Ranking threats using species distribution models in the IUCN Red List assessment process

Abstract

Within the Red List of the International Union for Conservation of Nature (IUCN), species distribution models (SDM) are used with two main purposes: (1) to estimate extents of occurrence as a parameter of risk of extinction and, more recently, (2) to explore potential impacts of climate change on species distribution. In this article I propose a third use of SDM: to generate objective and quantitative rankings of threats for the species categorized within the Red List. Although, some authors have published threat analyses based on SDM, most current ranking of threats conducted within IUCN Specialist Groups still relies on the subjective perspectives of workshop attendees or individual experts. I found that SDMs are ideal for incorporating theoretical and mathematical rigour to the ranking threat process, because: (1) they are of relatively easy and fast implementation, (2) they can be used with different levels of knowledge about the species in question, and (3) they are particularly suitable for use at the geographical scale for which the IUCN Red List is designed.