Extensive climate-induced range shifts in butterflies across the globe

Global changes are leading to widespread species redistribution. Comprehensive assessments of range shift dynamics and their drivers are difficult, partly due to the variation in range shift detection over space and taxa. Here we compile documented range shift records for 1,758 butterfly species from 105 countries and territories, representing ~10% of the known diversity of these insects. Most species (80%) experienced range expansions, and most range shifts (79%) were associated with climate change and extreme weather events. A substantial proportion of species in our dataset contracted their ranges (27%) or shifted along elevational gradients (22%). We report widespread horizontal range expansions and contractions across tropical countries, with less evidence for elevational range shifts. We show that a clearer picture of range shift dynamics emerged only through the combination of different types of data, with expert assessments and non-English studies alleviating potential biases. Our findings of climate-driven range shifts call for concerted efforts to improve inclusive data monitoring and conservation efforts, especially for tropical countries, where human-induced land-use changes exert additional critical pressure.