Sonoran desert tortoise populations are facing a number of serious threats, including increased habitat destruction, fragmentation, and degradation caused by invasive non-native plant establishment. Other threats include an altered fire regime, urbanization and development, and human-constructed barriers to tortoise movement. These threats led AZGFD to work with partners in the Arizona Interagency Desert Tortoise Team to complete a Candidate Conservation Agreement (CCA) for the Sonoran desert tortoise in 2015. Administered by the USFWS, a CCA is a voluntary conservation agreement between USFWS and partners, either public or private, to identify threats to species being considered for listing under the Endangered Species Act (ESA). The CCA for Sonoran Desert Tortoise identifies existing conservation measures, provides a comprehensive statewide conservation framework, and utilizes collective knowledge and funding to implement proactive conservation measures for the species.
In Arizona, the Sonoran desert tortoise primarily inhabits rocky, steep slopes and bajadas of Mojave Desertscrub and the Arizona Upland and Lower Colorado River subdivisions of Sonoran Desertscrub at elevations up to 4,200 feet (1280 meters). Long-term studies and monitoring programs have informed when tortoises are active, when they hatch, what they use for shelter, how they use their habitat, and how fast (or slowly) they grow. Adequate shelter is one of the most important habitat features for Sonoran desert tortoises, and is positively-correlated with population densities. In other words, the more shelters, the higher the density of Sonoran desert tortoises.
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Sixteen state and federal partners were signatories to the CCA, providing conservation actions to State and Federal lands throughout Arizona.
AZGFD, BLM, and other partners have been conducting capture-recapture surveys since the 1980s; each year, 3 of the 17 long-term monitoring plots are surveyed on a rotating basis.
Although population fluctuations have been documented, data analyses indicate that survivorship is high, and greater than 90% in most locations, suggesting that overall the population is stable.
In 1995, the Arizona Interagency Desert Tortoise Team was established, with partners including AZGFD, USFS, Luke Air Force Base, ADOT, Marine Corps Air Station, Yuma Proving Ground, BLM, Bureau of Reclamation, USFWS, and NPS. The team expanded in 2011 to include several Arizona counties where the species occurs.