The Mojave Desert’s summers are harsh, making it difficult to be active, with temperatures reaching well above 105 degrees Fahrenheit (41 degrees Celsius) and with very little (if any) rain. Yet the desert tortoise is well adapted to deal with such extreme weather by going intoestivation(decreased physiological activity) in aburrowduring the extreme heat of the summer.
A tortoise’s front limbs work like shovels, with long, sturdy nails that are good for digging. Large, cone-shaped scales on the limbs provide protection from scratchy vegetation the tortoise may encounter and help it retain water. Cleverly, the tortoise digs basins in the soil to catch the infrequent rain that falls. The tortoise remembers where these “watering holes” are and walks directly to them after a bit of rain. Another water-saving tactic is storing up to 40 percent of its body weight in water inside the bladder, to be absorbed as necessary.
Desert tortoises live in underground burrows. By spending so much time underground, they are able to survive on very little food. Thesecold-bloodedcritters are the same temperature as their surroundings, so their burrow allows them to keep cool in the hot temperatures. During the winter, when food is scarce, tortoises brumate, a form of reptilian hibernation, in their burrow with a wall of dirt at the entrance to keep out the rain and cold for the entire winter season. Come spring, tortoises emerge and bask in the warm sun to jump-start their metabolism. They then devour vegetation with great relish!
Burrows also protect the tortoises from predators. Coyotes and kit foxespreyon adult tortoises. Badgers, skunks, ground squirrels, ravens, Gila monsters, and roadrunners can prey onjuveniletortoises and tortoise eggs. Interestingly, other wildlife such as pack rats, burrowing owls, kangaroo rats, desert jackrabbits, gopher snakes, banded geckos, and cactus wrens also use tortoise burrows. From ground level, they extend down about 3 to 4 feet (1 to 1.2 meters), typically at a 45-degree angle. Normally one burrow houses a single individual, or one male and one female.
Desert tortoises may also create a den or cave, dug horizontally into the banks of dry washes and extending 8 to 30 feet (2.4 to 9 meters). Several tortoises can occupy one den at the same time, especially during brumation. One record showed 17 tortoises using the same winter den!
Rainfall and temperature control the tortoises’ movements; desert tortoises are most active in spring, early summer, and fall before the colder weather sets in. During the active season, they move across theirhome rangeto forage, using multiple burrows as needed. After foraging, tortoises may plop down in a limp, spread-eagle posture with limbs and neck extended, possibly to increase body temperature and help digestion.
Desert tortoises are herbivores, dining on grasses, flowers, fruit, and cactus. These foods contain a lot of moisture, and desert tortoises can go for up to one year without access to fresh water! Tortoises do not have teeth; instead, they have a beak and grind their food. Examples of preferred tortoise forage are prickly pear cactus, primrose, beavertail cactus, white clover, hibiscus, globemallow, desert dandelion, and desert marigold. Desert tortoises need about 20 to 30 days to digest their food, spreading the seeds from their meals across their habitat as they poop. This aids in the repopulation of native plants and grasses in the Mojave Desert.
