No safety in numbers

Abstract

Clements et al. (Front Ecol Environ 2011; 9[9]: 521-525) proposed a single metric that describes a "species' ability to forestall extinction" (referred to by the acronym "SAFE") as a "scientifically defendable rule of thumb for when complete demographic data are unavailable" to rank the relative threat status of a species. SAFE is calculated on a logarithmic scale and reflects the difference between a species' current population size and 5000, the estimate for a universal minimum viable population (MVP) promoted by Traill et al. (2010). Clements et al. advocated SAFE as a useful tool for triage to allocate resources in conservation, and as a measure of population viability that would be more easily understood by the public than the IUCN Red List categories (Mace et al. 2008). We believe that SAFE is not a useful metric to guide conservation planning for three main reasons.

Citation

Beissinger, Steven R.; Flather, Curtis H.; Hayward, Gregory D.; Stephens, Philip A. 2011. No safety in numbers. Frontiers in Ecology and the Environment. 9: 486.