MANEMALE 01‘ NUKIHEABWKN uumamuv, "luau-v Thais fa? (”he £16m“ :25 M. S. MYEHIGAN STATE UNWERSETY Jahn Kaever Gram E960 ‘‘‘‘‘ ‘‘‘‘‘‘‘ ”WMITI'IWHWWWWW ; 93 00108 5525 g LIB R A R Y ‘ Michigan scan University (1" MSU ’ RETURNING MATERIALS: PIace in book drop to LIBRARIES remove this checkout from -:—. your record. FINES will » be charged if book is returned after the date stamped below. 1 rg‘gwqgfi / W MAMMALS 0F NORTHEASTERN'DURANGO, MEXICO BY John Keever Greer AN ABSTRACT OF A.thesia submitted to the College of Science and Arts Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Zoology Approved W THESIS ABSTRACT This report will contribute to our knowledge of the natural history of a poorly-known part of Durango, Mexico. The study area includes part of a large inland basin known as the Bolson de Mapimi. Approxi- mately 10,000 square miles in northeastern.Durango are divided into three arbitrary plant-soil associations to facilitate the separation of small mammal papulations. Small mammals were trapped and game were studied to determine their occurrence and relative abundance and effect of land-use on their distribution. .Also, data.were obtained pertaining to habitat preference and competition between related and unrelated small mammals. Some mammals were found to have narrowly restricted habitats; others were widespread. Evidence shows that increased utili- zation by man of previously undisturbed areas has adversly affected the status of game and locally diminished papulations of many small mammals. Data on.which this report chiefly is based.was obtained by field parties from the Museum, Michigan State University in the summers of 1958 and 1959. ACKNOWLEDGMENTS CONTENTS LIST OF PLATES AND FIGURES INTRODUCTION . . . . 'METHODS . . . . LOCALITIES IN NORTHEASTERN DURANGO . TOPOGRAPHY . . . CLIMATE . . . . LAND USE . . . . . . CONSERVATION OF MAMMALS . . . . . . PLANT-SOIL ASSOCIATIONS Desert Association . . . . . . . Mixed Grassland Association . . . . Alluvial Association . . . . . . MAMMAL HABITAT RELATIONSHIPS CHECK-LIST OF EXTANT MAMMALS OF NORTHEASTERN DURANGO ACCOUNTS OF SPECIES AND SUBSPECIES . . . HYPOTHETICAL LIST OF ADDITIONAL MAMMALS . SUMMARY . . . . LITERATURE CITED page . 10 10 .13 16 .18 .20 42 4S PLATES AND FIGURES l. The Desert Association . . . . .I. . . . . . . . . 2. "La Cueva de Los Indios" . . . . . . . . . . . . . 3. The Mixed Grassland Association . . . . . . . . . 4. The Mixed Grassland Association . . . . . . . . . S. The Alluvial Association . . . . . . . . . . . . . 6. The Alluvial Association . . . . . . . . . . . . . FIGURES 1. Northwestern Mexico showing the location of the B0186n de Ma‘Pimi O O O O O O O O O O O O O 0 page 12 12 .14 .14 l7 l7 2 2. Plant-Soil.Associations in Northeastern.Durango . . . . . .4 MAMMALS OF NORTHEASTERN DURANGO, MEXICO by John Keever Greer A.THESIS Submitted to the College of Science and Arts Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Zoology 1960 ACKNOWLEDGMENTS I want to thank Leslie C. Drew of the Museum staff and Robert G. Webb of the University of Kansas for their valuable c00peration and companionship in the field undertakings. ‘ Ing. Luis Macias Arellano, 31 Director General de Caza, Departamento de Conservation de la Fauna Silvestres de Mexico, graciously issued a permit allowing for the collection of animals in Mexico. I appreciate the assistance given me by residents of northeastern Durango: Peter Barboglio, owner of the Guitarra ranch; Frederico Hermosillo, owner of the San Javier farm and cotton exporter; N.B. Honeycut, owner of the Pelayo ranch; Thomas l-Iorkay, engineer for the electrical company in Torredn, Coahuila; Manuel Medina, M.D., Professor in the School of Medicine, University of Coahuila; Fernando Patifio, mine inspector in the state of Coahuila; Panfilo Sanchez, Torredn, Coahuila, businessman and big-game hunter; Lewis Wheless and his family, owners of the Cortijo ranch; the cowboys and goatherds, "campesinos", who were always available to answer questions concerning the wildlife. I also appreciate the help of the members of the guidance comittee, Marvin Max Hensley and c.w. Prescott and am especially grateful to the head of the comittee, Rollin H. Baker, for his advice and encouragement. Financial assistance for field work was provided, in part, by the Michigan State University Deve10pment Fund. INTROUCTION The northeastern part of . the Mexican state of Durango is included within a large inland basin known as theBolsdn de Mapimi(see Figure 1) , which also encompasses parts of Chihuahua and 'Coahuila. This vast area with its deserts and low mountain ranges offers an excellent opportunity for the biologist to study both restricted and wide-spread mamalian . species. Although the basin is large, few biologists have studied in the area and little has been published concerning its biota. The pre- sent knowledge of the distribution of the fauna has been interpreted largely from isolated records reported in the literature. Zoologists from Michigan State University have been studying the fauna inhabiting the deserts and mountains of Durango since 1957. Data on which this report is chiefly based were obtained by field parties from the Museum in northeastern Durango in the sunners of 1958 and 1959. This report is submitted as a contribution to our knowledge of the natural history of this poorly-known part of Durango. METHODS Manuals in northeastern Durango were collected by various means to determine their distribution and relationship to the environment. Museum special traps as well as other collecting devices were used to sample small rodent populations; collecting guns were used to obtain larger species of manuals; and mist nets were stretched over water sources and in the mouths of caves to snare bats. Specimens were identified with the assistance of Rollin H. Baker and deposi‘ ted in the collections at The Museum, Michigan State \06 ‘04 I02 CHIHUAHUA Figure 1. Northwestern Mexico showing the location of the Bolsdn de Mapimi. University. The arrangement of genera in this report follows that of Miller and Kellogg (1955). Measurements given are for adults and are in millimeters; weights are given in grams. Most distances were measured by car speedometer, and elevations are listed in feet. Notes on habitats were recorded at each collecting station, and local residents, farmers and ranchers, were questioned as to the ' occurrence and abundance of game and small manuals. In this account, northeastern Durango is divided into three arbitrary associations of plants and soils (see Figure 2) to facilitate the separation of mam- mal populations. Maps of northeastern Durango mark highways and railroads connecting the larger villages but leave a major portion of the'area, which is lightly populated, poorly charted. The names used as localities appear on one or more of the following maps: N.G-13‘ (Culiacan), of the American Geographical Society of New York, Scale: l:l,000,000; Lake Santiguilla 521, of the World Aeronautical Charts of the United States Air Force Aeronautical Information Service, Scale: l:l,000,000; the Carta Geoldgica de La Parte Septentrional de la Repdblica Mexico by Phillip B. King (1947) published .in collaboration with the Geological Survey, United States-Department of Interior; and the map of the state .of Durango prepared by the Departamento Geogragico, Oficina de I Cartografia y Calcula, Mexico. The following is a list of place-names in northeastern Durango used in recording localities from which manuals were collected in the sunners of 1958 and 1959 or which is concerned with the distribution 25 '04 T Lozuna de La Dolomns [19,02 .. .' HP?" '.'-'_- -..- /«.*‘:-H=-ZA¥AL25.:; , '-: .. T ‘- 4t§g .a. A. .L .. --— me' or STUDY AREA |04 26 Figure 2. Plant-soil Associations in Northeastern Durango pattern of mammals. in feet. LOCALITIES IN NORTHEASTERNWDURANGO Localities Zavalza Villa Ocampo Yermo Las Nieves Conejos Bermejillo Boquilla Campans Tlahualilo Gregio Garcia Rancho Tres Hermanos Indé Sancho Guitarra Zarca Mapimi Dinamita Cadena deez Palacio Palmito Longitude LatitUde 104°16' 105°30? 104°03? 105°20? 103°53? 103°30? 105°10? 104°30? 103°27? 103°27? 104°28? 105°15? 104°43? 104°43? 103°50? 103°38? 103°32? 104°30? 104°58? 104°10? 26°37! 26°29? 26°23? 26°22? 26°13? 25°50? 26°09? 26°08? 26°05? 25°45? 25°57? 25°55? 25°48? 25°48? 25°47? 25°42? 25°41? 25°32? 25°28? 25°12? Bach name-place is followed by its elevation Elevation 5150 3900 5400 4000 5400 3750 5500 6000 4100 4100 4850 4100 TOPOGRAPHY The study area, shown in Figure 2, includes approximately 10,000 square miles in northeastern Durango, north and northeast of the Rio Nazas and east of the Rio Florida. Two undrained basins containing extensive playas (generally dry like beds) occur in this area. One is the Laguna de las Palomas to the northeard at the Chihuahuan boun- dary. The Arroyo de Cadena, an intermittent stream that drains much of the central part of the study area, enters this Laguna. The other is the Laguna de Tlahualilo in the extreme eastern part of the area. The Rio Nazas drains the southern and southwestern parts of the area. This river flowed, before the advent of extensive irrigation projects, chiefly into the Laguna de Mayran in southwestern.coahuila. The Rio Florida drains a portion of the northwestern part of the study area. This streamflows northward and eventually into the Gulf of Mexico by way of the Rio Conchos and the Rio Grande. The lake beds contain de- posits of soft, deep, alkaline soils. Both these soils and the alluvial soils along rivers and arroyos have a pronounced effect on the dis- tribution and abundance of both.vegetation and animals. Menotonous desert flats are interrupted by occasional isolated mountains. These are generally low in elevation (less than 1000 feet above the plain) and consist usually of massive limestone, dissected by deep cut arroyos.‘ To the westward the land gradually rises in elevgation toward the Meseta de Zarca, which marks the beginning of the foothills of the Sierra Madre Occidental. Gradual changes in vegetation and animal life occur as a result of this change in ele- vation. CLIMATE The climate of the Bolsdn de Mapflmi is determined largely by the prevailing westerly winds. These pass over the Sierra Madre Oriental (where mmch moisture is precipitated) and hot desert country to the eastward before reaching the Bolsdn de Mapimi. Consequently, northeastern.Durango is characterized by extreme aridity. In the Bolsdn de Mapimi, the small amount of rain received usually falls in summer with June through September having 64 to 75 percent -of the annual precipitation (Shreve, 1942:193). Most of the rains drain into arroyos rather than being absorbed by the packed ground. As a result, extensive weathering of topography due to infrequent, but heavy, rains is evident. In desert areas, arroyos may be broad ”and shallow or deep and heavily eroded. Steep canyons are charac- teristic of mountainous areas. Disturbed patches of soil along these arroyos encourage the growth of various floras which form cover and provide food for many mammals. High temperatures, continous wind and scarcity of water are ele- ments of nature to which all species of the Bolsdn de Mapimi must adapt before becoming permanent members of the desert community. Cover, in the form of plants andiunderground burrows protect mammals from the sun and.wind. ‘Hater, when not available in the free state, is often obtained by animals from succulent plants or the bodies of other animals and metabolic synthesis of water is characteristic of some desert rodents. LAND USE Irrigation of crops has played an important part in the exploita- tion of northeastern Durango. Cultivation centers around the Laguna de Tlahualilo, the Laguna de las Palomas, and farmlands in the valley of the Rio Nazas where the river water can be channeled into irriga- tion canals, or where water from shallow wells is readily available. Cotton, wheat, alfalfa and grapes are the chief crops in northeastern Durango. Industry and agriculture have flourished simultaneously. Cotton seed oil refineries, alfalfa drying-plants, wineries, tractor and implement manufacturing companies, and other industries have kept pace with the growing needs of the expanding agriculture. Cultivation makes areas uninhabitable to most mammals by destroying the natural food supply and proper cover. iAlso, the use of insecti- cides in combating insect pests has probably affected adversely the abundance of mammals in areas adjacent to the cultivated fields. CONSERVATION OF MAMMALS The abundance and distribution of game animals in northeastern Durango is interpreted chiefly from reports by residents, who are well-acquainted with the areas involved in this study. Cowboys and goatherds in various localities related interesting accounts of local animals; these reports have been edited and used.when;considered pertinent. Modern highways and the development of irrigation have enticed farmers and ranchers to move onto formerly uninhabited lands during recent years. The increased hunting pressures, the large areas for cultivated crops, and competation for available grazing lands have altered the distribution and abundance of game anflmals. Thirty years ago, the pronghorn (Antilocapra americana) ranged over much of the eastern half of Durango, but today these animals are almost extinct. Panfilo Sanchez, a.we11known hunter and sportsman from.Torre6n, Coahuila, irecounts stories of his hunts when game, such as the pronghorn, was abundant near deez Palacio in Open areas which today are in cultiva- tion. Mule deer (Odocoileus hemionus) also roamed the Bolsdn de Mapimi in.Durango (Leopold, 1959:507), but have not been seen in re- cent years. White-tailed deer (Odocoileus virginianug) and collared peccaries (Pecari tajacu) still occur in northeastern.Durango, but seemingly in reduced numbers and in limited areas. Prdbably the num- ber of small mammals has diminished similarly, although there is evi- dence of an increase in some. For example, pocket gophers seemingly thrive where irrigation canal dikes present ideal localities for underground tunnels, while jackrabbits reportedly are a nuisance in some areas of extensive agriculture. The status of game in northeastern.Durango is similar to the situation which existed in the arid southwestern United States before strict enforcement of conservation laws made possible the reestablish- ment of game papulations. Baker (1956:155-156) has suggested methods of conservation to preserve the diminishing game in northern Mexico which could apply in northeastern.Durango as well. The enforcement of exist- ing laws to limit the kill of game, the limiting of herds of domestic 10. animals in overgrazed areas, and the setting aside of special areas designated as game preserves would materially increase and insure sur- vival of game. PLANT-SOIL.ASSOCIATIONS The 30136n de Mapimi lies within the limits of the Chihuahuan Biotic Province of Dice (1943). Goldman and Moore (1945:349) list this area as part of the Chihuahua-Zacatecas