The concept of threatened and endangered species as applied to Texas mammals.
The roots of wildlife protection extend back to Roman times, perhaps beyond, when the private landowner was acknowledged to have control over harvest of animals that ranged on his property. In the Middle Ages, with the development of royal forests, preserves, and estates, wildlife became the property of kings and their cronies. Gradually, in England for example, the royal prerogative passed under parliamentary control.
In this country, the several states assumed the responsibility of protecting wildlife, but this activity was confined for many years to animals of economic importance in an attempt to prevent significant decline in numbers or local extinction. The concept of federal control first was manifested in laws governing maritime and freshwater animals--the take of oysters from Atlantic mud flats, for example--with responsibility for the harvest of terrestrial animals left to the states.
The first significant step in federal wildlife law was the Lacey Act of 1900. The major provision of this legislation was the prohibition of interstate transportation of "any wild animals or birds" killed in violation of state law. Thus the principal thrust of the Lacey Act was to enlist the aid of the federal government in the enforcement of state game laws.
It has been only in the past 25 years or so that federal and state laws have been developed to protect nongame animal species, including invertebrates, and also plants. The first federal legislation in this area was the Endangered Species Preservation Act of 1966, in which the Secretary of the Interior was directed to "carry out a program in the United States of conserving, protecting, restoring and propagating selected species of native fish and wildlife." Interior was given authority to acquire land as well as to work with Agriculture and Defense (the other federal departments with large land holdings) in carrying out provisions of the act. A species was to be determined as threatened with extinction upon a finding by the Secretary of the Interior "after consultation with the affected states that its existence is endangered because its habitat is threatened with destruction, drastic modification, or severe curtailment, or because of over exploitation, disease, predation, or because of other facts, and that its survival requires assistance."
While the 1966 Act marked a significant first step in an effort to protect endangered species, it had a number of serious limitations. Among these were: 1) it placed no limits at all on harvest or taking of endangered species--that power remained solely with the states; 2) it did not restrict interstate commerce in endangered species or parts thereof; and 3) it applied only to native wildlife, not to endangered species of foreign origin--spotted cats (furs) or elephants (ivory), for example.
This led to the Endangered Species Act of 1969, which essentially provided protection for species that may be in danger of "worldwide extinction." Importation of such animals or their parts, and subsequent sale in this country, both were prohibited, except for educational, medical, and related purposes, as was interstate commerce in protected species. The 1969 Act also broadened potential coverage to species of "wild mammal, fish, wild bird, amphibian, reptile, mollusk, or crustacean," thus including under the provisions for the first time noneconomically important lower vertebrates and two economically important groups of invertebrates. This act also called for an international meeting of ministers to deal with the problems relating to details and enforcement of laws to protect endangered and threatened wildlife species.
The international conference was held in Washington, D.C., early in 1973 and led to a signing by many countries of the Convention on International Trade in Endangered Species of Wildlife Fauna and Flora (CITES). It was the intent of this convention to restrict international commerce in plant and animal species believed to be endangered by economic exploitation.
Later that year, the Congress passed the Endangered Species Act of 1973, by far the most comprehensive of the three acts. Its principal new provisions were: 1) United States and foreign lists were combined and uniform provisions applied to species on the combined list; 2) categories of "endangered" and "threatened" were defined for the first time; 3) plants and all groups of invertebrates were made eligible for protection, as they were under the CITES provisions; 4) all federal agencies were required to undertake programs for conservation of threatened or endangered species, and were prohibited from actions that might jeopardize such a species or destroy or modify its habitat; 5) broad provisions against taking protected species were authorized, overriding the rights of the several states to set limits or otherwise circumvent the law; 6) cooperative agreements with states became possible using matching federal funds; and 7) additional authority to acquire land to protect affected species was authorized; and 8) implementation of provisions of the CITES treaty was approved.
The 1973 Act has remained more or less intact for the past 20 years, with important amendments in 1978, 1982, and 1988. In 1978 provisions were made to: 1) exempt some situations from the law when a cabinet-level committee convened for that purpose agreed; 2) designate critical habitat concurrent with listing of a species when prudent, taking into consideration economic and other impacts of designating habitat boundaries; and most importantly 3) allow for definition and designation of "populations" of species or vertebrates, as well as any species, subspecies, or variety of plant or invertebrate. Thus for vertebrates, a segment of a species or even of a subspecies--namely a "population"--could be designated as threatened or endangered.
