Defenders' Experts
Desert Tortoise Background and Recovery
General History
The threatened desert tortoise (Gopherus agassizii) of the Mojave Desert faces many natural challenges such as drought and disease. Being long-lived and slow to reach reproductive age, it is especially susceptible to human disturbance such as habitat degradation and fragmentation due to urbanization and development, and impacts from off-road vehicles.
Defenders’ Role
Defenders was influential in listing the Mojave population in 1989, and in the early 1990s helped secure key acquisition lands. The Mojave population of the desert tortoise is still declining drastically due to staff constraints, funding shortfalls, and lack of public support for necessary recovery actions. The Desert Tortoise was listed under the Endangered Species Act in 1989 and a team of experts developed a recovery plan to guide its recovery in 1994. Currently there is a mandated review of the recovery plan which Defenders is involved in.
Threats
The threats to the desert tortoise include habitat loss, degradation and fragmentation, urbanization and development, impacts from vehicles, disease and impacts from predation by increased numbers of ravens. Recent research is revealing that this iconic symbol of the desert could very well be extinct in the Mojave Desert within the next 50 years if current human impacts remain unchanged (Desert Managers Group, 2007)
Tortoise Biology
A tortoise is a land dwelling turtle with high domed shell and columnar, elephant-shaped hind legs. Tortoises go to water only to drink or bathe. The desert tortoise is one of the most elusive inhabitants of the desert, spending up to 95% of its time under ground. Females do not breed until they are 15 to 20 years old. Courting and copulation usually occur in late summer and early fall. Yet females store sperm, and egg laying doesn’t occur until May, June and July.
To escape the heat of the summer and the cold of winter the desert tortoises live in burrows which they dig. These can be three to six feet deep. They will spend November through February in a torpid state in their underground burrows. Their most active time is in the spring when they will forage for food. During the hottest, driest periods of the year the tortoise conserves water already stored in its body. This is especially important in the hot, dry Mojave Desert summers. Winter hibernation aids in minimizing water loss.
Desert Tortoise Data and Information Portal
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