DESCRIPTION: A large (shell up to 380 mm or 15" in length) land tortoise with a dome-shaped carapace (top part of shell) that is marked by distinct growth rings. Coloration can be horn, orange-brown, gray-brown, dark gray, or nearly black. The underside of the shell (plastron) is usually tan or yellow. The tail is short. The hind limbs are short, rounded, thick, and elephant-like. The forelimbs are flattened for digging, are longer than the hind limbs, and are armored with large, thick scales. The head is relatively small and rounded. In males the gular shields of the plastron extend out underneath the throat (see figure below).

DISTRIBUTION: This tortoise occurs along the western border and most of southwestern and south-central Arizona at elevations ranging from near sea level along the Colorado River to just over 5,000'.

HABITAT: Primarily an inhabitant Arizona Upland Sonoran Desertscrub and Mohave Desertscrub but also enters Semidesert Grassland and Madrean Evergreen Woodland communities in some parts of the state. Across most of our state this tortoise inhabits rugged uplands such as rocky bajadas, hillsides, mountain slopes, and canyons. Populations in far northwestern Arizona inhabit more moderate terrain such as gentle bajadas and low valleys with loamy soil.

BEHAVIOR: Primarily diurnal and crepuscular but occasionally active into the night. The Desert Tortoise is entirely terrestrial. It shelters and hibernates in self constructed burrows that are often excavated under bushes or large rocks. It uses its strong, paddle-like forelimbs to dig. Also shelters in naturally occurring cavities under rocks or in the banks of washes. When threatened it pulls the body and head into the shell and covers the opening with its thick, armored forelimbs.

DIET: An herbivore that feeds on grasses, herbs, cacti, tree shoots, and other plant material.

REPRODUCTION: In the southern part of its Arizona range this tortoise mates in July or August and lays a single clutch of up to 12 eggs the following June or July. The eggs are usually buried inside the burrow. Populations in far northwestern Arizona (north of the Colorado River) mate in spring and summer and lay 1 to 3 clutches of eggs the following spring and summer.

REMARKS: This tortoise is in the same family (Testudinidae) as the giant tortoises of the Galapagos Islands.

By Thomas C. Brennan


FEDERALLY PROTECTED
Gopherus agassizii that occur north and west of the Colorado River are listed as THREATENED under the Endangered Species Act. It is against Federal law to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect this animal or to attempt to engage in any such conduct. More information on federal listing here: http://www.fws.gov/arizonaes/Desert_Tortoise.htm
Info on the Sonoran population here: http://www.fws.gov/arizonaes/Sonoran_Tort.htm

PROTECTED throughout Arizona
It is against Arizona State law to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect this animal in any part of the state. It is also illegal to attempt to engage in any such conduct.