In 1982, the determination of a species considered for listing was required to be based entirely on biological and trade information, and there was additional protection for plants found on federal lands and several provisions for procedures of consideration and listing. In 1988, provisions were added for monitoring the status and recovery of listed species, with periodic reports to the Congress, plus additional protection for plants.
The Endangered Species Act of 1973 expired in 1992. Reauthorization of it surely will engender serious discussions and past experience with application of provisions of the several acts certainly will be considered. The first big case was that of the snail darter, which held up completion of Tellico Dam, a Tennessee Valley Authority project, for almost a decade (until viable populations of the fish were found elsewhere). And we all remember surburban expansion and Bufo houstonensis (the Houston toad), more recently the controversy over the spotted owl and logging in forests of the Northwest, and most recently conflict concerning several species of salmon in the Columbia and Snake river drainages.
Before turning to Texas law, the Marine Mammal Protection Act of 1972 should be mentioned. Up to 1972, only eight species of whales threatened with extinction, plus the manatee, the monk seal, the sea otter, and the North Pacific fur seal were federally protected. The remaining marine mammals--all the whales, seals, and their allies--were either protected only by state law or not at all. The Marine Mammal Protection Act removed state authority over all marine mammals, substituting a comprehensive federal program. But provisions were included for the states to re-establish authority with federal assistance and under federal guidelines for operations of their approved management plan. Limited exceptions to protection were carved out for scientific research, public display in aquaria, sea gardens, and the like, and capture incidental to commercial fishing. All this applied to United States territorial waters only, but laid the groundwork for international accords to follow.
Why are state laws needed concerning endangered or threatened species? Aren't all species covered by federal law also listed by states in which they occur? The answer is affirmative in that species listed by the U.S. Fish and Wildlife Service (USFWS) are, de facto, also included by any state in which they are found. However, state lists allow inclusion of species that, although not endangered or threatened throughout a large part of their range encompassing several or many states or countries, may be rare or have a restricted distribution in one or more states--at the periphery of their overall distribution, for example. Thus, state authorities realistically may feel that protection is needed because of the small area or narrow habitat in which a species may be found there.
The first endangered species legislation in Texas was enacted in 1973, and subsequently has been amended several times. Chapter 68 of the Parks and Wildlife Code provides for the establishment of a list of fish or wildlife threatened with statewide extinction, sets up the procedure to allow the Executive Director of the Texas Parks and Wildlife Department (TPWD) to recommend designation of species for inclusion on the list following public notice, and authorizes procedures for the handling and propagation of endangered species. The statutory definition of fish and wildlife excluded most terrestrial invertebrates from designation as state endangered species.
Legislative authority for the designation of threatened animals is embodied in Chapter 67 of the Code pertaining to nongame species. This legislation authorizes the Parks and Wildlife Commission to adopt a list of protected nongame wildlife following public notice and to regulate the taking and possession of such wildlife. The statutory definition of nongame wildlife does permit the designation of invertebrates as threatened species; however, none has been listed to date.
Chapter 88 of the Code, adopted in 1981 and amended in 1985, set up the designations of endangered, threatened, and protected plants. The Executive Director is authorized to recommend designation of plants for inclusion on any of the lists following public notice, and also to prohibit commercial collection or sale of any listed plant without departmental permits.
Animals and plants are placed on Texas lists of endangered or threatened species by action of the Texas Parks and Wildlife Commission upon recommendation by the Executive Director. Proposed changes and additions must be published in the Texas Register prior to consideration by the Commission.
It should also be pointed out that there are several private organizations and groups that also rank animal or plant species, or both, as to their survival status. On a global scale, the International Union for the Conservation of Nature and Natural Resources (IUCN) ranks species. In Texas, the Texas Organization for Endangered Species (TOES) considers species of both plants and animals as endangered, threatened, or on their "watch list", the latter meaning surveillance from year to year. And the Nature Conservancy, Audubon Society, and others also contribute significantly to the effort of monitoring the well-being of native plants and animals. The real contribution of private organizations to protection of endangered or threatened species lies in the fact that, unencumbered by governmental bureaucracy, whether at the state or federal levels, they can react rapidly to call attention to a recently developed and serious situation, thus bringing public pressure on the various agencies. They also can acquire land through gift or purchase, which later may be turned over to a governmental agency, such as the Harte Ranch addition to Big Bend National Park.
