scrub and grass¬ land, with no significant difference in capture rates be¬ tween these two habitats (P=0. 167), Prickly pear cac¬ tus, creosote, mesquite, and catclaw were plants com¬ monly associated with this woodrat. Large, elaborate nests, which are characteristic of this species (Finley, 1958), often were noted at the bases of these plants. These dens usually were constructed of sticks, cactus pads, and other debris. During this study, N. micropus w as taken during January, February, June, and July. This woodrat re¬ mains active throughout the year, but may spend a greater proportion of time in the den during w'intcr (Braun and Mares, 1989). In parts of its range, N. micropus is known to breed throughout the year. However, Schmidly (1977a) re¬ ported that in the Trans-Pecos, this woodrat breeds only in early spring. I examined two gravid females from BBRSP, one on 4 February (2 embryos, crown-rump length, 9), and the oilier on 2 June (2 embryos, crown- rump length, 10). A subadult wns noted on 1 June. Tes¬ ticular measurements of adult males were as follows: 12 January, 16X9; 14 January; 14 X 9; 23 May 14 X 7; 22 June, 15 X 10. These figures indicate that at BBRSP, N. micropus is rcproductivcly active at times other than early spring. Given a gestation period that ranges from 30 to 39 days (Braun and Mares, 1989), and embry os on 4 February and 2 June with a crown- rump lengths of 9 and 10, respectively , mating must have occurred in late December and mid-May. In addition, males with enlarged testes during January; May, and June suggest that breeding occurs in w inter, late spring, and possibly early summer. Therefore, it is possible that the breeding season of A. micropus extends through¬ out the year, as it docs in south Texas (Raun, 1966), or at least from winter to late spring. Litter sizes range from one to four, but two or three is the norm In the Trans-Pecos, females were thought to produce only a single litter each year (Schmidly, 1977a) However, 142 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY KILOMETERS Figure 51. Localities of known specimens of Neotoma micropus from Big Bend Ranch State Park, Texas. this assumption was based on the premise that the breed¬ ing season of this woodrat was restricted to early spr ing. With an extended breeding period as suggested above, N. micropus conceivably could produce multiple litters annually, as does the species in other parts of its range (Bimey* 1973). N. micropus is nocturnal, with most activity oc¬ curring between dusk and midnight (Raun, 1966). At twilight, this woodrat begins foraging for foods such as the pads and fruit of prickly pear cactus, sotol leaves, the blades of lechuguilla and yucca, and mesquite beans (Finley, 1958; Schmidly, 1977a; Braun and Mares, YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 143 1989). In addition to food, N. micropus also relies on many of these items for its water supply (Finley, 1958; Davis and Schmidly, 1994). Southern plains woodrats occasionally cache small amounts of food for daytime feeding, but not for use over winter (Finley, 1958). In the southern part of its range, adult southern plains woodrats reportedly molt once a year during sum¬ mer or fall, and the process usually is complete by No¬ vember (Bimey, 1973). During this study, I examined molting adults during January, Februaiy, May, June, and July. Bimey (1973) also noted adults molting at vari¬ ous times during the year that were inconsistent with a single autumn molt. He temied these molts “vernal molts,” and explained them as mechanisms to maintain the pelage that may be complete, abbreviated, or ab¬ sent. Other species of rodents taken at the same locali¬ ties as N. micropus at BBRSP included Perognathus flavus , Chaetodipus eremicus , C. nelsoni, Dipodomys merriami , Reithrodontomys megalotis , Peromyscus eremicus , and P. mcmiculatus. Fleas were the only external parasites found on specimens of N. micropus from BBRSP. In addition to fleas, other ectoparasites known to infest this woodrat include mites, ticks, lice, and botfly larv ae. Known in¬ ternal parasites include protozoans, cestodcs, and nema¬ todes. Of medical significance, the protozoan Trypa¬ nosoma cruzi , which is responsible for Chaga disease, is known to infect N. micropus (Braun and Mares, 1989). Comments The subspecies of N. micropus at BBRSP is N. m. canescens J. A. Allen, 1891. See the account on Neotoma albigula for the etymology of the generic name. The specific epithet micropus is from the Greek “mikros” and “pous,” meaning small and foot, respectively (Stangl et al., 1993). Specimens Examined (II).— Presidio Co.; BBRSP, UTM coordinates: 13 576206E 3268568N, 1; BBRSP, UTM coordinates: 13 583096E 3272189N, 1; BBRSP, UTM coordinates: 13 600694E 325975 IN, 1; BBRSP, UTM coordinates: 13 60520IE 326043 IN, I; BBRSP, UTM coordinates: 13 605576E3257735N, 1; BBRSP, UTM coordinates: 13 606085E 3259112N, 1; BBRSP, UTM coordinates: 13 612594E 3268946N, 1; BBRSP, UTM coordinates: 13 612683E 3265440N, 1; BBRSP, UTM coordinates: 13 615371E 3261358N, 1. Brewster Co.: BBRSP, UTM coordinates: 13 619081E 3260561N, 2. Family Erethizontidae Erethizon dorsatum (Linnaeus, 1758) Porcupine Description .— Erethizon dorsatum is a large ro¬ dent with distinct dorsal pelage that consists of long, yellowish and brown guard hairs intermixed with pale, dark tipped quills. The tail is relatively short, and the ears are small. Tire dental formula for E. dorsatum is: i 1/1, c 0/0, p 1/1, m 3/3, total 16. No measurements of E. dorsatum from BBRSP were obtained. Woods (1973) listed the following ranges of external and cranial measurements for the species: total length, 645 to 1030; length of tail verte¬ brae, 145 to 300; length of hind foot, 75 to 91; weight, 3.5 to 18 kg; greatest length of skull, 93 to 112. Males average considerably larger than females (Schmidly, \911a). The unique nature of the dorsal pelage of E. dorsatum makes it impossible to confuse this rodent with any other mammal at BBRSP Distribution .— E. dorsatum ranges from north¬ ern Mexico, northw ard throughout most of the western and northeastern United States, and across most of Canada and Alaska (Woods, 1973). No specimens of E. dorsatum are known from BBRSP, but it has been reported from the Fresno Canyon area (Scudday, 19766). Natural History — During this study, E dorsatum wns neither taken nor observed. Scudday (19766) re- 144 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY ported occasional encounters with porcupines at BBRSP, but found little evidence of tree damage caused by this rodent. He speculated that predation by mountain lions probably was responsible for the low numbers of por¬ cupines in the area. Based on this information, E. dorsatum should be considered rare at BBRSP. How¬ ever, the porcupine is known to exhibit considerable fluctuations in its population sizes (Woods, 1973), there¬ fore its status at the park is subject to changed. In the Trans-Pecos, E dorsatum is known to pre¬ fer rocky, forested mountains, as opposed to the flats, valleys, and gulches (Schmidly, 1977a) typical of BBRSP. The lack of suitable forested areas undoubt¬ edly contributes to the scarcity of this rodent in the park. Porcupines are active throughout the year (Roze, 1989), but may exhibit a decrease in activity during extended cold periods (Woods, 1973). In the Trans-Pecos, E. dorsatum breeds in late summer or early autumn, with the young being bom in April or May (Schmidly, 1977a). The gestation period of about 210 days is uncharacteristically long for a ro¬ dent (Roze, 1989). Typically a single young is bom, but apparently there are rare instances of twins (Woods, 1973). E. dorsatum typically forages at night (Roze, 1989). The diet of this rodent varies by season. Dur¬ ing the cooler months, porcupines subsist on the inner bark of trees, w hereas in the warmer months, they feed on a variety of plant parts including roots, stems, ber¬ ries, seeds, and flowers (Woods, 1973). Thcrmophylic cellulose-decomposing bacteria present in the gut aid in the digestion of these foods (Dodge, 1982). Porcu¬ pines do not receive adequate quantities of sodium in there diet, and therefore must actively ingest items that contain large amounts of this element, such as soil, salt- rich plants, and bone (Roze, 1989). E. dorsatum usually molts during summer, at which time the underfur becomes short or absent (Woods, 1973). Ectoparasites reported from E. dorsatum include mites, lice, fleas, and ticks (Roze, 1989). One of the mites, Sarcoptes scabei , is the etiologic agent of sca¬ bies (Woods, 1973), and severe epidemics of this dis¬ ease have been reported among porcupines. Endopara- sites known from porcupines include cestodes and nema¬ todes (Roze, 1989). Comments — The subspecies of E. dorsatum at BBRSP is E. d. epixanthum Brandt, 1835 . The generic name Erethizon is Greek for to irritate. The specific epithet dorsatum is derived from the Latin “dorsum,” meaning back (Stangl et al., 1993). Specimens Examined (0), ORDER CARNIVORA—CARNIVORES Family Canidae (Dogs and Allies) Can is latrans Say, 1823 Coyote Description .— Canis latrans is a medium-sized canine with a grayish-buffy dorsal pelage that is washed w'ith black, resulting in a grizzled appearance. The muzzle is long and narrow, the tail long, bushy, and black-tipped, and the ears are of moderate size. The dental formula for C. latrans is: i 3/3, c 1/1, p 4/4, m 2/3, total 42, but according to Davis and Schmidly (1994) molars may be 2/2, 3/2, or 3/3, resulting in a total of 40, 42, or 44 teeth. No measurements of adult C. latrans specimens from BBRSP were obtained. Schmidly (1977a) lists the following means of external measurements for coy¬ otes from the Trans-Pecos: total length, 1200; length of tail vertebrae, 400; length of hind foot, 180. The w eight of coyotes ranges from 14 to 20 kg (Davis and Schmidly, 1994). The greatest length of skull measure¬ ment for the subspecies that occurs in BBRSP averages about 200. Males average larger than females (Bekolf, 1977). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 145 Of the canids known from BBRSP, C. latrans is confused most easily with C. familiaris , the domestic dog. However, most domestic dogs do not have the gen¬ eral appearance as that described above for the coyote, and these two canids usually arc distinguished rather easily. In addition, cranial features of C. latrans and C. familiaris differ. In C. latrans , the lateral view of the dorsal profile of the skull is relatively straight, and the upper tooth row is greater than 3.1 times the width of the palate. In contrast, the lateral view of the dorsal profile of the skull shows a bulging forehead, and the upper tooth row is less than 3.1 times the palatal width in C. familiaris (Howard, 1949). C. latrans is distin¬ guished easily from Vulpes velox and Urocyon cinereoargenteus , the only other canids at the park, by its larger size. Distribution. — C latrans ranges from Central America, northward throughout Mexico, most of the United States and Canada, and into Alaska (Bekoff, 1977). One specimen of C. latrans from BBRSP exists from the Sauceda area (Fig. 52). In addition, coyotes were seen or heard at several locations tliroughout the park. Natural History. — Only one specimen of C. latrans was taken during this study, but animals and signs were observed on countless occasions Based on these observations, C. latrans should be considered common in BBRSP. C. latrans is adapted for a variety of habitats (Jones and Bimey, 1988), but in the Trans-Pecos, seems to favor desert scrub and grasslands (Schmidly, 1 911a), which may, in part, account for its abundance at BBRSP. The specimen taken at the park during this study was acquired from desert scrub dominated with creosote, opuntia, and mesquite. In addition, coyotes frequently were sighted in both desert scrub and grassland. Coyotes are known to be active tliroughout the year (Bekoff, 1977) and were observed as such at BBRSP. The breeding season of C. latrans in the Trans- Pecos extends from January to March, with parturition occurring from April through June (Schmidly, 1977a). Litter sizes vary in response to population densities (Knowiton, 1972) and food abundance, but in general, range from four to seven (Bekoff, 1977), with an aver¬ age of 5.1 (Knowiton, 1972). Females are monestrous, giving birth to a single litter a year (Bekoff, 1977). At BBRSP, a subadult w r as noted on 1 June. C. latrans primarily is nocturnal and crepuscular, but may be active at any time of the day (Caire et al, 1989). This canine tends to be most active in the early morning and around sunset (Bekoff, 1982). The diet of the coyote is extremely catholic and varies by geogra¬ phy and season. Major food items consumed by coy¬ otes include lagomorphs, rodents, birds, carrion, inver¬ tebrates, and fruits. In addition, C. latrans occasion¬ ally preys on large game animals, such as deer, and on domestic livestock. In these instances, young, old, and sick prey individuals primarily arc targeted (Bekoff, 1977). Typically, a single seasonal molt occurs in C. latrans. This takes place between late spring and early fall, with the guard hairs and undercoat of the summer pelage being shorter than those of the winter pelage (Bekoff, 1977). No parasites were noted on the one coyote taken at BBRSP This canid is known to harbor numerous parasites. Ectoparasites known from C latrans include ticks, fleas, and lice. Endoparasites known to infect C. latrans include numerous cestodcs, and nematodes. Pathogenic organisms that afflict coyotes include the plague and tularemia bacilli (Yersinia pestis and Francisella tularensis , respectively), and the distem¬ per and rabies viruses (Bekoff, 1977). Comments. — The subspecies of C latrans at BBRSP is C. /. texensis Bailc>, 1905. The generic name Canis is Latin lor dog. The specific epithet latrans is from the Latin “latrarc,” meaning bark (Stangl ct al., 1993). SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Figure 52. Localities of known specimens of Canis latrans from Big Bend Ranch State Park, Texas. Specimens Examined (1).— Presidio Co.: BBRSP, UTM coordinates: 13 603790E 3260448N, 1 Vulpes velox (Say, 1823) Kit Fox DescriptionVulpes velox is a small fox with a pale, grizzled gray dorsal pelage. The tail is long and bushy, and is gray in color except for a black tip. The ears are noticeably large. The dental formula for V velox is: i 3/3, c 1/1, p 4/4, m 2/3, total 42. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 147 No external or cranial measurements of V. velox from BBRSP were obtained. Mean external measure¬ ments (with sample size and extremes in parentheses) for the kit foxes in general are: total length, 788 (19, 730-840); length of tail vertebrae, 290 (19, 260-323); length of hind foot, 122 (19, 113-137); length of ear from notch, 85 (19, 78-94). Greatest length of skull measurements of 35 specimens averaged 114.4. The mean weight of V velox is about 2.1 kg . Secondary sexual dimorphism has not been documented, but males tend to weigh more than females (McGrew, 1979). V. velox might be mistaken for Ccmis latrans , C. famiHaris, or U. cinereoargenteus . However, the small size and fox-like appearance distinguish it from mem¬ bers of the genus Canis. The large ears and black-tipped (but not striped) tail distinguish the two foxes. In addi¬ tion, the skull of U, cinereoargenteus has temporal ridges that form the shape of a lyre, and each dentary' has a noticeable step at the posterioventral end, whereas the temporal ridge in V. velox is not lyre-shaped, and the lower margin of each dentary is smooth. Distribution .— The range of V velox extends from north-central Mexico, northward throughout much of the western United States (Egoscue, 1979; McGrew, 1979). Previously, it was known to occur as far north as south-central Canada, but this fox may have become extirpated from that area (Egoscue, 1979). V velox has been documented in BBRSP, but specific localities of its presence in the park are unknown. Natural History—- V. velox was not documented at BBRSP during this study. Pittman (1995) reported its presence in the park where he estimated its density at 0.1 individuals per km 2 during one year. These data indicate that the kit fox is rare in BBRSP In the Trans-Pecos, kit foxes inhabit open desert country-, and seem to be absent from rough, rocky situ¬ ations (Schmidly, 1977a). There are no data available as to the type of habitat in which kit foxes were en¬ countered at BBRSP. The only encounters of V. velox at BBRSP has been during the fall (Pittman, 1995). This fox is known to remain active throughout the year (Brown and Wemette, 1988). The breeding season of V velox extends from December through February. After an estimated gesta¬ tion period of 49 to 55 days, four or five pups are bom in February or March (Samuel and Nelson, 1982). Fe¬ males arc monestrous, breeding once a year (McGrew, 1979). V velox is monogamous, and has been reported by some to mate for life (Jones et al., 1983). V. velox primarily is nocturnal, but may be active at anytime during the day (Davis and Schmidly, 1994). Tliis fox relies on a variety of foods, including lago- morphs, rodents, birds, grasses (Samuel and Nelson, 1982), and insects (Brown and Wemette, 1988). In addition to nutrition, prey items may supply the water requirements of this fox (McGrew', 1979). No information is available regarding annual molt¬ ing in kit foxes. Ectoparasites associated with V. velox include fleas and ticks. Internal parasites include protozoans, cestodes, and nematodes (Samuel and Nelson, 1982). One of the cestodes harbored by this fox (Dipylidium caninum) occasionally infects humans (Brown, 1975). Comments.