Metropolitan Observatory butterflies mBMS has released its fourth final report and its findings have informed many of Barcelona’s metropolitan parks. The study tracks seven butterfly species native to natural and mature habitats, some of which are declining in Catalonia. It is the result of a volunteer team of 67 people who visit metropolitan parks and beaches every two weeks for four years, gathering observations and data.
These butterflies inhabit their typical natural environments, so sightings are scarce. The researchers emphasize that the few individuals found require time and persistence to document. The team from CREAF led by Joan Pino, director and professor of Ecology at Universitat Autònoma de Barcelona, notes that new species are likely to be recorded in coming years.
The flowering meadows are working
The findings reinforce the Barcelona Metropolitan Region strategy to support flowering meadows. These are areas where mowing is minimal, irrigation is avoided, and herbicides and phytosanitary products are not used. The results show that parks with flowering meadows sustain butterfly populations at levels similar to naturalized herbaceous areas found around the parks. Jordi Bordanove, coordinator of Park and Beach Management Services for AMB, explains that the effect is visible around the parks as well.
Barcelona’s city parks attract prominent butterflies
Metropolitan flowering meadows provide nectar for adults and hosts for egg laying. To increase opportunities to observe more species, the civic science project supported by the ECB in collaboration with partner organizations expanded participation in 2023 from 26 locations to 31. This expansion invites the public to join the effort and broadens knowledge of these bioindicator insects.
Seven unique species
Volunteer-led butterfly studies have revealed several distinctive species. Among those associated with typical Mediterranean forests and naturalized riparian forests are the dawn butterfly Anthocharis cardamines, the Spanish flag Anthocharis euphenoids, the Mediterranean nymph Limenitis reducta, and a white butterfly with green veins Pyrex nappe. Others linked to natural grasslands include the Iberian medioluto Melanargia laxasis, the medlar Coenonympha pamphylus, and the black evening Coenonympha dorus. The team notes that the presence of the last two species is expanding within Catalan territory, a finding of particular interest to conservationists.
The report also summarizes the 2022 season results. A total of 8,437 butterflies across 40 species were observed in the studied parks and beaches, representing about 20 percent of the butterfly species recorded in Catalonia. The dominant metropolitan species tend to be generalists with caterpillars that feed on a wide range of plants and high dispersal capacity, capable of thriving in both natural and landscaped environments. These traits are essential for sustaining butterfly populations in urban parks surrounding the city.
The data underscore the need to promote and maintain metropolitan green infrastructure. The director of IERMB’s Ecology and Regional Department highlights the role of green spaces not only for environmental goods and services but also for biodiversity conservation and monitoring the effects of global change, a perspective shared by the scientific co-director of mBMS.
A team of 67 volunteers
All data for mBMS come from volunteers who are eager to learn, participate, and contribute to knowledge. The volunteer community now spans thirty metropolitan parks and beaches, with teams venturing out every two weeks to explore their assigned sites.
The work is valued for its scientific contribution and personal benefits. Volunteers follow the Butterfly Tracing Chart protocol, widely used in many countries, and receive training to recognize butterflies and record observations during spring, summer, and parts of autumn.
The 2023 expansion added five new sites Ermita Park Castellbisbal, Nou Park El Prat de Llobregat, Can Buxeres Park Hospitalet de Llobregat, Sant Adrià Beach Sant Adrià de Besòs, and La Solana Park Sant Andreu de la Boat. This brings the total to 31 locations, including 26 parks and 5 beaches. Metropolitan areas often sit between dense urban fabrics and large natural areas, harboring rich biodiversity and offering socio-environmental value. They also contribute to ecological connections across the region and support the movement of native fauna into cities.
The project focuses on diurnal butterflies, which provide valuable information for assessing and improving biodiversity across habitats, including metropolitan zones. To expand knowledge about these biomarker insects, volunteers are invited to train and commit to watching butterflies in their preferred park or beach. Those interested should complete the registration form on the project website at mbms.creaf.cat.
International outreach and ongoing learning continue as the effort grows and adapts to new environments. The environmental department remains open to collaboration and ongoing citizen science engagement as a practical way to monitor biodiversity in urban-adjacent landscapes.
Citations: information summarized from CREAF, AMB, and IERMB program reports and official project communications.