Use of standardized methods to improve extinction-risk classification

Caitlin C. Mothes, Stephanie L. Clements, Dishane K. Hewavithana, Hunter J. Howell, Aaron S. David, Nicole D. Leventhal, Christopher A. Searcy

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)754-761
Number of pages8
JournalConservation Biology
Issue number3
StatePublished - Jun 1 2020


  • classification trees
  • conservation priority
  • criterios de listado
  • decisiones de listado
  • especies amenazadas
  • evaluación del riesgo
  • listing criteria
  • listing decisions
  • medidas cuantitativas del riesgo
  • prioridad de conservación
  • quantitative risk metrics
  • risk assessment
  • threatened species
  • árbol de clasificación

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Nature and Landscape Conservation


Dive into the research topics of 'Use of standardized methods to improve extinction-risk classification'. Together they form a unique fingerprint.

Cite this