Desert tortoise

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Desert tortoise
Gopherus agassizii.jpg
Agassiz's desert tortoise, G. agassizii
Desert tortoise turtle gopherus morafkai.jpg
Sonoran desert tortoise, G. morafkai
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Family: Testudinidae
Genus: Gopherus
Groups included
Cladistically included but traditionally excluded taxa
Synonyms [2]
  • Xerobates agassiziiCooper, 1863
  • Testudo agassiziiCope, 1875
  • Xerobates agassizi [sic] Garman, 1884(ex errore)
  • Gopherus agassiziiStejneger, 1893
  • Testudo aggassizi [sic] Ditmars, 1907(ex errore)
  • Testudo agassizi— Ditmars, 1907
  • Gopherus agassiziV. Tanner, 1927
  • Testudo agasizzi [sic] Kallert, 1927(ex errore)
  • Gopherus polyphemus agassiziiMertens & Wermuth, 1955
  • Gopherus agassiz [sic] Malkin, 1962(ex errore)
  • Gopherus polyphemus agassizi— Frair, 1964
  • Geochelone agassizii— Honegger, 1980
  • Scaptochelys agassizii— Bramble, 1982
  • Scaptochelys agassizi— Morafka, Aguirre & Murphy, 1994

The desert tortoises (Gopherus agassizii and Gopherus morafkai), also known as desert turtles, are two species of tortoise native to the Mojave and Sonoran Deserts of the southwestern United States and northwestern Mexico and the Sinaloan thornscrub of northwestern Mexico. [3] G. agassizii is distributed in western Arizona, southeastern California, southern Nevada, and southwestern Utah. [3] The specific name agassizii is in honor of Swiss-American zoologist Jean Louis Rodolphe Agassiz. [4] Recently,[ when? ] on the basis of DNA, geographic, and behavioral differences between desert tortoises east and west of the Colorado River, it was decided that two species of desert tortoises exist: Agassiz's desert tortoise (Gopherus agassizii ) and Morafka's desert tortoise (Gopherus morafkai). [5] G. morafkai occurs east of the Colorado River in Arizona, as well as in the states of Sonora and Sinaloa, Mexico. This species may be a composite of two species.

In biology, a species ( ) is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more closely they represent problematic species concepts. For example, the boundaries between closely related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, and in a ring species. Also, among organisms that reproduce only asexually, the concept of a reproductive species breaks down, and each clone is potentially a microspecies.

Tortoise family of turtles that live on land

Tortoises are reptile species of the family Testudinidae of the order Testudines. They are particularly distinguished from turtles by being land-dwelling, while many turtle species are at least partly aquatic. However, like turtles, tortoises have a shell to protect from predation and other threats. The shell in tortoises is generally hard, and like other members of the suborder Cryptodira, they retract their necks and heads directly backwards into the shell to protect them.

Mojave Desert desert in southwestern United States

The Mojave Desert is an arid rain-shadow desert and the driest desert in North America. It is in the southwestern United States, primarily within southeastern California and southern Nevada, and it occupies 47,877 sq mi (124,000 km2). Very small areas also extend into Utah and Arizona. Its boundaries are generally noted by the presence of Joshua trees, which are native only to the Mojave Desert and are considered an indicator species, and it is believed to support an additional 1,750 to 2,000 species of plants. The central part of the desert is sparsely populated, while its peripheries support large communities such as Las Vegas, Barstow, Lancaster, Palmdale, Victorville, and St. George.


The new species name is in honor of the late Professor David Joseph Morafka of California State University, Dominguez Hills, in recognition of his many contributions to the study and conservation of Gopherus.

California State University, Dominguez Hills university

California State University, Dominguez Hills is a public university in Carson, California. It was founded in 1960 and is part of the California State University (CSU) system.