— The subspecies of V velox at BBRSP is V v. macrotis (Merriam, 1888). The generic name Vulpes is Latin for fox. The specific epithet macrotis is from the Greek “makros” and * 4 ous,” mean¬ ing long and ear, respectively (Stangl ct al., 1993) Pre¬ viously, the kit fox and swift fox were considered dis¬ tinct species, V macrotis and V velox , respectively (Wozcncraft, 1993). However, based on morphologi¬ cal and electrophoretic data, Dragoo ct al. (1990) sunk macrotis to subspecific status under velox. Specimens Examined (0). 148 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Urocyon cinereoargenteus (Schreber, 1775) Gray Fox Description .— Urocyon cinereoargenteus is a medium-sized fox with a grizzled gray dorsal pelage that is the result of guard hairs banded with white, gray, and black. The sides and legs are rusty, and a black stripe is present along the dorsum of the bushy tail. The ears are moderate in size. The dental formula for U. cinereoargenteus is: i 3/3, c 1/1, p 4/4, m 2/3, total 42. External and cranial measurements of an adult male from BBRSP are: total length, 1001; length of tail vertebrae, 441, length of hind foot, 140; length of ear from notch, 75; weight, 2.1 kg; greatest length of skull, 125.16. Males tend to be slightly larger than fe¬ males (Fritzell and Haroldson, 1982). U. cinereoargenteus might be mistaken for Ca- nis latrans or C. familiaris. However, the unique pel¬ age coloration and its fox-like appearance distinguish the former from the latter two. In addition, the skull of U. cinereoargenteus has temporal ridges that form a distinct lyre-shape, and each dentary has a noticeable truncated indentation or “step” at the posterioventral end, characteristics that are absent from the skulls of other canids known from BBRSP Distribution— The range of U. cinereoargenteus extends from southern South America, northward across Central America and Mexico, and throughout the United States, excluding most of the northwestern fourth of the country. It reaches its northern limits in southern Canada (Fritzcll and Haroldson, 1982). In BBRSP, this fox has been documented only from one locality in the Los Alamos area (Fig. 53). An additional individual was sighted just outside the park boundary' in the Cicncga area. Natural History. — Only one specimen of U. cinereoargenteus was collected during this study, and no additional individuals were sighted in BBRSP These data suggest that the gray fox is rather uncommon in BBRSP. In the Trans-Pecos, gray foxes are known to pre¬ fer mountainous regions with pihon-juniper forests. They reportedly associate with cliffs and canyons in these montane areas and usually do not occur in open desert or grassland that lacks juniper (Schinidly, 1977a), typical of most of BBRSP. The gray fox taken at BBRSP during this study was found in a shallow canyon with a small stream in the bottom. Associated vegetation in¬ cluded willow, false willow, cottonwood, oak, and wal¬ nut. The habitat above of the canyon was juniper roughland. The scarcity of juniper-associated habitats probably accounted for the rarity of this fox at BBRSP. U. cinereoargenteus is active throughout the year (Fritzell and Haroldson, 1982). The specimen taken at BBRSP w'as acquired in March, and the individual ob¬ served near the park w'as sighted in November. The breeding season of U. cinereoargenteus var¬ ies geographically (Samuel and Nelson, 1982). In the Trans-Pecos, this fox apparently breeds from January through March (Sclimidly, 1977a). An adult male from BBRSP had testes measuring 24 X 14 on 24 March. After a 53 to 63 day gestation period, one to seven (mean, 3.8, mode, 4) pups are bom. Following birth, males assist the females in raising the pups until au¬ tumn, at which time the pups begin to disperse (Sclimidly, 1977a). U. cinereoargenteus is mostly nocturnal or crep¬ uscular, but may be active during the daytime (Fritzell and Haroldson, 1982). Gray foxes are adept climbers; some foraging takes place in trees (Fritzell and Haroldson, 1982). The diet of this canid is diverse, and varies seasonally and geographically. Principal foods consumed include rabbits, rodents, juniper berries and other fruits, invertebrates, and fresh carrion (McKinncmey, 1978; Fritzcll and Haroldson, 1982). Adult gray foxes undergo a single annual molt that extends from summer through autumn (Grinnell et al., 1937). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 149 kilometers Figure 53. Localities of known specimens of Urocyon cinereoargenteus from Big Bend Ranch State Park, Texas. Another carnivore, Bassariscus as tutus, was taken at the same locality at BBRSP as U . cinereoargenteus. No parasites were noted in association with the one gray fox from BBRSP. Ectoparasites that U. cinereoargenteus is known to host include multiple spe¬ cies of mites, lice, and fleas. Endoparasites that infect this canid include trematodcs, cestodcs, and nematodes Bacterial diseases known to afflict gray foxes include tularemia (Francisella tularensis), listeriosis (Listeria monocytogenes ), and leptospirosis (Letptospira sp ). Viral diseases include rabies, canine distemper, and St. Louis encephalitis. The fungal disease histoplasmosis (Histoplasma capsulation) and the rickettsial disease Q-fcvcr (Coxiella burnetii) also occur in U cinereoargenteus (Frilzell and Haroldson, 1982). 150 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Comments. — The subspecies of U . cinereoargenteus at BBRSP is U. c. scottii Meanis, 1891. The generic name Urocyon is derived from the Greek “oura ,? and “kyon,” which translate to tail and dog, respectively. The specific epithet cinereoargenteus is from the Greek “cinereus” and “argenteus,” meaning ashen and silver, respectively (Stangl et al., 1993). Specimens Examined (1).— Presidio Co.: BBRSP, UTM coordinates: 13 615599E 3268863N, 1 . Family Ursidae (Bears) Ursus americanus Pallas, 1780 Black Bear Description .— Ursus americanus is a large, ro¬ bust carnivore with a dorsal pelage that ranges from cinnamon to brown to black in color. It has relatively short, stocky legs, a short tail, and small ears. Short, curved claws are present on all feet. The dental for¬ mula for U. americanus is: i 3/3, c 1/1, p 4/4, m 2/3, total 42. No measurements of U. americanus specimens from BBRSP were obtained. Schmidly (1977r/) lists the following means of external measurements for black bears from the Trans-Pecos: total length, 1500; length of tail vertebrae, 125; length of hind foot, 175. Black bears usually weigh between 54 and 158 kg, although they may weigh as much as 340 kg . Males are consid¬ erably larger than females (Ford, 1981). Because of its large size and unique appearance, U. americanus cannot be mistaken for any other mam¬ mal that occurs at BBRSP. Distribution .— U. americanus ranges from north- central Mexico, northward throughout most of the United States and Canada, including Alaska (Hall, 1981). No specimens of U. americanus are known from BBRSP. However, sightings of this bear have been re¬ ported from the Los Alamos area within the past five years. Natural History. — U. americanus was neither collected nor sighted at BBRSP during this study. How¬ ever, during the autumn of 1994, a female black bear and her two cubs were relocated to the park from a site near Langtree, Texas. Soon after their release, the three bears wandered outside BBRSP, apparently headed to¬ wards Big Bend National Park (Anonymous, 1995c). With the exception of these translocated individuals, the last black bear sighting at BBRSP was by a ranger about five years ago. Currently, U. americanus should be considered rare or possibly extirpated from BBRSP. Black bears typically inhabit wooded and forested areas (Nowak, 1991), but have been known to occur in the rugged lowlands of the Trans-Pecos (Schmidly, 1977 a). The last sighting of a non-introduced black bear occurred in juniper woodland. The lack of ad¬ equate wooded areas, along with excessive hunting and overgrazing (Schmidly, 1977a), probably account for scarcity of black bears at BBRSP. U americanus hibernates in the colder parts of its range (Davis and Schmidly, 1994), but is thought to be active tliroughout the year in Coahuila, Mexico (Baker, 1956). I assume the latter situation to apply to black bears in the BBRSP area. Black bears generally breed in June or July. Fol¬ lowing a gestation period of about 220 days, females give birth to one to five (usually 2 or 3) cubs in January or February'. Females typically breed every other year (Nowak, 1991). U. americanus may be nocturnal, diurnal, or cre¬ puscular, depending on the season and location (Ford, 1981). This bear feeds on a variety of plant and animal materials, but the former comprises at least 75 percent of its diet (Nowak, 1991). Typical food items include fruits, berries, nuts, grasses, roots, insects, rodents, birds, carrion, honey, and occasionally large mammals (Jones ct al., 1983; Now r ak, 1991). In nearby Coahuila, YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 151 Mexico, Baker (1956) found seasonal variation in the diet of black bears. Acorns were its main food in win¬ ter spring and fall, whereas fruits, berries, and animal products dominated the menu in late spring, summer, and early fall Sotol shoots and yucca leaves and blooms may be eaten at various times during the year. Occa¬ sionally, black bears may kill livestock, but these in¬ stances apparently are few (Nowak, 1991). Male black bears frequently cannibalize young bears (Bauer, 1985). U. americanus begins its annual molt in late spring. The process is gradual, not being completed until mid-autumn (Bauer, 1985). Ectoparasites known from U. americanus include ticks, lice, and fleas (Pelton, 1982). Endoparasites in¬ clude protozoans (Pelton, 1982), trematodes, and nema¬ todes (Ford, 1981; Jones et al., 1983; 1985). One of the nematodes that commonly infects U. americanus is Trichinella spiralis , the causative agent of trichinosis (Brown, 1975; Ford, 1981). Black bears also are known to be infected with the spirochaete Leptospira sp., the etiologic agent of leptospirosis (Ford, 1981). Comments .— The subspecies of U. americanus at BBRSP is U a. amblyceps Baird, 1859. The ge¬ neric name Ursus is Latin for bear. The specific epithet americanus refers to of (North) America (Stangl et al., 1993). Specimens Examined (0). Family Procyonidae (Raccoons and Allies) Bassariscus astutus (Lichtenstein, 1830) Ringtail Description .— Bassariscus astutus is a small, cat-like carnivore with a tan to pale brown dorsal pel- age that is washed heavily with black. The tail is long and bushy, and does not taper. The underside of the tail is whitish, whereas the top is distinctly annulated with 14 to 16 alternating dark brown and white rings The ears are relatively moderate in size, All feet have five digits and bear semi-retractile claw's. The dental for¬ mula for B. astutus is: i 3/3, c 1/1, p 4/4, m 2/2, total 40. External and cranial measurements of a tw o adult males from BBRSP are: total length, 708, 788; length of tail vertebrae, 348, 415; length of hind foot, 68, 73; length of ear from notch, 52, 50; weight, 950, 1300; greatest length of skull, 76.51, 83.07. Males generally are larger than females (Poglayen-Ncuwall and Toweill, 1988, Davis and Schmidly, 1994). The only other mammal at BBRSP that B. astutus might be confused with is P. lotor. However, these two procyonids are distinguished easily on the basis of size and build. B. astutus is small and rather slender, whereas P. lotor is larger and stout. Furthermore, the tail of B. astutus is long (longer than the head and body) and has 14-16 alternating rings of white and dark, as opposed to a short tail (less than length of head and body) with five to seven alternating buff and dark rings in P. lotor , Distribution .— The range of B astutus extends from southern Mexico, northward throughout Mexico, thence across the south-central, southwestern, and much of the western United States (Poglayen-Neuwall and Toweill, 1988). In BBRSP, ringtails have been recorded from the Ciencga and Los Alamos areas (Fig. 54). Natural History .— Two ringtails w ere taken dur¬ ing this study, and a third was sighted. However, B astutus undoubtedly is more common in BBRSP than these figures indicate. Relatively little effort was made to trap these small carnivores, and they are known to be quite secretive (Jones et al., 1985). In addition, what appeared to be ringtail scat frequently was observed among rocks in suitable habitat. Therefore, I believe B astutus to be fairly common in BBRSP B. astutus is known to inhabit a variety of habi¬ tats This procyonid favors areas with rocky outcroppings, or canyons associated with vegetation such as jumper and oak Ringtails also arc known to exploit riparian woodlands for their abundance of food and water (Poglayen-Ncuwall and Toweill, 1988). The 152 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY KILOMETERS Figure 54. Localities of known specimens of Bassariscus astutus from Big Bend Ranch State Park, Texas. two specimens acquired, as well as the one individual sighted, were in riparian woodland. Vegetation at two of the sites was dominated by willow, false willow, and cottonwood. Both of these sites were relatively flat and rocky outcroppings were absent. The third site where B. astutus was encountered was in a shallow canyon with a small stream at the bottom. Associated vegeta¬ tion included, oak, willow, false willow, walnut, and cottonwood. The area above the canyon was dominated by juniper and various scrub species. During this study, B . astutus was taken or ob¬ served in March and November. This mammal does not hibernate (Caire et al., 1989) and should be consid¬ ered active year round. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 153 B. astutus, in general, breeds from February to May, but most mating occurs during March and April (Poglayen-Neuwall and Toweill, 1988). The little re¬ productive data available from the Trans-Pecos indi¬ cate that breeding in the region is ongoing in April (Schmidly, 1977a). Adult males taken during this study had testes measuring 15X11 and 10 X 6 on 3 May and 8 November, respectively. The enlarged testes noted in May suggest that breeding in BBRSP continues into that month. Gestation ranges from 51 to 54 days, and parturition, therefore, probably occurs mostly in May and June (Poglayen-Neuwall and Toweill, 1988). Lit¬ ter sizes range from one to five (Poglayen-Neuwall and Toweill, 1988), but average about three (Schmidly, 1977a), B . astutus is almost strictly nocturnal, although some crepuscular activity has been documented (Poglayen-Neuwall and Toweill, 1988). This mammal is omnivorous, feeding on a wide variety of foods (Kaufmann, 1982). Some primary food items include small mammals, arthropods, and fruits (Poglayen- Neuwall and Toweill, 1988). Ringtails are excellent climbers (Jones et al., 1985), and some foraging un¬ doubtedly takes place up in trees. Due to an aversion to daylight that is acquired shortly afterbirth (Toweill and Toweill, 1978) and persists in adults (Kavanau and Ramos, 1975), ringtails rarely are active during the day (Poglayen-Neuwall and Toweill, 1988). However, dur¬ ing this study, an adult individual was sighted at 1200 h on a bright, sunny day. It was sitting motionless on a large, unshaded rock next to a stream. Ringtails are known to occasionally feed on frogs and fish (Poglayen- Neuwall and Toweill, 1988), and possibly this indi¬ vidual was foraging for these vertebrates, as both were abundant in the stream. Seasonal molting in adult ringtails commences in late summer and is complete by late autumn (Poglayen- Neuwall and Toweill, 1988). At BBRSP, a molting adult was observed on 8 November. Other species of carnivores taken at the same lo¬ calities as B. astutus at BBRSP included Urocyon cinereoargenteus , Procyon lotor, Conepatus mesoleucus , and Mephitis mephitis. No parasites were observed in association with B. astutus from BBRSP. Ectoparasites previously re¬ ported from ringtails include mites, ticks, lice, and fleas. Endoparasites known from B. astutus include cestodes and nematodes. Ringtails are known to be afflicted by the rabies virus (Poglayen-Neuwall and Toweill, 1988). Comments.