Butterfly abundances but not patch occupancy buffered by vegetation heterogeneity during climatic extremes

Data and scripts belonging to the manuscript "Butterfly abundances but not patch occupancy buffered by vegetation heterogeneity during climatic extremes", accepted in Ecography June 2026 doi: 10.1002/ecog.08686. We investigated whether vegetation heterogeneity influences metapopulation persistence and growth and how this effect is modulated by drought magnitude, using a metapopulation of the Glanville fritillary butterfly (Melitaea cinxia) in the Åland island archipelago in Finland as our model system. With 24 years of long-term monitoring data from over 4000 habitat patches, we modelled temporal trends in butterfly habitat patch occupancy and abundance as a function of vegetation productivity and its heterogeneity during the growing season, using yearly Normalized Difference Vegetation Indices (NDVI) calculated from satellite data. We then tested whether these vegetation heterogeneity effects differed between years depending on the magnitude of drought, measured as the cumulative climatic water balance during the growing season.