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The Mammals of Texas - Online Edition

CRITICAL SPECIES

Within the past 100 years, 9 species of land mammals and one marine mammal (the Caribbean monk seal) have become extirpated in Texas. A variety of factors can cause extinction, but in the case of these species, persecution and habitat alteration by man probably had more to do with their disappearance than any other single factor. Overharvesting definitely seems to have caused the disappearance of the grizzly, elk, bison, and seal. Predator control activities probably had much to do with the extirpation of the gray wolf, red wolf, and the jaguar. The black-footed ferret disappeared primarily as a result of destruction of prairie dog towns, which removed most of their natural food supply. The big factors in the decline of the bighorn sheep were the introduction of domestic sheep and net wire fences into rangelands. Bighorns were unable to compete with the sheep, and the fences prevented their wandering about from one mountain range to another. The margay was probably only marginal in Texas and never represented by an established breeding population.

About 16% of the land mammals remaining in Texas today can be viewed as having some sort of biological problem that threatens or potentially threatens their existence. These are species that, in the opinion of biologists and conservation groups, currently face or likely will face serious conservation problems in the future (Table 2). State and federal agencies as well as private organizations have developed lists of rare and endangered mammals in Texas. The Texas Parks and Wildlife Department has a list of protected non-game wildlife. Similarly, the Texas Organization of Endangered Species (TOES) periodically publishes a watch-list of endangered, threatened, and peripheral vertebrates of Texas which includes mammals. The United States Fish and Wildlife Service also has produced a list of endangered and threatened species, which includes mammals listed in these categories in the Federal Register. The mammals listed in Table 2 are distributed throughout the state. There is no obvious geographic pattern or concentration of occurrence of these species within the state.

TABLE 2. List of critical mammals as defined by Texas Parks and Wildlife Department (TPW) and Department of Interior, Fish and Wildlife Services (DOI)1.

Scientific Name Common Name TPW DOI
Leptonycteris nivalis Mexican Long-nosed Bat E2 E
Choeronycteris mexicana Mexican Long-tongued Bat C2
Myotis austroriparius Southeastern Myotis T C2
Myotis lucifugus Little Brown Myotis C2
Myotis septentrionalis Northern Myotis C2
Lasiurus ega Southern Yellow Bat T C2
Euderma maculatum Spotted Bat T C2
Plecotus rafinesquii Rafinesque’s Big-eared Bat T C2
Eumops perotis Western Mastiff Bat C2
Dipodomys elator Texas Kangaroo Rat T C2
Oryzomys couesi Coues’ Rice Rat T C2
Sigmodon ochrognathus Yellow-nosed Cotton Rat C2
Canis lupus3 Gray Wolf E E
Canis rufus3 Red Wolf E E
Ursus americanus Black Bear E PT
Nasua narica White-nosed Coati E
Mustela nigripes3 Black-footed Ferret E E
Conepatus leuconotus Eastern Hog-nosed Skunk C2
Felis pardalis Ocelot E E
Felis yagouaroundi Jaguarundi E E
Felis wiedii3 Margay E E
Panthera onca3 Jaguar E E
Trichechus manatus West Indian Manatee E E
Eubalaena glacialis Northern Right Whale E E
Balaenoptera musculus Blue Whale E E
Balaenoptera physalus Fin Whale E E
Megaptera novaeangliae Humpback Whale E
Physeter macrocephalus Sperm Whale E E
Kogia breviceps Pygmy Sperm Whale T
Kogia simus Dwarf Sperm Whale T
Mesoplodon europaeus Gervais’ Beaked Whale T
Ziphius cavirostris Cuvier’s Beaked Whale T
Orcinus orca Killer Whale T
Pseudorca crassidens False Killer Whale T
Feresa attenuata Pygmy Killer Whale T
Globicephala macrorhynchus Short-finned Pilot Whale T
Steno bredanensis Rough-toothed Dolphin T
Stenella frontalis Atlantic Spotted Dolphin T
1 As of January, 1992.
2 T = Threatened; E = Endangered; C2 = Listed in Federal Register as Category 2 species (this
refers to taxa for which information now in hand indicated that proposing to list the species as
endangered or threatened is possible appropriate, but for which substantial data are not currently
available to biologically support a proposed rule); PT = Proposed to be listed in Federal Register as
Threatened.
3 Species considered by the authors to now be extinct in Texas.

Although vigorous action must be directed to prevent direct human impacts on such species as the ocelot and jaguarundi, the continued existence and size of the populations of rare and endangered species are ultimately dependent upon availability and quality of their habitats. Therefore, for the most part, the problem of rare and endangered Texas mammals boils down to the problem of rare and endangered Texas habitats. The survival of these species is synonymous with protection and proper management of their habitats.

Other topics under Texas Mammals:

Diversity of Land Mammals
Geographic Distribution of Land Mammals
Conservation Strategies
Key to the Major Groups (Orders) of Mammals in Texas