— The subspecies of B. astutus at BBRSP is B. a. flaws Rhoads, 1894, The generic name Bassariscus is derived from the Greek “bassara,” which translates to fox. The specific epithet astutus is Latin for cunning (Stangl et al, 1993). Specimens Examined (2).— Presidio Co.: BBRSP, UTM coordinates: 13 576790E 329621 IN, 1; BBRSP, UTM coordinates: 13 615404E 3268775N, 1 . Procyon lotor (Linnaeus, 1758) Common Raccoon Description .— Procyon lotor is a stout, medium¬ sized carnivore with a dorsal pelage that is composed of coarse black, brown, buff, and rusty hairs, resulting in an overall grizzled grayish-black appearance. An obvious dark mask is present on the otherwise pale- colored face. The tail is relatively short, bushy, and has five to seven alternating dark brown and light bully rings. The cars are fairly small. All feet have five dig¬ its and bear non-retraclile claws. The dental formula for P. lotor is: i 3/3, c 1/1, p 4/4, m 2/2, total 40. External and cranial measurements of an adult male from BBRSP are: total length, 785; length of tail vertebrae, 242, length of hind foot, 110; length of car from notch, 60; weight, 5.0 kg; greatest length of skull, 114.54 Males are larger than females (Lotzc and Anderson, 1979). 154 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY P. lotor might be confused with the other procyonid known from BBRSP, B. astutus, but is distinguished easily as described in the previous account. Distribution. — P. lotor ranges from southern Cen¬ tral America, northward throughout Mexico, most of the United States, and much of southern Canada (Lotze and Anderson, 1979). In BBRSP, one specimen of P. lotor is known from the Cienega area (Fig. 55). In ad¬ dition, raccoons were noted at Sauceda, Lava Canyon, and along the Rio Grande. Natural History. — Only one specimen of R lotor was acquired during this study, but the distinct tracks of this mammal were observed on several occasions. Schmidly (1977a) reported raccoons as common in suit¬ able habitat throughout the Trans-Pecos, and this un¬ doubtedly is the situation at BBRSP. Throughout its range, R lotor utilizes a variety of habitats (Lotze and Anderson, 1979), and in the Trans- Pecos occurs just about anywhere there is a source of w ater (Schmidly, 1977a). All signs of raccoons noted at BBRSP were in areas associated with abundant wa¬ ter. An individual was taken and several tracks w r ere noted in riparian woodlands dominated by willow, cot¬ tonwood, and false willow. Additional tracks were seen along the Rio Grande among salt cedar, tree tobacco, and giant reed. Other tracks w r ere noticed in drainages transecting desert scrub. During this study, R lotor was noted during July and September. Raccoons, may exhibit a decrease in activity during cold periods, but do not hibernate (Lotze and Anderson, 1979) and should be considered active year round at BBRSP. The reproductive habits of R lotor vary through¬ out its range (Lotze and Anderson, 1979), In the Trans- Pecos, raccoons mate during February and March (Schmidly, 1977a). Following a gestation period of 60 to 73 days (Davis and Schmidly, 1994), two to four (mean, 3) young are bom in April or May (Schmidly, 1977a). On rare occasions, a second litter may be pro¬ duced (Lotze and Anderson, 1979). An adult male from BBRSP taken on 6 September had testes measuring 31 X 16. Raccoons primarily are nocturnal (Jones et al, 1983), although they are known to wander toward for¬ aging sites as early as 1600 h. They are omnivores, and seem to consume whatever foods are available. Major food items of R lotor include berries, nuts, and seeds of various plants, as well as miscellaneous inver¬ tebrates. Vertebrates are eaten at a lesser degree (Lotze and Anderson, 1979). Raccoons commonly are thought to wash their food prior to ingesting it. However, they may be feeling their food, rather than washing it, as individuals are known to rub their food between their hands in the absence of water (Whitney, 1933). The annual molt in R lotor begins in spring (Jones et al, 1985) and lasts throughout much of the summer (Lotze and Anderson, 1979). New guard hairs appear in fall, and by December, the pelage is in full winter condition (Jones et al., 1985). Other species of carnivores taken at the same lo¬ cality as P. lotor at BBRSP included Bassariscus astutus, Conepatus mesoleucus , and Mephitis mephi¬ tis. No parasites were noted in association with the specimen of P. lotor from BBRSP. Previously reported ectoparasites include ticks, lice, and fleas. Known en- doparasites include protozoans, trematodes, cestodes and nematodes. In addition, raccoons are known to harbor several agents known to cause disease in hu¬ mans, including the protozoan Trypanosoma cruzi (Chaga disease), the bacteria Francisella tularensis (tu¬ laremia), Leptospira sp. (leptospirosis), and Mycobac¬ terium sp. (tuberculosis), and the rabies virus (Lotze and Anderson, 1979; Jones et al., 1983). Comments. — The subspecies of P. lotor at BBRSP is P l. fuscipes Meams, 1914. The generic name Procyon is derived from the Greek “pro” and “kyon,” which translate to before and dog, respectively. The specific epithet lotor is modern Latin for washer (Stangl et al., 1993). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 155 KILOMETERS Figure 55. Localities of known specimens of Procyon lotor from Big Bend Ranch State Park, Texas. Specimens Examined (1).— Presidio Co.: Family Mustelidae BBRSP, UTM coordinates: 13 576783E 3296202N, (Weasels, Skunks, and Allies) 1 Taxidea taxus (Schreber, 1777) American Badger Description .— Taxidea taxus is a stout, short- legged mustelid with shaggy, grayish brown dorsal pel¬ age. A white mid-dorsal stripe extends posteriorly from 156 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY the nose as far back as the rump. Each side of the face has a black patch or “badge” that is surrounded by white. The tail is short, broad, and bushy, and the ears are small. All feet have five digits, the forefeet bearing long claws, and the hind feet with much shorter claws. The dental formula for T. taxus is: i 3/3, c 1/1, p 3/3, m 1/2, total 34. No measurements of T. taxus from BBRSP were obtained. Schmidly (1977a) reported the following average external measurements for male and female badgers, respectively, from the Trans-Pecos: total length, 788, 730; length of tail vertebrae, 133, 150; length of hind foot, 120, 114. The weight of badgers ranges from 4 to 10 kg (Davis and Schmidly, 1994). A single specimen taken just outside BBRSP had a great¬ est length of skull measurement of 125.37. Males are larger than females (Long, 1973). Its short, stout build and coloration of its pelage easily distinguish T. taxus from all other mammals known from BBRSP. Distribution .— T. taxus ranges from central Mexico, northward throughout the western three fourths of the United States and Canada (Long, 1973). No specimens of T. taxus are known from BBRSP How¬ ever, it has been sighted in the Temeros Creek area, and a specimen was collected just outside the park in the Cienega area. Natural History .— T. taxus was not collected at BBRSP during this study, and it was seen only on rare occasions. Badgers are not known to be common any¬ where in the Trans-Pecos (Schmidly, 1977a), and ap¬ parently that is the situation at BBRSP. Badgers are known to occur in a variety of habi¬ tats (Davis and Schmidly, 1994), but in the Trans-Pecos they seem to prefer desert flats and grasslands (Schmidly, 1977a). All sightings of badgers occurred in lowland desert scrub dominated by creosote-bush. A specimen collected just outside the park was found in that type of habitat. T. taxus was encountered in the vicinity of BBRSP during May and August. It does not hibernate, although it may spend proportionally more time in its underground den during cold weather (Lindzey, 1982). Badgers breed during late July and August. Fol¬ lowing fertilization, implantation of the blastocyst is delayed until Februaiy. Parturition occurs in late march or early April, at which time one to five young are bom (Lindzey, 1982). T. taxus primarily is nocturnal (Lindzey, 1982) or crepuscular (Jones et al, 1983), but may be active during the day as well (Long, 1973). Young of the year tend to be more diurnal than adults (Lindzey, 1982). Badgers primarily prey on burrowing rodents, espe¬ cially ground squirrels, but also will feed on other mam¬ mals, invertebrates, birds, snakes, and carrion (Long, 1973; Lindzey, 1982; Jones et al., 1983; Davis and Schmidly, 1994). Food items sometimes are cached in old dens for future consumption (Lindzey, 1982). There are reports of badgers teaming with coyotes in an effort to catch rodents (Long, 1973). Annual molting in adult badgers occurs in sum¬ mer or fall (Jones et al, 1983). Ectoparasites known to infest T. taxus include ticks, lice, and fleas. Various trematodes, cestodes, and nematodes are endoparasites reported from badgers. Agents of medical significance that T. taxus harbors in¬ clude the nematode Trichinella spiralis , the bacterium Francisella tularensis , and the rabies virus. In addi¬ tion, antibodies to Yersinia pestis have been detected in badgers (Lindzey, 1982). Comments .— The subspecies of T. taxus at BBRSP is T. t. berlandieri Baird, 1858. The generic name Taxidea is derived from the modem Latin “taxus” and Greek “idea,” which translate to badger and fomi, respectively. The specific epithet taxus is modem Latin for badger (Stangl et al, 1993). Specimens Examined (0). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 157 Mephitis mephitis (Sc h re be r, 1776) Striped Skunk Description .— Mephitis mephitis is a medium¬ sized skunk with a dorsal pelage that is solid black with two white stripes, one on each side of the back. Schmidly (1977a) reported that three different stripe patterns ex¬ ist among striped skunks from the Trans-Pecos. In each pattern, the two stripes are joined at the neck region where they divide into a “V.” In the broad-stripe phase, two relatively wide stripes extend from the neck to the rump. The narrow-stripe phase is similar, except that both stripes are fairly slender. The short-stripe pattern is similar to the narrow-stripe pattern, except that the two stripes extend only about halfway down the back. All striped skunks taken or observed at BBRSP were of the narrow-stripe variety. A narrow, white stripe is present between the eyes on the rostrum and forehead. The tail of this skunk is long, bushy, and usually con¬ sists of both black and white hair, although black seems to predominate. The ears are short and round. All feet have five digits; the forefeet bearing long, curved claws, and the hind feet with shorter, straighter claws. The dental formula for M. mephitis is: i 3/3, c 1/1, p 3/3, m 1/2, total 34. Means of external and cranial measurements (with sample size, extremes, and standard deviation in pa¬ rentheses) of adult specimens from BBRSP are: total length, 649.2 (6, 620-696, 27.0); length of tail verte¬ brae, 302.5 (6,260-341,31.3); length of hind foot, 69.8 (6, 65-73, 3.3); length of ear from notch, 28.2 (6, 26- 30, 1.8); weight, 1552 (6, 1150-2200, 391.2); greatest length of skull, 71.12 (6, 67.69-73.82, 2.55). Males are significantly larger than females (Wade-Smith and Verts, 1982). M. mephitis can be distinguished easily from C. mesoleucus , the only other skunk known from BBRSP, by having two narrow dorsal stripes as opposed to a single broad dorsal stripe as found in C. mesoleucus . Furthermore, M. mephitis has three upper premolars on each side, whereas C. mesoleucus has two. Distribution .— M. mephitis ranges from north¬ ern Mexico, northward throughout the United States and much of Canada (Wade-Smith and Verts, 1982). In BBRSP, M. mephitis was taken only in the Cienega area (Fig. 56), but was sighted in the Sauceda area and along the Rio Grande as well. Natural History — Six striped skunks were trapped during this study, and several additional indi¬ viduals were sighted. This species has been reported as common throughout the Trans-Pecos (Schmidly, 1977 a) as well as in parts of northern Coahuila (Baker, 1956), and evidently is common in BBRSP. Throughout their range, striped skunks are known to utilize various habitats (Wade-Smith and Verts, 1982), but in parts of the Chihuahuan Desert report¬ edly favor rough, rocky terrain (Schmidly, 1977a) and low elevation riparian habitats (Baker, 1956). All in¬ dividuals taken or sighted during this study were among the latter. The six striped skunks that were collected were trapped in riparian woodland dominated by wil¬ low, false willow, and cottonwood. An individual was sighted near the Rio Grande in association with salt cedar At BBRSP, striped skunks were encountered dur¬ ing May, July, August, September, and November. M. mephitis does not hibernate, but in the northern part of its range, enters a period of prolonged inactivity during winter. Throughout Texas, this skunk is active year round, but may show less activity during summer (Godin, 1982). M. mephitis breeds once (rarely twice) a year, usu¬ ally in February' or March. Following a gestation pe¬ riod of approximately 60 days, two to 10 (mean, 5) kits are bom in April or May (Schmidly, 1977a, Godin, 1982). At BBRSP, lactating females were noted on 3 and 6 July. Testicular measurements of males were as follows: 2 May, 19 X 14; 3 September, 20 X 10; 4 November, 17 X 13; 26 November, 22 X 6, 158 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Figure 56. Localities of known specimens of Mephitis mephitis from Big Bend Ranch State Park, Texas, Striped skunks primarily are nocturnal or crepus- ally hunts its animal prey by lying in wait or slowly cular, but occasionally may be active during the day. stalking its prey (Godin, 1982). Foraging activity typically begins around sunset. M. mephitis is omnivorous and is known to feed on a vari¬ ety of food items (Godin, 1982). In the Trans-Pecos, The annual molt in M, mephitis begins around its diet mostly consists of insects, w ith plant and verte- April, at which time the underfur starts to shed. Shed- brate material comprising only a small percentage ding of the guard hairs is delayed until July. At this (Schmidly, 1977a). Other invertebrates, as well as car- time, replacement of both underfur and guard hairs oc- rion and garbage, also are consumed. This skunk usu- YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 159 curs. The molting process is complete by early Sep¬ tember (Godin, 1982). Other species of carnivores taken at the same lo¬ calities as M. mephitis at BBRSP included Bassariscus astutus, Procyon lotor, and Conepatus mesoleucus. No ectoparasites were noted on specimens of M mephitis from BBRSP. Mites, ticks, lice, fleas, and bot¬ fly larvae previously have been reported to infest this skunk. Nematodes were collected from subcutaneous areas of several specimens at BBRSP. Additional en- doparasites known to infect striped skunks include pro¬ tozoans, acanthocephalans, trematodes, and ccstodes. Microbes of medical importance harbored by this skunk include Leptospira sp. (leptospirosis). Listeria monocytogenes (listeriosis), Francisella tularensis (tu¬ laremia), Aspergillus fumigatus (farmer’s lung). His- toplasma capsulatum (histoplasmosis), Coxiella burnetii (Q-fever), and the rabies virus (Godin, 1982). Comments .— The subspecies of M. mephitis at BBRSP is M m. varians Gray, 1837. The generic name (and specific epithet )Mephitis is derived from the Latin “mefitis,” which translates to noxious exhalation (Stangl etal., 1993). Specimens Examined (6).— Presidio Co.: BBRSP, UTM coordinates: 13 576785E 3296105N, 1; BBRSP, UTM coordinates: 13 576805E 3296248N, 2; BBRSP, UTM coordinates: 13 576699E 3296276N, 2; BBRSP, UTM coordinates: 13 576830E3296165N, 1 . Conepatus mesoleucus (Lichtenstein, 1832) Common Hog-nosed Skunk Description .— Conepatus mesoleucus is a fairly large skunk with a dorsal pelage that is solid blackish brown with a single thick, solid white stripe extending from the crown of the head to the tail. The tail is long, bushy, and completely white. The snout of this skunk is noticeably long and the ears are small. All feet have five digits and bear long claws. The dental formula for C. mesoleucus is: i 3/3, c 1/1, p 2/3, m 1/2, total 32. No measurements of adult C. mesoleucus speci¬ mens from BBRSP were obtained. Schmidly (1977a) lists the following means of external measurements for male and female hog-nosed skunks, respectively, from the Trans-Pecos: total length, 602, 551; length of tail vertebrae, 233, 215; length of hind foot, 68, 65; length of ear from notch, 27, 24. Davis and Schmidly (1994) list the range for the weight of this skunk as 1 to 2.7 kg. Males are larger than females (Davis and Schmidly, 1994). Of other mammals known from BBRSP, C. mesoleucus might only be mistaken for M. mephitis , but the two can be identified easily as described in the previous account. Distribution .