The range of the Mojave desert tortoise, a federally threatened species in the U.S., occurs across four states in Mojave and Colorado Deserts. The United States Fish and Wildlife Service (USFWS) has identified mortality and illegal capture along roads as a priority issue to the recovery of this species. The construction of over 60,000 km of roads throughout the desert tortoise range results in mortality of an estimated 18,000 tortoises each year and has permanently fragmented previously contiguous habitat, reducing connectivity among populations. Restricted movement may limit or entirely prohibit access to suitable habitat, resources, and mates, and the desert tortoise has been identified as one of the highest risk species for road mortality, which can have significant cumulative effects on population viability.
The USFWS has identified installation of fencing and wildlife crossings as one of the highest priorities for desert tortoise recovery. However, most roads throughout their habitat remain unfenced with few suitable safe crossing opportunities. Technical and administrative obstacles to the installation of fencing and crossing structures are common and currently stand in the way of effective mitigation. To begin identifying and addressing these issues, the USFWS partnered with the Center for Large Landscape Conservation (CLLC) to develop a series of events to evaluate the challenges and opportunities faced by state and federal agencies trying to implement transportation mitigation measures.
Through a series of webinars, site visits, and a capstone workshop held in 2021, we identified the major issues to effective, range-wide implementation of conservation actions along priority roadways including the need for range-wide BMPs for prioritization, design, maintenance, and monitoring of mitigation measures; better interagency coordination and collaboration; consistent regulatory mandates and management techniques; funding for installation, maintenance, and monitoring; and resolution of maintenance and jurisdictional issues.
The Desert Tortoise Transportation Ecology Task Force was formed in 2022 as a product of the Workshop to address these issues and develop guidance. The Task Force is comprised of representatives from state transportation and wildlife agencies; local, state, and Federal agencies, NGOs, and academic researchers and road ecology experts. The overall goal of the Task Force was to develop a set of guidelines related to the mitigation of transportation infrastructure to reduce desert tortoise road mortality and increase habitat permeability across the range of the species. These guidelines will be complete in early 2023 and published for distribution to help support better implementation of measures to reduce mortality and improve connectivity for this threatened species.