The desert tortoise lives about 50 to 80 years; [6] it grows slowly and generally has a low reproductive rate. It spends most of its time in burrows, rock shelters, and pallets to regulate body temperature and reduce water loss. It is most active after seasonal rains and is inactive during most of the year. This inactivity helps reduce water loss during hot periods, whereas winter hibernation facilitates survival during freezing temperatures and low food availability. Desert tortoises can tolerate water, salt, and energy imbalances on a daily basis, which increases their lifespans. [7]


These tortoises may attain a length of 10 to 14 in (25 to 36 cm), [8] with males being slightly larger than females. A male tortoise has a longer gular horn than a female, his plastron (lower shell) is concave compared to a female tortoise. Males have larger tails than females do. Their shells are high-domed, and greenish-tan to dark brown in color. Desert tortoises can grow to 4–6 in (10–15 cm) in height. They can range in weight from .02 to 5 kg (0.044 to 11.023 lb). [9] The front limbs have sharp, claw-like scales and are flattened for digging. Back legs are skinnier and very long.


Agassiz's desert tortoise in Rainbow Basin near Barstow, California DesertTortoise.JPG
Agassiz's desert tortoise in Rainbow Basin near Barstow, California

Desert tortoises can live in areas with ground temperatures exceeding 140 °F (60 °C) because of their ability to dig underground burrows and escape the heat. At least 95% of their lives are spent in burrows. There, they are also protected from freezing winter weather while dormant, from November through February or March. Within their burrows, these tortoises create a subterranean environment that can be beneficial to other reptiles, mammals, birds, and invertebrates.

Scientists have divided the desert tortoise into two types: Agassiz's and Morafka's desert tortoises, with a possible third type in northern Sinaloan and southern Sonora, Mexico. An isolated population of Agassiz's desert tortoise occurs in the Black Mountains of northwestern Arizona. [10] They live in a different type of habitat, from sandy flats to rocky foothills. They have a strong proclivity in the Mojave Desert for alluvial fans, washes, and canyons where more suitable soils for den construction might be found. They range from near sea level to around 3,500 feet (1,100 m) in elevation. Tortoises show very strong site fidelity, and have well-established home ranges where they know where their food, water, and mineral resources are.

Black Mountains (Arizona)

The Black Mountains of northwest Arizona are an extensive, mostly linear, north-south 75-mile (121 km) long mountain range. It forms the north-south border of southwest Mohave County as it borders the eastern shore of the south-flowing Colorado River from Hoover Dam.

Canyon Deep ravine between cliffs

A canyon or gorge is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic timescales. Rivers have a natural tendency to cut through underlying surfaces, eventually wearing away rock layers as sediments are removed downstream. A river bed will gradually reach a baseline elevation, which is the same elevation as the body of water into which the river drains. The processes of weathering and erosion will form canyons when the river's headwaters and estuary are at significantly different elevations, particularly through regions where softer rock layers are intermingled with harder layers more resistant to weathering.

Soil mixture of organic matter, minerals, gases, liquids, and organisms that together support life

Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body of soil, called the pedosphere, has four important functions:

Desert tortoises inhabit elevations from below mean sea level in Death Valley to 5,300 feet (1,600 m) in Arizona, though they are most common from around 1,000 to 3,500 feet (300 to 1,070 metres). Estimates of densities vary from less than eight individuals/km2 on sites in southern California to over 500 individuals/km2 in the western Mojave Desert, although most estimates are less than 150 individuals/km2. The home range generally consists of 10 to 100 acres (4.0 to 40.5 ha). In general, males have larger home ranges than females, and home range size increases with increasing resources and rainfall. [7]

Desert tortoises are sensitive to the soil type, owing to their reliance on burrows for shelter, reduction of water loss, and regulation of body temperature. The soil should crumble easily during digging and be firm enough to resist collapse. Desert tortoises prefer sandy loam soils with varying amounts of gravel and clay, and tend to avoid sands or soils with low water-holding capacity, excess salts, or low resistance to flooding. They may consume soil to maintain adequate calcium levels, so may prefer sites with higher calcium content. [7]