— C. mesoleucus ranges from Cen¬ tral America, northward throughout Mexico, and into parts of the south-central and southwestern United States (Hall, 1981). In BBRSP, C. mesoleucus is known only from the Cienega area (Fig. 57). Natural History — One specimen of C. mesoleucus was taken during this study and an addi¬ tional individual was sighted This skunk reportedly is common in parts of the Trans-Pecos (Schmidly, 1977a), but is uncommon throughout most of its range (Davis and Schmidly, 1994), which appears to be the situation in BBRSP In the Trans-Pecos, C. mesoleucus is known to exploit a variety of habitats, including desert scrub, grasslands, and woodlands, but prefers rugged, rocky situations in mountainous areas (Schmidly, 1977a) Both encounters with hog-nosed skunks at BBRSP were in riparian woodland dominated by willow', false wil¬ low, and cottonwood. During this study, C. mesoleucus was recorded in September and November. This skunk is active year 160 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY I_l__J KILOMETERS Figure 57. Localities of known specimens of Conepatus mesoleucus from Big Bend Ranch State Park, Texas. round, although its activity patterns are known to vary by season (Davis and Schmidly, 1994). The breeding season of C. mesoleucus begins in February (Davis and Schmidly, 1994). Following a ges¬ tation period of about two months, two to four (mean, 3) young arc bom (Schmidly, 1977a). At BBRSP, a sub adult was noted on 6 September. Females may pro¬ duce two litters a year (Davis and Schmidly, 1994). Hog-nosed skunks primarily are nocturnal, but during winter may be more active during the daytime than at night. Typically they forage by overturning rocks and rooting in the soil in search of a variety of foods. Their diet varies by season, but insects seem to be the favorite food of these skunks. Other materials consumed include arachnids, small mammals, plant parts, reptiles, and mollusks (Davis and Schmidly, 1994). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 161 Nothing has been reported on the annual molt of C. mesoleucus. Other species of carnivores taken at the same lo¬ cality as C. mesoleucus at BBRSP included Bassariscus as tutus, Procyon lotor , and Mephitis mephitis . No parasites were found in association with the specimen of C. mesoleucus from BBRSP. Howard and Marsh (1982) speculated that this skunk harbors mites, ticks, lice, and fleas. The only endoparasite reported from the common hog-nosed skunk is a subcutaneous nematode, Filaria martis (Tiner, 1946). Skunks in gen¬ eral have been implicated as reservoirs for the rabies virus (Howard and Marsh, 1982), but I know of no re¬ ports of infected C. mesoleucus. Comments. — The subspecies of C. mesoleucus at BBRSP is C. m. mearnsi Merriam, 1902. The ge¬ neric name Conepatus is derived from either the Greek “konis” and “patein,” which translate to dust and walk, respectively, or the Aztec “conepatyl,” which means digging skunk. The specific epithet mesoleucus is from the Greek “mesos” and “leukos,” meaning middle and white, respectively (Stangl et ah, 1993). Specimens Examined (1).— Presidio Co.: BBRSP, UTM coordinates: 13 576783E 3296202N, 1 . Family Felidae (Cats) Fells concolor (Linnaeus, 1771) Mountain Lion Description .— Felis concolor is a large cat with a uniform tan or grayish brown dorsal pelage. The tail is long and black-tipped, and the ears are short, rounded, and nontufted. Each forefoot has five digits, with the pollex raised high above the other toes. Each hind foot has four digits. All toes bear sharp, retractile claws. The dental formula for F concolor is: i 3/3, c 1/1, p 3/2, m 1/1, total 28. No linear measurements of F. concolor from BBRSP were obtained. Schmidly (1977tf) reported the following external measurements for a male and a fe¬ male, respectively, from the Trans-Pecos: total length, 2134, 1778; length of tail vertebrae, 876, 698; length of hind foot, 127, 89; length of ear from notch, 108, 76; w r eight, 50 kg, 36 kg. The mean weight (with extremes and standard deviation in parentheses) of 11 adult moun¬ tain lions from BBRSP reported by Pittman (1995) was 46.1 kg (28.1-63.5 kg, 14.9 kg). Hoflmeister (1986) reported specimens of F concolor from southwestern North America with greatest length of skull measure¬ ments that ranged from 170.5 to 217.3. Males gener¬ ally are larger than females (Currier, 1983). F. concolor is not easily confused with any other species of mammal at BBRSP. It is distinguished eas¬ ily from the other felids known from the park, F catus and L. rufius , by its large size and uniform pale brown coloration. Distribution.— F. concolor ranges from north¬ ern South America, northward throughout Central America, Mexico, the United States, and much of south¬ ern Canada (Hall, 1981), although it primarily is found in the western third of the United States and Canada (Currier, 1983). In BBRSP, a specimen is known from the Solitario (Fig. 58). In addition to the Solitario, li¬ ons have been trapped at Panther Mountain, Alamo Spring, Fresno Canyon, Arroyo Segundo, Las Burras, Botella Spring, Las Quevas, Alazan, Madera Canyon, and southeast of La Mota (Pittman, 1995). Mountain lion signs were sighted in the Los Alamos area and near Papalote Colorado. Given home ranges of up to 903 km 2 (Pittman, 1995), these cats undoubtedly range throughout the park. Natural History. — No mountain lions were en¬ countered during this study. However, in conjunction with another study conducted by Texas Parks and Wild¬ life personnel, 20 mountain lions have been trapped in the park between 22 January, 1993, and 21 April, 1995 (Pittman, 1985). These figures suggest that F concolor is more abundant in the area than previously thought (Schmidly, 1977a) Throughout its range, F concolor is known to oc¬ cupy a wide variety of ecological situations (Currier, 1983). In the Trans-Pecos, this cat reportedly is most 162 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY KILOMETERS Figure 58. Localities of known specimens of Felts concolor from Big Bend Ranch State Park, Texas. abundant in mountainous habitats (Schmidly, 1977a). At BBRSP, trapping records suggest that mountain li¬ ons have an affinity for canyonlands, especially those associated with water (Pittman, 1995). Mountain lions have been captured at BBRSP from December through April, but active individuals were tracked throughout the year (Pittman, 1995), Mountain lions may breed at any time during the year, but mating most often occurs between January and June. The gestation period ranges from 82 to 96 days, and most young are bom between April and September (Currier, 1983). Pittman (1995) reported immature mountain lions at BBRSP on the following dates (with approximate age in parentheses): 4 February (2 to 4 weeks), 23 February (4 months), 24 February (2 YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 163 months), and 21 April (6 months). Litter sizes range from one to six, but average 2.4 (Currier, 1983). Fe¬ males typically breed every 18 to 24 months (McKinney, 1996). F. concolor primarily is nocturnal or crepuscular (McKinney, 1996), but may be active at any time of day (Jones et al., 1983). This cat is an opportunistic carnivore that preys on a wide variety of animals. Throughout its range, deer are the most important prey item, but other large mammals (occasionally including domestic livestock), small mammals, birds, fish, and insects also may be consumed (Currier, 1983). Adult males may cannibalize cubs (Jones et al., 1983). At BBRSP, Pittman (1995) found mountain lions to feed on (in descending order of importance) collared pec¬ caries, deer, and lagomorphs. F concolor typically hunts large prey by stalking (McKinney, 1996). It approaches to within about 15 m of the prey, takes a few strides, then leaps on the victim’s back. Rapid death of the prey is achieved by breaking the neck, crushing the esophagus, or puncturing the skull with a powerful bite. The kill is then dragged to an isolated area and fed upon. The remaining portion is covered with brush or other debris (but not buried), and often returned to later (Cur¬ rier, 1983; McKinney, 1996). Annual molting in F. concolor occurs in the spring. Known ectoparasites of F. concolor include mites, ticks, lice, and fleas. Endoparasites include protozo¬ ans, trematodes, cestodes, and nematodes. Agents of human disease harbored by mountain lions include Toxo¬ plasma gondii (toxoplasmosis), Trichinellaspiralis (tri¬ chinosis), Echinococcus granulosis (hydatid disease), and the rabies virus (Dixon, 1982). Comments. — The subspecies of F concolor at BBRSP is F c. stanleyana Goldman, 1938. The ge¬ neric name Felis is derived from the Latin “feles,” which translates to small carnivore. The specific epithet concolor is Latin for having the same color (Stangl et al., 1993). Some workers (Hemmer, 1978; Kratochvil, 1982) contend that F concolor does not belong in the genus Felis, but rather in the genus Puma. Thus, F concolor often is regarded as P. concolor (Wozencraft, 1993). I recognize the debate, but follow Jones et al. (1992) and retain F concolor as the scientific name for the mountain lion. Specimens Examined (1).— Presidio Co.: the Solitario, near Lower Shutup, 1 (SRSU). Lynx rufus (Schreber, 1777) Bobcat Description — Lynx rufus is a medium-sized cat w'ith a dorsal pelage that is rufus brown or grayish with numerous dark spots. The tail is short (typically shorter than the hind foot), and the ears are medium-sized, pointed, and slightly tufted. The forefeet have five dig¬ its with the pollex raised high above the other toes, and the hind feet have four digits. Each toe bears a sharp, retractile claw. The dental formula for L. rufus is: i 3/ 3, c 1/1, p 2/2, m 1/, total 30. No measurements of L. rufus from BBRSP were obtained. Schmidly (1977a) lists the following mean external measurements for males and a females, respec¬ tively, from the Trans-Pecos: total length, 870, 772; length of tail vertebrae, 146, 144; length of hind foot, 171,158. Weight typically ranges from 5 to 9 kg (Davis and Schmidly, 1994). HofTmeister (1986) reported specimens of L. rufus from Arizona with greatest length of skull measurements that ranged from 109.3 to 129.4. Males generally are larger than females (McCord and Cardoza, 1982). Among other mammals known from BBRSP, L. rufus might be mistaken for F catus , the feral cat, but can be differentiated easily on the basis of size and color pattern. The latter is larger and spotted, whereas the former is smaller and usually is not spotted. Also, L rufus has two sets of upper prcmolars versus three sets in F catus . Other than F. catus , the only other felid known from BBRSP is F concolor. L. rufus can be distinguished from this felid as describcrd in th previ¬ ous account. Distribution .— L. rufus ranges from Central Mexico, northw ard tliroughoul most of the United States and much of southern Canada (McCord and Cardoza, 1982). In BBRSP, the bobcat has been documented only from the Cicncga area (Fig. 59). 164 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Natural History .— The only sign of L rufus en¬ countered during this study was a single set of tracks. Schmidly (1977a) reported the bobcat as fairly com¬ mon throughout the Trans-Pecos, but Pittman (1995) estimated the density of L. rufus at BBRSP to be ex¬ tremely low as compared to estimates nationwide (McCord and Cardoza, 1982). L rufus is known to exploit a variety of habitats (McCord and Cardoza, 1982), but in the Trans-Pecos seems to prefer rocky canyons (Schmidly, 1977a). The only bobcat sign noted at BBRSP during this study was in a dry wash traversing desert scrub near riparian wood¬ land. During this study, L. rufus was noted only in No¬ vember. This cat is active year round, although pat¬ terns in daily activity may vaiy by season (McCord and Cardoza, 1982). The breeding season of bobcats begins in Febru¬ ary' and probably continues through April. Following a gestation period of about 62 days, one to eight (mean, 2-4) kittens are bom in late spring or early summer. A single litter is produced annually, although there is some speculation that, in rare instances, females may give birth to two litters a year (McCord and Cardoza, 1982). L rufus has been described as both a crepuscular (McCord and Cardoza, 1982) and a nocturnal hunter (Jones et ah, 1983). In either case, it seldom is active during the day. As are many carnivores, the bobcat is an opportunistic hunter, and will take almost any prey that is available. Favorite prey items of this cat that occur at BBRSP include desert cottontails, black-tailed jackrabbits, and woodrats. Occasionally this cat will kill and consume young deer and pronghorn (McCord and Cardoza, 1982). Bobcats typically capture prey by sitting motionless and waiting for its victim to wander within range of a single bound. The cat then pounces on the prey and subdues it with its sharp daws and ca¬ nine teeth (Jones et ah, 1983). A single annual molt in F. rufus begins in fall and is complete by late fall or early winter. No molt occurs in spring as the summer pelage actually is worn winter pelage (Jones et al., 1983). Ectoparasites known to infest L rufus include mites, lice, and fleas. Internal parasites documented to infect this cat include trematodes, cestodes, and nema¬ todes. Medically important organisms associated with bobcats include Leptospira sp. (leptospirosis), Brucella sp. (brucellosis), Salmonella sp. (enteritis), Toxoplasma gondii (toxoplasmosis), Pasturella multocida (septice¬ mia), and the rabies virus (McCord and Cardoza, 1982). Comments. — The subspecies of L. rufus at BBRSP is L. r. texensis J. A. Allen, 1895. The generic name Lynx is Greek for lynx. The specific epithet rufus is Latin for red (Stangl et ah, 1993). Some workers consider all North American felids to belong to the ge¬ nus Felis. I acknowledge this controversy, but follow Jones et ah (1992) and retain Lynx as a distinct genus. Specimens Examined (1).— Presidio Co.: BBRSP, Cienega Ranch, 1 (SRSU). ORDER ARTIODACTYLA—EVEN-TOED UNGULATES Family Bicotylidae (Peccaries) Tayassu tajacu (Linnaeus, 1758) Collared Peccary Description.— Tayassu tajacu is a medium-sized piglike mammal with a long, coarse, dorsal pelage that is grizzled grayish black in color. A pale, whitish col¬ lar is present about the shoulders. The snout is short and piglike. The tail is short and the ears are small. The feet are hoofed; the forefeet with four toes and the hind feet with only tliree. The canines are large, straight, and tusklike. The dental formula for T. tajacu is: i 2/3, c 1/1, p 3/3, in 3/3, total 38. No external measurements of T. tajacu from BBRSP were obtained. Schmidly (1977a) lists the fol¬ lowing mean external measurements for a single sped- 165 166 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY men from the Trans-Pecos: total length, 940; length of tail vertebrae, 55; length of hind foot, 180; length of ear from notch, 100. Davis and Schmidly (1994) re¬ ported the weight to range from 13 to 25 kg. The great¬ est length of skull measurement of a single specimen from BBRSP is 216.5. No sexual dimorphism has been documented in collared peccaries (Bissonette, 1982). The only other mammal at BBRSP that T. tajacu might be confused with is Sus scrofa , the feral pig. These two artiodactyls can be distinguished as follows. T. tajacu has a pale collar about its shoulders, three toes on each hind foot, upper canines that are directed downward, and two sets of upper incisors and three sets of upper premolars. In contrast, S. scrofa lacks a collar around the shoulders, has four toes on each hind foot, has upper canines that curv e upward and outw ard, and three and four sets of upper incisors and premolars, re¬ spectively. Distribution .