The desert tortoise (Gopherus agassizili), a reptile typically found in sandy areas of the Southwestern United States and northern Mexico, can live more than 100 years. Fully grown, the creature has a green, brown, or black shell and can generally reach up to 15 inches (38 centimeters) in length, a height of up to 6 inches (15 centimeters), and a weight of 15 pounds (6.8 kilograms). Due in part to development of its habitat, the Mojave Desert and Sonoran Desert in California, Nevada, and Utah, the desert tortoise is considered a threatened species.
Territorial in nature, the desert tortoise generally spends its entire life in one place. The majority of the reptile's life is spent in burrows that may be up to 6 feet (1.8 meters) below the ground and can reach 30 feet (9.1 meters) in length. Sharp claws and round, stubby feet help the tortoise maneuver through the sand and dig burrows. The underground dens protect the tortoise from predators and summer heat that may reach 140° Fahrenheit (60° Celsius), and cold desert winters. From about November to February, the cold-blooded tortoise hibernates in its subterranean lair.
In the spring, the vegetarian desert tortoise is busy hunting for food, which may include grass, shrubs, flowers, cacti, and legumes. The plants provide moisture for the reptile in the arid desert. With water at a minimum in the desert, the tortoise will often dig holes in the soil in preparation for when it does rain. The creature is able to access water from its bladder when needed.
Between the ages of 15 and 20 years, desert tortoises are capable of reproducing. The tortoises generally mate in late summer or early fall. Males will make a grumbling sound to attract a mate and may even fight other males for the right to mate with females. A female will typically lay four to six eggs that may take three or four months to hatch.
During breeding season, a female may lay eggs up to three times. Weather plays a role in determining the sex of the hatchlings. Cooler temperatures are more likely to bring about female hatchlings and males are more apt to be produced during warmer weather.
Slow-moving land dwellers, few of the hatched tortoises live to adulthood. Before reaching maturity, the tortoises are preyed on by creatures including ravens, road runners, and coyotes. Native Americans used to eat the reptiles after roasting them on a fire.