Biotic Province, a natural grouping of plants and animals. Leopold‘s (1952:437-448) vegetational zones of Mexico classify this area (at lower elevations) as Mesquite-Grassland and.Desert. Merriam (1898:1-79) proposed that areas such as the Bolsdn de Mapimi be classified in Lower Sonoran Life Zone. Shreve (1942:196) lists flora which are found in the Bolsdn de Mapimi according to arbitrary divisions of the Chihuahua Desert Vegetation-type flora. To my knowledge, no detailed studies of plant species or soil types of northeastern Durango have been published; consequently, this report attempts merely to use conspicuous plants and soil types to assist in distinguishing distributional pattern; of non-flying mammals. Field studies indicate that there are three major plant-spil associations in northeastern Durango (see Figure 2). Each of these is discussed below. Characteristic mammals are listed; those taken from traplines are followed by percentages which indicate their relative frequency in the total catch in any one association. DESERT ASSOCIATION: The Desert Association includes the broad, relatively flat, lowest part (3900 feet to 4500 feet) in the ll. northeastern half of ‘the study area (see Figure 2) and lies within an annual isotherm of from 68 degrees (F) to 77 degrees (F). Within the assOciation, several limestone mountainous areas emerge, two of which are prominent: the Sierra de la Bandera and the Sierra de Campana. Except for sand dunes extending in? a narrow belt across the desert 30 miles north of Gomez Palacio, chernozem soils occur throughout this association at lower elevations. Field observation indicates that the Laguna de las Palomas at the northern edge of the association is cen- tered within a plays of soft, alkaline soils, whereas soils in the southern parts of the association, where reportedly there is more rain, are hardpacked. Throny shrubs and cactus with some scattered grasses characterize the desert. Larrea, with Acacia and Prosopis are prominent on the desert flats and gale, 19535, guntia, Euphorbia and Dasyliron occur on the slopes of rocky hillocks. Grasses (mostly Hilaria) are of minor importance in the vegetational character of the association. Plate 1 illustrates typical vegetation and physiognomy in this association. ‘Mammals present are adapted for the arid habitats where ground cover is scant. Characteristic large mammals include coyote (ggnig_latrans), and probably gray fox (Urocyon cinereoargenteus), kit fox (Vulpes macrotis), hooded skunk (Mephitis macroura), bobcat (Lynx rufus) and collared peccary (Pecari tajacu). Characteristic small mammals: Lepus californicus Sylvilagus audébonii Ammospermophilus interpres 12. Plate 1. The Desert Association. Vegetation is spotty and the soil is hard-packed. Dust-devils are caused by thermal updrafts and erratic wind direction and carry dust and debris high above the desert flats. r-""-’:Z " k ? , ' ' . " ’ h \‘M’ p; ‘ “k ? ' 17:. . '.- 'Vfl. 1.?;.e4 ‘43. ‘ 0 Plate 2. "La Cueva de los Indies" This limestone cave contained few bats in July but large guano deposits indicate that many bats may occur there, perhaps in.winter. 13. Spermgphilus variegatus Spermophilus spilosoma Thomomys umbrinus Perognathus flavus '1 percent Perognathus nelsoni 16 ” Perognathus penicillatus l9 " Dipodomys ordii 5 " pipodomgg,merriami 12 " Dipodomys nelsoni 4 " Peromyscus maniculatus 20 " Peromyscus eremicus 17 " Peromyscus pectoralis 2 " Neotoma albigula 2 " Myg_musculus l " Sigmodon hispidus 1 " MIXED GRASSLAND ASSOCIATION: The Mixed Grassland Association consists of higher plains and adjacent mountains westward of the Desert Association (see Figure 2). Typical habitat is grassland with associated thorn shrub, (such as 55933, 2952, Larrea, _Ac_a_c_i§_ and Prosopis). There is no clear cut separation between the desert and the higher grassland plain, but a gradual transition between the two associations occurs over an extensive area. Grasslands with juniper, oak and some pifion pine occur at higher elevations. Intermontane valleys in the Meseta de Zarca display extensive grasslands with scattered shrubby, thorny legumes. Plates 3 and 4 illustrate typical vegetational forms in this association. 14. ' . a; "- so ‘ ‘Q - ' .4 . Vu‘ ‘ (N L'- 1 A ' s x ~ ' \ ~‘b- _ : — - 'uvxdfififiv Y‘VFV '7’ 1" ‘i'm"'.'f. _-, _ ‘. -Q. ‘ h . "-‘ J , . A ‘1 ’i 13 3.- ’ b , TM! ‘1'”. “‘41-! L If‘a.‘ Plate 6 The Alluvial Association. Squash and corn are planted on the flood plains of the Rio Nazas near Nazas and cottonwood trees grow well on the banks of the river 18. Thomomys baileyi Crstogeomys castanOps Perognathus flavus 3 percent Perognathus nelsoni .30 " Perognathus penicillatus 3 " Dipodomys ordii 6 " Reithrodontomys fulvescens 2 " Peromyscus maniculatus 10 " Peromyscus eremicus ll " Peromyscus pectoralis 2 " Egromyscus leuc0pus 8 " Neotoma albiguls 6 " Mus musculus 12 " Sigmodon hispidus 7 " MAMMAL HABITAT RELATIONSHIPS The mammals in the study area either show preference to a specific habitat, or occur widely. Most of the larger mammals occur in all of the associations and due to the absence of major barriers and the rela- tively small size of the study area, this fact seems understandable. On the other hand, several small mammals show a tendency to be restricted to certain soil and plant types. For example, the antelope ground squirrel (Ammospermophilus interpres) inhabits only rocky outcroppings in the Desert Association; the Bailey pocket gopher (Thomomys baileyii) lives only in deep alluvial soils along streams; and the harvest mice (Reithrodontomys fulvescens and R. megalotis) occur only in grassy 19. areas. Some small mammals are well-distributed throughout north- eastern Durango, but differ in local habitat preference. For example, the Nelson pocket mouse (Perggnathus nelsoni) chiefly lives in rocky areas in the Desert Association and in the Mixed Grassland Association, but in the latter the species occurs on flats of coarse soils as well. The hispid cotton rat (Sigmodon hispidus) in the Alluvial Association is the most abundant species trapped gin areas of succulent vegetation near the banks of the Rio Nazas, but in the Desert Association this mammal is found infrequently in coarse grasses and other xeric vege- tation. The relative percentages of mammals trapped show that there are dominant species in each association. Notable, also, is the relation- ships between groups of allied mammals. The relative percentages of species of Peromyscus trapped in each association shofis that, generally, the deer mouse (Peromyscus maniculatus) and the cactus mouse (Peromyscus eremicus) are probably in direct competition for habitat, especially near the junction of the Desert Association and the Mixed Grassland Association. The deer mouse is better adapted to the environment of the Mixed Grassland Association, whereas the cactus mouse occurs more abundantly in the Open habitat of the Desert .Association. The Nelson pocket mouse (Perognathus nelsoni) and the desert pocket mouse (g. penicillatus) occur together, but differ locally in their relative abundance. Probably these species are not in direct competition for survival as they are found in different 'micro-habitats. 