Desert tortoises spend most of their lives in burrows, rock shelters, and pallets to regulate body temperature and reduce water loss. Burrows are tunnels dug into soil by desert tortoises or other animals, rock shelters are spaces protected by rocks and/or boulders, and pallets are depressions in the soil. The use of the various shelter types is related to their availability and climate. The number of burrows used, the extent of repetitive use, and the occurrence of burrow sharing are variable. Males tend to occupy deeper burrows than females. Seasonal trends in burrow use are influenced by desert tortoise gender and regional variation. Desert tortoise shelter sites are often associated with plant or rock cover. Desert tortoises often lay their eggs in nests dug in sufficiently deep soil at the entrance of burrows or under shrubs. Nests are typically 3 to 10 inches (7.6 to 25.4 centimetres) deep. [7]

Shelters are important for controlling body temperature and water regulation, as they allow desert tortoises to slow their rate of heating in summer and provide protection from cold during the winter. The humidity within burrows prevents dehydration. Burrows also provide protection from predators. The availability of adequate burrow sites influences desert tortoise densities. [7]

The number of burrows used by desert tortoises varies spatially and temporally, from about 5 to 25 per year. Some burrows are used repeatedly, sometimes for several consecutive years. Desert tortoises share burrows with various mammals, reptiles, birds, and invertebrates, such as white-tailed antelope squirrels (Ammospermophilus leucurus), woodrats (Neotoma), collared peccaries (Pecari tajacu), burrowing owls (Athene cunicularia), Gambel's quail (Callipepla gambelii ), rattlesnakes (Crotalus spp.), Gila monsters (Heloderma suspectum), beetles, spiders, and scorpions. One burrow can host up to 23 desert tortoises – such sharing is more common for desert tortoises of opposite sexes than for desert tortoises of the same sex. [7]



A captive male Sonoran Desert tortoise with visible chin glands eats strawberries. Tortoise Chin Glands 2.jpg
A captive male Sonoran Desert tortoise with visible chin glands eats strawberries.

Tortoises mate in the spring and autumn. Male desert tortoises grow two large white glands around the chin area, called chin glands, that signify mating season. A male circles around female, biting her shell in the process. He then climbs upon the female and insert his penis (a white organ, usually only seen upon careful inspection during mating, as it is hidden inside the male and can only be coaxed out with sexual implication) into the vagina of a female, which is located around the tail. The male may make grunting noises once atop a female, and may move his front legs up and down in a constant motion, as if playing a drum.[ not in citation given ] [11]

Hatching baby desert tortoise Baby Desert Tortoise (16490346262).jpg
Hatching baby desert tortoise

Months later, the female lays a clutch of four to eight hard-shelled eggs, [12] which have the size and shape of ping-pong balls, usually in June or July. The eggs hatch in August or September. Wild female tortoises produce up to three clutches a year depending on the climate. Their eggs incubate from 90 to 135 days; [3] some eggs may overwinter and hatch the following spring. In a laboratory experiment, temperature influenced hatching rates and hatchling gender. Incubation temperatures from 81 to 88 °F (27 to 31 °C) resulted in hatching rates exceeding 83%, while incubation at 77 °F (25 °C) resulted in a 53% hatching rate. Incubation temperatures less than 88 °F (31 °C) resulted in all-male clutches. Average incubation time decreased from 124.7 days at 77 °F to 78.2 days at 88 °F (31 °C). [13]


The desert tortoise grows slowly, often taking 16 years or longer to reach about 8 in (20 cm) in length. The growth rate varies with age, location, gender and precipitation. It can slow down from 12 mm/year for ages 4–8 years to about 6.0 mm/year for ages 16 to 20 years. Males and females grow at similar rates; females can grow slightly faster when young, but males grow larger than females. [7]