MAMMALIAN SPECIES EXTINCT IN TEXAS
Ten species of mammals that once occurred in Texas no longer are found there, except for three that were reintroduced, having been driven to extinction within the borders of the state directly or indirectly by humans.
Canis lupus (gray wolf). -- Gray wolves once were common in western and central Texas, especially in association with the vast herds of bison that occurred there. This species is listed by USFWS as endangered throughout its distribution in North America except in Alaska and Canada, where reasonably good populations are extant in some areas. Small numbers prevail in the northern Great Lakes states.
The last wolves known to have been taken in Texas were two killed in December of 1970 in Brewster County (Davis, 1974). It is possible that a few individuals still cross over into the Trans-Pecos region from Mexico, but the species is endangered there too. There have been some discussions of reintroducing C. lupus to Big Bend National Park, but any action on that proposal is years away and is likely to be strongly questioned by representatives of the livestock industry.
Canis rufus (red wolf). -- This species once ranged throughout eastern Texas, northward into Arkansas and southern Oklahoma. None has been taken in Texas since the early 1960s (from Kenedy and Chambers counties--Davis, 1974), and the species is listed as endangered throughout its range in the southeastern United States. Genetic swamping by expanding coyote populations (with which this species is cross-fertile) probably was responsible for much of the decline of the red wolf in Texas.
Fortunately, captive breeding programs for this canine have been remarkably successful, and monitored reintroduction of individuals into the wild now is underway in the Carolinas and Mississippi. If these efforts prove to be successful, reintroduction in eastern and coastal Texas may be possible.
Ursus arctos (grizzly or brown bear). -- This species probably occurred sparingly in western Texas from the Panhandle to the Trans-Pecos up until the days of early exploration of the region. However, only one specimen is on record from the state--a large male killed by hunters in October 1890 in the Davis Mountains of Jeff Davis County (Bailey, 1905). The grizzly is regarded as endangered throughout its former range in the conterminous United States and in Mexico.
Mustela nigripes (black-footed ferret). -- Closely associated with the vast colonies of black-tailed prairie dogs that once obtained over much of western and central Texas, this mustelid now is extinct in the state and apparently in the wild over its entire former range.
Ferrets were driven to extinction in Texas with the demise of prairie dogs, their principal food source. In one report, it is stated that the last specimen taken in the state was a young animal "3 to 6 weeks old" captured alive in May 1953 in Dallam County, in the extreme northwestern part of the Panhandle. This record, not substantiated by a specimen, seems implausible to me for several reasons; I suspect ferrets disappeared from Texas at least a decade or so earlier.
The last known wild ferrets occurred in Wyoming and died out several years ago from an outbreak of distemper. Fortunately, captive breeding by USFWS has been successful, and reintroductions in Wyoming are scheduled. TPWD is drawing up plans for potential reintroductions in Texas, the only problem being the availability of large enough prairie dog towns to support a breeding population of ferrets. Prairie dogs are widespread and common now, but in small and scattered colonies.
Monachus tropicalis (West Indian monk seal). -- This seal rarely occurred in Texas waters, but once was common in the Gulf of Mexico to the south and east. It now may be totally extinct throughout its range.
Panthera onca (jaguar). -- The distribution of the jaguar once extended northward well into central Texas, including much of the Edwards Plateau, as well as all along the southern part of the state. There are many records and sightings that date from the late 1800s and early 1900s, and this large cat actually was regarded as common in some areas. The most recent documented record from the state was in the early 1950s (Tewes, 1990). This species is regarded as endangered throughout its relatively broad range in Central and South America.
Felis wiedii (margay). -- The inclusion of this small cat in the fauna of the United States is based on a single specimen taken at (or near) Eagle Pass sometime prior to February 1852 (Goldman, 1943). It presently is known from tropical eastern and western Mexico southward to Paraguay and northern Argentina. One of the smallest of American spotted cats, it is regarded as endangered throughout its range.
