Documenting Desert Tortoise use of interstate underpasses in alluvial fans and washes

Focus Area

Wildlife & Ecosystems


Natural Resources






Under 1 year

Research Idea Scope

Within the Colorado desert area of southern California, the Coachella Valley Multiple Species Habitat Conservation Plan (CVMSHCP) spans 1.1 million acres across the Coachella Valley. Bordered by Joshua Tree National Park to the north and the Imperial Valley to the south, the Coachella Valley is bisected by Interstate 10 which creates a significant barrier to species movement and enhanced fragmentation of populations. The Coachella Valley Conservation Commission and CalTrans have worked with US Fish and Wildlife Service, California Department of Fish and Wildlife, and the Bureau of Land Management to identify appropriate linkages within the reserve system that may be used by desert tortoise and other vertebrates to travel beneath Interstate 10.The Desert Tortoise Linkage and Conservation Area was established between Joshua Tree and the Orocopia Mountains focusing on the washes emanating from the Hexie/Cottonwood area and Orocopia Mountains, with the goal of encouraging dispersal from populations of desert tortoise regularly documented by Joshua Tree National Park north of Interstate 10. Since these linkages have been established however, no research has been done to document their effectiveness. This project will follow the CVMSHCP objectives for science-based monitoring, including collection of detailed demographic data on tortoise populations as well as data on biotic and abiotic variables influencing tortoise ecology, and will help prioritize adaptive management needs for the species in the planning area. (1) Establish baseline data on the effectiveness of the corridors under Interstate 10 for vertebrate species using wildlife cameras. (2)Conduct genetic studies on tortoise populations on both sides of I-10 to estimate historic and current connectivity of these populations. (3) Document nesting success along the freeway corridor and the effects of anthropogenic influences using surveys and replicated sampling. (4). Document existing habitat using California VEG-CAMP protocol and determine what modifications can potentially enhance population viability. (5) Develop and refine habitat characteristics necessary to maintain connectivity for desert tortoises and refine land management goals for wildlife corridors.

Urgency and Payoff

If the trend in climate continues, and it continues to get both warmer and drier, species may need to shift their current ranges toward cooler, wetter and more upland habitats. I-10 lies along the Sonoran/Mojave Desert transition where much of that movement may need to occur; it also represents a potential barrier for many species. Tortoises represent an iconic desert species that occurs on both sides of I-10 and are expected to be impacted by climate change

Suggested By

Kathleen Flemin Coachella Valley Association of Governments 760 346 1127

[email protected]