Desert tortoises generally reach reproductive maturity at age 15 to 20 years, when they are longer than 7 in (18 cm), though 10-year-old reproductive females have been observed. [7]


Their activity depends on location, peaking in late spring for the Mojave Desert and in late summer to fall in Sonoran Desert; some populations exhibit two activity peaks during one year. Desert tortoises hibernate during winters, roughly from November to February–April. Females begin hibernating later and emerge earlier than males; juveniles emerge from hibernation earlier than adults. [7]

Temperature strongly influences desert tortoise activity level. Although desert tortoises can survive body temperatures from below freezing to over 104 °F (40 °C), most activity occurs at temperatures from 79 to 93 °F (26 to 34 °C). The influence of temperature is reflected in daily activity patterns, with desert tortoises often active late in the morning during spring and fall, early in the morning and late in the evening during the summer, and occasionally becoming active during relatively warm winter afternoons. The activity generally increases after rainfall. [7]

Although desert tortoises spend the majority of their time in shelter, movements of up to 660 feet (200 m) per day are common. The common, comparatively short-distance movements presumably represent foraging activity, traveling between burrows, and possibly mate-seeking or other social behaviors. Long-distance movements could potentially represent dispersal into new areas and/or use of peripheral portions of the home range. [7]


Desert tortoises can live well over 50 years, with estimates of lifespan varying from 50 to 80 years. [6] Causes of mortality include predation, disease, human-related factors, and environmental factors such as drought, flooding, and fire. [7]

The annual death rate of adults is typically a few percent, but is much higher for young desert tortoises. Only 2–5% of hatchlings are estimated to reach maturity. Estimates of survival from hatching to 1 year of age for Mojave Desert tortoises range from 47 to 51%. Survival of Mojave Desert tortoises from 1 to 4 years of age is 71–89%. [7]


Desert tortoise tds.jpg
Desert tortoise.jpg
A young desert tortoise Young desert tortoise.JPG
A young desert tortoise

The desert tortoise is an herbivore. Grasses form the bulk of its diet, but it also eats herbs, annual wildflowers, and new growth of cacti, as well as their fruit and flowers. Rocks and soil are also ingested, perhaps as a means of maintaining intestinal digestive bacteria as a source of supplementary calcium or other minerals. As with birds, stones may also function as gastroliths, enabling more efficient digestion of plant material in the stomach. [7]

Much of the tortoise’s water intake comes from moisture in the grasses and wildflowers they consume in the spring. A large urinary bladder can store over 40% of the tortoise's body weight in water, urea, uric acid, and nitrogenous wastes. During very dry times, they may give off waste as a white paste rather than a watery urine. During periods of adequate rainfall, they drink copiously from any pools they find, and eliminate solid urates. The tortoises can increase their body weight by up to 40% after copious drinking. [14] Adult tortoises can survive a year or more without access to water. [7] During the summer and dry seasons, they rely on the water contained within cactus fruits and mesquite grass. To maintain sufficient water, they reabsorb water in their bladders, and move to humid underground burrows in the morning to prevent water loss by evaporation. [14]

Emptying the bladder is one of the defense mechanisms of this tortoise. This can leave the tortoise in a very vulnerable condition in dry areas, and it should not be alarmed, handled, or picked up in the wild unless in imminent danger. If it must be handled, and its bladder is emptied, then water should be provided to restore the fluid in its body.

Predation and conservation status

Ravens, Gila monsters, kit foxes, badgers, roadrunners, coyotes, and fire ants are all natural predators of the desert tortoise. They prey on eggs, juveniles, which are 2–3 inches long with a thin, delicate shell, or, in some cases, adults. Ravens are thought to cause significant levels of juvenile tortoise predation in some areas of the Mojave Desert – frequently near urbanized areas. The most significant threats to tortoises include urbanization, disease, habitat destruction and fragmentation, illegal collection and vandalism by humans, and habitat conversion from invasive plant species ( Brassica tournefortii , Bromus rubens and Erodium spp.).

