Description: These tortoises may attain a length of 10 to 14 inches, 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 to 6 inches in height. They can range in weight from 0.71 oz to 11 lb 0.37 oz. The front limbs have sharp, claw-like scales and are flattened for digging. Back legs are skinnier and very long.

Habitat: Desert tortoises can live in areas with ground temperatures exceeding 140℉ because of their ability to dig 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.

Range: Desert tortoises are found in the southwestern United States and northwestern Mexico. They range from northern Sinaloa up through Sonora and western Arizona to southeastern California, southern Nevada, and the southwestern tip of Utah.

Found in these States: AZ | CA | NV | UT

Diet: 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.

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. Adult tortoises can survive a year or more without access to water. 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 burrows in the morning to prevent water loss by evaporation.

Reproduction: 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 cloaca 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.

Months later, the female lays a clutch of four to eight hard-shelled eggs, 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; some eggs may overwinter and hatch the following spring. In a laboratory experiment, temperature influenced hatching rates and hatchling sex. Incubation temperatures from 81 to 88℉ resulted in hatching rates exceeding 83%, while incubation at 77℉ resulted in a 53% hatching rate. Incubation temperatures less than 88℉ resulted in all-male clutches. Average incubation time decreased from 124.7 days at 77℉ to 78.2 days at 88℉.

Status: 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 22 miles away.

Another potential threat to the desert tortoise's habitat is a series of proposed wind and solar farms. 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.

Subspecies: None

Taxonomy: