Time Horizons and Extinction Risk in Endangered Species Categorization Systems

Assessing extinction risk is a fundamental issue in conservation biology. However, national and international legislation and the implementing regulations that establish categorization procedures often include vague definitions of analytic time horizons (e.g., the “foreseeable future”). Because there is no single framework for interpreting these vague terms, individual decisions are often made on a case-by-case basis. We examine how the lack of an a priori framework for assessing extinction risk over time can lead to capricious decisionmaking, which can in turn hinder biodiversity conservation and scientific credibility. We give recommendations for making more transparent and consistent categorization decisions with respect to time horizons and extinction risk.