Desert tortoise populations in some areas have declined by as much as 90% since the 1980s, and the Mojave population is listed as threatened. It is unlawful to touch, harm, harass, or collect wild desert tortoises. It is, however, possible to adopt captive tortoises through the Tortoise Adoption Program in Arizona, Utah Division of Wildlife Resources Desert Tortoise Adoption Program in Utah, Joshua Tree Tortoise Rescue Project in California, or through Bureau of Land Management in Nevada. When adopted in Nevada, they will have a computer chip embedded on their backs for reference. According to Arizona Game and Fish Commission Rule R12-4-407 A.1, they may be possessed if the tortoises are obtained from a captive source which is properly documented. Commission Order 43: Reptile Notes 3: one tortoise per family member.

The Fort Irwin National Training Center of the US Army expanded into an area that was habitat for about 2,000 desert tortoises, and contained critical desert tortoise habitat (a designation by the US Fish and Wildlife Service). In March 2008, about 650 tortoises were moved by helicopter and vehicle, up to 35 km away. [15]

Another potential threat to the desert tortoise's habitat is a series of proposed wind and solar farms. [16] As a result of legislation, solar energy companies have been making plans for huge projects in the desert regions of Arizona, California, Colorado, New Mexico, Nevada, and Utah. The requests submitted to the Bureau of Land Management total nearly 1,800,000 acres (7,300 km2). [17]

Human development

Landfill proposal

In 2006, a proposal was made in California to build a landfill in Kern County, a site near the Desert Tortoise Natural Area, to dump trash for Los Angeles residents. A landfill would attract many of the tortoise’s predators – ravens, rats, roadrunners, and coyotes – which would threaten their population. [18]

Ivanpah solar power project

Concerns about the impacts of the Ivanpah Solar thermal project led the developers to hire some 100 biologists and spend US$22 million caring for the tortoises on or near the site during construction. [19] [20] Despite this, in a 2011 Revised Biological Assessment for the Ivanpah Solar Electric Generating System, the Bureau of Land Management anticipated the loss or significant degradation of 3,520 acres of tortoise habitat and the harm of 57–274 adult tortoises, 608 juveniles, and 236 eggs inside the work area, and 203 adult tortoises and 1,541 juvenile tortoises outside the work area. The BLM expects that most of the juvenile tortoises on the project will be killed. [21] [22]

Conservation efforts

The Desert Tortoise Preserve Committee protects roughly 5,000 acres of desert tortoise habitat from human activity. This area includes 4,340 acres in Kern County, 710 acres in San Bernardino County, and 80 acres in Riverside County. [18]


In the summer of 2010, Public Employees for Environmental Responsibility filed a lawsuit against the National Park Service for not having taken measures to manage tortoise shooting in the Mojave National Preserve of California. Biologists discovered numerous gunshot wounds on dead tortoise shells. These shells left behind by vandals attracted ravens and threatened the healthy tortoises. [23]


Reptiles are known to become infected by a wide range of pathogens, which includes viruses, bacteria, fungi, and parasites. More specifically, the G. agassizii population has been negatively affected by upper respiratory tract disease, cutaneous dyskeratosis, herpes virus, shell necrosis, urolithiasis (bladder stones), and parasites. [24] [25] [26]

Upper respiratory tract disease

Upper respiratory tract disease (URTD) is a chronic, infectious disease responsible for population declines across the entire range of the desert tortoise. It was identified in the early 1970s in captive desert tortoise populations, and later identified in the wild population. [24] URTD is caused by the infectious agents Mycoplasma agassizii and Mycoplasma testudineum, which are bacteria in the class Mollicutes and characterized by having no cell wall and a small genome. [27] [28] [29]

