Family: Testudinidae, Tortoises view all from this family
Description 9 1/4-14 1/2" (23.5-36.8 cm). Terrestrial, with domed shell and round, stumpy elephantine hind legs. Front limbs flattened for digging and heavily scaled; all toes webless. Carapace oblong, horn-brown; scute centers often yellowish. Bridge well developed, single axillary scute. Plastron yellowish, with brown along scute margins; adult throat scutes project beyond carapace. Head small, rounded in front, reddish-tan; iris greenish-yellow. Front and hind feet about equal in size. Male plastron concave.
Endangered Status The Desert Tortoise is on the U.S. Endangered Species List. It is classified as threatened in Arizona (except in areas south and east of the Colorado River), California, Nevada, and Utah. Desert Tortoises have suffered declines due to the degradation of habitat, predation of eggs and young, disease, and collection for the pet trade. Mining, agriculture, industrial and residential development, and the proliferation of off-road vehicles have contributed to the alteration of their desert habitat. Tortoise populations are slow to recover from population losses because the females do not breed until they are 15 to 20 years old. Then they may lay eggs only when feeding conditions are favorable. The young tortoises are so vulnerable to predators and other hazards, it is estimated that only 2 to 3 percent survive into adulthood.
Breeding Mates chiefly in spring; nests May to July. Lays 2-3 clutches of 2-14 hard, chalky, elliptical or spherical eggs, in funnel-shaped nest, 6" (15.2 cm) deep - sometimes located at mouth of burrow. Hatching occurs mid-August to October. Maturity reached in 15-20 years.
Habitat Arid sandy or gravelly locales with creosote, thorn scrub, and cacti; also washes, canyon bottoms, and oases.
Range Se. California and s. Nevada southeast into Mexico.
Discussion Desert Tortoises feed on grasses in early morning and late afternoon. During the heat of the day they retreat to a shallow burrow dug in the base of an arroyo wall. They have been known to dig horizontal tunnels up to 30' (9.1 m) in length. In September they may congregate in a communal den to spend the winter, becoming active again in March. When two males meet, they bob their heads rapidly, rushing toward each other and striking their gular scutes together. One of the two may be overturned.