20. CHECKPLIST OF EXTANT MAMMALS OF NORTHEASTERN DURANGO Order Chiroptera - bats Family Vespertilionidse - common bats Pipistrellus hesperus austrslis Miller - western pipistrelle Eptisicus fuscus pallidus Young - big brown bat Dasypterus ega zsnthinus Thomas - southern yellow bat Plecotus townsendii austrslis (Handley) - lumppnosed bat Anthrozoas pallidus pallidus (LeConte) - pallid bat Order Lagamorpha - hares, rabbits and pikas Family Leparidae - hares and rabbits Lepus californicus texianus Waterhouse - black-tailed jackrabbit Sylvilsgus audubonifminor (Mearns) - desert cottontail I Order Rodentia - rodents Family Sciuridae - squirrels Spermophilus apilosoma spilosoma (Bennett) - spotted ground squirrel Spermophilus apilosoms palescens (A.H. Howell) - spotted ground squirrel Spermophilus vsriegatus repestris J.A. Allen - rock squirrel Ammospermophilus interpres (Merriam) - antelope ground squirrel Family Geomyidae - pocket gophers Thomomys umbrinum goldmani - pigmy pocket gopher Thomomys baileyinelsoni Merriam - Bailey pocket gopher Cratogggmys csstanops excelsus Nelson and Goldman - plateau pocket gopher Cratogeomys csstanops consitus Nelson and Goldman - plateau pocket gopher 21. Family Heteromyidae - pocket mice and kangaroo rats Perognsthus flavus pallescens Baker - silky pocket mouse Perognsthus penicillatus eremicus Mearns - desert pocket mouse Perognsthus nelsoni nelsoni Merriam - Merriam pocket mouse Perognsthus nelsoni canescens Merriam - Nelson pocket mouse Dipodomys nelsoni Merriam - Nelson kangaroo rat Dipodomys merriami merriami Mearns - Nerriam kangaroo rat Dipodomys ordii obscurus (J.A. Allen) - ord kangaroo rat Dipodomys ordii idoneus Setzer - ord kangaroo rat Family Cricetidae - native rats and mice Reithrodontomys megslotis megslotis (Baird) - fulvus harvest mouse Reithrodontomys fulvescens canus Benson - fulvus harvest mouse Peromyscus pectoralis eremicoides Osgood - white-ankled mouse Peromyscus eremicus eremicus (Baird ) - cactus mouse Peromyscus maniculatus blandus Osgood - deer mouse Peromyscus leucopus tornillo Mearns - wood.mouse §igmodon hispidus berlandieri Baird - hispid cotton rat Neotoma albiguls albiguls Hartley - white-throated woodrat Neotoma slbiggla durangae J.A. Allen - white-throated woodrst Neotoms‘ggldmani Merriam - pigmy woodrat Family Muridae - introduced rats and mice Mus musculus brevirostris Waterhouse - house mouse Order Carnivora - carnivores Family Canidae Canis latrsns mearnsi Merriam - coyote Vulpes macrotis zinseri Benson - kit fox 22. Family Procyonidse - racoons and allies Bassariscus sstutus flavus Rhodes - ring-tailed cat Family Mustelidse - skunks and allies Mustela frensts neomexicana Barber andeockerell - ling-tailed weasel Mephitis macroura milleri Mearns - hooded skunk Family Felidae - cats Lynx rufus baileyi Merriam - bobcat Order Artiodactyla - even-teed ungulates Family Tayassuidae - peccaries Pecsri tajacu angulstus (Cope) - collared peccary Family Cervidse - deer Odocoileus virginisnus carminis Goldman and Kellogg - white-tailed deer 23. ACCOUNTS OF SPECIES AND SUBSPBCIES Pipistrellus hesperus - western pipistrelle ‘ This bat was observed, or taken, on the desert plains and in the low ranges of mountains where surface water was available. This species is usually the first bat seen in the evening, sometimes as early as 30 minutes before sunset. .. The specimens from near Mapimi are lighter brown than those collected near L88 Nieves; however, all seem to be referable to the subspecies, g. _l_1_. austrslis Miller. Specimens examined: Four from 3 mi. E Lee Nieves, 5400 feet; one from 3 mi. E Conejos, 4000 feet; one from 12 mi. SW Mapimi, 5000 feet; one from 2 mi. S Palmito, 4850 feet; one from 135 mi. NE Nazas, 4100 feet. Eptesicus fuscus - big brown bat This large bat occurs in and near mountains and on the plains in northeastern Durango. Two specimens were snared, along with two other kinds of bats, in a mist net stretched over a shallow pool of water in a mountain canyon near Mapimi. On geographic grounds specimens from the study area are referred to the subspecies g. _f_. pallidus Young. Specimens examined: two from 12 mi. SSW Mapimi, 5500 feet. Other records: ten mi. USN Lerdo (Univ. Mich.). Dasypterus ega - southern yellow bat One male was snared on a rainy evening after dark, but before 9:00 P.M., in a mist net stretched across a shallow pool of murky water in a narrow mountain canyon in the Sierra de Mapimi. 24. Heretofore, the only known records of the southern yellow bat in close proximity to the state of Durango, to my knowledge, are listed by Hall and Kelson (1959:194) from Coahuila, Zacstecas and Sinaloa. The present record, considered as belonging to the subspecies Q, g, xanthinus Thomas, extends the known range of this species to north- eastern Dursngo. This bat probably also occurs uncommonly in other parts of central Mexico. Measurements for this specimen (MSU no. 3287) are: total length, 109; length of tail vertebrae, 49; length of hind foot, 10; height of ear from notch, 14; weight 13.7 grams; length of forearm, 43.7; condylobasal length of skull, 16.5; zygomatic breadth, 9; breadth of brain case, 8.4; length of maxillary tooth row, 5.7; breadth across upper canines, 5.8; breadth across upper molars, 7.4. Specimens examined: one from 12 mi. SSW Mapimi, 5500 feet. Plecotus townsendii - lump-nosed bat Four bats were seen in one of the chambers of a cave north of Campsna known locally as "La Cueva de los Indies" in late July. Three lump-nosed bats, assigned to the subspecies austrslis (Handley), along with a pallid bat (Anthrozous pallidus) were snared in a mist net stretched across the entrance. This entrance at 100 yards from the base of a mountain is at the edge of a shelf of ltmestone (see Plate 2). Guano is reported by residents to be collected each year from this cave. The presence of sizable quantities of guano, but only a few bats in July, may mean that the cave is attractive to bats only at other seasons, perhaps in winter. 25. Specimens examined: three from 6 mi. N Campana, 3750 feet. Records in the literature: 12 mi. N Lerdo (Handley, 1959:141). Antrozous pallidus - pallid bat This large-cared bat occurs commonly in northeastern.Durango where there are suitable daytime retreats. Specimens were taken from.caves, adobe houses, trees and in nets stretched over water sources. A.mes- quite tree was the daytime roost of one pallid bat obtained on the Tree Hermanos ranch. Two pregnant females also were taken there in a mist net stretched over a watering tank on June 26. Four others were shot with a .22 pistol as they flew through the entrance of an abandoned sulfur mine near Conejos. Antrozous was taken at all places in associa- tion with either Sptesicus,‘gipistrellus, Dasypterus, or Corynorhinus. Durangan specimens are assigned to the subspecies A, p, pallidus (Le Conte). Specimens examined: five from 3 mi. E Conejos, 4000 feet; 6 from 35 mi. W Mapimi, 5500 feet; one from 6 mi. N Campana, 3750 feet. Lepus californicus - black-tailed jackrabbit This jackrabbit is the most conspicuous mammal of the deserts and plains. The jackrabbit is locally variable in numbers; areas where grain is cultivated seemingly support a larger pepulstion than areas which are grazed or where cotton is the principal crop. The jackrabbit reportedly was a nuisance and was hunted constantly on the San Javier wheat farm near Mapimi; more than 200 animals were killed there in 1959. On the other hand, field studied indicated that there were few rabbits near stslza where cotton was grown. A female taken near 26. Boquilla on July 12 had three embryos, the largest being 100 millimeters in length. A lactating female was collected near Mapimi in June. The subspecies found in northeastern Durango is L5 2, texianus Waterhouse. Specimens examined: three from 4 mi. NNW Boquilla, 5400 feet; one from 3 mi. E Conejos, 4000 feet; one from 4 mi.'w Bermejillo; 4 from 7 mi. NNW La Zarca, 6000 feet; 2 from 35 mi. W'Mapimi, 5500 feet. Sylvilagus audubonii - desert cottontail Records of this cottontail reported in the literature from northern Durango, as well as records included here, show that this animal is well-established in the Bolson de Mapimi. This rabbit favors desert country where ample cover exists along arroyos and at the bases of low mountains. Cactus and tender growing parts of grasses probably supply the animals' need for moisture in areas where surface water is scarce. Local residents prefer eating the meat of the cottontail, "conejo", to that of the jackrabbit, "liebre". All females collected in 1958 were pregnant; these were taken between June 1 and 18. According to Hall and Kelson (1959:266), the subspecies §_. _a_. 