OOS 13-2
Evaluating landscape-level extinction risk: New tools for setting science-based recovery targets
Establishing measurable, objective recovery criteria for listed species remains among the most difficult challenges in implementing the Endangered Species Act. Generally low abundance values and weak associations with species characteristics have called the scientific basis of the criteria into question. We suggest that integrating the ‘3R’s’ (representation, redundancy, and resilience) into a quantitative extinction-risk framework would allow determining if criteria for different species and threat contexts are consistent and ensure that abundance levels are sufficient to ensure a species is not in danger of extinction now or in the foreseeable future. It would also meet the biological and statutory requirements that criteria reflect all threat factors that triggered listing. We suggest a landscape theoretic approach to quantifying the 3Rs that can be evaluated in an extinction risk framework. The probability value and time horizon chosen as acceptable would remain normative decisions, but the decisions would be transparent and would allow science-based comparison across species and recovery strategies to determine if the chosen probabilities are achieved.
Results/Conclusions
We evaluate the probability of persistence that would result from multiple threat and conservation scenarios to demonstrate the utility of this approach in providing objective and measurable species status assessments. These assessments can be used in all aspects of the Endangered Species Act form listing; to Sections 7, 9, and 10; to recovery. The resulting criteria would meet the requirements of the Act to address conservation of species and the ecosystems on which they depend throughout all or a significant portion of their range. It would also allow assessment of the benefits of threat abatement.