A new paper, entitled “The Decline of Butterflies in Europe: Problems, Significance, and Possible Solutions,” which is part of a special article entitled “The Global Insect Decline in the Anthropocene,” has just been published in the Proceedings of the National Academy of Sciences of the United States of America and features key contributions from the science and conservation workers at Butterfly Conservation.
The main author is Dr. Martin Warren, currently Head of Development at Butterfly Conservation Europe, but previously Chief Executive of Butterfly Conservation, while Sam Ellis (International Director), Nigel Bourn (Chief Scientist) and Dan Hoare (Director of Conservation) make important contributions.
The paper examines changes in the status of butterflies in Europe and focuses on long-term population data available for the UK, the Netherlands and Belgium based on standardized surveillance transactions. In the UK, 8% of the resident species are extinct, and the total has decreased by around 50% since 1976. In the Netherlands, 20% of species are extinct and the total number in the country has decreased by 50% since 1990. Distribution trends indicated that butterfly distributions declined long ago, declining 80% between 1890 and 1940. In Flanders, Belgium, 20 butterflies are extinct (29%) and the total number decreased by around 30% between 1992 and 2007.
Marsh Fritillary, Copyright Darren Chapman, from the Surfbirds Galleries
A European grassland butterfly indicator from 16 European countries shows that the number of grassland butterflies has decreased by 39% since 1990. On the 2010 Red List of European Butterflies, 38 of the 482 European species (8%) were listed as threatened and 44 species (10%) were listed as near threatened (note that 47 species were not assessed). An analysis at the country level shows that the average rating of the Red List is highest in Central and Central Western Europe and lowest in the far north of Europe and the Mediterranean region.
The causes of butterfly decline are believed to be similar in most countries, mainly habitat loss and degradation (including the abandonment of grassland and poor forest management) and chemical pollution in the form of pesticides and herbicides. Due to climate change, many species can spread northwards and at the same time re-threaten vulnerable species.
The paper also describes examples of possible preservation solutions. In the UK, Butterfly Conservation runs a comprehensive conservation program.
The Duke of Burgundy is one of the UK’s most endangered species. Between the 1980s and 2012, more than 60% of its colonies died out. The concerted effort to reverse its decline began in 2003 with a landscape conservation program of targeted emergency habitat management with rotary cutting of scrub and fencing off sites to relieve grazing pressures. This has caused the butterfly population to recover, increasing the number by 90% between 2007 and 2016. The paper also reports on a very successful nature conservation project in southern Belgium as part of a LIFE + project funded by the European Union. Driveways and clearings have been enlarged, and moist grasslands have been restored or created to increase the area of suitable habitat. In total, the project contributed to the restoration of over 600 hectares of habitat. After just three to four years, the number of target species (Marsh Fritillary, Large Copper, and Violet Copper) increased, and several other threatened butterflies colonized or increased, including Pearl Fritillary, Heath Fritillary, Dark Green Fritillary, and Purple-Edged Copper.
Dr. Nigel Bourn, chief scientist
The Decline of Butterflies in Europe: Problems, Significance, and Possible Solutions. (2021) Warren, MS, Maes, D., van Swaay, CAM, Goffart, P., Van Dyck, H., Bourn, NAD, Wynhoff, I., Hoare, D. and Ellis, S., Proceedings of the National Academy of Sciences, 118, e2002551117 ..