11333 (Mearns) occurs in the study area. Specimens examined: one from.4 mi. NNE Boquilla, 5400 feet; one from 35 mi.‘w Mapimi, 5500 feet; three from 7 mi. NNW La Zarca, 6000 feet. ' Other reCords: ten.mi. WSW Lerdo (Univ. Mich). 27. Spermophilus spilosoma - spotted ground squirrel This ground squirrel is characteristic of both grassy plains and arid desert in northeastern Durango. These pale-colored animals are active even_during the hottest part of the day. They seemingly prefer the Open lands where there is sparse grass or brush for cover. Speci- mens collected in the Mixed Grassland.Association were paler in color than those examined from the Desert Association. Specimens examined: Spermophilus g, pallescens (Bennett): one from 4 mi. NNE Boquilla, 5400 feet; one from 2% mi. SE Campana, 4100 feet; 4 from 7 mi. NW La Zarca, 6000 feet; one from 35 mi. W'Mapimi, 5500 feet. Records in the literature: Rio Ocampo (Allen, 1904:209). Spermophilus variegatus - rock squirrel The subspecies, rupestris (J.A..Allen), is well-distributed in northeastern.Durango. Manrmade structures, such as rock fences, have contributed to extensions, locally, of the habitat of the species. Animals were observed among rocks where white-throated'wood rats (Neotoma albigula) were ensnared in traps primarily set for rock squirrels. This species is considered a choice, edible animal by ranchers and farmers. Squirrels taken in July and August were in molt. Specimens examined: one from 3 mi. E Las Nieves, 5400 feet; one from 4 mi. NNE Boquilla, 5400 feet. Other records: ten mi. WSW Lerdo (Univ. Mich.). 28. Amospermophilus interpres - antelope ground squirrel This ground squirrel, Amospermophilus interpres (Merriam), lives in arid, rocky areas in the Desert Association. Specimens were col- lected near Lerdo (Baker, 1954:209) on rocky slopes of low hills simi- lar to areas in the Sierra de Campana where this ground squirrel oc- curred in association with the rock squirrel (Spermophilus variegatus). One live Amospermophilus brought into camp by two cowboys, had been trapped in a rocky habitat containing cover of lechuguilla and candelia. Numerous nematodes of the family myuridae (identified by David Clark of the Department of Microbiology and Public Health at Michigan State University) were found in the caecum of this specimen. Specimens examined: one from 6 mi. N Campana, 3750 feet. Other records: four mi. WSW Lerdo, 3800 feet (Univ. Kans.); and 3 mi. SW Lerdo (Univ. Kans.). Thomomys umbrinus - southern pocket gopher The subspecies, _T_. 3. goldmani Merriam, is probably restricted to the Bolson de Mapimi. No specimens were obtained, but mounds of earth, presumed 'to have been made by this species, were observed on the dike of an irrigation canal on a farm west of Mapimi. Farmers complain that pocket gophers, locally called "topo", cause much damage each year to the dikes. Near Lerdo, specimens were trapped in sandy-loam soils in 1953 by a field party from the University of Kansas. Records in the literature: one mi. WSW Mapimi, 3000 feet (Univ. Kans.); 4 mi. WSW Lerdo, 3800 feet (Univ. Kans.); Mapimi (Bailey, 1915:95) . 29. Thomomys baileyi #- Bailey pocket gopher This pocket gopher occurs chiefly in loose sandy soils on stream banks. The subspecies, 1. b. nelsoni Merriam, ranges northward into Chihuahua along the river valleys. Burrows in Durango often extended to a depth of two feet and were found always within 50 feet of stream banks. Two males and one female were obtained in a narrow ledge of soft earth between a rocky hill and the Rio Florida near Las Nieves. Specimens examined: three from 3 mi. E Las Nieves, 5400 feet; one from 2 mi. S Palmito, 4850 feet. Cratogegys csstanops - plateau pocket gopher Easily trapped (and utilized for food by the natives), this large g0pher is found in most plains localities in eastern and north-central Durango. The subspecies g. g. consitus (Nelson and Goldman) was col- lected in the Mixed-Grassland Association where soils were generally deep and sandy and in broad intermontane valleys of the Meseta de Zarca. The subspecies, g. g. excelsus (Nelson and Goldman) has been reported in the literature to occur in the extreme northern part of Durango. The two subspecies seem separated by shallow soils having sparse vege- tation. Irrigation ditches near the highway north of Gomez Palacio display typical Cratogiomys burrows in deep, soft soils. Man has pro- bably been a factor affecting the local distribution of this manual by constructing these artificial habitats. A snake (Pituophis s3.) was found living in the burrow of a gopher near La Zarca. Specimens examined: Cratogems g. consitus: three from 3 mi. E Boquilla, 5400 feet; five from 7 mi. NW La Zarca, 6000 feet. 30. Other records: Cratogeomys g. excelsus (Nelson and Goldman): 4 mi. WSW Lerdo (Univ. Kans.), 10 mi. WSW Lerdo, 3800 feet (Univ. Mich.). Reported in the literature: Tlahualilo (Nelson and Goldman, 1934:144). geroglathus flavus - silky pocket mouse This small pocket mouse was trapped in all associations. It is dif- ficult to estimate the abundance of this animal due to difficulty in obtaining it. Seemingly, it prefers open areas with grass or bushy plants as cover. This species was found well-established in an over .grazed pasture in central Durango by a field party from the University of Kansas in 1955. Specimens collected at La Zarca and near Boquilla in the Mixed Grassland Association were darker across the upper parts than those trapped in light, sandy soils in the Desert Association. However, all specimens are assignable to g; j; pallescens Baker. Specimens examined: six from 3 mi. NNW Boquilla, 5400 feet; one from 7 mi. N Campana, 4100 feet; 5 from 7 mi. NNW La Zarca, 6000 feet; 5 from 35 mi. W’Maphmi, 5500 feet; 3 from 1% mi. NW Nazas, 4100 feet. Other records: one mi. WSW Mapimi, 3800 feet (Univ. Kans.). Re- ported in the literature: 4 mi. WSW Lerdo, 3800 feet (Baker, 1954:346). Perognsthus penicillatus - desert pocket mouse The desert pocket mouse and the Nelson pocket mouse often occur to- gether where soils are suitable. The desert pocket mouse prefers open areas with scattered shrubs, and avoids coarse, rocky soils. The sub- species, eremicus Mearns, was found to be as common in the Desert Association (19 percent of all small mammals trapped) as in the Mixed Grassland Association (18 percent of all small mammals trapped). 