Use of standardized methods to improve extinction‐risk classification

Abstract

Standardized classification methods based on quantifiable risk metrics are critical for evaluating extinction threats because they increase objectivity, consistency, and transparency of listing decisions. Yet, in the United States, neither federal nor state agencies use standardized methods for listing species for legal protection, which could put listing decisions at odds with the magnitude of the risk. We used a recently developed set of quantitative risk metrics for California herpetofauna as a case study to highlight discrepancies in listing decisions made without standardized methods. We also combined such quantitative metrics with classification tree analysis to attempt to increase the transparency of previous listing decisions by identifying the criteria that had inherently been given the most weight. Federally listed herpetofauna in California scored significantly higher on the risk-metric spectrum than those not federally listed, whereas state-listed species did not score any higher than species that were not state listed. Based on classification trees, state endemism was the most important predictor of listing status at the state level and distribution trend (decline in a species' range size) and population trend (decline in a species' abundance at localized sites) were the most important predictors at the federal level. Our results emphasize the need for governing bodies to adopt standardized methods for assessing conservation risk that are based on quantitative criteria. Such methods allow decision makers to identify criteria inherently given the most weight in determining listing status, thus increasing the transparency of previous listing decisions, and produce an unbiased comparison of conservation threat across all species to promote consistency, efficiency, and effectiveness of the listing process. Article impact statement: Using standardized, quantitative methods to assess extinction risk can improve listing decisions by increasing consistency and transparency

Treatment of climate change in extinction risk assessments and recovery plans for threatened species

“…We found a strong positive relationship between the use of the threats calculator and the probability that climate change was identified as a threat. Application of standardized processes helps to ensure that decision‐making practices, such as listing species for legal protection, are informed by consistent, repeatable and transparent criteria (Mace et al, 2008; Mothes et al, 2020). Despite the importance of using standardized criteria for threat classification, it has been typically overlooked (Hayward, 2009; Murray et al, 2014).…”

“…Knowledge gaps related to the impacts of climate change on threatened species may be compounded by factors related to legal extinction risk assessment and recovery planning processes. For example, transparency and consistency in assignments of species' conservation status is improved by the use of standardized classification criteria, including the systematic identification of relevant threats (Mothes et al, 2020). The International Union for Conservation of Nature (IUCN) Red List of threatened species is a process to quantify the global extinction risk of species, and uses a standardized threats classification scheme to identify and calculate the impact of threats on species (Mace et al, 2008; Salafsky et al, 2008).…”