The Consistency of Extinction Risk Classification Protocols TRACEY J. REGAN, ∗ MARK A. BURGMAN,† MICHAEL A. MCCARTHY,‡ LAWRENCE L. MASTER,§ DAVID A. KEITH, ∗∗ GEORGINA M. MACE,†† AND SANDY J. ANDELMAN‡‡ ∗ The Ecology Centre, School of Life Sciences, The University of Queensland, Brisbane QLD 4072, Australia, email t.regan@uq.edu.au †School of Botany, The University of Melbourne, Parkville, Victoria 3010, Australia ‡Australian Research Centre for Urban Ecology, Royal Botanic Gardens Melbourne, School of Botany, University of Melbourne, Victoria, 3010, Australia §NatureServe, 11 Avenue de Lafayette, 5th Floor, Boston, MA 02111, U.S.A. ∗∗ New South Wales National Parks and Wildlife Service, Hurstville, New South Wales 2220, Australia ††Institute of Zoology, Zoological Society of London, Regents Park, London NW14RY, United Kingdom ‡‡National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, CA 93101, U.S.A Abstract: Systematic protocols that use decision rules or scores are seen to improve consistency and trans- parency in classifying the conservation status of species. When applying these protocols, assessors are typically required to decide on estimates for attributes that are inherently uncertain. Input data and resulting classifica- tions are usually treated as though they are exact and hence without operator error. We investigated the impact of data interpretation on the consistency of protocols of extinction risk classifications and diagnosed causes of discrepancies when they occurred. We tested three widely used systematic classification protocols employed by the World Conservation Union, NatureServe, and the Florida Fish and Wildlife Conservation Commission. We provided 18 assessors with identical information for 13 different species to infer estimates for each of the required parameters for the three protocols. The threat classification of several of the species varied from low risk to high risk, depending on who did the assessment. This occurred across the three protocols investigated. Assessors tended to agree on their placement of species in the highest (50–70%) and lowest risk categories (20–40%), but there was poor agreement on which species should be placed in the intermediate categories. Furthermore, the correspondence between the three classification methods was unpredictable, with large vari- ation among assessors. These results highlight the importance of peer review and consensus among multiple assessors in species classifications and the need to be cautious with assessments carried out by a single as- sessor. Greater consistency among assessors requires wide use of training manuals and formal methods for estimating parameters that allow uncertainties to be represented, carried through chains of calculations, and reported transparently. Key Words: conservation status, classification protocols, threatened species lists, uncertainty, operator error, IUCN Red List, NatureServe La Consistencia de los Protocolos de Clasificaci´ on del Riesgo de Extinci´ on Resumen: Los protocolos sistem´ aticos que utilizan reglas o puntuaciones de decisi´ on mejoran la consis- tencia y transparencia de la clasificaci´ on del estatus de conservaci´ on de especies. Al aplicar estos protocolos, t´ ıpicamente se requiere que los asesores tomen decisiones con estimaciones de atributos que inherentemente son inciertos. Los datos de entrada y las clasificaciones resultantes generalmente son tratadas como si fueran exactas y, por lo tanto, sin error de operario. Investigamos el impacto de la interpretaci´ on de datos sobre la consistencia de protocolos de clasificaci´ on del riesgo de extinci´ on y diagnosticamos las causas de discrepancias Paper submitted June 28, 2004; revised manuscript accepted December 14, 2004. 1969 Conservation Biology 1969–1977 C 2005 Society for Conservation Biology DOI: 10.1111/j.1523-1739.2005.00235.x