Protocols for listing threatened species can forecast extinction

Abstract

Risk-ranking protocols are used widely to classify the conservation status of the world's species. Here we report on the first empirical assessment of their reliability by using a retrospective study of 18 pairs of bird and mammal species (one species extinct and the other extant) with eight different assessors. The performance of individual assessors varied substantially, but performance was improved by incorporating uncertainty in parameter estimates and consensus among the assessors. When this was done, the ranks from the protocols were consistent with the extinction outcome in 70-80% of pairs and there were mismatches in only 10-20% of cases. This performance was similar to the subjective judgements of the assessors after they had estimated the range and population parameters required by the protocols, and better than any single parameter. When used to inform subjective judgement, the protocols therefore offer a means of reducing unpredictable biases that may be associated with expert input and have the advantage of making the logic behind assessments explicit. We conclude that the protocols are useful for forecasting extinctions, although they are prone to some errors that have implications for conservation. Some level of error is to be expected, however, given the influence of chance on extinction. The performance of risk assessment protocols may be improved by providing training in the application of the protocols, incorporating uncertainty in parameter estimates and using consensus among multiple assessors, including some who are experts in the application of the protocols. Continued testing and refinement of the protocols may help to provide better absolute estimates of risk, particularly by reevaluating how the protocols accommodate missing data.

Effect of ecological uncertainty on species at risk decision-making: COSEWIC expert opinion as a case study

“…In this sense, great uncertainty need not cripple the designation process, leaving vulnerable species without protection for lack of information (Akc¸akaya et al, 2000;Bradshaw & Borchers, 2000;Keith et al, 2004). It may be highly desirable for managers to deploy different strategies to recover species that receive a relatively equal split between not at risk and at risk designations (e.g.…”

“…An important consequence of explicitly characterizing uncertainty in ecological variables is the potential for an assessment protocol to use Monte Carlo sampling to return a probability distribution of risk designations rather than a single risk designation. To date, there have been few empirical studies to evaluate the effect of characterizing uncertainty, using even simple probability distributions, on species at risk decision-making Keith et al, 2004).…”

Improvements to the Red List Index

“…[7], [22]. However, assessments are now required to have supporting documentation detailing the best available data, with justifications, sources, and estimates of uncertainty and data quality [23].…”

Rates of Movement of Threatened Bird Species between IUCN Red List Categories and toward Extinction

“…The results of some studies suggest that criterion E is more precautionary than A-D (Gärdenfors 2000); others indicate that criteria A-D may not be very precautionary, particularly when data are limited (Keith et al 2004). Owing to the paucity of convincing empirical tests of the relationship between the criteria, recent guidelines for using the IUCN Red List Categories and Criteria (Standards and Petitions Committee 2006) now include a caveat that the extinction probability for an individual species should not be assumed to match exactly the appropriate criterion E threshold.…”