-— The range of T tajacu extends from Central America, northward throughout much of Mexico, and into Texas, southern New Mexico, and Arizona (Hall, 1981). In BBRSP, specimens of col¬ lared peccaries are known from the Cienega Mountains, Sauceda, and Los Alamos areas (Fig. 60). Furthermore, T. tajacu was sighted throughout the park. Natural History. — Six specimens of T. tajacu were acquired during this study, and countless individu¬ als, as well as considerable peccary sign, were noted. Based on these observations, collared peccaries should be regarded as common in BBRSP Collared peccaries reportedly favor brushy habi¬ tats where prickly pear cactus is abundant (Davis and Schmidly, 1994). At BBRSP, these mammals were en¬ countered most frequently in such areas, but also were observed in grassland and riparian habitats. In addi¬ tion, T tajacu was common near human dwellings. Collared peccaries are active throughout the year, and were observed as such at BBRSP. They do, how¬ ever, exhibit seasonal fluctuations in activity patterns (Bissonette, 1982) T. tajacu is the only wild ungulate in the New’ World that breeds throughout the year (Davis and Schmidly, 1994). Typically, only the dominant (alpha) male mates with estrous females. Following a gesta¬ tion period of about 145 days, two to five young are bom. Typical litters consist of only two young, and in larger litters, seldom do more than two survive. Fe¬ males usually breed once a year, but are capable of mul¬ tiple births during a given year (Bissonette, 1982). At BBRSP, juveniles were noted in the population in March. The daily activity patterns of T. tajacu are known to vary by season. During summer, peccaries mostly arc nocturnal and crepuscular, whereas they are more diurnal in autumn and winter. This ungulate is social, and frequently was observed foraging in herds. The bulk of the peccary’s diet consists of plant material. Little or no animal material usually is consumed. Prin¬ cipal food items include the fleshy parts of prickly pear cactus and lechuguilla, as well as various forbs, grasses, seeds, and nuts. In addition to providing nutrition, prickly pear cactus apparently supplies most of the water requirements (Bissonette, 1982). Peccaries do not typi¬ cally root in the ground for food as do pigs. Rather they push around surface soil in an effort to turn up pieces of cactus and other plant material (Davis and Schmidly, 1994). At BBRSP, peccaries frequently were observed feeding on garden fruits, horse feed, and garbage near human habitations. Seasonal molting in T. tajacu apparently occurs by summer as hairs begin to fall off and bristles break at the tips. This results in a paler color, which allows for greater reflectance and less absorption of solar ra¬ diation. By winter, the pelage again becomes longer and darker (Sowls, 1984). Ectoparasites previously reported from T. tajacu include mites, biting lice, sucking lice, and fleas. En- doparasites include protozoans, trematodes, cestodes, and nematodes (Sowls, 1984). Comments. — The subspecies of T. tajacu at BBRSP is T. t. angulatus (Cope, 1889). The generic name Tayassu and the specific epithet tajacu are de¬ rived from the Tupi “taya” and “cu,” which translate to farinaceous tuberous root and eat, respectively (Stangl et al., 1993). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 167 kilometers Figure 60. Localities of known specimens of Tayassu tajacu from Big Bend Ranch Slate Park, Texas. Specimens Examined (6).— Presidio Co.: BBRSP, UTM coordinates: 13 601203E 3260197N, 1; BBRSP, UTM coordinates: 13 603273E 3263098N, 1; BBRSP, UTM coordinates: 13 614458E 3265716N, 1;BBRSP, UTM coordinates: 13 577589E 3287154N, I; BBRSP, UTM coordinates: 13 614933E 3267912N, 2 . Family Cervidae (Deer) Odocoileus he mi on us (Rafinesque, 1817) Mule Deer Description .— Odocoileus hemionus is a me¬ dium to large deer with a grayish tan dorsal pelage mixed 168 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY with black. The tail is short, white or buff above, and tipped in black. The ears are noticeably large. Di- chotomously branched antlers are present in males (rarely in females). Each foot has four toes, but only digits three and four are hoofed, the lateral toes being greatly reduced. The dental formula for 0. hemionus is: i 0/3, c 0/1, p 3/3, m 3/3, total 32. No external measurements of 0. hemionus from BBRSP were obtained. Schmidly (1977a) presented the following ranges of external measurements for males and females, respectively, from the Trans-Pecos: total length, 1370-1830,1160-1800; length of tail vertebrae, 106-230, 115-200; length of hind foot, 330-585, 325- 475; length of ear from crown, 118-250,118-243. Davis and Schmidly (1994) reported the weight of 0. hemionus to range from 57 to 102 kg, although large individuals have been known to weigh as much as 112.3 kg (Anderson and Wallmo, 1984). The greatest length of skull measurement of a male specimen from BBRSP is 301.5. Males are considerably larger than females (Anderson and Wallmo, 1984). 0. hemionus can be mistaken easily for 0. virginianus, the only other cervid at BBRSP. How¬ ever, these two deer can be separated on the basis of tail appearance, antler structure, ear size, and cranial morphology. 0. hemionus has a black-tipped tail, di- chotomously branched antlers, large ears, and a deep preorbital pit. On the other hand, 0. virginianus has a tail that is brown above with white fringe, antlers with a single main beam, smaller ears, and a shallow preor¬ bital pit. Distribution ,— O. hemionus ranges from north¬ ern Mexico, northward throughout the western United States and Canada (Anderson and Wallmo, 1984). Specimens of mule deer are known from scattered ar¬ eas in BBRSP (Fig. 61). In addition, O. hemionus w f as sighted throughout the park. Natural History. — During this study, eight speci¬ mens of O. hemionus were collected at BBRSP. In ad¬ dition, numerous individuals were sighted, indicating that this deer is fairly common at BBRSP. Mule deer usually do not occur in high densities, especially in open areas such as those typical of much of BBRSP (Mackie et al., 1982). Pittman (1995) estimated mule deer den¬ sities to be as high as 1.4 individuals per km 2 at BBRSP. Throughout the range of O. hemionus , open areas usu¬ ally support less than two deer per km 2 , and often less than 0.5 deer per km 2 (Mackie et al., 1982). These fig¬ ures suggest that the mule deer population at BBRSP is relatively healthy. 0. hemionus is highly adapted, and may utilize a w ide variety of habitats (Mackie et al, 1982). In the Trans-Pecos, this deer occupies almost all habitat types, but seems to prefer barren foothills and desert ranges 900 to 1500 m in elevation (Schmidly, 1977a). At BBRSP mule deer were encountered most often in such habitats. During this study, mule deer were encountered throughout the year. This deer is active year round, but often uses different parts of its home range at various times of the year (Mackie et al., 1982). 0. hemionus is polygynous, but practices a tend¬ ing-bond type breeding system rather than a harem- breeding system (Anderson and Wallmo, 1984). The breeding period occurs in autumn or early winter. Fol¬ lowing a gestation period of about 203 days, young are bom in summer. Typically, litters consist of tw o fawns but one is not uncommon; triplets are rare (Mackie et al., 1982). At BBRSP, a gravid female was examined on 13 May. Only a single fetus w as noted (crown-rump length, 1300); however, the deer was a fresh mountain lion kill and the one fetus was found a few meters from the carcass. It is conceivable that the doe was carrying more than one fetus at the time of the kill. 0. hemionus typically is crepuscular (Jones et al., 1983), but at BBRSP often was observed at night and during the day as well. This deer browses on several types of woody plants, but also is known to graze on grasses and forbs (Jones et al., 1983). Yucca, sumac, lechuguilla, and grama grasses were typical foods eaten by mule deer in the nearby Sierra Vieja (Anderson, 1949), and are likely to be consumed at BBRSP as well. Adult mule deer exhibit two annual molts. In late spring, the winter coat is replaced by a reddish summer pelage. Then in early fall, a dark gray winter pelage with woolly underfur replaces the summer coat (Mackie et al., 1982). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 169 L_l_ KILOMETERS Figure 61, Localities of known specimens of Odocoikus hemionus from Big Bend Ranch State Park, Texas. No parasites were noticed in association with O. hemionus from BBRSP. Ectoparasites reported previ¬ ously from mule deer include ticks, lice, and fleas. En- doparasites include protozoans, trematodes, cestodcs, and nematodes. Organisms of medical significance that have been associated with O. hemionus include Pas - teurella multocida (septicemia). Brucella sp. (brucel¬ losis), and Bacillus anthracis (athrax; Anderson and Walimo, 1984). In addition, mule deer arc known to harbor Ixodespacificus (Anderson and Walimo, 1984), a tick known to transmit Lyme disease (Bcnach et al , 1990). Comments. — The subspecies of O. hemionus at BBRSP is O. h crooki (Mcams, 1897). The generic name Odocoikus is derived from the Greek “odous" 170 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY and “koilos,” which translate to tooth and hollow, re¬ spectively. The specific epithet hemionus is from the Greek “hemionos” meaning half-ass (Stangl et al, 1993). Specimens Examined (8).— Presidio Co.: BBRSP, UTM coordinates: 13 580522E 3264400N, 1; BBRSP, UTM coordinates: 13 587667E 3266036N, 1; BBRSP, UTM coordinates: 13 597663E3252298N, 1; BBRSP, UTM coordinates: 13 602053E 3260740N, 1; BBRSP, UTM coordinates: 13 602506E 3260843N, 1;BBRSP, UTM coordinates: 13 603101E3263765N, 1; BBRSP, UTM coordinates: 13 612120E 3267800N, 1 ; BBRSP, UTM coordinates: 13 614618E 326611 ON, 1 Odocoileus virginianus (Zimmerm an n, 1780) White-tailed Deer Description .— Odocoileus virginianus is a small to medium sized deer with a dorsal pelage that ranges from reddish tan to grayish brown in color. The tail is short, brown above, fringed in white, and white below. The ears are relatively short. Males (rarely females) possess antlers that have a single main beam from which tines project vertically. The feet have four toes; the two middle digits are hoofed and the two lateral toes are reduced. The dental formula for O. virginianus is: i 0/3, c 0/1, p 3/3, m 3/3, total 32. No external or cranial measurements of O. virginianus from BBRSP were obtained. Krausman and Abies (1981) presented the following external and cranial measurements for a white-tailed deer from the Big Bend area: total length, 1512; length of tail verte¬ brae, 214; length of hind foot, 403, greatest length of skull, 242.3. The length of ear of white-tails in general typically ranges from 139to228(Schmidly, 1983). The weight of males and females average 47 kg and 30 kg, respectively. Males are larger than females (Krausman and Abies," 1981). O. virginianus might be mistaken for O. hemionus , but these two species of deer can be distin¬ guished as described in the previous account. Distribution .— O. virginianus ranges from north¬ ern South America, northward throughout Central America, Mexico, and most of the United States and southern Canada (Smith, 1991). No specimens of white¬ tailed deer are known from BBRSP; however, this spe¬ cies has been sighted along the Rio Grande. Natural History .— No specimens of O. virginianus were collected during this study, and no in¬ dividuals were sighted by me. This deer is known from BBRSP only on the basis of rare sightings by park natu¬ ralist David Alloway. O. virginianus probably is not a regular inhabitant of the park, but rather wanders into the area on rare occasions. O. virginianus is known to utilize a wide variety of habitats (Smith, 1991), but in the Big Bend region, this deer reportedly favors the high elevations of moun¬ tainous areas (Schmidly, 1977tf). The lack of this to¬ pography at BBRSP probably accounts for the transient status of white-tailed deer at the park. O. virginianus is active year round, but its use of habitat may vary by season (Hesselton and Hesselton, 1982). Throughout its range, white-tailed deer typically breed in the fall (Hesselton and Hesselton, 1982). How¬ ever, peak reproductive activity in the Big Bend area runs from mid-December through mid-January. Fol¬ lowing a gestation period of about 201 days, fawns are bom in July and August (Krausman and Abies, 1981). Almost all litters consist of twins (Hesselton and Hesselton, 1982), but litter sizes range from one to three (Smith, 1991). White-tailed deer are primarily crepuscular, but may be active at any time of day (Krausman and Abies, 1981). The specific diet of this deer varies by location and season (Smith, 1991). In the Big Bend region, it is knowm to feed on browse, forbs, succulents, and grasses (Krausman and Abies, 1981). O. virginianus molts two times a year. The sum¬ mer coat, which is acquired in early spring, is short, thin, and reddish in color. In late summer or early fall, the summer pelage is replaced by a longer, thicker, and darker winter coat (Hesselton and Hesselton, 1982). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 171 Ectoparasites documented to infest 0. virginicmus include ticks, lice, and botfly larvae. Endoparasites in¬ clude protozoans, trematodes, cestodes, and nematodes. 0. virginicmus is afflicted by several viral, bacterial, and fungal diseases. Those that are important from a medical perspective include Bacillus anthracis (an¬ thrax), Brucella sp. (brucellosis), and Mycobacterium tuberculosis (tuberculosis; Hesselton and Hesselton, 1982). Comments .— The subspecies of O . virginianus at BBRSP is O. v. carminis (Goldman and Kellog, 1940). See the account on Odocoileus he mi onus for the etymology of the generic name. The specific epi¬ thet virginianus refers to of Virginia (Stangl et al, 1993). Specimens Examined (0). Family Antilocapridae (Pronghorn) Antilocapra americana (Ord, 1815) Pronghorn Description .—- Antilocapra americana is a small, antelope-like mammal with a dorsal pelage that prima¬ rily is tan with white sides, rump patches, chest, throat bands, and cheeks. Dark markings are present about the head, chin, and neck. The tail is short and the ears are moderate in size. Both sexes may possess horns from which the homy sheaths are shed annually. The horns of males are long and pronged, whereas those of females are shorter and usually not pronged. Each foot has only two toes; lateral toes are absent. The dental formula for A . americana is: i 0/3, c 0/1, p 3/3, m 3/3, total 32. No external or cranial measurements of A. americana from BBRSP were obtained. Schinidly (1977a) reported the following mean external measure¬ ments of one male and one female from Presidio County: total length, 1325; length of tail vertebrae, 62; length of hind foot, 388; length of ear, 149. Members of the subspecies found at BBRSP average about 40 kg in weight (O’Gara, 1978). Females are somewhat smaller than males (Kitchen and O’Gara, 1982). The size, color pattern, and presence and mor¬ phology of horns make it difficult to confuse A. americana with any other species of mammal known from BBRSP. Distribution .