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Mammals
There are 128 native mammal species and subspecies recorded in the state. Sixteen are game mammals, and therefore subject to hunting regulations set by the State Board of Wildlife Commissioners and enforced by the NDOW. Nine mammal taxa are endemic to Nevada. Fifty-three are considered rare or sensitive. Nevada mammals are very diverse. Among them are tiny shrews and jumping mice, large elk, secretive nocturnal bats, not so reclusive black bears, snowshoe hare, and the fastest land animal in North America, the pronghorn antelope.
Large native mammal species compete with introduced mammals (e.g., livestock and wild horses). Estimated numbers of large native mammals, livestock, and wild horses populating Nevada's wildlands are presented in Table 3-2.
Large mammals greatly add to the wild appeal of open space, perform important ecological functions, and provide recreation for wildlife enthusiasts. The desert bighorn sheep is Nevada's state animal and exemplifies historic population trends of many wildlife species. Desert bighorn were formerly found in most mountain ranges south of the Humboldt River. As the frontier population and ranching industry expanded, bighorn numbers were reduced because of over-hunting and competition with domestic livestock. Desert bighorn disappeared over most of their range. Only small isolated groups were found in the southernmost mountain ranges. There, conditions were too severe for domestic livestock or large settlements. Wildlife interest groups, federal agencies, and the NDOW have reintroduced desert bighorn into most of their former range. The population has grown to approximately 5,000 animals.
Similar efforts for California bighorn sheep and Rocky Mountain bighorn sheep have resulted in stable populations of these animals in suitable habitats
throughout the state (Table 3-3). Mountain goats and Rocky Mountain elk have also been successfully introduced into Nevada. Exotic mountain goats are found in the East Humboldt and Ruby mountain ranges in Elko County. The special habitat requirements for goats limit their range substantially. Exotic mountain goat populations are estimated at 260 animals. Elk, which do not have such special habitat requirements, are currently found in several locations in northeastern and central Nevada. Elk populations continue to expand due to immigration from adjoining states, growth of established herds, and transplanting by the NDOW. About 5,700 elk currently inhabit the state
Mule deer is the most common wild ungulate found in Nevada today. However, mule deer numbers were much lower prior to settlement. Wildlife biologists relate the "explosion" of mule deer during the first half of the 1900's to removal of woodlands, forests, and native grasses and replacement by shrub-dominated communities. The vegetation changes came about primarily by excessive livestock grazing and clear-cutting of trees for mines, mills, and towns. Also, deer predation by mountain lions was sharply curtailed while aggressive hunting, trapping and poisoning occurred.
In 1988, the statewide deer population hit a record peak of 251,000 animals. Subsequently, a seven-year drought followed by a severe winter reduced the population by half. In 2000, wildlife biologists estimated 145,000 mule deer inhabited the state. Herd sizes naturally fluctuate with extreme weather and corresponding changes in habitat conditions (Nevada Division of Wildlife, 2001). Longer-term changes that affect the suitability of rangeland for large deer herds include nonnative plant invasions (especially cheatgrass), and large wildfires, and overcrowded forest and woodlands.
Pronghorn antelope are native mammals, unique in their ability to run fast and survive under harsh conditions. Reaching speeds of 60 to 70 miles per hour, the pronghorn is North America's fastest land mammal. Not a true antelope, the pronghorn is the only living representative of a group of ungulates that evolved in North America. The West-wide pronghorn population declined to critically low
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| American pronghorn antelope inhabit expansive open rangelands throughout Nevada. Forbs and browse, including sagebrush, bitterbrush, and rabbitbrush, make up most of their diet. Pronghorn generally eat different plants than cattle. Sometimes they migrate between summer and winter ranges. Due to limited jumping capability, improperly designed fences can block their movement. During settlement of the West, pronghorn numbers declined from an estimated 35 million to 13,000. Populations are gradually rebounding after decades of complete protection and special management programs -- Photo by Pete Rissler. |
levels by the early twentieth century. Factors in their near demise were over-hunting, habitat conversion, and competition with livestock for food. During the 1990's, the state's population of pronghorn fluctuated, roughly in proportion to mule deer population changes (Table 3-3). Live trapping and transplanting along with habitat improvement projects, primarily guzzlers (i.e., small, artificial water development designed to trap and store runoff), help maintain pronghorn population and distribution. Their preferred shrub/grassland habitat consists of lower growing (less than 24 inches), well-spaced shrubs with plentiful forbs on rolling to flat slopes at low to moderate elevations. Fawns predation is likely to be higher where shrubs are overgrown. Improvements in grazing practices and management of livestock distribution can also improve the suitability of rangeland for pronghorns (U.S. Department of Agriculture, 2002).
