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Published July 21, 2025 | Version v2
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EU Grassland Butterfly Index 1991-2023 Technical report

Creators

  • 1. De Vlinderstichting / Dutch Butterfly Conservation
  • 2. Butterfly Conservation Europe
  • 3. ROR icon UK Centre for Ecology & Hydrology
  • 4. EDMO icon Centre for Ecology and Conservation, University of Exeter
  • 5. ROR icon Butterfly Conservation
  • 6. Bulgarian Butterfly Monitoring Scheme, National Museum of Natural History, Sofia, Bulgaria
  • 7. SOCEME - Society for the Conservation and Study of Butterflies in Spain, Spanish Butterfly Monitoring Scheme, Spain
  • 8. Swedish Butterfly Monitoring Scheme
  • 9. EDMO icon Lund University, Department of Biology
  • 10. Latvian Butterfly Monitoring Scheme, Institute of Life Sciences and Technology, Daugavpils University, Daugavpils, Latvia.
  • 11. Environment and Water Agency, Ministry of Sustainability, Environment and Blue Economy of the Andalusian Government, Provincial Office of Granada, Granada, Spain
  • 12. Danish Butterfly Monitoring Scheme (Danmarks Dagsommerfugle), Aarhus, Denmark
  • 13. Italian Butterfly Monitoring Scheme, Zoolab Department of Life Sciences and Systems Biology, University of Turin, Italy
  • 14. CSIC-National Museum of Natural Sciences, Madrid, Spain
  • 15. Andorran Butterfly Monitoring Scheme, Andorra Research + Innovation, Andorra
  • 16. Italian Butterfly Monitoring Scheme, ZEN Lab, Department of Biology, University of Florence, Italy
  • 17. Swiss Butterfly Monitoring Scheme, Switzerland
  • 18. French Butterfly Monitoring Scheme (STERF), Office pour les insectes et leur environnement (Opie), France
  • 19. Wallonia Butterfly Monitoring Scheme, Natagriwal asbl, Gembloux, Belgium
  • 20. ZERYNTHIA Spanish Butterfly Monitoring Scheme. ZERYNTHIA (Asociación Española para la Protección de las Mariposas y su Medio), Spain
  • 21. Czech Butterfly Monitoring Scheme, Biology Centre CAS, České Budějovice, Czech Republic
  • 22. Basque Country Butterfly Monitoring Scheme, Hazi Foundation, Granja Modelo, Arkaute, Spain
  • 23. French Butterfly Monitoring Scheme, Muséum national d'Histoire naturelle - Office Français pour la Biodiversité, France
  • 24. Slovenian Butterfly Monitoring Scheme, Society for the Conservation and Study of Lepidoptera in Slovenia, Slovenia
  • 25. Norwegian Butterfly Monitoring Scheme, Norwegian Institute for Nature Research (NINA), Norway
  • 26. Austrian Butterfly Conservation – ABC, Austria
  • 27. University of Vienna, Vienna, Austria
  • 28. German Butterfly Monitoring Scheme, (Tagfalter-Monitoring Deutschland - TMD), Helmholtz-Centre for Environmental Research – UFZ, Germany
  • 29. Finish Butterfly Monitoring Scheme, Finnish Environment Institute (Syke), Finland
  • 30. Aarhus University
  • 31. Irish Butterfly Monitoring Scheme, National Biodiversity Data Centre, Carriganore, Waterford, Ireland
  • 32. Greek Butterfly Monitoring Scheme (apollo-grBMS), University of Ioannina, Department of Biological Applications & Technology, Biodiversity Conservation Laboratory, Greece
  • 33. Büro Lang, Zell im Wiesental, Germany
  • 34. Flanders Butterfly Monitoring Scheme, Research Institute for Nature and Forest (INBO), Belgium
  • 35. Jersey Butterfly Monitoring Scheme (UKBMS), Land Resource Management, Government of Jersey, Jersey
  • 36. Urban Butterfly Monitoring Scheme (uBMS), CREAF and University of Barcelona, Spain
  • 37. Luxembourg Butterfly Monitoring Scheme, Luxembourg Institute of Science and Technology, Luxembourg
  • 38. Portugal Butterfly Monitoring Scheme, Tagis - Centro de Conservação das Borboletas de Portugal, Portugal
  • 39. Universidad Autónoma de Madrid
  • 40. Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid (UAM), Spain
  • 41. Red de Seguimiento de Mariposas Diurnas de Sierra Nevada. Parque Nacional y Parque Natural de Sierra Nevada, Pinos Genil (Granada), Spain
  • 42. Cyprus Butterfly Monitoring Scheme, Near East University, Nicosia, Cyprus
  • 43. Czech Butterfly Monitoring Scheme, Czech Butterfly Conservation Society, Czech Republic
  • 44. Swedish Butterfly Monitoring Scheme, Lund University, Lund, Sweden
  • 45. Romania Butterfly Monitoring Scheme, Department of Taxonomy and Ecology, Babes-Bolyai University, Cluj, Romania
  • 46. Biodiversity Monitoring Switzerland (BDM), Hintermann & Weber AG, Switzerland
  • 47. Viel-Falter Monitoring, University of Innsbruck, Department of Ecology, Austria
  • 48. Croatia Butterfly Monitoring Scheme, Croatian Natural History Museum, Croatia
  • 49. Italian Butterfly Monitoring Scheme, CREA Research Centre for Forestry and Wood, Rende, Italy
  • 50. City of Vienna, Austria
  • 51. Department of Conservation Biology and Social‑Ecological Systems, Helmholtz Centre for Environmental Research - UFZ, Halle, Germany
  • 52. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
  • 53. Polish Butterfly Monitoring Scheme, Association for Butterfly Conservation, Poland
  • 54. Polish Butterfly Monitoring Scheme, Division of Biodiversity and Behavioural Ecology, University of Bialystok, Poland
  • 55. Catalan Butterfly Monitoring Scheme, Natural Sciences Museum of Granollers, Spain
  • 56. Lithuanian Butterfly Monitoring Scheme, Ukmerge, Lithuania
  • 57. Hungarian Butterfly Monitoring Scheme, Hungarian Lepidoptera Monitoring Network, Jozsef Szalkay Hungarian Lepidopterists' Society, Hungary
  • 58. Estonian Butterfly Monitoring Scheme, University of Tartu, Department of Zoology, Estonia
  • 59. Cyprus Butterfly Monitoring Scheme, Cyprus Butterfly Study Group, Nicosia, Cyprus/Open University of Cyprus, Faculty of Pure and Applied Sciences, Latsia, Cypru
  • 60. Lithuanian Butterfly Monitoring, Lithuanian Entomological Society, Lithuania

