Species Spotlight

Picture of a Desert tortoise (Gopherus agassizii) available at the U.S. Fish and Wildlife Service Image Library
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.

U.S. range map of the Desert tortoise (Gopherus agassizii), from the National Biological Service publication, 'Our Living Resources' 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:

Reptiles of the Southwest Region

Gopher Snake (Pituophis melanoleucus) [Photo: Hal Cross, National Park Service]
Gopher Snake (Pituophis melanoleucus)
[Photo: Hal Cross, National Park Service]

Reptiles are a class of vertebrates with over 7,000 species worldwide. There are four orders of reptiles: lizards and snakes (Squamata) , crocodiles (Crocodilia) , turtles (Testudinata) , and tuataras (Rhynchocephalia) . Lizards and snakes are the largest order, with more than 6,000 species. Commonly called "cold-blooded," reptiles are ectotherms, meaning they are unable to regulate their own body temperature and are instead influenced by the temperature of their surroundings. Reptiles are characterized by skin with scales or horned plates and commonly reproduce by laying eggs, although some types of snakes bear live young.The Southwest is home to a variety of ecosystems which provide diverse terrestrial and freshwater habitat for reptiles in the orders Squamata and Testudinata .

Reptiles Species of Greatest Conservation Need
One hundred and twenty-nine reptile species have been identified in state wildlife action plans as Species of Greatest Conservation Need (GCN) for the Southwest Region, which includes Arizona, Colorado, Nevada, New Mexico, and Utah. The Southwest Species of Greatest Conservation Need interactive application brings together resources on these 129 GCN reptile species and other GCN taxa from multiple authoritative sources including the Integrated Taxonomic Information System (ITIS) and NatureServe.

Southwest Species of Greatest Conservation NeedSpecies of Greatest Conservation Need
Browse the interactive application to find out more about the 129 reptile species of greatest conservation need in the Southwest Region.

More about reptiles...

Five-lined skink (Eumeces fasciatus).
Five-linked skink (Eumeces fasciatus) Photographer Credit: John J. Mosesso/NBII.gov.

Visit the reptiles section of the NBII to learn more about reptiles.

Taxonomy Helper

Integrated Taxonomic Information System (ITIS)


    Kingdom: Animalia
    Division: Chordata
    Subdivision: Vertebrata
    Class: Reptilia
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