— Populations of A americana are scattered from Central Mexico, northward throughout much of the western United States and parts of south¬ ern Canada (O’Gara, 1978). No specimens of pronghorns are known from BBRSP; however, this spe¬ cies has been sighted north of the Solitano near the northeastern park boundary. In addition, pronghorns were observed outside park boundaries in the Cienega Mountains area. Natural History. — A. americana was not encoun¬ tered in BBRSP during this study. It is known from the park only on the basis of an observ ation reported to me by David Riskind of the Texas Parks and Wildlife De¬ partment. Pronghorns are fairly common just north of BBRSP, but apparently are extremely rare in the park. A. americana typically inhabits grasslands and shrublands with low; rolling topography, a combination of grasses, forbs, and shrubs for foraging, and an an¬ nual precipitation of 25 to 35 cm (Kitchen and O’Gara, 1982). There are some areas of BBRSP that fulfill the first two requirements, but the precipitation rate at the park is far below what this ungulate typically requires. Individuals that occur in BBRSP probably wander in from the more optimal habitats to the north. Pronghorns are active throughout the year, al¬ though daily activity may vary by season (Kitchen and O’Gara, 1982). The early literature indicates that pronghorns are a harem-breeding mammal, but later studies suggest a territorial-breeding system (Kitchen andO Gara, 1982). The breeding season of A americana varies by geog¬ raphy (Kitchen and O’Gara, 1982), but in the Trans- Pecos is known to occur from late August through early October. Following a gestation period of about seven months, parturition occurs from early April to late May Typically twins are produced, but litter sizes range from one to three (Schmidly, 1977a). A. americana is known to be nocturnal, diurnal, or crepuscular, be seems most oltcn to prefer the latter Foods consumed by this species vary geographically 172 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY (Kitchen and O’Gara, 1982), but in the Trans-Pecos, it is known to forage on such plants as bitterweed, cut- leaf daisy, side-oats grama, blue grama, dalea, eriogonum, deer vetch, paper flower, coneflower, and woolly senecio (Schmidly, 1977a). Annual molt in A. americcma begins in late win¬ ter or early spring. By August, the old pelage is re¬ placed entirely with new, shorter pelage. The hairs of this new r pelage lengthen with the approach of winter (Kitchen and O’Gara, 1982). Ectoparasites reported to infest A. americcma include ticks and hippoboscid flies. Internal parasites include protozoans, trematodes, cestodes, and nematodes. Diseases known to afflict pronghorns are epizootic hemorrhagic disease, bluetongue, necrobacillus, vibriosis, actinomycosis, and keratitus (Kitchen and O’Gara, 1982). Comments. — The subspecies o fA. americana at BBRSP is A. a. mexicana Merriam, 1901. The generic name/I ntilocapra is derived from the Greek “antholops” and the Latin “capra,” which translate to beast with elongated horns and she-goat, respectively. The spe¬ cific epithet americana refers to of (North) America (Stangl et al, 1993). Specimens Examined (0). Nondomestic Introduced Species Nondomestic introduced mammals at BBRSP in¬ clude two species of bovids that are not indigenous to the park, but are known to occur there as free-ranging populations due to introduction into the area by humans. These two mammals are treated in the following abbre¬ viated accounts. Capra ibex Ibex Capra ibex is a large, reddish-tan to dark brown goat. Both sexes possess horns, with those of males being large (700 to 1400) and those of females consid¬ erably smaller (150 to 380). The horns of males are scimitar-shaped with a flat anterior surface that is bro¬ ken by prominent transverse ridges. Homs of females are more slender. Both sexes have a conspicuous woolly beard on the chin. No specimens from BBRSP were measured, but for the species in general, the total length ranges from 1250 to 1900, and the tail length ranges from 100 to 200. Weights range from 35 to 150 kg (Nowak, 1991). The characteristics of the horns and the presence of a beard distinguish the ibex from other ungulates at BBRSP. C. ibex is a native inhabitant of the European Alps and the mountains of India, Pakistan, Afghanistan, and northern Africa (Nowak, 1991). In the early 1970s, this goat was introduced into BBRSP for sport hunting. I did not encounter C. ibex during this study, but during the 1994 hunting season four individuals were taken in the park (Armendariz, pers. comm., 1996). The ibex is known to occur in open montane ar¬ eas up to 6700 m (Nowak, 1991). It rarely is encoun¬ tered in BBRSP, partially due the low number of indi¬ viduals that occurs there, and partially because of this goat’s attraction to rough, mountainous topography (Nowak, 1991). Ammotragus lervia Aoudad The aoudad, or Barbary sheep, is a robust, ru¬ fous-tawny colored bovid (Gray and Simpson, 1980) that shares characters with both goats and sheep (Manwell and Baker, 1977). Both sexes possess large, moderately long (up to 840), spiraled horns that project inward, or inward and downward. Shallow, uniform sulci and periodic growth rings may be present, but prominent transverse ridges are lacking (Gray and Simpson, 1980). A long ventral mane that extends down the neck to the chest is present (Nowak, 1991). In adults, this fringe of hair bifurcates and descends down the fore- limbs forming chaps. No specimens from BBRSP were measured, but large males taken in New Mexico had total lengths up to 1960, and weights up to 145 kg. Tail lengths of this species range from 175 to 205 (Gray and Simpson, 1980). YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 173 A. lervia can be distinguished easily from other ungulates at BBRSP by the presence of its unique horns, long ventral mane, and foreleg chaps. The aoudad is a native inhab itant of North Africa (Gray and Simpson, 1980), but for the purpose of sport hunting, was introduced into the United States during the early 1900s (Nowak, 1991). Several aoudads were released into the BBRSP area in the early 1970s (Armendariz, pers. comm., 1996 ). Annual public hunts for aoudads were held each year during the course of this study, but no individuals were taken. No speci¬ mens were collected during this study, but one individual was sighted in the Sauceda area. This species is known to occur in arid to semi arid regions from sea level to up to 1929 m in elevation (Gray and Simpson, 1980), and therefore might be found nearly anywhere in BBRSP. However, it is not commonly en¬ countered in the park, probably because only a small population resides there and because of the animal’s affinity for rough, rocky situations, and its ability to conceal itself by remaining motionless when threatened (Nowak, 1991). A major concern regarding the aoudad’s presence m BBRSP arises when considering the reintroduction of bighorn sheep. It has not been documented, but there is speculation that where the two species might occur sympatrically, the aoudad would out compete the big¬ horn for limited, shared resources (Barrett, 1967; Simpson et ah, 1978). Domestic Species Seven species of mammals that have been domes¬ ticated by humans and are known to occur in BBRSP are discussed in the abbreviated accounts below. Sci¬ entific and vernacular names follow Nowak (1991). Canis familiaris Domestic Dog Domestic dogs may take on a variety of sizes, shapes, and colors. Measurements for all breeds of do¬ mestic dogs combined range as follow's: total length, 360 to 1450; tail length, 130 to 510; weight, 1 to 79 kg (Anonymous, 1981). At BBRSP, domestic dogs poten¬ tially may be confused with coyotes, kit foxes, or gray foxes. For distinguishing characters, see the accounts on Canis latrans , Vulpes velox , and Urocyon cinereoargenteus. Free-ranging dogs are not common in BBRSP, but may occur anywhere in the park, especially in the Rio Grande Corridor. They are known to subsist on a vari¬ ety of foods, including deer, livestock, rodents, ground¬ nesting birds, carrion, and garbage. In addition, unre¬ strained pet dogs may be encountered, mostly in the vi¬ cinity of Sauceda. Fells catus Domestic Cat Depending on the breed, feral domestic cats may present a variety of morphotypes, but typically have the appearance of pet cats. The average total and tail lengths for several breeds combined are 460 and 300, respec¬ tively (Anonymous, 1981). The only mammal known to occur in BBRSP that F. catus might be mistaken for is the bobcat. See the account on the bobcat for a com¬ parison of characters. Free-ranging cats were noted in BBRSP only on rare occasions near human dwellings, but may be en¬ countered anywhere in die park, especially in die Rio Grande Corridor. They are carnivorous and may cause considerable damage to native wildlife, particularly songbirds (Lowery, 1974). Also, unrestrained pet cats are present in the Sauceda area. Equus caballus Domestic Horse Domestic horses vary greatly in appearance. They have a wide range of color patterns and sizes. Size usually is large with the average height at the shoulder about 1550, and average weight about 530 kg (Nowak, 1991). The domestic horse might be mistaken for the burro. Externally, these vary in that the horse is larger and usually has a mane of long hairs that hang down, whereas the burro is smaller and has a mane that usu¬ ally is directed upright. In addition, the burro usually is grayish with a dark cross on its shoulders Horses arc variable in color, but dark crosses on the shoulders usu- 174 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY ally are absent. Horses also may be mistaken for mules, which also occur at BBRSP. These animals are hybrids between E. cab alius and E. asinus (see the following account). Mules can be identified by their variable col¬ oration, absence of a dark cross, and presence of long ears (Anderson, 1972). No feral populations of the domestic horse occur in BBRSP. However, approximately 10 to 12 individu¬ als are maintained at the park for use by park person¬ nel. These animals often are allowed to roam free while grazing. They most frequently are seen in the grassy pastures near Sauceda. Equus asinus Burro The burro is horse-like in appearance, but smaller. It usually is gray in color, and often sports a dark cross- shaped pattern on its shoulders. The end of its muzzle, the rings about its eyes, and the hairs inside its ears usually are paler in color than the rest of the head (Anderson, 1972). Average measurements of individu¬ als taken in the wild are: total length, 2450; tail length, 450, height at shoulder, 1250; weight, 250 kg. The burro may be confused with the horse or mule, but can be distinguished as described in the previous account. Feral populations of E. asinus are common in the southwestern United States, but appear to be rare in BBRSP, where only a single individual was noted. It was sighted from a helicopter in desert scrub in the area between Alamito Creek and the Cienega Mountains. Wild burros are known to cause tremendous damage to the environment. Furthermore, this mammal is known to adversely affect desert bighorn populations via com¬ petition (Nowak, 1991). The presence of burros in BBRSP should be a concern given the plan to reintro¬ duce the bighorn into the park. Sus scrofa Domestic Pig Sus scrofa may present a variety' of appearances, but typically is large and squat in stature. The pelage is scant, usually consisting of only some stiff bristles and fine fur (Nowak, 1991). The fur is coarser and denser in feral individuals (Sweeney and Sweeney, 1982). To¬ tal length ranges from 1200 to 2100 and tail length is about 300. S. scrofa may weigh from 50 to 450 kg (Nowak, 1991). In the BBRSP area, S. scrofa can be confused only with the collared peccary. Distinguish¬ ing characteristics are presented in the account of the latter. Feral pigs are common in many regions of Texas, including areas along the Rio Grande (Jones and Jones, 1992). In the early 1970s, S. scrofa was introduced into BBRSP for sport hunting (Armendariz, pers. comm., 1996). Pigs were not encountered during this study, but one w f as sighted just outside park boundaries in the Cienega Mountains area, and the species, no doubt, still occurs in the park. As with most other non-native spe¬ cies, free-ranging populations of S', scrofa are known to adversely affect elements of the natural environment (Singer, 1981; Wood and Barrett, 1979). Bos taurus Domestic Cow The domestic cow is highly variable in appear¬ ance. The body is large and stout with short hair. Col¬ oration and the presence and appearance of horns var¬ ies, depending on the breed (Nowak, 1991). In the Texas longhorn, the breed that is maintained at BBRSP, color usually is a combination of browns and white, and both sexes have long, foreword-directed horns. However, cattle of other breeds from neighboring ranches fre¬ quently wander on to BBRSP, and these individuals may appear differently. Domestic cows usually have shoul¬ der heights that range from 900 to 1100, and weights between 450 and 1000 kg (Nowak, 1991). It is un¬ likely that these animals could be confused with any other mammal that occurs on the park. A herd of approximately 100 longhorn cattle is maintained at BBRSP. They reportedly are restricted to eight pastures within the park, one of w'hich is in the Sauceda area. Four additional areas have been desig¬ nated as alternative pastures. There is considerable op¬ position to these cattle from various environmental groups, which insist that the animals are destructive to the ecosystem. Proponents maintain that retaining the cattle will allow the park to preserve the culture of its ranching heritage (Anonymous, 1995a), YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 175 Capra hircus Domestic Goat As with most other domesticated animals, the goat takes on a multitude of appearances. Coloration is highly variable, and horns may be present or absent (Nowak, 1991). If present, horns are flattened from side to side (Ingles, 1965), and may be scimitar-shaped or spiraled, but lack strong transverse ridges (Nowak, 1991). Males possess a prominent beard under the chin (Anderson, 1972). Approximate measurements of C. hircus are as follows: total length, 1225 to 1525; tail length, 100 to 150; height, 760 to 1015 (Ingles, 1965). At BBRSP, the domestic goat might be mistaken for the aoudad or ibex. Distinctions are discussed in the accounts of those species. Feral goats are known from BBRSP but are not common. The skull of a single individual was acquired in a small cave in Lava Canyon. Because these goats are very nimble and can subsist on a variety of foods, they conceivably could be found anywhere in the park. As with other feral mammals, free-ranging goats are very destructive to the natural environment (Nowak, 1991). Species of Postulated Occurrence The following accounts pertain to native mam¬ mals that, based on their known distributions, may ex¬ ist in BBRSP but have yet to be documented there. Twenty-seven species of mammals are treated briefly in this section. Di del phis Virginian a Virginia Opossum The Virginia opossum is known from Trans-Pccos Texas, but, because of its intolerance of desert habitats, is rare in the region (Schmidly, 1977a). It favors areas near waterways (McManus, 1974; Gardner, 1982), and therefore, if present at BBRSP, would be restricted to areas along the Rio Grande and other watercourses in the park. Notiosorex crawfordi Desert Shrew The desert shrew is known from scattered loca¬ tions across the Trans-Pecos (Armstrong and Jones, 1972; Schmidly, 1977a). Records exist from Big Bend National Park to the east of BBRSP (Schmidly, 1977a), and from near Marfa, Presidio County, to the northwest (Yancey and Jones, 1996). In addition, N. crawfordi has been recorded from the nearby Mexican states of Chihuahua (Anderson, 1972) and Coahuila (Baker, 1956). It favors desert scrub habitat (Baker, 1956; Schmidly, 1977a), but also may be found in desert grass¬ land (Yancey and Jones, 1996). It is highly probable that this shrew resides in these types of habitats at BBRSP, probably having gone undetected because of the difficulty of collecting shrews by conventional meth¬ ods (Blair, 1954; Schmidly, 1977a; Jones et al., 1988). Scalopus aquaticus Eastern Mole The eastern mole is known from the Trans-Pccos on the basis of a single specimen acquired in 1887 (Schmidly, 1977a). It was taken from an unknown site in Presidio County (Allen, 1891), which at that time consisted of modern-day Brewster, Jell Davis, and Presidio counties (Baker, 1951). Therefore, the speci¬ men could have been taken in any of these three coun¬ ties. An additional individual of this species is known from the Sierra del Carmen of northern Coahuila (Baker, 1951; Yates and Schmidly, 1977; Schmidly and Yates, 1978). This mole favors soils that allow for easy bur¬ rowing and usually is absent from heavy' clay' or rocky soils (Yates and Pedersen, 1982). If the eastern mole occurs in BBRSP, it would most likely reside in the loose, moist soils along the Rio Grande (Schmidly, 1977a). Leptonycteris nivalis Mexican Long-nosed Bat The Mexican long-nosed bat has been recorded in Texas only from Big Bend National Park and the Chinati Mountains (Hensley and Wilkins, 1988, Schmidly, 1991) Because BBRSP is situated geo¬ graphically between these two sites, one might expect tins species to occur there as well However, these bats prefer mountainous areas of 1500 to 2300 m (Schmidly 176 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY 1991), which are less common in BBRSP than Big Bend National Park or the Chinatis. Furthermore, in Texas, L. nivalis relies on the nectar and pollen of century’ plants (Agave sp.) as its primary source of food (Schnhdly, 1991). These plants are common in the Chisos Moun¬ tains of Big Bend National Park and the Chinati Moun¬ tains (Powell, 1988), but are scarce in BBRSP. There¬ fore, it is conceivable that L. nivalis is absent from BBRSP due to the lack of suitable resources. Myotis auriculas Southwestern Myotis In the United States, the southwestern myotis is known from Arizona and New Mexico, but has yet to be recorded from Texas (Warner, 1982). Its occurrence also has been documented in Chihuahua and Coahuila, Mexico (Baker, 1956; Anderson, 1972). Because the projected range of this bat approaches the southern bor¬ der of BBRSP (Warner, 1982), and given its affinity for arid woodlands and desert scrub (Barbour and Davis, 1969), it is included as a possible inhabitant of the park. Myotis lucifugus Little Brown Myotis The little brown myotis is known from Texas on the basis of a single individual from the Trans-Pecos collected near Fort Hancock, Hudspeth County' (Findley and Jones, 1967; Schmidly, 1991). Because there are no shortages of buildings, trees, or rock crevices, the preferred roosting structures of M. lucifugus (Fenton and Barclay, 1980), it is not unlikely that this species exists in BBRSP. Myotis volans Long-legged Myotis Myotis volans is known from several localities near BBRSP, including the Guadalupe, Davis, Chinati, Chisos, Sierra Vieja (Schmidly, 1991), and Sierra del Carmen ranges (Baker, 1956). This species prefers high, mountainous, open woodlands, characteristic