At least 10 of the species declined across the European Union due to intensive agriculture and the failure to manage grassland ecosystems, said the report, 'The European Grassland Butterfly Indicator'.
This could have dramatic effects on Europe’s biodiversity as butterflies may be key to maintaining the health of grassland ecosystems.
Hans Bruyninckx, the EEA’s executive director, said: “This dramatic decline in grassland butterflies should ring alarm bells – in general Europe’s grassland habitats are shrinking. If we fail to maintain these habitats we could lose many of these species forever. We must recognise the importance of butterflies and other insects – the pollination they carry out is essential for both natural ecosystems and agriculture.”
After birds, butterflies are the EU’s most reliable indicator for the state of its biodiversity due to the detailed long-term data available from across the European Union, the report’s lead author, Chris van Swaay, told EurActiv.
Van Swaay, from Dutch Butterfly Conservation, said: “The Grassland Butterfly Indicator shows a clear decline in biodiversity … Butterflies is one of the few group for which we have data for a large part of the continent and since at least 1990.”
Butterflies examined in the report include Polyommatus Icarus (known as the Common Blue), which has declined significantly, Euphydryas aurinia (the Marsh Fritillary), a grassland specialist species which also declined, and Anthocharis cardamines (the Orangetip), seemingly stable since 1990.
Separately, the EU has stepped up efforts to restrict insecticides in a bid to stave off the decline in bee populations.
The report flags the over-intensification of agriculture in Western Europe as major cause of the decline.
A statement accompanying the report blames agricultural intensification for creating vast sterile, uniform grasslands which do not provide the habitat needed for many indigenous species to survive. Butterflies, and other species, are also vulnerable to the over-use of chemical pesticides, a major component of intensive farming.
The authors also expressed concerns about the abandonment of traditional farmland in southern and eastern Europe as a factor in the degradation of the butterfly's habitat.
In southern and eastern Europe in particular, socio-economic concerns have led farmers to quit their family’s land in search of work in cities or abroad.
“Young farmers leave their villages and go to the big cities and the land is left as it and turns into scrubland and forest,” van Swaay said.
For van Swaay, the EU's Common Agricultural Policy could provide a two-fold solution, supporting local farmers in Europe’s poorer regions and protecting biodiversity.
“The Common Agricultural Policy is going into a new seven-year period in which there is more attention for nature but still we think it’s not enough … The EU is doing some things but we could do more, support more local farms.”
Protecting local farms could also play a key role in preserving the EU’s heritage, van Swaay says. “Small farms in the grasslands are full of butterflies and also flowers. It is an important part of our cultural heritage. What makes Europe special is these semi-natural areas … The forests are bigger in Russia and the mountains are higher in Asia."
Recently, there have also been stark warnings about the potential impacts on biodiversity if the EU’s bee population continues to decline due to agricultural intensification, in particular the widespread use of pesticides.