Cervus elaphus (wapiti or elk). -- This well known species once ranged over parts of northern and western Texas, but there seem to be no actual specimens to document its modern occurrence there. In any event, it was hunted to extinction within the borders of the state before the turn of the last century. Fortunately, good populations remain in several western states. Wapiti were reintroduced into the Guadalupe Mountains National Park in 1928, and a herd that was estimated to number 150 in the late 1970s still occurs there and there also is a small herd in the Davis Mountains area. The reintroductions were not of the native subspecies (Cervus elaphus merriami), however, which evidently is extinct.
Bos bison (bison). -- This magnificent creature, once numbering in the millions, was hunted to extinction in Texas. It once ranged over most of the state. The last verified report of wild bison was from the northwestern part of the Panhandle (Dallam County) in 1889 (Jones et al., 1988). Though no longer wild-ranging, herds prevail on many national and state sanctuaries in the West. In Texas, bison are kept in captivity on many farms and ranches.
Ovis canadensis (bighorn sheep). -- The desert bighorn sheep, which once occurred in the Guadalupe Mountains, on many of the arid ranges in Trans-Pecos Texas, and probably eastward into the rugged lands that form the western edge of the Edwards Plateau proper, was last seen in the Sierra Diablo Mountains, in 1959, when the population was estimated at fourteen (Davis, 1974). After extinction, reintroductions in the Trans-Pecos area, not always of individuals representing the native subspecies, have been successful and bighorn sheep now occur in several mountainous areas in the Trans-Pecos.
In conclusion relative to species extinct in Texas, it should be underscored that of the 10, only the West Indian monk seal is thought to be extinct throughout its range, although the red wolf and black-footed ferret may be extinct in the wild (except for recent reintroductions), the two spotted cats are recognized as endangered, and bison are found only on reservations.
MAMMALIAN SPECIES ENDANGERED IN TEXAS
Six taxa of land mammals currently are considered as endangered in Texas. Four of these, Leptonycteris nivalis, Felis pardalis, Felis yagouaroundi, and Trichechus manatus appear on both state and federal lists, whereas the black bear (Ursus americanus) and the white-nosed coati or coatimundi (Nasua narica) are listed as endangered in Texas by TPWD (Table 1).
Leptonycteris nivalis (Mexican long-tongued bat). -- This bat acquired its endangered status primarily because it is known in the United States only from the Texas Big Bend. A cave-dwelling species, it is to be looked for elsewhere in the southern Trans-Pecos as well.
Aside from a few records of foraging individuals, L. nivalis is known only from a cave on Emory Peak in the Chisos Mountians, where a maternity colony, along with some adult males, is present in spring and early summer, and from the Chinati Mountains in Presidio County (Schmidly, 1991). Several years ago, the Chisos colony was estimated by one investigator to contain 5000 to 6000 individuals, but more recent investigations suggest a lesser number. This is one of a group of Neotropical species that feeds on pollen and nectar of flowering plants, using a long, extensible tongue. It is an important pollenator of some species of agave and cactus.
Ursus americanus (black bear). -- This bear once occurred throughout the state. The last native animals were taken in the woods and swamps of eastern Texas in the 1940s, but a stocking program in Louisiana has resulted in a few reports from along the border in recent years. As an aside, the population in Louisiana was pronounced as endangered in 1991 by USFWS even though part of it is descendent from 161 black bears transplanted there in the 1960s from Minnesota.
A small number of black bears, perhaps numbering as many as eight, now occur in Big Bend National Park, presumably from natural invasion from Mexico in the past few years. It is hoped that a breeding population will become reestablished in the park.
Nasua narica (white-nosed coati). -- The coatimundi is listed by TPWD as in the endangered category primarily because of its sporadic occurrence along the southern border of the state--from the lower Rio Grande Valley to the Trans-Pecos. It evidently has not been listed as endangered by USFWS because of the relatively good populations extant in southeastern Arizona. It is widespread in Mexico and Middle America. The current status of this procyonid in Texas definitely is in need of serious study.