31. Specimens examined: five from 6 mi. E Zavalza, 5150 feet; 7 from 7 mi. NW Yermo, 3900 feet; 5 from 7 mi. NW Conejos; 2 from 7 mi. N Campana, 3750 feet; 12 from 7 mi. NW La Zarca, 6000 feet; 8 from 35 mi. W Mapimi; 3 from 135 mi. w Nazas, 4100 feet; 2 from 13 mi. N Gomez Palacio; one from 2 mi. W Mapimi; one from 7 mi. W Mapimi. . Other records: 10 mi. WSW Lerdo, 3800 feet (Univ. Mich.). Records in the literature: Mapimi (Osgood, 1900:49). Perognsthus nelsoni - Nelson pocket mouse Inhabiting coarse soils with spotty vegetation adjacent to rocky areas, the Nelson pocket mouse is a characteristic small manual in all associations. Perognsthus _t_l_. nelsoni Merriam is found in the Mixed Grassland Association and the Alluvial Association, and g. g. canescens Merriam, on the other hand, is found where light soils prevail in the Desert Association. Where g. nelsoni and _P_. pencillatus occurred in the same general locality, pencillatus usually was trapped at a some- what lower elevation. Specimens examined: three from 6 mi. E Zavalza, 5150 feet; one from 7 mi. 1W Yermo, 3900 feet; one from 7 mi. N La Zarca, 6000 feet; 3 from 35 mi. W Mapimi, 5500 feet. Other records: one mi. WSW Mapimi (Univ. Kans.). Dipodomys merriami - Merriam kangaroo rat The Merriam kangaroo rat, assigned to the subspecies merriami Mearns, is confined to sandy and coarse soils where vegetation is sparse 32. in the study area. Grassy slopes at higher elevations in the western part of the Mixed Grasslands Association seemingly are unoccupied by this species, whereas this manual was easily trapped at lower elevations in the Mixed Grassland Association and in the Desert Association. The Merriam kangaroo rat was taken in association with E. nelsoni and D, an. Specimens examined: four from 6 mi. E 2avalza, 5150 feet; 3 from 7 mi. NW Yer-mo, 3900 feet; one from 7 mi. NNW Conejos; 3 from 3 mi. E Conejos, 4000 feet; 5 from 7 mi. NW La Zarca, 6000 feet; 9 from 35 mi. W Mapimi, 5500 feet; one from 7 mi. SW Cadena, 4100 feet. Dipodomys ordii - Ord kangaroo rat The subspecies obscurus (J.A. Allen) inhabits grassy areas in the Mixed Grassland Association and slightly differs morphologically (Setzer, 1949:547) from g. 2. idoneus Setzer which is found at! lower elevations in the Mixed Grassland Association and in the Desert Association. The 0rd kangaroo rat and Merriam kangaroo rat occur to- gether in the study area with more 9_r_'_d_i_i_ than merriami being trapped. Since Baker (1956:246) and Dalquest (1953:114) have suggested that 33% are less likely to be attracted to traps than merriami, the high number or 25d}; trapped in the study area might indicate a relatively high population. Dale (1939:730) points out environmental factors which influence the abundance and distribution of kangaroo. rats in general; viz, arid or semi-arid climate, proper drainage, any combination of soil and cli- matic factors to provide an abundance of seed plants with light ground cover, provision for shelter and available dusting places for a part 33. of the year. The Bolson de Mapimi provides ideal environment for the kangaroo rat, "tusa", shown by the abundance of burrows found through- out the area. Specimens examined: Dipodomys g. idoneus: five from.6 mi. E Zavalza, 5150 feet; 13 from 35 mi. W'Mapimi, 5500 feet; 2 from 1% mi. NW Nazas, 4100 feet; and reported in the literature: one mi. WSW Mapimi and 5 mi. SE Lerdo (Hall and Nelson, 1959:514); 12 mi. SSW Lerdo 1 (Univ. Mich.). Dipodomys ordii obscurus: four from 3 mi. E Las Nieves, 5400 feet; 4 from 4 mi. NNE Boquilla, 5400 feet; 8 from 7 mi. NW La Zarca, 6000 feet. Reithrodontomyg fulvescens - fulvous harvest mouse The fulvous harvest mouse, assigned to the subspecies gangs Benson, is found in heavy or sparse grass, principally along arroyos where there is cover of shrubby vegetation, and.may be found in association with Peromyscus leucopus. This widely ranging species is probably found in most localities in the Mixed Grassland and Alluvial Associations. Specimens examined: two from 3 mi. E Las Nieves, 5400 feet. Reported in the literature: 14 mi. E Zarca (Hooper 1952:98). Reithrodontomys megalotis - western harvest mouse This harvest mouse is found in habitats similar to those used by Eh fulvescens and the two species have been collected together at the same locality (see HoOper, 1952:98). These mice seemingly are 34. restricted to grassy areas in plains and intermontane valleys in higher elevations of the Mixed Grassland Association. On geographic grounds, the subspecies megslotis Baird is the assignment of this specimen. Specimens examined: one from 4 mi. NNE.Boquilla, 6300 feet. Reported in the literature: 14 mi. E La Zarca (Hooper, 1952:55). Peromyscus eremicus - cactus mouse The cactus mouse, assigned to the subspecies eremicus (Baird) was taken in all associations in northeastern.Durango. Generally the species occurred where vegetation was scarce on both rocky and fine soils under cover of Opuntia, Acacia and 12253. Reports in the litera- ture, as well as locality records from the study area, show that this species is widely distributed in northeastern.Durango, but prefers the desert-type habitat. Probably the animal gradually becomes less common in the higher grasslands to the westward. Three pregnant females and one lactating female were trapped in late June and early July. Specimens examined: four from 6 mi. E Zavalza, 4150 feet; 5 from 7 mi. NW Yermo, 3900 feet; 4 from 7 mi. N Campana, 3750 feet; 6 from 3 mi. E Las Nieves, 5400 feet; 4 from 3 mi. E Conejos, 4000 feet; one from 4 mi. W Mapimi; one from 7 mi. NW La Zarca, 6000 feet; 3 from 2 mi. 8 Paimito, 4850 feet. Other records: 2 mi. ENE Mapimi, 3800 feet (Univ. Kans.); one mi. WSW Mapimi, 3800 feet (Univ. Kans.); 4 mi. WSW Lerdo, 3800 feet (Univ. Kans.); 5 mi. SE Lerdo, 3800 feet (Univ. Kans.). Reported in the liter- ature: Lerdo and Inde (Osgood, 1909:242). 35. Permscus pectoralis - white-ankled mouse The white-ankled mouse was trapped in rocky areas by clumps of lechguilla, candalilla, and prickly pear in the Desert Association, whereas they were taken on flats below rocky areas in the Grassland Association and in the higher elevations of the Alluvial Association. The species occupied local habitats where, seemingly, other Peromyscus (maniculatus, eremicus and leucopus) did not occur; similar relation- ships have been reported by Dalquest (1953:145) and Baker (1956:269). This specimen has been assigned to the subspecies eremicoides Osgood on geographic grounds. Specimens examined: two from 3 mi. E Las Nieves, 5400 feet; one from 4 mi. NNE Boquilla, 5400 feet; one from 3 mi. E Conejos, 4100 feet; one from 35 mi. W Mapimi, 5500 feet; one from 12 mi. SSW Mapimi, 4850 feet; one from 4% mi. W, % mi. S Cadena. Peromyscus maniculatus - deer mouse The distribution of the deer mouse, 3. m. blandus Osgood, is spotty, but there is a greater population where there is a greater cover of grass, with shrubs, such as lechuguilla, prickly pear, mesquite and shrubby catclaw. The distribution of g. maniculatus coincides in this area with that of g. eremicus, and the pale color of g. maniculatus resembles that of g eremicus. Three females trapped in August were pregnant. Specimens examined: 6 from 6 mi. E Zavalza, 4150 feet; 14 from 7 mi. 1W Yermo, 3900 feet; one from 4 mi. NNE Boquilla, 5400 feet; one from 7 mi. NW La Zarca, 6000 feet; 6 from 35 mi. W Mapimi, 5500 feet; 36. 