IUCN / SSC Cat Specialist Group - Digital Cat Library
   

 

View printer friendly
Kindvall, O.; G„rdenfors, U.
Temporal extrapolation of PVA results in relation to the IUCN Red List Criterion E
2003  Conservation Biology (17): 316-321

The World Conservation Union ( IUCN ) Red List threat categories of critically endangered, endangered and vulnerable are defined by a set of five criteria ( A-E ). Criterion E is quantitatively defined by three specified threshold extinction risks ( 50%, 20%, and 10% ), each associated with a particular time frame. For a population viability analysis ( PVA) to be useful for assessing a species' threat category, the results must have been expressed as the full extinction probability function over time or at least for the three specified time frames. Often this is not the case, and extrapolations from different kinds of PVA results ( e.g., mean time to extinction ) are often necessary. By means of analytic models, we investigated the possibilities of extrapolation. Based on our results, we suggest that extrapolation is not advisable due to the huge errors that can occur. The extinction probability function is the best kind of summary statistic to use when applying criterion E, but even then the threat categorization may be ambiguous. If the extinction risk is low in the near future but increases rapidly later on, a species may be classified as vulnerable even though it is expected to become extinct within 100 years. To avoid this, we suggest that the guidelines to the IUCN Red List criteria include three reference lines that allow for interpretation of the PVA results in the context of the three threat categories within the entire period of 100 years. If the estimated extinction probability function overshoots one of these functions, the species should be classified accordingly.

PDF files are only accessible to Friends of the Cat Group. Joining Friends of the Cat Group gives you unlimited access and downloads in the Cat SG Library for one year, and allows you to receive our newsletter Cat News (2 regular issues per year plus special issues). More information how to join here

 

(c) IUCN/SSC Cat Specialist Group ( IUCN - The World Conservation Union)