This book is devoted to mammals, which are the class of vertebrate animals possessing hair, with the females having milk-secreting glands. One group of mammals, the cetaceans (whales and dolphins), have a layer of blubber instead of hair. Mammals, having among their representative genera certain species that fly, others that glide, swim, climb, burrow, leap, or run, are perhaps the most versatile and adaptable of the vertebrate animal groups in Texas.
Texas, with its variety of soils, climate, vegetation, and topography, as well as extensive coastline and offshore ocean, is the home of at least 184 free-ranging species of mammals. The locomotive versatility of the various members of the class is responsible in part for the occurrence of mammals in our deserts, forests, mountains, prairies, high plains, inland and coastal waters, and oceans.
This book represents the sixth account detailing the kinds of mammals that occur in Texas with information about their lives and economic importance. The Texas Parks and Wildlife Department and its predecessor, the Texas Game and Fish Commission, published the previous five editions. Dr. W. P. Taylor and Dr. W. B. Davis collaborated in 1947 to prepare The Mammals of Texas as Bulletin No. 27 of the former Texas Game and Fish Commission. Recognizing the growing interest in Texas mammals and the expanding knowledge about the many kinds of mammals in the state, Dr. Davis in 1960 wrote an entirely new bulletin, designated as Bulletin No. 41 of the Texas Parks and Wildlife Department, which served as an identification key to Texas mammals and also provided information on their distribution and life histories. Dr. Davis revised Bulletin No. 41 in 1966 and again in 1974. The bulletin was revised for a fifth time in 1994, with myself (DJS) as coauthor, and distributed by the University of Texas Press. Dr. Davis died in 1995, and by agreement with him this version is authored solely by DJS. The University of Texas Press has agreed to publish this latest revision in cooperation with Texas Parks and Wildlife.
This latest edition incorporates updated and needed revisions in the species distribution maps, taxonomic names, and other portions of the bulletin. Most of the changes were made to update the identification keys and geographic ranges of mammals in Texas and its adjacent waters. The natural history descriptions include some of the same information detailed by Dr. Davis and DJS in the 1994 edition, as well as pertinent new material.
Simplicity is the basic goal in organizing this book. Accounts for each species are arranged so that they contain in sequence: (1) a brief description of the mammal, with special emphasis given to distinguishing features, accompanied in most cases by a photograph; (2) a description of the geographic distribution of the species in Texas, with reference to a map; (3) a list of the subspecies recognized for each species (not provided for introduced, nonnative species); (4) a discussion of some of the basic life history of the mammal, including habitat preferences, reproduction, behavior, and food habits; and (5) a brief discussion of the conservation status of the species in Texas. The information for the life history discussions has been taken from observations recorded by other researchers and reported in the scientific literature, as well as the personal experience of DJS based on nearly 40 years of studying mammals in Texas. On the distribution maps, counties where specimens of mammals have been reported, either in the literature or represented by a scientific specimen located in a museum collection, are indicated by black dots; the probable range for most species is shaded in.
This is the first edition of this guide to include subspecies of mammals in the state. Subspecies are geographically defined aggregates of local populations that differ taxonomically (usually morphologically) from other such subdivisions of the species. Where the boundaries of subspecies abut, they interbreed with one another, creating zones of intergradation, whereas different species in areas of abutment or overlap are reproductively isolated and maintain their distinctness. The subspecies designations have been adapted from "Annotated Checklist of Recent Land Mammals of Texas," by Richard Manning and Clyde Jones (Occasional Papers 182, The Museum, Texas Tech University, 1998). Subspecies are not depicted on the distribution maps because detailed studies of geographic variation have not been performed on all Texas mammals, making it difficult to map subspecies boundaries accurately.
Another new feature of this guide is information about the conservation status of each species. This information is adapted from my book, Texas Natural History: A Century of Change, for land mammals, and from The Marine Mammals of the Gulf of Mexico, by Bernd Würsig, Thomas Jefferson, and DJS, for marine mammals. Other useful references about the conservation status of Texas’ mammal fauna have been included in Appendix 3. Species considered to be in trouble are those with legal status as endangered or threatened as determined by the U.S. Fish and Wildlife Service and the Texas Parks and Wildlife Department. The late J. Knox Jones, Jr., of Texas Tech University, wrote a paper in the Texas Journal of Science on the concept of threatened and endangered species as applied to Texas mammals. The Texas Organization for Endangered Species and the Texas Natural Heritage Program database, administered by the Nature Conservancy of Texas, maintain lists of rare or watch-list species that may be in trouble. Many rare species have highly localized distributions and others are only migrants in the state. Others were formerly widely distributed and in recent decades have suffered from a variety of circumstances that caused local extinctions in substantial parts of their range in the state. Finally, several native mammals in Texas are now extinct, primarily as a result of overharvesting in the latter part of the nineteenth and early part of the twentieth centuries.
Those readers interested in more detail about the natural history of Texas mammals are referred to the Mammalian Species series, published by the American Society of Mammalogists. The series provides detailed references and information for individual species of mammals. To date, Mammalian Species accounts are available for 137 of the 184 species of Texas mammals. Appendix 5 provides a list of the accounts available for Texas mammals. Mammalian Species may be found in many university libraries or can be ordered from the Web site at http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/. Many of the accounts can be downloaded free from that site. In addition, the Web site of the American Society of Mammalogists, www.mammalogy.org, is an excellent resource for information about mammals and the science of mammalogy.
It is my sincere hope that students of wildlife and citizens interested in conservation and natural history will find much help in this version of The Mammals of Texas.