Felis pardalis (ocelot). -- This beautiful spotted cat once ranged over much of southern, eastern, and central Texas, inhabiting dense brushy country. Currently, the population is estimated to be between 80 and 120 individuals (Tewes, 1990), which are known to occur at a small number of fragmented sites in the lower Rio Grande Valley, especially on the Santa Ana National Wildlife Refuge. Destruction of the dense cover needed by this cat and its prey species has been the principal reason for its decline, and only habitat restoration will enhance its recovery. Its biology in the state presently is under intense study. The ocelot is considered endangered throughout its entire range.
Felis yagouaroundi (jaguarundi). -- This cat is known in two color phases--brown and grayish-black. It was never as widely distributed in Texas as the ocelot, but shares the latter's prediliction for brushy country. According to Tewes (1990), the jaguarundi is the rarest of native cats currently extant in the state, being represented in the lower Rio Grande Valley by no more than 15 individuals. With numbers so low, it is doubtful it will survive in the state. Like the ocelot, the jaguarundi has a broad but threatened distribution in Neotropical America. All subspecies occurring from Panama northward are listed by the USFWS as endangered. The last specimen taken in Texas was a road-killed individual found near Brownsville in 1986 (Tewes, 1990).
Trichechus manatus (manatee). -- This is an aquatic mammal of coastal bays and estuaries. Probably the manatee never was especially common along the Texas coast, but reasonably good populations remain in Florida and at some places along the Caribbean Coast of Latin America. Despite this, the manatee is listed as endangered throughout its range by USFWS. The most recent Texas records are a sighting near Corpus Christi in 1979 and a dead animal stranded near the Louisiana border in February 1986 (Fernandez and Jones, 1990).
MAMMALIAN SPECIES THREATENED IN TEXAS
Six species of mammals, three bats and three rodents, are listed as threatened in the state by TPWD (Table 1), but none is thusly recognized on federal lists.
Lasiurus ega (southern yellow bat). -- This bat is listed as threatened only because of its limited distribution in the southern part of the state. It is common around Brownsville and in other areas in the lower Rio Grande Valley, and is known northward to Corpus Christi (Schmidly, 1991). Tall palms are necessary roost sites, and this species would really be threatened only if such habitats were destroyed or in danger of destruction.
Euderma maculatum (spotted bat). -- This beautiful bat has a wide distribution in western North America, but is not known to be common anywhere within its range. In Texas, it is known only from Big Bend National Park (Schmidly, 1991), but probably will be found elsewhere in the Trans-Pecos region. The restricted range in Texas accounts for the threatened status there. The USFWS has taken the position that much more knowledge is needed about the biology of this widespread western species, which is known from southern Canada to northern Mexico, before listing should be considered.
Plecotus rafinesquii (Rafinesque's big-eared bat). -- This bat, which occurs in mountainous and hilly country through the middle part of eastern North America, has a restricted distribution in eastern Texas (Schmidly, 1991), and thus is listed as threatened by TPWD.
Dipodomys elator (Texas kangaroo rat). -- The Texas kangaroo rat is unique in that it is the only species of native mammal that is restricted in distribution to Texas. A beautiful kangaroo rat with a banner tail, the species occurs in a band just south of the Red River from Motley County in the west to Montague County in the east, but with substantial populations apparently only in Hardeman, Wichita, and Wilbarger counties. Its status is even more peculiar when it is realized that three specimens of D. elator have been reported from Oklahoma, one taken in 1904 and another in 1905 in Comanche County, and the third from Cottle County, just across the Red River from Texas, obtained in 1969. The provenance of the latter specimen is doubtful to me but, in any case, this rat evidently does not occur in Oklahoma at the present time.
Because of its restricted geographic range and because of habitat alteration from time to time for agricultural purposes within that range, this species is justly listed as threatened by TPWD. USFWS has taken a somewhat more cautious view of the status, all the while seeking additional information on D. elator. Several state- and federally-sponsored studies of the Texas kangaroo rat have been completed in recent years (see, for example, Jones et al., 1988). It appears that heavily grazed rangeland and the eroded sides of well-worn rangeland roadways may provide optimum habitat for this species--much as overgrazing and trampling by bison may have done in the past (Stangl et al., 1992).