Mycoplasmae appear to be highly virulent (infectious) in some populations, while chronic, or even dormant in others. [30] The mechanism (whether environmental or genetic) responsible for this diversity is not understood. Infection is characterized by both physiological and behavioral changes: nasal and ocular discharge, palpebral edema (swelling of the upper and/or lower palpebra, or eyelid, the fleshy portion that is in contact with the tortoises eye globe) and conjunctivitis, weight loss, changes in color and elasticity of the integument, and lethargic or erratic behavior. [24] [31] [32] [33] These pathogens are likely transmitted by contact with an infected individual. Epidemiological studies of wild desert tortoises in the western Mojave Desert from 1992 to 1995 showed a 37% increase in M. agassizii. [29] Tests were conducted on blood samples, and a positive test was determined by the presence of antibodies in the blood, defined as being seropositive.

Cutaneous dyskeratosis

Cutaneous dyskeratosis (CD) is a shell disease of unknown origin and has unknown implications on desert tortoise populations. Observationally, it is typified by shell lesions on the scutes. Areas infected with CD appear discolored, dry, rough and flakey, with peeling, pitting, and chipping through multiple cornified layers. [34] Lesions are usually first located on the plastron (underside) of the tortoises, although lesions on the carapace (upper side) and fore limbs are not uncommon. In advanced cases, exposed areas become infected with bacteria, fungi, and exposed tissue and bone may become necrotic. [32] [34] CD was evident as early as 1979 and was initially identified on the Chuckwalla Bench Area of Critical Environmental Concern in Riverside County, California. [35] Currently, the means of transmission are unknown, although hypotheses include autoimmune diseases, exposure to toxic chemicals (possibly from mines, or air pollution), or a deficiency disease (possibly resulting from tortoises consuming low-quality invasive plant species instead of high-nutrient native plants). [25] [30]

Impacts of disease

Two case studies outlined the spread of disease in desert tortoises. The Daggett Epidemiology of Upper Respiratory Tract Disease project, which provides supporting disease research for the Fort Irwin translocation project, lends an example of the spread of disease. In 2008, 197 health evaluations were conducted, revealing 25.0–45.2% exposure to M. agassizii and M. testudineum, respectively, in a core area adjacent to Interstate 15. The spread of disease was tracked over two years, and clinical signs of URTD spread from the core area to adjacent, outlying locations during this time. Overlaying home ranges and the social nature of these animals, suggests that disease-free individuals may be vulnerable to spread of disease, and that transmission can occur rapidly. [36] Thus, wild tortoises that are close to the urban-wildlife interface may be vulnerable to spread of disease as a direct result of human influence.

The second study indicated that captive tortoises can be a source of disease to wild Agassiz's desert tortoise populations. Johnson et al. (2006) tested blood samples for URTD (n = 179) and herpesvirus (n = 109) from captive tortoises found near Barstow, CA and Hesperia, CA. Demographic and health data were collected from the tortoises, as well from other reptiles housed in the same facility. Of these, 45.3% showed signs of mild disease, 16.2% of moderate disease, and 4.5% of severe disease, and blood tests revealed that 82.7% of tortoises had antibodies to mycoplasma, and 26.6% had antibodies to herpesvirus (which means the tortoises were seropositive for these two diseases, and indicate previous exposure to the causative agents). With an estimated 200,000 captive desert tortoises in California, their escape or release into the wild is a real threat to uninfected wild populations of tortoises. Projections from this study suggest that about 4400 tortoises could escape from captivity in a given year, and with an 82% exposure rate to URTD, the wild population may be at greater risk than previously thought. [37]

Domestic pets

Edwards et al. reported that 35% of desert tortoises in the Phoenix area are hybrids between either Gopherus agassizii and G. morafkai, or G. morafkai and the Texas tortoise, G. berlandieri. The intentional or accidental release of these tortoises could have dire consequences for wild tortoises. [38]

Before obtaining a desert tortoise as a pet, it is best to check the laws and regulations of the local area and/or state. Desert tortoises may not be moved across state borders or captured from the wild. They may, however, be given as a gift from one private owner to another. Desert tortoises need to be kept outdoors in a large area of dry soil and with access to vegetation and water. An underground den and a balanced diet are crucial to the health of captive tortoises.

