Seventeen species that were once commonly found in pastures and meadows across 22 countries, including the small copper, common blue and meadow brown, declined by 36% on average between 2011 and 2020.
Conservation scientists attribute the ongoing declines to agricultural intensification. This includes the ploughing of traditional grasslands and the heavy use of fertilisers and herbicides, which destroy the wildflowers and grasses that butterfly caterpillars feed on.
Nitrogen deposition from vehicle emissions and agriculture is also a factor, alongside global heating.