Applying IUCN Red List criteria at a small regional level: A test case with butterflies in Flanders (north Belgium)

► We applied the new IUCN Red List criteria to butterflies in Flanders. ► We analysed the impact of spatial resolution on the final Red List outcome. ► Sixty six percentage of all resident butterfly species classified as (near) threatened in Flanders. ► Coarse grid cells understimate the Red List status of species.