Aim Effective policy making for biological conservation requires the identification and ranking of the most important areas for protection or management. One of the most frequently used systems for selecting priority areas is Key Biodiversity Areas (hereafter KBAs), developed by the International Union for Conservation of Nature (IUCN). However, KBAs cannot be used to rank areas, potentially limiting their use when limited funding is available. To tackle this shortcoming and facilitate spatial prioritization, here we develop and validate the “WEGE index” (Weighted Endemism including Global Endangerment index), consisting of an adaptation of the EDGE score (Evolutionarily Distinct and Globally Endangered). WEGE allows the ranking of any set of locations according to the KBA guidelines and on a continuous scale. Location Global. Methods We calculated the EDGE score, Weighted Endemism, Evolutionary distinctiveness, Extinction risk and our newly developed WEGE index for all terrestrial species of amphibians, mammals and birds accessed by IUCN. We then compared the performance of each of those five indices at prioritizing areas according to the KBA guidelines. Results We found that for all taxa surveyed, WEGE was consistently better at identifying areas that trigger KBA status. Main conclusions In our analyses, WEGE outperformed all other methods and metrics designed for similar purposes. It can therefore serve as a robust evidence-based methodology to prioritize among otherwise equally qualified sites according to the KBA categories. WEGE can therefore support transparent, evidence-based and biologically meaningful decision-making for conservation priorities.

Using IUCN’s range maps for all assessed terrestrial amphibians (6,615 species), mammals (5,610) and birds (10,549) (2019-3: IUCN 2019) we calculated EDGE, ED, ER, WE, WEGE and cells that trigger KBA status for criteria A1a, A1b, A1e and B1 in a global scale in resolutions of c. 100 x100 km (10,000 km²) and c. 20 x 20 km (400 km²) grids on a Berhmann projection map. We note that the sizes of the cells are area-true but involve some modifications of the shapes. The actual size is only 100 x100 km at 30 degrees North or South.