of these surrounding areas, but mostly absent from BBRSP. M. volans rarely occurs in arid lowlands (Warner and Czaplewski, 1984) typical of much of BBRSP. It may, however, occur in the park at some of the higher eleva¬ tions or as a transient during migration. Lasionycteris noctivagans Silver-haired Bat The silver-haired bat has been recorded from the northwest portion of the Trans-Pecos, but is unknown from the Big Bend Region (Schmidly, 1991). This bat typically is considered a forest-dwelling species (Kunz, 1982), w'hich would explain its absence from BBRSP However, during migration, L. noctivagans may be found in more xeric habitats (Schmidly, 1991) and should be regarded as a potential inhab itant of the park at this time. Lasiurus blossevillii Western Red Bat The western red bat has been recorded in Texas from only a single locality in the Sierra Vieja of Presidio County (Genoways and Baker, 1988; Schmidly, 1991). The species often is taken in riparian habitats consist¬ ing of cottonwood, oak, and walnut (Findley et al., 1975; Hoflmeister, 1986). Because of the close proximity of BBRSP to the Sierra Vieja and the presence of the above described habitat in the park, L blossevillii eventually may be found in the park. Lasiurus borealis Eastern Red Bat The eastern red bat is a common inhabitant of east Texas, but records are spotty in the Trans-Pecos where it mostly is restricted to mountainous habitats (Schmidly, 1991). It has been taken from the Chisos and Chinati mountains to the east and west of BBRSP, respectively. If L. borealis occurs in BBRSP, it probably does so only as a summer migrant, at which time it might be found in riparian woodland (Schmidly, 1991). Euderma maculatum Spotted Bat The spotted bat is known from Texas only from Big Bend National Park (Easterla 1970a; 1973; Sclunidly, 1991). In this area, E. maculatum is thought to roost in cracks and crevices of the w alls of deep can¬ yons (Easterla, 1970a). The most probable sites in BBRSP at which this species might occur are Colorado Canyon, Chorro Canyon, and Arroyo Segundo. YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 177 Nyctinomops femorosaccus Pocketed Free-tailed Bat The pocketed free-tailed bat is known from Texas only from Big Bend National Park (Easterla, 1968; Schmidly, 1991). It also is known from across the Rio Grande in Coahuila, Mexico (Easterla, 19706). It ap¬ pears to favor , desert areas with deep, rocky canyons (Easterla, 1973; Schmidly, 1991). Colorado Canyon, Chorro Canyon, and Arroyo Segundo seem to be the most probable localities where this bat might be dis¬ covered in BBRSP. Sylvilagus floridanus Eastern Cottontail In Trans-Pecos Texas, the eastern cottontail has been documented from several localities in the vicinity of BBRSP, including the Davis, Guadalupe, and Chisos Mountains. This species is found in pinon-oak-juniper woodlands at elevations from about 1500 to 2500 m (Schmidly, 1977a). As this habitat is lacking from BBRSP, it is unlikely that S', floridanus resides in the park. However, because the park is within the overall distribution of the species (Schmidly, 1977a, Chapman et al., 1980), the possibility of its presence should not be discounted. Spermophilus mexicanus Mexican Ground Squirrel The Mexican ground squirrel is known from throughout much of the eastern and central Trans-Pecos (Schmidly, \917a), but BBRSP lies outside its interpo¬ lated range (Schmidly, 1977a; Young and Jones, 1982). However, because S. mexicanus has been recorded from northern Presidio County, and in the Trans-Pecos pre¬ fers desert scrub habitats like those found in BBRSP (Schmidly, 1977a), this squirrel should be considered a possible resident of the park. Dipodomys spectabilis Banner-tailed Kangaroo Rat The banner-tailed kangaroo rat is well known from western and north-central parts of the Trans-Pecos, but records from the Big Bend area arc nonexistent (Schmidly, 1977a; Best, 1988). But, given that this kangaroo rat inhabits desert scrub and grassland habi¬ tats similar to those present at BBRSP, and that records exist from northern Presidio County (Schmidly, 1977a), this species should not be discounted as a possible resi¬ dent of the park. Reithrodontomys montanus Plains Harvest Mouse The montane harvest mouse is a rare inhabitant of the Trans-Pecos (Schmidly, 1977a). The closest record to BBRSP is one near the northern boundary' of Big Bend National Park (Jones et al., 1993). It was taken in scrub habitat identical to that found in areas of BBRSP. R. montanus probably occurs in the park, but, because it is uncommon in the area, its presence has yet to be confirmed. Peromyscus nasutus Northern Rock Mouse The northern rock mouse is known from scattered localities in the Trans-Pecos, including the Chinati and Chisos mountains (Schmidly, 1977 a). It seems to pre¬ fer rocky areas at elev ations greater than those that oc¬ cur in BBRSP (Schmidly, 1977a; Genoways et al., 1979). However, because P. nasutus has been recorded from such proximate localities, it is included as a pos¬ sible inhabitant of BBRSP. Sigmodon fulviv enter Tawny-bellicd Cotton Rat In Texas, the tawny-bcllicd cotton rat has been recorded only from the Davis Mountains near Fort Davis (Stangl, 1992a; 19926). Additional records from near BBRSP exist in northern Chihuahua (Anderson, 1972). The specimens from Texas were taken in dense grass with scattered mesquitc and catclaw r at an elevation of about 1580 m (Stangl, 19926). In Chihuahua, S. fulviventer was acquired from several sites al lower el¬ evations similar to those found in BBRSP (Anderson, 1972). 178 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Rattus norvegicus Norway Rat There are no known specimens of the Norway Rat from Trans-Pecos Texas (Schmidly, 1977a). This in¬ troduced species is presented in this section only on the basis of its close association with humans, and should therefore be considered a possible inhabitant where hu¬ mans and their dwellings exist (Jackson, 1982). Rattus rattus Roof Rat The black rat has been collected from nearby Al¬ pine in Brewster County, but no doubt occurs in all towns in the Trans-Pecos (Schmidly, 1977 a). As with the Norway rat, this non-native species is included in this section because of its association with humans. Mus musculus House Mouse The house mouse occurs throughout the Trans- Pecos, and can be found even at isolated human dwell¬ ings (Schmidly, 1977a/ Although not documented, this introduced mouse probably resides at many of the ranches located within BBRSP. Ondatra zibethicus Common Muskrat In Trans-Pecos Texas and Chihuahua, Mexico, the muskrat previously was a common inhabitant along the Rio Grande and its tributaries (Anderson, 1972; Schmidly, 1977a/ Recent rises in the human popula¬ tion in the area, as well as an increase in levels of w'ater pollution, have led to the demise of O. zibethicus in the Trans-Pecos (Schmidly, 1977a). It is possible, but not probable, that this species exists along the Rio Grande in BBRSP. Nasua narica White-nosed Coati The white-nosed coati is known from the Trans- Pecos on the basis of a single specimen collected from near Big Bend National Park (Schmidly, 1977a/ Lo¬ cal residents have reported the occurrence of A. narica in BBRSP, but these reports are unsubstantiated. The species prefers woodlands and rocky areas (Davis and Schmidly, 1994), both present in BBRSP, so an occa¬ sional individual may wander into the park from Mexico. Mustela frenata Long-tailed Weasel The long-tailed weasel is known from scattered areas across the Trans-Pecos, but is considered rare in the region (Schmidly, 1977a). It is known from Big Bend National Park (Schmidly, 1977a), and although there are no published accounts from Presidio County, I have examined a specimen from Marfa, Presidio County (SRSU 2452). M frenata is catholic in its habitat re¬ quirements (Davis and Schmidly, 1994), and it is prob¬ able that the species exists in BBRSP. Spilogale gracilis Western Spotted Skunk In Trans-Pecos Texas, the western spotted skunk is w idespread but records are rare. This skunk often is associated with rocky canyons, which are common in BBRSP (Schmidly, 1977a/ The species may occur in the park, but if so, probably at low numbers. Mephitis macroura Hooded Skunk The hooded skunk is the rarest skunk known from the Trans-Pecos, but has been documented from both Presidio and Brewster counties. It is a lowland species that prefers rocky canyons and densely vegetated wa¬ tercourses (Schmidly, 1977a), both common to BBRSP It probably occurs in the park in small numbers. Fells pardalis Ocelot The Ocelot is known from the Trans-Pecos on the basis of one specimen acquired in 1903 from a site be¬ tween Marfa and Terlingua, Brewster County (Bailey, 1905; Schmidly, 1977a). This locality is adjacent to what is now BBRSP. F pardalis may be found in a wide variety of habitats (Kitchener, 1991), but appears to prefer rocky situations with dense vegetation (Davis and Schmidly, 1994). As with the white-nosed coati, YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 179 there have been unsubstantiated reports of ocelot sightings in BBRSP. Given the habitat preference and the proximity of the historical record, it is concei vable that F pardalis occasionally may make an appearance in BBRSP. Extirpated Species This section includes brief accounts on two spe¬ cies of mammals that are known to have occurred dur¬ ing the historical past in what is now BBRSP, but are now absent from the area. Cants lupus Gray Wolf Gray wolves once were common in Trans-Pecos Texas, but resident populations presently are nonexist¬ ent. The last verified reports of C. lupus in the area date to 1970 (Davis and Schmidly, 1994). However, on rare occasions, individuals may wander into the re¬ gion from Mexico (Schmidly, 1977 a; Jones and Jones, 1992). The extinction of C. lupus in the Trans-Pecos was due, in part, to a campaign against the wolf be¬ cause of its depredation on livestock and game animals (Nowak, 1991). The extirpation of bison ( Bos bison), the wolf’s principle food in the region, also contributed its demise (Schmidly, 1977 a). Currently, the Mexican wolf (C. /. baileyi), the subspecies of gray wolf that occurs to the south of the Trans-Pecos in Mexico (Schmidly, 1977a), is under con¬ sideration for reintroduction into Big Bend National Park. Because the home range of C. lupus is known to be as great as 13,000 km 2 (Mech, 1974), the species undoubtedly would makes its way into BBRSP Ovis canadensis Mountain or Bighorn Sheep Once widespread in the mountainous areas of the Trans-Pecos, the mountain or bighorn sheep has suf¬ fered a fate similar to that of the gray wolf, albeit for different reasons. Extirpation of bighorns from the re¬ gion primarily was in response to the ascent of the sheep ranching industry. Domestic sheep outcompeted moun¬ tain sheep, and fences that accompanied the former pre¬ vented the latter from relocating. In addition, diseases transmitted from domestic sheep, as well as overhunting, contributed to the bighorn’s decline. The last docu¬ mented sighting of a native bighorn in the Trans-Pecos was in 1960 (Schmidly, 1977a). Since the extirpation of the mountain sheep in the Trans-Pecos region, the species has been reintroduced into several areas within the region (Davis and Schmidly, 1994). The reintroduction of 20 individuals into the Madera Canyon area of BBRSP is scheduled for the fall of 1997. CONCLUSIONS AND RECOMMENDATIONS With data obtained during two years of extensive field work supplemented by examination of museum specimens and a thorough review of the literature, sev¬ eral questions regarding the mammalian fauna of BBRSP were answered. Fifty-nine species of native mammals were verified to occur within the boundaries of BBRSP. In addition, two nondomestic introduced species and seven domestic species were documented to inhabit the park. There are 27 additional species that, based on their overall distribution, have a reason¬ able chance of occurring in the park. In addition to determining the number and kinds of species of mammals in the park, considerable data regarding the distribution and ecology of the mammals of BBRSP were acquired during the study. This infor¬ mation undoubtedly will be vital to Texas Parks and Wildlife personnel when considering the management of the BBRSP ecosystem. The following is a list of five common objectives of ecosystem management (Grumbine, 1994), with recommendations that apply to mammals for achieving these goals in BBRSP: 1. Sustain viable populations for each native spe¬ cies that occurs in the area.—The first action to achieve this goal is to continue collecting data on mammals in BBRSP. Efforts should focus on acquiring additional data on the diversity and distribution of mammals, as well as on long-term monitoring programs aimed at obtaining temporal data on the status of mammal popu¬ lations, especially those of species that were under-rep¬ resented in this study, such as Thomomys bottae y Sigmodon ochrogncithus , Neotoma mexicana , and sev ¬ eral species of bats. In addition to adding to our knowledge of the dis¬ tribution and ecology of mammals known to occur in BBRSP, continued sampling probably will result in the addition of new mammals to the current species list. Special effort should be made to determine if any spe¬ cies listed as threatened or endangered occur in the park. The most likely candidates that fit this description are Leptonycteris nivalis (state and federal endangered), Euderma maculatum (state threatened), Nasua narica (state threatened), and Felis pardalis (state and federal endangered). From each mammal specimen collected at BBRSP in the future, 1 recommend the collection of tissue samples consisting of skeletal muscle, liver, heart, kid¬ ney, spleen, lung, and brain. These materials, if archived in a suitable cryogenic facility, have the potential for serving as an important source of data for future re¬ search in conservation biology, molecular systematics, and public health issues (Baker, 1994) regarding the mammals of BBRSP. The curators and collections man¬ ager at the Natural Science Research Laboratory at the Museum of Texas Tech University have agreed to house and archive any such materials acquired from BBRSP. In addition to widespread sampling, long-term monitoring of sensitive areas is recommended. This research should focus on trends in mammal populations, especially those due to changes in the condition of the environment (e g., what are the effects of sustained drought on mammal populations at BBRSP?). I sug¬ gest periodic sampling of Arroyo Segundo, the Ciencga area, the Solitario (near Tres Papalotcs), the Las Quevas area, creek drainages near Sauccda, and the Los Alamos area (at the South Fork of Alamo de Ccsario Creek). Data acquired during these long-term monitoring programs should be maintained in the CIS system at TPWD headquarters. With this system, spatial and tem¬ poral data on mammals can be integrated with informa¬ tion regarding other taxa of animals, management deci¬ sions, land use, hydrology, physiography, and geology, as well as v egetation, water quality, pollution, and other aspects of the environment as they becomes available (Johnston ct al., 1994; D'Erchia, 1995). Examination of mammal data with respect to these attributes can then be prov ided to resource managers as a guide to making effective management decisions that will allow for the maintenance of viable populations of the native mam¬ mals of BBRSP. In the strict sense, achiev ing the goal of main¬ taining viable populations of all native species of mam¬ mals would require the re-introduction of extirpated species This action has received much consideration, especially regarding the Mexican wolf and the bighorn sheep However, because the areas adjacent to BBRSP primarily arc used lor livestock ranching, there is con- 181 182 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY siderable objection and political pressure against the reintroduction of a large predator, such as the Mexican wolf. Therefore, this mammal probably will not be¬ come part of the BBRSP fauna in the near future. On the other hand, there currently are plans for the re-in¬ troduction of the bighorn sheep into BBRSP. In the fall of 1997,20 Bighorns from Arizona reportedly are to be transplanted into the Madera Canyon area (Anonymous, 1995c). In preparation for the arrival of the bighorns, an attempt should be made to eradicate the non-native aoudad from the park. It is speculated that should these two bovids occur sympatrically, they would compete for similar resources, probably to the disadvantage of the bighorn (Gray and Simpson, 1980; Nowak, 1991). 2. Provide protected areas that consist of all na¬ tive habitat types.