Mountain lions and black bears are the largest predators in Nevada. Both are classified as game animals, though bear hunting is not allowed. Mountain lions are widely distributed and are found in most mountain ranges. Region-specific annual quotas are set to control mountain lion sport harvest. Lions can also be hunted to protect livestock under the authority of depredation permits issued to the U.S. Dept. of Agriculture. The highest harvest on  record occurred during the 1997-98 period, when 230 lions were taken by both sport and depredation hunters. In 1999-2000, 144 animals were taken. Mountain lion populations peaked in the mid 90's as the result of high mule deer populations and since have declined with deer numbers. Mountain lion are secretive, so the population is difficult to estimate. Overall, lions are believed to be secure and in balance with the prey base.
Black bears occupy a limited area of Nevada, mainly along the east side of the Sierra Nevada Range and in the Carson Range. In the Sierra Nevada and Carson Ranges, bear populations are at high densities. The number of confrontations between bears and humans is rising as western Nevada urban areas expand. Subdivisions built in the mountains and foothills encroach into bear habitat and displace food supplies. Residential, commercial, and campground developments often attract bears where garbage is not properly managed. Bears have adapted to the more reliable supply of garbage, and young bears are developing the same foraging habits. In addition, the intensity of backcountry travel and mountain oriented recreation has increased. The Nevada Division of Wildlife (NDOW) and the University of Nevada, Reno are currently studying the status and habits of black bears in the urban interface along the Sierra front and Tahoe Basin. The black bear population is estimated to exceed 200 animals.
A variety of mid to small sized mammals inhabit the state. In addition to fur bearers listed in Table 3-4, other mid to small sized mammals include river otter, pine marten, ringtail, weasel, and ermine are other mid to small sized mammals.  In some situations these mammals are seen to be a nuisance, but overall they are critical to healthy ecosystems. For example, beaver and muskrat are removed from irrigation and domestic water systems to alleviate disease concerns and to prevent damage to water distribution structures. However, ponds created by beaver dams create special aquatic and riparian habitats and enhance water resources. The carnivorous furbearers keep populations of rodents and rabbits in check, and some eat carrion, which may otherwise be a source of disease.
Ten mammals are classified by NDOW as furbearers. Historically, furbearers were important commercial species. In recent years, market demand for fur has decreased significantly, lowering commercial trapping activity (Table 3-4). Relatively little biological information is available on these important mammals.
Many small mammal species inhabit a great variety of niches, from (sub)alpine mountaintops, along riparian zones, to sand dunes. Of the nine mammal species and subspecies endemic to Nevada, the only full species is the Palmer's chipmunk (Tamias palmeri). It lives in the Spring Mountains, near Las Vegas. Palmer's chipmunk is one of 16 North American mammal species that became isolated in "mountain islands" as the climate and vegetation shifted to drier conditions.
Rodents, which include desert dwelling kangaroo rats and a variety of mice, rats, squirrels and ground squirrels, gophers, and voles, perform important ecological functions, such as seed dispersal and soil aeration. The range of a
different type of beaver, the mountain beaver (Aplodontia rufa), extends into riparian areas of the Sierra Nevada's in western Nevada. Pygmy rabbits and five other species of rabbits and hares are widespread. The pika, a relation of the rabbit, occupies alpine talus slopes. Several species of shrews and one mole species also live in Nevada.
Twenty-three species of bats are found throughout the state. Bats are well known for their nocturnal feeding habits, consuming large quantities of insects. One species, the Mexican long-tongued bat (Choeronycteris mexicana) feeds on the nectar and pollen of Mojave Desert plants. All bat species are considered rare or sensitive (Nevada Natural Heritage Program, personal communication, 2002). However, only the spotted bat is designated as a threatened species and protected by state law. Bats inhabit or utilize many niches. These include abandoned mines, urban structures, caves, cliffs, springs, riparian, aspen, pinyon-juniper, and desert shrub habitats.
Though bats benefit the environment and mankind in many ways, bats are misunderstood and feared. Unfounded fear coupled with habitat loss among other factors has caused many bat populations to decline. A bat conservation plan has been developed by the Nevada Bat Working Group, which includes the NDOW and NNHP (Bradley et al., 2002). The purpose of this Plan is to reduce the threats to bat populations and their habitats, and also to reduce the risk that any bat species in Nevada will require protection under the Endangered Species Act. Because bats are part of a much larger ecosystem, the goal of the Plan is to promote healthy bat habitats and stable and/or increasing bat populations throughout western North America.
Five mammal species are classified as protected and another as threatened. With the exception of the pika (Ochontona princeps), all mammals classified as protected inhabit the eastern Sierra Nevada ecoregion. The mammals are mountain beaver (Aplodontia rufa), Douglas squirrel (Tamiasciurus douglasi), northern flying squirrel (Glaucomys sabrinus), and western gray squirrel (Sciurus griseus). The spotted bat (Euderma maculatum) is the only mammal species designated as threatened in Nevada. Many wildlife species that inhabit the mountains around Lake Tahoe and the east Sierra Front are at the eastern edge of their range. The number of protected mammals highlights the unique biology of the mountain range, and the encroachment of urban development into wildlands.
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