Management activities and spread of disease

Tortoise Monitoring and Research at Joshua Tree National Park Tortoise Monitoring and Research JTNP.jpg
Tortoise Monitoring and Research at Joshua Tree National Park


Wild populations of tortoises must be managed effectively to minimize the spread of diseases, which includes research and education. Despite significant research being conducted on desert tortoises and disease, a considerable knowledge gap still exists in understanding how disease affects desert tortoise population dynamics. It is not known if the population would still decline if disease were completely absent from the system; are tortoises more susceptible to disease during draught conditions? How does a non-native diet impact a tortoise’s ability to ward off pathogens? What are the causes of immunity exhibited by some desert tortoises? The 2008 USFWS draft recovery plan suggests that populations of tortoises that are uninfected, or only recently infected, should likely be considered research and management priorities. Tortoises are known to show resistance to disease in some areas, an effort to identify and maintain these individuals in the populations is essential. Furthermore, increasing research on the social behavior of these animals, and garnering a greater understanding of how behavior facilitates disease transmission would be advantageous in understanding rates of transmission. Finally, translocation of tortoises should be done with extreme caution; disease is typically furtive and moving individuals or populations of tortoises across a landscape can have unforeseen consequences. [30]


Corollary to research, education may help preventing captive tortoises from coming in contact with wild populations. [37] Education campaigns through veterinarians, government agencies, schools, museums, and community centers throughout the range of the desert tortoise could limit the spread of tortoise diseases into wild populations. Strategies may include encouraging people to not breed their captive tortoises, ensure that different species of turtles and tortoises are not housed in the same facility (which would help to prevent the spread of novel diseases into the desert tortoise population), ensure captive tortoises are adequately housed to prevent them from escaping into the wild, and to ensure that captive turtles and tortoises are never released into the wild.

Desert tortoises have been severely affected by disease. Both upper respiratory tract disease and cutaneous dyskeratosis have caused precipitous population declines and die-offs across the entire range of this charismatic species. Both of these diseases are extremely likely to be caused by people, and URTD is easily linked with people releasing captive tortoises into the wild. The combination of scientific research and public education is imperative to curb the spread of disease and aid the tortoise in recovery.

State reptile

The desert tortoise is the state reptile of California and Nevada.

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Osteophagy is the practice in which animals, usually herbivores, consume bones. Most vegetation around the world lacks sufficient amounts of phosphate. Phosphorus is an essential mineral for all animals, as it plays a major role in the formation of the skeletal system, and is necessary for many biological processes including: energy metabolism, protein synthesis, cell signaling, and lactation. Phosphate deficiencies can cause physiological side effects, especially pertaining to the reproductive system, as well as side effects of delayed growth and failure to regenerate new bone. The importance of having sufficient amounts of phosphorus further resides in the physiological importance of maintaining a proper phosphorus to calcium ratio. Having a Ca:P ratio of 2:1 is important for the absorption of these minerals, as deviations from this optimal ratio can inhibit their absorption. Dietary calcium and phosphorus ratio, along with vitamin D, regulates bone mineralization and turnover by affecting calcium and phosphorus transport and absorption in the intestine.

Darwin Falls Wilderness

The Darwin Falls Wilderness is the area adjacent to Darwin Falls, it has a unique location in the northern Mojave Desert, just west of Death Valley National Park. The Darwin falls Wilderness is a part of the National Wilderness Preservation System rooted by the California Desert Protection Act and guided by the Bureau of Land Management. The Darwin Falls Wilderness Area was founded on October 31, 1994 totaling up to 8,176 acres of land. The Darwin Wilderness is made up of several distinct landmarks, including The Darwin Plateau, an area between The Inyo Mountains to the north, and the Coso Range to the south. The wilderness area is also near the Darwin Hills, a mountain range in Inyo County and the Argus Range, west of the Panamint Range.

