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Image: Desert tortoise (Gopherus agassizii) Photo Credit: U.S. Fish and Wildlife Service Image Library
Desert tortoise Gopherus agassizii
Description:A typical land-dwelling tortoise with the following features: head is roofed with small unevenly sized scales; front feet are club shaped, scaled, and terminate in unwebbed toes with broad, thick claws; the hindlegs are columnar and elephantine, again with unwebbed broad claws; the carapace is highly domed, steep sided and flattened dorsally, brown (dull yellow to light brown in young), and has prominent growth lines; unhinged plastron is yellowish and generally has prominent growth lines; limbs are stocky; tail is short; adult carapace length 20-36 cm.
Life History:The Desert tortoise is primarily an herbivore, whose diet consists of grasses, cacti, and shrubs. Occasionally insect and insect larvae may be eaten. Desert tortoise mature between 12 and 20 years and reproduce through laying up to 15 pale eggs in the spring. Over its 50 to 100 year lifetime, a tortoise may use 1.5 square miles of habitat and make forays of more than 7 miles at a time.
Habitat:Desert tortoise are mainly found in shrubland/chaparral vegetation communities and almost entirely confined to warm creosote bush (Larrea tridentata) vegetation of the Upper Sonoran life zones of the Mojave, Colorado, and Sonoran deserts.
Distribution:The Desert tortoise is a widespread species of the southwestern United States and Mexico. Within the United States, Desert tortoises live in the Mojave, Colorado, and Sonoran deserts of southeastern California, southern Nevada, southwestern Utah, and western Arizona. A substantial portion of the habitat is on lands administered by the U.S. Department of the Interior.
Image:
U.S. range map of the Desert tortoise,
(Gopherus agassizii)
, from the National Biological Service "Our Living Resources" publication chapter titled Desert Tortoises in the Mojave and Colorado Deserts.
Status:Populations in California, Nevada, Utah, and Arizona north and west of the Colorado River are listed by the US Fish and Wildlife Service (USFWS) as Threatened (Federal Register, 2 April 1990). Populations in Mexico and in Arizona south and east of the Colorado River are listed by USFWS as Threatened (due to similarity of appearance) when found outside this range.
Resources:Please go to NatureServe Explorer for more detailed species information, or for additional Desert tortoise information, please use the following links:
Image: Cactus wren (Campylorhynchus brunneicapillus) Photo Credit: John J. Mosesso, NBII Digital Library
The southwestern state of Arizona, nicknamed the "Grand Canyon State," is located in the southwestern United States and borders New Mexico, California, Colorado, Nevada, and Utah, as well as the Mexican States of Sonora and Baja California.
Over 500 species of birds utilize the diverse habitats of Arizona, making bird watching a popular hobby for Arizona residents, and Arizona a destination for avid birdwatchers. The Cactus wren (
Campylorhynchus brunneicapillus
) is the state bird of Arizona.
Water is an important resource for Arizona's arid ecosystems. The major river basins of Arizona, as described by the USGS National Water Information System, include the Colorado River Basin, Little Colorado River Basin, Gila River Basin, Salt River Basin, San Pedro River Basin, Santa Cruz River Basin, Verde River Basin, and Whitewater Draw River Basin.
To find out more about regional issues such as wildlife disease, invasive species, fire, and water and drought, including links to state-specific resources, visit the SWIN Regional Themes page.
To find out about geospatial products, databases, and other information for Arizona and the Southwest, visit the SWIN Live Maps and Data page.
Mojave Desert Ecosystem
Mojave Desert. Credit: John J. Mosesso, NBII Digital Image Library
The objectives of the USGS Recoverability and Vulnerability of Desert Ecosystems (RVDE) project are to conduct basic scientific research on ecological processes within the Mojave Desert ecosystem and to use this knowledge to provide land managers with scientific understanding and tools needed to conserve and restore threatened desert landscapes.
The Mojave Desert covers 125,000 square kilometers of southern Nevada, western Arizona, southwestern Utah, and southeastern California. It is home to over 1 million people, including the nation's fastest growing city, Las Vegas, and is within a day's drive of 40 million people.
The NBII Program is administered by the Biological Informatics Program of the U.S. Geological Survey
