Basic Facts About Desert Tortoises
No other tortoise in North America shares the extreme conditions of habitats occupied by the desert tortoise.
It has a high domed shell, which is usually brown in adults and dark tan in younger individuals. Its powerful limbs are equipped with claws to dig its underground burrows, and its front limbs are protected with a covering of thick scales.
© Jonathan S. Blair / National Geographic Stock
What a desert tortoise eats depends on where it’s located within the species’ range. A desert tortoise's diet is made up of a variety of vegetation, including annual wildflowers, grasses, and new growth of selected shrubs, cacti and their flowers. Desert tortoises forage in the spring and again in the fall. During the late summer, desert tortoises may emerge from their underground burrows to drink standing water after periodic thunderstorms. Increased water intake allows them to forage on dried herbaceous vegetation and grasses.
Did You Know?
With their burrows, desert tortoises create a subterranean environment that can be beneficial to other reptiles, mammals, birds and invertebrates.
In some areas, the number of desert tortoises has decreased by 90% due primarily to human activity. Desert tortoise declines appear to have been most severe and widespread in the Western Mojave Desert. Recent estimates indicate that there are about 100,000 individual desert tortoises remaining in the Mojave and Sonoran deserts. As late as the 1950’s the desert tortoise population averaged at least 200 adults per square mile. More recent studies show the level is now between 5-60 adults per square mile.
Habitat & Range
Most desert tortoises live in creosote bush scrub habitat at elevations ranging from 1,000 to 3,000 feet above sea level, although they are known to occur in suitable habitats up to about 5,000 feet in elevation. Within suitable habitat they occur over a relatively large region including the Mojave and Sonoran Deserts of California, Nevada, Utah and portions of Arizona.
The desert tortoise is able to live where ground temperatures may exceed 140 degrees F because of its ability to dig underground burrows three to six feet deep to escape the heat of summer and the cold of winter. It is one of the most elusive inhabitants of the desert, spending up to 98% of its time underground. Desert tortoises spend November through February in a torpid or dormant state in their underground burrows.
Did You Know?
Adult desert tortoises can survive a year or more without access to water!
Their most active time is in the spring when they will forage for food. During the hottest, driest periods of the year, these tortoises conserve the water already stored in their bodies. This is especially important in the hot, dry Mojave Desert summers.
Much of the tortoise’s water intake comes from moisture in the grasses and wildflowers they consume in the spring. To get the most out of the rain that falls so infrequently in their habitat, desert tortoises dig basins in the soil to catch rainwater. The tortoises always remember where these basins are, and may be found waiting by them when rain appears imminent.
Females do not breed until they are 15 to 20 years old. When hatchlings emerge from eggs they are approximately 2 inches long. Only about 2 percent of hatchlings survive to become adults.
Mating Season: Late summer to early fall
Gestation: 10-12 months
Clutch size: 4-6 eggs