Solar power plants in the Mojave Desert construction

There are several solar power plants in the Mojave Desert which supply power to the electricity grid. Insolation in the Mojave Desert is among the best available in the United States, and some significant population centers are located in the area. These plants can generally be built in a few years because solar plants are built almost entirely with modular, readily available materials. Solar Energy Generating Systems (SEGS) is the name given to nine solar power plants in the Mojave Desert which were built in the 1980s, the first commercial solar plant. These plants have a combined capacity of 354 megawatts (MW) which made them the largest solar power installation in the world, until Ivanpah Solar Power Facility was finished in 2014.

Ornate box turtle subspecies of reptile

The ornate box turtle is one of only two terrestrial species of turtles native to the Great Plains of the United States. It is one of the two different subspecies of Terrapene ornata. It is the state reptile of Kansas. It is a relatively small turtle, that is currently listed as threatened in Illinois but is of concern and protected in six Midwestern states. Males and females generally look alike but males are often smaller; there is color variation with yellow lines from the center of the shell to the edges through gray, red-brown, or black coloration. Besides the size, males can be distinguished from females in several ways; a large curved inner claw on the back feet, a cloacal opening that is farther back in males, a longer and thicker tail, and reddish color on the legs and occasionally on the jaw.

<i>Mycoplasma gallisepticum</i> species of bacterium

Mycoplasma gallisepticum (MG) is a bacterium belonging to the class Mollicutes and the family Mycoplasmataceae. It is the causative agent of chronic respiratory disease (CRD) in chickens and infectious sinusitis in turkeys, chickens, game birds, pigeons, and passerine birds of all ages.

Eriogonum pusillum is a species of wild buckwheat known by the common name yellowturbans. It is native to the western United States where it grows in sandy soils in a number of habitats, especially in the Mojave Desert and Great Basin.


A xerocole, commonly referred to as a desert animal, is an animal adapted to live in the desert. The main challenges they must overcome are lack of water and excessive heat. To conserve water, they both avoid evaporation and concentrate excretions. Some are so adept at conserving water or obtaining it from food that they do not need to drink at all. To escape the desert heat, xerocoles tend to be either nocturnal or crepuscular, most active at dawn and dusk.

Ivanpah Solar Power Facility Concentrated solar thermal plant in the Mojave Desert

The Ivanpah Solar Electric Generating System is a concentrated solar thermal plant in the Mojave Desert. It is located at the base of Clark Mountain in California, across the state line from Primm, Nevada. The plant has a gross capacity of 392 megawatts (MW). It deploys 173,500 heliostats, each with two mirrors focusing solar energy on boilers located on three centralized solar power towers. The first unit of the system was connected to the electrical grid in September 2013 for an initial synchronisation test. The facility formally opened on February 13, 2014. In 2014, it was the world's largest solar thermal power station.

Fauna of Nevada

The fauna of the U.S. State of Nevada is mostly species adapted to desert, temperature extremes and to lack of moisture. With an average annual rainfall of only about 7 inches (180 mm), Nevada is the driest – and has the largest percentage of its total area classified as desert – of all states in the United States. Two-thirds of the state is located within the largest desert on the North American continent, the Great Basin Desert, while the lower one-third is the Mojave Desert.

Mycoplasma agassizii is a species of bacteria in the genus Mycoplasma. This genus of bacteria lacks a cell wall around their cell membrane. Without a cell wall, they are unaffected by many common antibiotics such as penicillin or other beta-lactam antibiotics that target cell wall synthesis. Mycoplasma are the smallest bacterial cells yet discovered, can survive without oxygen and are typically about 0.1 µm in diameter.


PD-icon.svg This article incorporates  public domain material from the United States Forest Service document "Gopherus agassizii " .

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Further reading