Data from: 'The Red List Index of European butterflies: Extinction risk is trait-dependent'

These data contain the species-level data used in reproducible analyses of changes in the conservation status of European butterflies between the 2010 and 2025 European Red Lists. It combines Red List assessment data with ecological, biogeographical, and life-history trait data for European butterfly species. The data consists of two CSV files: one containing species trait data and one containing the Red List assessment data (see Technical info). Abstract <add abstract of manuscript>