8 from 2 mi. S Palmito, 4850 feet. Reported in the literature: Indé, Villa Ocampo (Osgood, 1909:86). Peromyscus leucopus - white-footed mouse The white-footed mouse 3. l. tornillo Mearns, prefers lowlands in the Mixed Grasslands and Alluvial Associations where there is grassy or bushy cover along streams or near the bases of mountains. This sub- species seemingly reaches the southern edge of its range in northern Durango. The white-footed mouse and the fulvous harvest mouse (Reithrodontomys fulvescens) were taken together in the same habitat near Las Nieves. Specimens examined: two from 3 mi. E Las Nieves, 5400 feet; five from 1% mi. NW Nazas, 4100 feet. Reported in the literature: Rosario, (Osgood, 1909:26). Sigmodon hispidu - hispid cotton rat The widely distributed cotton rat, assigned to the subspecies berlandieri Baird, occurs commonly along the valley of the Rio Nazas where vegetation is thick and succulent; seemingly, it was the most abundant species in and around agricultural areas near Nazas. The rodent also occurred in an arid situation in the Desert Association (near Yermo) under cover of mesquite in sparse, dried grass. Baker (1956:276) reports that the cotton rat was collected in Coahuila in similar arid habitat in clumps of grass under cover of prickly pear. Specimens examined: six from 1% mi. NW Nazas, 4100 feet; one from 7 mi. NW Yermo, 3900 feet. Other records: from 10 mi. WSW Lerdo, 37. 3800 feet (Univ. Mich.). Neotoma albiLula - white-throated wood rat The white-throated wood rat was trapped where soils were coarse and the vegetation diverse, generally, but rocky outcroppings and man-made structures, such as fences constructed of rocks, are ideal habitats. The subspecies, durggae J.A. Allen, is a typical manual of higher ele- vations in the Mixed Grassland Association, but it also occurs in river valleys of the Alluvial Association. Neotoma _a_. albigula Hartley is pro- bably restricted to the Desert Association and to arid parts of the Alluvial Association. - Specimens examined: Neotoma g. duraggae: one from 3 mi. E Lee Nieves, 5400 feet; 2 from 4 mi. NNE Boquilla, 5400 feet; 6 from 7 mi. NW La Zarca, 6000 feet; reported in the literature: Indé (Goldman, 1910:38). Neotoma a. albigula: one from 6 mi. E Zavalza, ‘5150 feet; one from 7 mi. NW Conejos, 4100 feet; 4 from 2 mi. S Palmito, 4850 feet; other records from 10 mi. WSW Lerdo (Univ. Mich.);recorded in the literature from Mapimi (Golhan, 1910:33). Neotoma goldmani Merriam - Goldman's wood rat Records in the literature indicate that this wood rat is restricted to arid situations in the Bolsdn de Mapimi. It probably occurs uncom- monly in the intermontane valleys into the Grassland Association. Records: one mi. SSE Mapimi, 4100 feet (Univ. Kans.). 38. Reported in the literature: four mi. WSW Lerdo, and 5 mi. SSW Lerdo (Rainey and Baker, 1955:623). Murid rodents The house mouse (Mus musculus) and probably the Norway rat (Rattus norvegieus) occur in all areas inhabited by Man. No special attempt was made to collect these introduced species, although a number of house mice were collected in the summers of 1958 and 1959. In the valley of the Rio Nazas, the house mouse was trapped in thick stands of vegeta- tion adjacent to fields of squash and corn. Specimens of Ming musculus examined: one from 3 mi. E Conejos, 4100 feet; one from 4 mi. NNE Boquilla, 5400 feet; 10 from 13 mi. NW Nazas, 4100 feet. Reported in the literature: Boquilla (Allen, 1903:598). Canis latrans - coyote The coyote, Canis latrans mearnsi Merriam, is widespread in north- eastern Durango and is found on some occasions far from'water. Re- portedly, the coyote is a nuisance in some localities; Frederico Hermosillo reports that coyotes killed goats and sheep on his ranch. One ranch hand was assigned the job of killing the coyote whenever pos- sible, and since then (three years ago) there has been a decline in the number of coyotes seen, and also an increase in the number of jack- rabbits seen. Reportedly, more than two hundred rabbits were killed ‘within a half mile of the ranch house in 1959. More than a score of 39. coyotes had been trapped during the spring and summer of 1958 an the Guitarra ranch north of Zarca; the foreman of the ranch reported that the coyote harasses the cattle. Traps, mostly, are used by the hunter to take coyotes, and a bounty is usually paid by the owner of the ranch or farm to which the carcass is brought. Specimens examined: fifteen (M.S.U. nos. 3546-3560) from 7 mi. NW La Zarca, 6000 feet; one from 4 mi. NNE Boquilla, 5400 feet. Vulpes macrotis - kit fox This small, pale-colored mamal prefers the desert plains of the Bolsdn de Mapimi to less arid conditions at higher elevations. Ranch- era in northeastern Durango report that the kit fox is rarely seen and that it was more abundant in previous years. This species is referable to 1. g. zinseri Benson. Measurements of one skull (M.S.U. no. 3563) are: - condylobasal length, 112.4; aveolar length of maxillary tooth row, 52.4. Specimens examined: one from 7 mi. NW La Zarca, 6000 feet. Other records: 8 mi. S and 11 mi. W Lerdo (Baker, 1956:296). Bassaricus sstutus - ring-tailed cat The ring-tailed cat, B. a. £19191 Rhodes, occurs in rocky areas in the valley of the Rio Nazas and where permanent water is available in the Mixed Grassland Association. According to farmers near Nazas, ring-tailed cats cross the river each year to feed on crops such as squash and corn, and live in the trees instead of their regular rocky 40. retreats higher in the hills. A ring-tailed cat was observed at night while it climbed easily over the limbs of the cottonwood trees, appear- ing quite distinct amid the leaves. Specimens were acquired from a lad who had dislodged two imature male ring-tailed cats from a small cottonwood tree at dusk. The lad's donkey, nearly hit by the falling creatures, was frightened and killed both animals with its hooves. The specimens were not badly damaged and the boy planned to sell them in the town market where each hide would be worth up to 14 pesos (about $1.16). Women use the pelts for trim on costs, he reported. Plate 6 illustrates the habitat from where these specimens were collected. Specimens examined: two (M.S.U. nos. 4105, 4106) from 195 mi. NW Nazas, 4100 feet. Mustela frensts - long-tailed weasel The long-tailed weasel, M. _f_. neomexicana Barber and Cockerell, is known well by the inhabitants of villages between Lerdo and Tlahualilo where the weasel, known locally as "onza", is abundant along irrigation canals adjacent to the cultivated fields. A specimen collected in August was shot as it crossed the highway at noontime; a first shotgun blast, a near miss, did not affect the small carnivore which presumedly was preoccupied with the hunting of ground squirrels which were seen in the brush by the side of the road. Measurements: total length, 420; length of tail, 162; length of hind foot, 41; height of ear from notch, 24; weight, 250.5 grams. 