Oryzomys couesi (Coues' rice rat). -- This small rat is regarded as threatened in Texas by TPWD only because it is restricted in occurrence to the grasslands along the southern coast and adjacent inland areas in Cameron and Hidalgo counties. It is a common small mammal from Mexico southward to Panama, where it is in absolutely no danger. Whether it should be continued to be listed in Texas is problematic.
Peromyscus truei (pinon mouse). -- TPWD has listed an endemic subspecies of this mouse, Peromyscus truei comanche, as threatened. This is sometimes referred to as the Palo Duro mouse because it occurs in Palo Duro Canyon State Park and adjacent areas, including Caprock Canyons State Park, in three Texas counties--Armstrong, Briscoe, and Randall (Jones and Jones, 1992). There it occupies high rocky ledges clothed with juniper along the break of the Llano Estacado. Taking into account the numerous side canyons, identations, and contours along the edge of the Llano caprock within its range, this mouse must have at least 100 miles of more-or-less continuous distribution. Whether it occurs beyond this area to the north or south remains to be determined, but it now is known that supposed records from as far south as Garza and Lynn counties represent misidentifications.
Actually, another subspecies of the pinon mouse, Peromyscus truei truei, also occurs in Texas, and is much rarer than P. t. comanche. It is known by only four specimens from Guadalupe Mountains National Park and five from along the northern edge of the Llano Estacado, just inside Texas from New Mexico in Deaf Smith County. To be consistent, all known populations in Texas should be regarded as threatened.
Although this mouse is not currently in direct danger from man's activities, it easily could fall victim to major climatic perturbations such as global warming. An upward shift of mean annual temperature of but a degree or two easily could put a competitor, Peromyscus attwateri of more southerly overall distribution in the region, at advantage. Elsewhere, the pinon mouse is widespread and common in pinon and yellow pine forests in western North America.
WHALES, DOLPHINS, AND PORPOISES
Although cetaceans, for several reasons, have not been a main thrust of this manuscript it is noteworthy that there are 20 or so species that occur in Gulf waters near the Texas coast, more than half of which are listed either as threatened or endangered. All are covered under the Marine Mammal Protection Act. The sperm whale and all three baleen whales occurring in the region are recorded as endangered on both federal and state lists. Another seven small cetaceans are listed as threatened by TPWD. The status of many of these species is not accurately known. Current research by marine biologists at Texas A & M University at Galveston is designed to provide much-needed data about the biology and status of several species. There is, of course, some question as to how far off shore TPWD should be concerned about marine life--three miles or perhaps up to 12 miles, which are recognized continental limits, would seem appropriate.
SPECIES POSSIBLY THREATENED OR ENDANGERED
There are several species of terrestrial mammals, or populations thereof, in Texas that may well warrant protection in the future. Certainly their situation bears watching; in some cases, considerable additional data are needed to establish the facts necessary to arrive at a meaningful and biologically defensible position as to their status. Several of these taxa are listed below by way of example.
There are two bats of the genus Myotis--lucifugus and septentrionalis--that are known from Texas each by a single specimen, the former from Ft. Hancock in Hudspeth County in the early 1900s and the latter from Winter Haven, Dimmit County, in 1942 (Schmidly, 1991). Probably these represent wanderers and neither species now is a part of the permanent Texas fauna. Similarly, the Mexican long-tongued bat (Choeronycteris mexicana) is known only from photographs of a single individual and observations of several others at Santa Ana National Wildlife Refuge in the lower Rio Grande Valley. Are these accidental occurrences or is there a tenuous, seasonal population of this pollen- and nectar-feeding species in southernmost Texas? Of certain accidental occurrence is the one specimen of a hairy-legged vampire bat (Diphylla ecaudata) found in a partially inundated railway tunnel in Val Verde County in 1967.
The large mastiff bat, Eumops perotis, has a restricted distribution along part of the southern border of the state and is recorded from few localities (Schmidly, 1991). It requires clefts in high, rocky cliffs as roosting sites. The pocketed free-tailed bat, Nyctinomops femorosaccus, requires similar habitats and has an even more restricted known range in Texas (southern Big Bend region). Another free-tailed species (N. macrotis), although widespread as a transient, is a rare resident of the southwestern part of the state.
