California State Park Desert Tortoise Survey

FirstCarbon Solutions (FCS) biologists conducted a study of Mojave desert tortoises (Gopherus agassizii) at a state park located in Los Angeles County, California. The 2,955-acre park, located in the western Mojave Desert, was established to protect its unique geological, biological, and cultural resources and is managed by the California Department of Parks and Recreation.  

Dr. Michael Tuma, FCS principal biologist, worked with department staff to develop a survey strategy that allowed for training opportunities for staff and volunteers. This strategy mimicked a 2004 population monitoring survey that the department conducted at the park with assistance from the U.S. Geological Survey.  

FCS developed a GIS database that marked the locations of the survey quadrat plot and the long, meandering survey transects that sampled different park areas in 2004, allowing these exact areas to be sampled in 2024. Dr. Tuma led a group of 15 biologists, comprised of department staff, volunteers, and FCS associate biologists, to survey the quadrat plot and transects in October 2024.  

During the effort, the team documented a desert tortoise burrow that had recently been inhabited by a tortoise, as evidenced by fresh scat on the burrow mound and tracks in the burrow tunnel. Various threats to desert tortoises existed inside the park, such as invasive plants, trash, and subsidized predators.  

FCS biologists compared the survey data between 2004 and 2024 in a report that also included an extensive review of desert tortoise biology, an assessment of habitat quality and distribution of threats at the park, and recommendations for management of the desert tortoise population inside the park. These methods included habitat restoration, installation of tortoise-proof fencing, and potential population augmentation through translocation and head-starting.