European Grassland Butterfly Index: further decline
Dutch Butterfly ConservationFor this analysis, data from 16,150 butterfly transects across Europe were compiled in the eBMS (European Butterfly Monitoring Scheme) database, which is managed by BCE and UKCEH. This database combines trends for individual species. In a recent report, trends for the 17 butterfly species included in the indicator were used to update the Grassland Butterfly Index (GBI) for 1991 until 2024, based on data from all 27 EU countries. The GBI is explicitly mentioned in the EU Nature Restoration Regulation (NHV) in Article 11 on the restoration of agricultural ecosystems, as one of the three indicators that Member States can choose to monitor. Member States that choose the GBI as one of their indicators, must achieve an upward trend at national level until satisfactory levels are reached. What those levels are, has yet to be determined.
Possible causes of decline
The EU grassland butterfly index has shown a decline of 47 percent since 1991. In Northwestern Europe, the decline is mainly attributed to habitat loss due to the intensification of agricultural grasslands, nitrogen deposition, and pesticides in nature areas. In Northern Europe (Scandinavia, Finland, and the Baltic States), Eastern and Southern Europe, and the Alps, the abandonment of grasslands is also an important factor, as scrub encroachment and afforestation lead to a net loss of habitat for grassland butterflies. The decline observed over the past 34 years probably reflects only part of the historical decline of grassland butterflies, as many populations had already disappeared from the landscape before 1990.
Alarming rate
This report contains an essential message from scientists to policymakers: butterflies are still declining at an alarming rate across the EU, and urgent action is needed to protect and restore habitats to reverse this trend, not only for butterflies but also for other wild pollinating insects and their ecosystem services. Butterflies are ideal biological indicators: they are well documented, measurable, sensitive to changes in the environment, occur in a wide range of habitat types, represent many other insects, and are popular with the public.
More information
- You can read and download the rapport (pdf: 2.4 MB) on the Butterfly Conservation Europe website.
Text: Chris van Swaay and Kars Veling, De Vlinderstichting (Dutch Butterfly Conservation)
Images: Kars Veling; Butterfly Conservation Europe