The Mojave desert tortoise is a large, herbivorous (plant-eating) reptile that occurs in the Mojave and Sonoran deserts north and west of the Colorado River in southwestern Utah, southern Nevada, southeastern California, and northwestern Arizona in the United States. The desert tortoise is one of most elusive inhabitants of the desert, spending up to 95% of its life underground. The desert tortoise lives in a variety of habitats from sandy flats to rocky foothills, including alluvial fans, washes and canyons where suitable soils for den construction might be found. Tortoises have lived in the area that is now the Mojave Desert for millions of years, even before it was a desert. As recently as the mid-1900s, people commonly encountered these familiar, gentle creatures. Today, they are rarely seen and in some places they have disappeared entirely. The Mojave desert tortoise was listed as Threatened on April 2, 1990, and was originally listed as the Mojave population of the desert tortoise. However, recent studies have concluded that the Mojave desert tortoise and Sonoran desert tortoise are distinct species.
The vast majority of threats to the desert tortoise or its habitat are associated with human land uses. The most apparent threats to the desert tortoise are those that result in mortality and permanent habitat loss across large areas, such as urbanization and large-scale renewable energy projects, and those that fragment and degrade habitats, such as proliferation of roads and highways, off-highway vehicle activity, habitat invasion by non-native invasive plant species, wildfire, and subsidized predators (especially common ravens). These threats interact in complex and synergistic ways to impact tortoise populations.
The desert tortoise requires 13 to 20 years to reach sexual maturity, has low reproductive rates during a long period of reproductive potential, and individuals experience relatively high mortality early in life. These factors make recovery of the species difficult. Even moderate downward fluctuations in adult survival rates can result in rapid population declines. Thus, high survivorship of adult desert tortoises is critical to the species’ persistence, and the slow growth rate of populations can leave them susceptible to extirpation events in areas where adult survivorship has been reduced. Another factor integral to desert tortoise recovery is maintaining the genetic variability of the species and sufficient ecological heterogeneity within and among populations to allow tortoises to adapt to changes in the environment over time. Because desert tortoises occupy large home ranges, the long-term persistence of extensive, unfragmented habitats is essential for the survival of the species. The loss or degradation of these habitats to urbanization, habitat conversion from frequent wildfire, or other landscape modifying activities place the desert tortoise at increased risk of extirpation.
The Mojave population of desert tortoise (Gopherus agassizii) includes all tortoises north and west of the Colorado River in Arizona, Utah, Nevada and California. Listed as threatened in 1990, these tortoises are impacted by ongoing threats, including loss, degradation and fragmentation of habitat due to development. They are also impacted by increased wildfire due to non-native invasive vegetation, disease, road mortality and predation of their eggs and hatchlings.
Mojave population of desert tortoise lives in a variety of habitats from sandy flats to rocky foothills, including alluvial fans, washes and canyons.
Area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.
Arid land with usually sparse vegetation.
The desert tortoise hibernates in burrows for up to nine months each year, and is most active from March to June and September to October.
The desert tortoise has a short tail, flattened front legs that are adapted for digging, elephant-like hind legs and a high-domed shell.
MeasurementsShell height: 4 to 6 inchesShell length: 8 to 15 inches
Adult tortoises weigh eight to 15 pounds.
The desert tortoise has a top shell is brown, gray or black, and the shell underneath is lighter.
The desert tortoise produces a variety of sounds - hisses, grunts, pops, whoops, huhs, echs, bips, etc.
Desert tortoises can live roughly 50 to 80 years, but take 13 to 20 years to reach sexual maturity.
The desert tortoise eat various herbs, grasses, cacti and wildflowers.
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