This project will seek to fill critical knowledge gaps and advance scientific understanding of the population response of a Department of Defense (DoD) relevant species, the federally threatened Mojave desert tortoise (Gopherus agassizii; hereafter ‘tortoise’), to varying levels of exposure from multiple stressors, over time and across the range of the species. In this context, the core objectives are to:

  1. Work with managers from multiple jurisdictions to employ a structured approach to co-production, building a shared understanding of the priority factors affecting tortoise populations, characteristics of exposure scenarios that respond to management decision spaces, and key information gaps;
  2. Compile existing, regional data on anthropogenic, climate, and other environmental stressors on tortoise populations. Deploy advanced machine learning modeling techniques to accurately map range-wide trends and patterns (historical and future) of priority environmental stressors identified in Objective 1;
  3. Use > 35 years of empirical data and a spatially explicit Bayesian hierarchical modeling framework to estimate range-wide trends (historical and future) in tortoise meta-population dynamics, and the cumulative influence of multiple stressors quantified in Objective 2, under varying exposure scenarios;
  4. Design, engineer, and deploy an interactive, web-based tool to allow managers and other stakeholders access to historical, near-real time, and likely future information on tortoise population status and the individual or cumulative effects of multiple stressors, under varying exposure scenarios.

Technical Approach

Despite substantial investments by DoD and other agencies in tortoise management and conservation, the species remains in perilous decline across much of its range. The project team will connect and build from various tortoise research efforts that, to date, have been independently implemented within and among multiple management jurisdictions. There are unique opportunities to develop and include data on previously unquantified stressors, and to complement or crosswalk existing monitoring tools. Novel hypotheses related to the cumulative effects of multiple stressors on range-wide tortoise meta-population dynamics under a variety of management-relevant exposure scenarios will be tested, and the project team will produce user-friendly tools that result in actionable science. Guided by early and continuous engagement of installation and natural resource managers, and drawing on a software engineering perspective and highly efficient, cutting-edge computational resources, this project will produce statistically robust models of historical, current, and future stressors on tortoise populations that can be easily accessed and flexibly evaluated in a single, web-based interface. The products of the ‘one stop shop’ approach will be designed to: inform installation species status assessments; complement impact evaluation and mitigation driven conservation strategies; and support installation and cross-jurisdictional efforts to develop cost-effective conservation and recovery options, including estimating how conservation actions might efficiently offset effects of stressors, such as impacts of military activities.


This project will directly support DoD mission readiness and flexibility by informing desert tortoise conservation and related decision-making efforts across installations and adjacent ownership in the 32 million-acre Mojave Desert ecoregion. The area contains several DoD military facilities and service units, as well as extensive adjacent federal public lands. The project team has engaged specific, key collaborators at several DoD installations and adjacent management agencies (e.g., U.S. Fish and Wildlife Service, Bureau of Land Management), who are the expected end-users of the products. Beyond addressing important knowledge gaps for a priority DoD species, the project will enable the development of cohesive, range-wide management strategies aimed toward more effective ecosystem and priority species recovery initiatives and partnerships between agencies. The truly interdisciplinary, integrative approach will provide a fresh perspective to comprehensive and adaptive management of desert tortoise populations, grounded in cutting-edge science and the delivery of knowledge and tools that DoD requires for mission success in a rapidly changing world.