The desert tortoise (Gopherus agassizii) is a large, herbivorous, terrestrial turtle of the family Testudinidae. It is found in both the southwestern United States and in northwestern Mexico. It is the official reptile in the states of California and Nevada. No other turtle in North America shares the extreme conditions of the habitats occupied by the desert tortoise. It inhabits desert oases, washes, rocky hillsides, and canyon bottoms with sandy or gravelly soil under hot, arid conditions.

Desert tortoises dig into dry, gravelly soil under bushes in arroyo banks or at the base of cliffs to construct a burrow, which is their home. Climatic conditions dictate daily activity patterns of these tortoises, and they can relieve the problems of high body temperature and evaporative water loss by retreating into their burrows. Since many desert tortoises live in areas devoid of water, except for infrequent rains, they...