Description

Executive Summary

Butterflies have been systematically monitored in Europe for several decades using standard protocols that are now adopted in over 30 countries. Butterflies are ideal biological indicators: they are well-documented, measurable, sensitive to environmental change, occur in a wide range of habitat types, represent many other insects, and are popular with the public because of their beauty.

Records from over 6,000 standardised butterfly transects are gathered into a central database as part of the European Butterfly Monitoring Scheme (eBMS) run by Butterfly Conservation Europe (BCE) and the UK Centre for Ecology and Hydrology (UKCEH). The database provides trends on individual species which can be combined to give trends for different habitats.

In this report, trends for 17 species have been used to generate an updated Grassland Butterfly Index (GBI) for 1991-2023, using data from all 27 EU countries. The GBI is specifically mentioned in the EU Nature Restoration Regulation (NRR) in article 11 on the Restoration of Agricultural ecosystems as one of the possible indicators that should be measured until the satisfactory levels as set in accordance with Article 14(5) are reached. In practice, for those Member States choosing the GBI as an Indicator, under NNR Article 11, this means that 2025 will be the first year for this indicator.

The EU Grassland Butterfly Index shows a decline of just over 50% since 1991. In North-western Europe, the decline is primarily attributed to habitat loss resulting from the intensification of agricultural grasslands and nitrogen deposition in nature reserves. In Northern (Scandinavia, Finland and the Baltic states), Eastern and Southern Europe, the abandonment of grasslands is also a strong driver as shrubs and secondary forest encroachment result in less habitat for grassland butterflies. The decline observed over the last 33 years probably reveals only part of the historical decline in grassland butterflies, as many populations were extirpated from the landscape before 1990

The GBI is the Indicator on the EU Dashboard Target 5, for evaluating progress with improving agroecosystems for biodiversity. It is also part of the EU Sustainable Indicator set, for evaluating the implementation of the Global Biodiversity Strategy.

This technical report provides an important message from scientists to policy makers - that butterflies are still declining at an alarming rate across the EU and that urgent action is required to protect and restore habitats to reverse this trend, not only for butterflies but also for other wild insect pollinators and their ecosystem services. The completion and appropriate management of the Natura 2000 network across Europe is a crucial step in helping grassland butterflies. Restoration and creation of landscapes with mosaics of habitats, both within and outside Natura 2000 areas, are essential to protect grassland butterflies in the EU.

We are grateful to all the many thousands of volunteer butterfly recorders who contribute their records to this important database, to the many BMS schemes, co-ordinators and funders who support the work, and to the EU for funding the EBMS through the EMBRACE project.

Files

VS2025.014 EU Grassland Butterfly Index 1991-2023 Technical report.pdf

Files (2.3 MB)

Additional details

Funding

European Union
Expanding Monitoring of Butterflies for Restoration and Conservation across Europe 2021-2026 Contract no. 090201/2024/929792/SER/ENV.D2