Natural History

The desert tortoise, Gopherus agassizii, is a long lived, slow growing, dinner plate sized tortoise and is estimated to live from 50 to possibly 100 years. They are found in parts of Arizona, California, Nevada, Utah, and south into Mexico. Sonoran Desert populations of desert tortoise live only in Arizona and Mexico. The habitat of the Sonoran Desert population of desert tortoise consists of rocky foothills of mountain ranges. Dominant plants include the saguaro cactus, prickly pear cactus, foothills paloverde, mesquite, triangle leaf bursage, and assorted grasses. The rocky, shallow soils in these regions are not suitable for digging burrows, and the tortoises here prefer natural cavities, or dens under boulders or rocky outcrops.

The diet of the desert tortoise is varied,but mostly consists of grasses, and herbaceous plants, of which they eat both the leaves and flowers. In the summer months, desert tortoises enjoy the fruit of the prickly pear cactus. If you see a tortoise with face stained purple, it was probably feasting on this treat.

Like all reptiles, the desert tortoise is an ectotherm, and is unable to control its body temperature through metabolism, as mammals and birds can. In the winter months, desert tortoises escape the cold by hibernating in their burrows. In the dry summer months, tortoises avoid the extreme heat by staying in their burrows, although they do venture out during the cooler hours of early morning and evening. They are most active in the spring and late summer / fall months.

Desert tortoises are well adapted to arid conditions and conserve water in several ways. They have thick skin, which helps to prevent water loss, and they excrete dry uric acid instead of urine. Also, desert tortoises can store water in their large urinary bladders. This water can be used in self defense. This water is distasteful to predators, and when frightened the tortoise may suddenly empty its bladder. However, this defense can be costly in times of drought, and the tortoise could die slowly of dehydration if it doesn’t replace the fluids.