—Two areas w'ithin BBRSP seem quite appropriate with regard to this objective. The most ideal location is the Cienega Mountains region. This area consists of variable topography with a consider¬ able amount of desert scrub and desert grassland, and, with Cienega Creek running through the area, stretches of riparian habitat several km in length. Also, one of the few stands of juniper woodland in the park occurs on the southern slope of Cienega Mountain. Further¬ more, this region is especially important in terms of mammalian diversity and is inaccessible to the public. The other site I suggest for special consideration is the Los Alamos Ranch area including the northeast rim of the Solitario. In addition to the abundance of desert grassland and scrub in the area, the South Fork of Alamo de Cesario Creek provides a unique riparian area dominated by willow, w alnut, and oak. Moreover, there are scattered stands of juniper w oodland in the area. Tills area supports a substantial population of ghost-faced bats, a species considered rare elsewhere in the United States. Setting aside these sites as regulated protected areas will allow for managing biodiversity with what Grumbine (1994:29) termed a “systems perspective.” Management using this philosophy focuses on all hier¬ archical levels of biodiversity, not simply individual species, populations, or habitats. 3. Preserve natural ecological and evolutionary processes.—This includes the maintenance of distur¬ bance regimes, such as natural fire and floods, and the retention of natural hydrologic features of the park. It also includes preserving interspecific relationships be¬ tween native species, and prevents interactions between native and introduced species. This would require the re-introduction of extirpated native species as well as the removal of exotics. These topics were covered above in the discussion of goal number one. 4. Design long-term management programs— Programs for the management of the BBRSP ecosys¬ tem should be designed to last long enough to allow' evolutionary processes to function. Much of BBRSP has been disturbed by over 100 years of extensive graz¬ ing, and management plans for the recovery of the eco¬ system will require several years to reverse the effect. The indices of diversity and species composition pre¬ sented in this document can serve as baseline data when assessing the effectiveness of restoration efforts (Hall and Willig, 1994). Levels of diversity often can be used to appraise environmental disturbances (Margules and Usher, 1981), and fluctuations in species composition can serve as an indicator that the ecosystem is under stress (Lovell ct al., 1985). Long-term management policies should be flexible, allowing for new scientific data, changes in the unpredictable environment, and alterations in park conditions. 5. Accommodate visitor use.—This should be attempted with as little impact on the environment as possible. Access to environmentally sensitive areas, such as those mentioned under goal number one and two, should be limited Unfortunately, and not by coin¬ cidence, many of these areas are popular with park visi¬ tors. And as park visitation undoubtedly will increase in the future, so will its negative impact on these areas. However, complete prohibition of access to these places is unreasonable, as many of them are what attracts visi¬ tors to the park. A solution is to provide limited access to sensitive areas, possibly through small guided tours. Visitor safety regarding mammals is yet another concern. Many people fear mammals because of the diseases they are known to transmit. During 1994,177 mammals were tested for rabies, and all were negative. But, because this disease occurs in cyclic epidemics, especially in certain bats in the area (Jimenez Guzman, 1982), I suggest continued monitoring of bats and car¬ nivores in areas of heavy visitor usage. Also, a survey of the incidence of hantavirus and plague among ro- YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 183 dents would provide valuable information for park man¬ agement. Another issue involving park visitors centers on the presence of the longhorn cattle herd within the park. Proponents of the longhorns claim that they attract visi¬ tors to the park and that they are beneficial to the envi¬ ronment, whereas opponents maintain that they are an “eyesore” and are destructive to the environment. In¬ terestingly, there are no data from BBRSP that I know of that support either view. I suggest each visitor be given a questionnaire asking their opinion on the cattle. Did they really come to see the longhorns? Also, there should be a scientific study conducted to determine the effects of the cattle on the BBRSP ecosystem. As visitor use increases, so should interpretive programs and exhibits, especially on the lesser known mammals such as bats and rodents. Many patrons visit parks to acquire knowledge about the natural history of the area. To be informed of the diversity of mammals at BBRSP, as well as the unique natural history of many of them, certainly would increase the quality of their stay. ACKNOWLEDGMENTS This research was conducted as partial fulfillment for the degree of Doctor of Philosophy from Texas Tech University. I wish to thank my committee members, Clyde Jones, Robert Baker, Marilyn Houck, Richard Manning, and Kent Rylander, for their assistance and advice throughout this project and for reviewing the re¬ sulting manuscript. I also would like to recognize the late J. Knox Jones Jr., who served as co-chairman of my committee until his death in 1992. In addition to members of my committee, techni¬ cal support was provided by David Alloway, Michael Bogan, Amelia Greene, Meredith Hamilton, David Riskind, David Schmidly, James Scudday, David Sissom, and Richard Strauss. Many individuals provided assistance in the field during the course of this study. Because they are too numerous to mention individually, I would like to thank them collectively. However, a few f people helped ex¬ tensively, and I herein recognize their efforts. They are: Mary Ann Abbey, Jim Goetze, Clyde Jones, Richard Manning, and George Menzies. Mammals were collected in Big Bend Ranch State Park in accordance with scientific collecting permits issued by the Texas Parks and Wildlife Department (per¬ mit numbers SPR-0790, SPR-189, 4-94, 25-95). This project was funded by the Natural Resources Program (David Riskind, Director) of the Texas Parks and Wi ld¬ life Department. Logistic support was provided by per¬ sonnel of the Big Bend Ranch State Park (Luis Armendariz, Superintendent). 185 LITERATURE CITED Alcorn, J. R. 1941. Counts of embryos in Nevadan kangaroo rats (genus Dipodomys). Journal of Mammalogy, 22:88-89. Allen, J. A. 1891. Allen on mammals from Texas and Mexico. Bulletin of the American Museum of Natural History, 3:221. Alloway,B. 1995. El Camino del Rio-The River Road, FM 170 from Study Butte to Presidio and through Big Bend Ranch State Park. Texas Parks and Wildlife Department, Austin, 52 pp. Anderson, A. E,, and 0. C. 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W Manning. 1995 The eastern pipistrelle, Pipistrellus subflavus (Chiroptera: Vespcrtilionidae), from the Big Bend Region of Texas. The Texas Journal of Science, 47:229-231. Yancey, F. D., II, C. Jones, and J. R. Goetze. 1995, Notes on harvest mice {Reithrodontomys) of the Big Bend Region of Texas. The Texas Jour¬ nal of Science, 47:263-268. Yancey, F. D., II, and C. Jones. 1996. Notes on three species of small mammals from the Big Bend Region of Texas. The Texas Journal of Sci¬ ence, 48:247-250. Yancey, F D., II, P. Raj, S. U. Neill, and C. Jones. 1997. Survey of rabies among free-flying bats from the Big Bend region of Texas. Occasional Pa¬ pers, the Museum, Texas Tech University, 165: 1-5. Yates, T. L., and D. J. Schmidly. 1977. Systematics of Scalopus aquaticus (Linnaeus) in Texas and adjacent states. Occasional Papers, the Mu¬ seum, Texas Tech University, 45:1-36. Yates, T. L., and R. J. Pedersen. 1982. Moles (Talpidae). Pp. 37-51 in Wild mammals of North America: biology, management, and eco¬ nomics (J. A. Chapman and G. A. Feldhamer, eds.). The Johns Hopkins University Press, Baltimore, xiii + 1147 pp. Young, C. J., and J. K. Jones, Jr. 1982. Spermophilus mexicanus. Mammalian Species, 164:1-4. APPPENDIXI. DATABASE FOR ENTRY OF FIELD DATA The database below was used for field entry of data on mammals collected at Big Bend Ranch State Park during 1994 and 1995. The database was constructed using Microsoft Excel version 3.0 for Macintosh computers. A description of the 31 fields that comprise the database follows. SPEC NO COLL CAT NO TK NO TTU NO ORDER FAMILY GENUS SPECIES SEX TL TV HF EAR WT REPRO PELAGE PARA DAY MO YR CO QUAD EASTING NORTHING SITE HABITAT ASSOC VEG SUBSTRATE TOPO NOTES Explanation of fields : SPEC NO-Refers to specimen number assigned to mammals at BBRSP. COLL-Initials of collector/cataloger, CAT NO-Catalog number of preparator. TK NO-TK number (number applied to frozen tissue) of specimen. TTU NO-Museum catalog number of specimen. ORBER/FAMILY/GENUS/SPECIES/SEX-Self explanatory TL/TV/HF/EAR-Standard external measurements of specimen in mm. TL=total length, TV=tail vertebrae, HF=hind foot, Ear=ear. WT-Weight of specimen in grams REPRO-Reproductive data taken from specimen. PELAGE-Coded description of pelage condition of specimen. A=adult, AM-adult with seasonal molt, SA=subadult J=juvenile. PARA-Notes on ecto/endo-parasites observed on or collected from specimen. DAY/MO/YR-Day, month, and year specimen was collected. CO-County from which specimen was collected. For this study, the first letter of either county (Presidio, Brewster) was used as an abbreviation 203 204 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY QUAD-Coded reference for USGS quad within which locality of specimen lies. EASTING-Distance of locality, in meters, east of a point 500,000 m west of the center of UTM zone 13. NORTHING-Distance of locality, in meters, north of the Equator. SITE-Numerical reference to traplines/nets from which specimen was taken. HABITAT-Coded general description of habitat from which specimen was taken. DG=de$ert grassland, DS=desert scrub, J^junipcr woodland, R=riparian. ASSOC VEG-specific types of plants (in order of dominance) in area from which specimen was taken. SUBSTRATE-General description of substrate in area from which specimen was taken. TOPO-Coded general description of the topography from which specimen was taken. L=lowland, U=upland, C^canyon. NOTES-Field to add any additional information about a specimen that is not appropriate for other fields. APPENDIX II. GAZETTEER OF LOCALITIES SAMPLED All localities are based on UTM coordinates taken in zone 13. Symbols for methods of collection used at various localities are as follows: A=mist nets, B=Sherman traps, C=Museum Special traps, D=Victor rat traps, E=gopher traps, F=Conibear traps, G=Havahart traps, H=leghold traps, I^firearms, J=hand-capture, K=salvaged. UTM Coordinates Easting Northing A B 573986 3270053 X 575323 3292088 X 576060 3288074 X 576206 3268568 X 576311 3271128 X 576390 3296223 X 576550 576564 3295203 3295022 X X 576591 3295069 X 576609 3295115 X 576628 3294971 X 576646 3296118 X 576658 3296469 X 576674 3295147 X 576699 3296276 X X 576699 3296292 X 576708 3296384 X X 576712 3296232 X 576721 3296287 X 576730 3296319 X 576730 576757 3295308 3296109 X 576760 3295806 X 576773 3295277 X 576777 3296362 X 576783 3296292 X 576783 576785 3296202 3296105 X 576788 3296184 X 576790 3296211 X 576795 3296125 X 576796 3295418 X 576799 576804 3296134 3296151 X 576805 3296248 X 576808 3295784 X 576808 576823 3296211 3296177 X 576830 576836 3296165 3296251 X X 576837 3296137 X 576839 576842 3296085 3296279 X X 576844 3296174 X X 576844 3296251 X 576846 3296245 X Method of Collection E F G X X X X X X X X X X X H X X I X X X X X X X X X J K X 205 206 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Appendix n. (continued). UTM Coordinates Easting Northing A B 576855 576866 576872 576931 3295469 3295865 3295728 3296613 X 576947 3295987 X 576969 3296359 X 576970 3296222 X 576985 3295102 X 577000 3287710 X 577002 3296360 X 577050 3287705 X 577066 3296038 X 577099 3296389 X 577106 3291796 X 577120 3295040 X 577120 3295100 X 577192 3295041 X 577321 3287548 X 577436 3293201 X 577472 3287353 X 577526 3287386 X 577553 3287272 X 577563 3287242 X 577570 3287269 X 577589 3287154 X X 577690 3290260 X 577797 3287037 X 578146 3288978 X 578150 3286073 X X 578883 3292424 X 579237 3292359 X 579410 3289121 X 579592 579607 3269404 3269545 X 579684 3269447 X 579859 3292474 X 579888 580095 3269478 3264240 X 580196 3264339 X 580238 3264348 X 580320 3264432 X 580327 3264457 X 580342 3288931 X X 580522 580916 3264400 3264339 X 581230 3264998 X 581288 3268847 X 581659 3279903 X 582110 3288790 X 582656 582900 582906 3265713 3268000 3266716 X 583096 3272189 X 583205 3282984 X Method of Collection _ E_ V _G_H I X X X XX X X X X X X K X X YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 207 Appendix n. (continued). UTM Coordinates Easting Northing A B 583788 3266885 X 583846 3290112 X 584021 3269813 X 584337 584531 3269447 3266930 X 584964 3273523 X 585434 3286791 X 586777 3249651 X 586809 3262961 X 586843 3262914 X 586886 3265832 X 586907 3262929 X 586937 3262923 X X 586938 3262910 X 586973 3262923 X 586978 3262992 X 586983 3262860 X 586983 3262869 X 587062 587137 587184 3262884 3262985 3262927 X 587250 3262918 X X 587250 3262981 X 587263 3263005 X 587281 587302 3262891 3262817 X 587448 3262943 X 587490 3262902 X 587570 587667 588746 3249037 3266036 3247263 X 589301 3246448 X 589319 3246461 X 589348 3246503 X 589354 3246455 X 589699 3262276 X 589824 3265632 X 590260 3264372 X 590643 3262195 X 590668 590728 3261956 3245948 X 590980 3262597 X X 591022 591202 3261963 3262771 X 591209 3262798 X 591851 3245491 X 592496 3244969 X 592858 3262597 X 592898 592955 3261518 3259156 X 593789 3264731 X 593790 3264766 X 593918 3264842 X V 595150 3252057 X A _ Method of Collection D E F G X X X X X H I J_ X X X X X X X 208 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Appendix n. (continued). UTM Coordinates Easting Northing A 595478 3262749 X 595848 3258744 596232 3258492 X 596255 3262051 596699 3259093 596963 3264505 597319 3251802 597424 3260494 597543 3261182 597663 3252298 598044 3263850 X 598124 3263864 X 598125 3260852 598198 3260782 598236 3263889 X 598326 3263912 X 598459 3260646 599495 3261227 599506 3259765 599525 3261240 599556 3259992 X 599607 3261323 599751 3261864 599794 3261524 X 599811 3261545 X 599957 3261615 X 599992 3265848 600515 3252408 600518 3256679 600634 3263701 600665 3259720 X 600684 3259365 600689 3259514 X 600694 3259751 600786 3260060 600868 3256344 600914 3260458 601031 3260217 601059 3260130 601105 3260471 601154 3260197 601203 3260197 601221 3260400 601273 3260059 601325 3260789 X 601335 3260787 X 601452 3260625 601508 3260673 601560 3260590 601605 3241136 X 601619 3260741 601622 3260685 601632 3241210 X 601973 3253265 B_ X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X c X X D Method of Collection __ E_F_ G H X X X X X X I X X X K X X X X YANCEY— MAMMALS OF BIG BEND RANCH STATE PARK 209 Appendix II. (continued). UTM Coordinates Easting Northing A B 602053 3260740 602211 3256243 X 602357 3260937 602473 3260516 602487 3241236 X 602506 3260843 602666 3260640 X 603101 3263765 603273 3263098 603790 3260448 603960 3241085 X 604886 3240689 X X 605201 3260431 X 605576 3257735 X 605667 3261229 X 605746 3261330 X 605774 3261181 X 605895 3261011 606085 3259112 X 606207 3256765 X 607243 3255556 X 607355 3255359 X X 607610 3263630 608255 3239563 X X 608309 3239482 X 608427 3250324 X 608437 3253203 X 608477 3253180 X 608597 3253243 X 608608 3253227 X 608629 3262171 X 608642 3253280 X 608747 3264582 X 608776 3253333 X 608870 3253520 X 608955 3253483 X 609027 3253496 X 609289 3253592 X 609394 3249918 X 609405 3261495 X 609522 3249929 X 609585 3249854 X 60% 11 3260698 X 609770 3253645 X 609772 3249673 X 611283 3249529 X 611393 3249399 X X 612120 3267800 612321 3268161 X 612594 3268946 v 612683 3265440 A V 613639 3265303 A V 614094 3266037 A 614303 3264882 Method of Collection E F G X X H I _J K X X X X X X X X X X 210 SPECIAL PUBLICATIONS, MUSEUM TEXAS TECH UNIVERSITY Appendix II. (continued). UTM Coordinates Easting Northing 614350 3268071 614360 3268395 614458 3265716 614618 3266110 614672 3246532 614933 3267912 614933 3246380 614935 3268144 615033 3263895 615063 3261184 615371 3261358 615404 3268775 615409 3268594 615458 3268807 615504 3263238 615515 3268870 615525 3268958 615559 3268762 615565 3268878 615599 3268863 615650 3268869 615747 3255837 615786 3263185 615800 3238476 615947 3262894 615951 3263099 616012 3263115 616984 3256548 617223 3256581 617281 3261484 617505 3256674 617542 3237777 618185 3257611 618322 3258007 619081 3260561 619125 3258986 619408 3260416 620694 3240946 620726 3238321 620927 3238664 621243 3239655 Method of Collection E F G J K V