Authors: Lumbierres, Maria; Nania, Dario;Dahal, Prabhat Raj ;Schuster, Richard;Butchart, Stuart H. M.;Donald, Paul F. ;Rondinini, Carlo;Di Marco, Moreno;

Key Biodiversity Areas (KBA) are 'sites contributing significantly to the global persistence of biodiversity' and they represent an indispensable tool for effective site-based conservation. Sites qualify as KBA under Criterion E if they have a very high irreplaceability value derived from a quantitative spatial prioritisation analysis. The irreplaceability of a site is determined by both the biodiversity found within it and the biodiversity contained in the other sites considered in the analysis, meaning irreplaceability values and patterns change depending on the scale. We found that under the current formulation of Criterion E, the 47% of regionally irreplaceable planning units were not represented in country-level analyses, while country-level analyses mainly represented a subset of the regional ones. This indicated that at the regional level, irreplaceability was driven by endemic species and species richness, while at the country level, exclusively by endemic species. For some areas, the analysis produced very few or no highly-irreplaceable planning units. This could indicate that the current targets were too low for these countries. The KBA Standards and Appeals Committee could take some actions to make the analysis more robust, such as setting the scale of application at the regional level and revising the targets.