Among the rodents, the muskrat subspecies Ondatra zibethicus ripensis of the Pecos River or the rock mouse, Peromyscus nasutus, which occupies only a few mountainous habitats in the southern and western Trans-Pecos, and which is poorly known ecologically, might be mentioned. One interesting case is that of the prairie vole, Microtus ochrogaster, known from but three localities in the state--from Hardin County in the southeast and Hansford and Lipscomb counties in the northern Panhandle. The single specimen from Hardin County was taken in 1902 and represents the relictual subspecies M. o. ludovicianus, now extinct. It once occurred also in adjacent western Louisiana.
The Panhandle specimens, nine in all, were collected in the late 1980s. They represent a totally different subspecies (M. o. haydenii) and are from along the southern border of the range of the species on the Great Plains. With only nine specimens known from but two localities in the Panhandle, it could be argued that this vole ought to be protected somehow, but much more information about where it does or does not occur is needed before any such action should be taken. A relatively large area of potentially suitable habitat still needs to be explored. This points up, once again, the fact that there still is much to learn about distributional patterns and biodiversity in otherwise rather well-studied groups of vertebrates.
Concern has been expressed from time to time about the swift and kit foxes, variously regarded as two species, Vulpes velox and V. macrotis, or as well-differentiated subspecies of a single species, the current view (Dragoo et al., 1990). These little foxes, which occur throughout much of the western part of Texas, were driven to near extinction by indiscriminate poisoning campaigns directed at wolves and later coyotes. With curtailment of this dastardly practice, the population of plains foxes has rebounded, and no longer are these animals threatened.
Another example involves the two species of spotted skunks in the state, Spilogale gracilis in the Trans-Pecos and adjacent regions and S. putorius in the east and north. Once relatively common, these two species now are rare in some areas and their current status in the state is unknown. This genus is in need of detailed study in Texas. Because these small skunks consume many insects, some believe populations (particularly those of putorius) were decimated by widespread use of chlorinated hydrocarbon insecticides, with the deadly effect passed (and concentrated) up the food chain.
Finally, no account of this kind would be complete without mention of the mountain lion (Felis concolor). This large cat occurs, at least sporadically, in many areas of Texas. For example, one was shot in Dallam County in 1985 (Jones et al., 1988) and a young adult male was taken in Irion County in 1987 (Engstrom and Maxwell, 1988). It is most often encountered, however, in the Trans-Pecos mountains and in the roughest parts of the southern Edwards Plateau and brushlands of the Rio Grande Plain.
Tewes (1990) estimated that the population of mountain lions in Texas numbered 300 to 500 animals. If this were not a large and feared predator, surely such low numbers would qualify F. concolor for special attention as threatened or endangered in the state.
Much remains to be learned about biodiversity in Texas, and both governmental and private organizations are urged to support the process of gathering much-needed baseline data about the natural history of plants and animals in the state. Obviously, decisions and actions concerning protection and conservation of animal and plant species will be much a part of our future. I urge all to become familiar with the issues so as to act as responsible citizens as an attempt is made to find the appropriate compromises between man's economic and social needs and the clear need to preserve our natural heritage.
TABLE 1. List of endangered and threatened species of land mammals presently extant in Texas as ranked by the U.S. Fish and Wildlife Service and Texas Parks and Wildlife Department. Endangered Threatened Species USFWS TPWD USFWS TPWD Leptonycteris nivalis X X Lasiurus ega X Euderma maculatum X Plecotus rafinesquii X Dipodomys elator X Oryzomys couesi X Peromyscus truei (comanche) X Ursus americanus X Nasua narica X Felis pardalis X X Felis yagouaroundi X X Trichechus manatus X X
Many individuals supplied, through one source or another, directly or indirectly, information that was used to complete this manuscript, and I thank them collectively here. I am especially mindful of the contributions of Eric G. Bolen and David J. Schmidly.
A modified version of this paper was presented as the plenary lecture at the 95th annual meeting of the Texas Academy of Science in Wichita Falls on 6 March 1992, in connection with recognition of the author as Distinguished Texas Scientist of the Year by the Academy.
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J KNOX JONES, JR.
The Museum and Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409-3191
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|Author:||Jones, J. Knox, Jr.|
|Publication:||The Texas Journal of Science|
|Date:||May 1, 1993|
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