Releasing Captive Tortoises: Under no circumstances should a captive tortoise be released into the wild. Recent studies have demonstrated that all captive tortoises die soon after being released in the wild. Captive tortoises do not adapt well to the rigors of life in the wild and to feeding on native plants and other vegetation. Desert tortoises are territorial and may fight to the death when introduced into an established tortoise's range. Further, captive tortoises may introduce diseases of captivity into the wild tortoise population for which wild tortoises have little or no immunity.
Wild Tortoise Habitat: In the desert environment, the desert tortoise has adapted well to the extreme changes of climate. These reptiles dig and inhabit large burrows for protection against the intense daytime sun. These same burrows are used for sleeping at night and for hibernation. Desert tortoises have modified their behavior to survive in different environments. Tortoises in Utah may migrate to summer or winter ranges. Those in Arizona, where the winters are not as harsh, may not dig burrows of their own but may, instead, share those of ground squirrels. In Sonora, Mexico, the tortoises often do not burrow at all because the winters there are mild. Desert tortoises are nomadic animals. They wander great distances, even under conditions of intense heat, but they usually retreat to their burrows at midday. The moisture in the depth of their burrows helps prevent dehydration. Despite their nomadic habits, desert tortoises are territorial and may fight to the death with an intruding desert tortoise.
Wild desert tortoises eat a wide variety of grasses, wild flowers, and high-protein plants. Water is consumed in large quantities during the spring (rain and flood) season. They can store water in their urinary bladder and resorb whatever water is required for metabolic needs during periods of water scarcity. The only other available sources of water during dry times are the plants consumed and the morning dew on plant surfaces. A wild desert tortoise, when disturbed, may urinate to discourage an attacker. Having done so, this same tortoise may be left in a precarious position without this reservoir of stored water. This is one of many good reasons why onlookers should not disturb wild tortoises. The desert tortoise mating season is in May and June and is often preceded by protracted combat between males. Nesting commonly takes place in June and July. The incubation period for the eggs is variable and temperature dependent (70-120 days; average of 90 days).
The Future of the Desert Tortoise: During recent years there has been increasing concern about the viability of desert tortoise populations in the United States. In California, tortoises are constantly threatened by habitat destruction from residential developments, land use for agriculture, unregulated control of off-road vehicles, surface mining, geothermal development, oil exploration, and overgrazing of range land by livestock. People who remove tortoises from their natural habitat for use as pets, in addition to predators, further reduce the already decreasing numbers. If conditions continue at the present rate, many experts predict near extinction of this species in the wild in the next 35 years. The Desert Tortoise Council, founded in 1976, is investigating ways to protect this reptile. Proposed projects include the purchase of land for preserves, studies of population dynamics and other research regarding the biology of this species, construction of safe highway crossings, and installation of protective fences. Everyone should support the efforts of the Desert Tortoise Council and seek membership in this organization.