41. Specimens examined: one (M.S.U. no. 4107) from 135 mi. W Gregio Garcio, 3750 feet. Mephitus macroura - hooded skunk Three hooded skunks, M. g. milleri Mearns, were taken with steel traps set primarily for coyotes, along arroyos where vegetation was thick. Ranchers in northeastern Durango report that the skunk, known to residents as "zorillo", is not a nuisance, although most cowboys kill them whenever possible. Specimens examined: three from 7 mi. NW La Zarca, 6000 feet. BEE Lain; - bobcat The bobcat, assigned to the subspecies L. 5. baileyi Merriam, is found chiefly in the thick brush in the Grassland and Alluvial Associations, but is also reported by residents to occur in brushy areas in isolated mountains throughout the Desert Association. The bobcat, known to Mexicans as "gato montez", rarely preys on domestic stock, but occasionally one will be trapped in a steel set placed for a coyote. Specimens examined: one from 7 mi. NW La Zarca, 6000 feet. Pecari tajacu - collared peccary The collared peccary, g. _t_:_. mulatus (Cape), is reported by the local herdsmen as numerous in intermontane valleys near Mapimi. The a- rid plains south of the'Pelayo Ranch support numerous peccaries, 42. according to Mr. N.B. Honeycutt, rancher and owner of the Pelayo. Hoof prints of the peccary, known as "jabali" to residents, were ob- served in the mud near a dirty pool of water in a mountain canyon south of Mapimi. Peccaries are taken for their meat whenever possible, but seldom hunted for sport in northeastern Durango because of the inaccessibility of the area to sportsmen. Odocoileus virginianus - white-tailed deer Panfilo Sanchez of Torredn, Coahuila, whose office is adorned with trophy heads taken from.nearby Durango, pointed out areas in the Bolsdn de Mapimi in northeastern.Durango where he had killed white-tailed . deer and pronghorn in years past, but remarked that the white-tailed deer may be missing from these areas today. Reports from local resi- dents indicate that deer still are there, but at higher elevations. Probably this mammal, referred to the subspecies carminus Goldman and Kellogg, occurs throughout the Mixed Grassland Association and at high- er elevations in the Alluvial Association and.Desert Association. HYPOI‘HETICAL LIST OF ADDITIONAL MAMMAIS w/irfi-é/flj The oppossum, cave myotis, free-tailed bat,-Gailierds jackrabbit, mule deer, gray fox, mountain lion and pronghorn are omitted from ac- counts of species due to insufficient evidence of their recent occur- rence in northeastern.Durango, but should be mentioned as possible inhabitants. 43. Didelphis morsupialis - Virginia oppossum Residents in the valley of the Rio Nazas claim that the oppossum, known as "talcuache", is a common mammal in areas adjacent to the river valley. Probably it occurs uncommonly in cultivated areas be- tween the valley of the Rio Nazas and Tlahualilo. Myotis velifer - cave myotis The cave myotis probably occurs throughout northeastern.Durango, where suitable daytime retreats exist. Baker (1956:178) reports a cave myotis from the Rio Aguanaval in southwestern Coahuila. Hall and Kelson (1959:165-166) map the range of velifer as including the Bolsdn de Mapimi. Tadarida braziliensis - Mexican free-tailed bat Baker (1956:191) reports several free-tailed bats collected from the valley of the Rio Aguanaval; bats would likewise be expected to occur in the valley of the Rio Nazas. Lepus mexicanus - white-sided jackrabbit This large jackrabbit occurs where grasslands are interspersed with pine and oak. possible in the Mixed Grassland Association at high- er elevations. 44. Urocyon cinereoargenteus - gray fox This animal occurs in open desert and plains, as well as in moun- tains. Residents in northeastern.Durango have reported this mammal as occurring near the base of the Meseta de Zarca. Felis concolor - mountain lion Lewis Wheless reported that the mountain lion had been troublesome on the Cortijo Ranch by killing cattle and horses. An arroyo where a female and cub were killed several years ago was inspected for sign, but none was seen. The hides of these lions had been taken to the local market place and sold, according to Mr. Wheless. Odocoileus hemionus - mule deer Panfilo Sanchez of Torredn reports that there still may be mule deer in the Sierra Mojada in southeastern Chihuahua and in the Sierra Tlahualilo in southwestern Coahuila. The mule deer had been hunted near deez Palacio in years past, reported Sanchez. Outdoor Life Magazine (Feb. 1955, 15(2): 58-59, 71-72) reports the mule deer near deez Palacio, Antelocapra americana - pronghorn antelope Leopold (1947:438) reports that the range of the pronghorn includes parts of Durango. Panfilo Sanchez reported hunting the pronghorn, known as "berenda", near deez Palacio in years past. Peter Barboglio relates 45. that a small herd of pronghorn stays in the vicinity of his ranch northwest of Zarca, and that during the past few years the size of the herd has visibly diminished. SUMMARY Forty-two kinds of mammals, occurring in northeastern Durango, were studied to determine their distribution, relative abundance, and the effect of land use on their distribution. Three arbitrary plant-soil associations were delineated to facilitate the separation of small mam- mal populations. The relative trapping percentages provide information concerning the preference of habitat and competition between both closely related and unrelated mammals. Evidence obtained during two summers of study shows that increased utilization by man of previously undisturbed areas has adversely affected the status of game and locally diminished populations of many small mammals. Effective limitations should be imposed on land use measures if natural floral and faunal populations are expected to survive. LITERATURE CITED Allen, J.A. 1881. List of mammals collected by Dr. Edward Palmer in north- eastern Mexico, with field notes by the collector. Bull. Mus. Comp. 2001. 8:183-189. 1903. List of mammals collected by Mr. J.H. Batty in New Mexico and Durango, with descriptions of new species and subspecies. Bull. Amer. Mus. Nat. Hist. 19:587-612. 1904. Further notes on mammals from northwestern.Durango. Bull. Amer. Mus. Nat. Hist. 20:205-210. Baker, Rollin H. 1954. Silky pocket mouse (Perognsthus flavus) of Mexico. Univ. Kans. Publ. Mus. Nat. Hist. 7:339-347, 1 fig. 1956. Mammals of Coahuila. Univ. Kans. Publ. Mus. Nat. Hist. 9:125-335, 75 figs. Bailey, V. 1915. Review of the pocket gophers of the genus Thomomys. No. Amer. Fauna 39:1-136, 10 figs., 8 pls.‘ Dale, F.H. 1939. Variability and environmental responses of the kangaroo rat, Dipodomys hermannii. Amer. Midland Nat. 22, No. 3:703-731. Dalquest, W. W. 1953. Mammals of the Mexican State of San Luis Potosi. Louisiana State Univ. Press 1:1-229. . Dice, L.R. 1943. 'Biotic provinces of North America. Univ. of Mich. Press, Ann Arbor, viii & 78pp. Ghldman, E.A. 1910. Revision of wood rats of the genus Neotoma. No. Amer. Fauna 31:1-124. Goldman, E.A. and R.T. Moore 1945. The biotic provinces of Mexico. Jour. Mamm. 26:347-360, 1 fig. Hall, E.R. and K.R. Nelson 1959. 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Press, Berkley and Los Angeles. xiii and p. 568, 194 figs., 1 map, other illus. 3., Jr., and A.R. Kellogg. List of North American Recent Mammals. U.S. Nat. Mus. Bull. 205:xii and p. 954. Merriam, C.J. 1898. Nelson, E. 1934. Osgood, W. 1900. 1909. Rainey, D. 1955. Setzer, H. 1949. Life zones and crop zones of the United States. U.S. Dept. Agric., Div. Biol. Surv. Bull. 10, pp. 1-79, 1 map. W. and E.A. Goldman Pocket gaphers of the genus Thomomys from Mexico mainland and bordering territory. Jour. Mamm. 15:(2), pp. 105-125. H. . Revision of the pocket mice of the genus Perognsthus. No. Amer. Fauna 18:1-72, 4 pls., 15 figs. Revision of the mice of the Amer. genus Peromyscus. N. Amer. Fauna, 28:1-285, 8 pls., 12 figs. G. and R.H. Baker - Distribution and systematic position of the pigmy wood rat, Neotoma goldmani. W. Subspeciation in the kangaroo rat, Dipodomys ordii. Univ. Kans. Publ. Mus. Nat. Hist. 23:473-573, 27 figs. Shreve, Forest 1942- Grassland and related vegetation in northern Mexico. Madrofio 6:190-198, 25 pls. Villa, R.B. 1955. Observaciones acerca de la ultima manuda de Berrendos (Antelocapra americana mexicana) en el estado de Chihuahua, Mexico. Sobretiro de los Anales del Instituto de Biologia. Tomo xxvi, No. 1 Mexico. ROG-5A USE ONLY. ,__.»..— -..... HICHIGRN STRTE UNIV. LIBRQRIES Hllll llsllll I“ llllll I!!!" ”U 312 3001085525