Barcelona has identified a new butterfly species, the Callophrys avis, also known as the verdeta d'ull ros in Catalan, for the first time. The finding was made weeks ago in the city's Laberint d'Horta Park as part of Barcelona's urban butterfly monitoring programme, uBMS, according to the City Council.
This observation brings the total number of diurnal butterfly species recorded in Barcelona to 52. This figure represents about 26% of all species present in Catalonia. The Callophrys avis is a univoltine species, meaning it has only one generation per year, and flies exclusively from March to May.
This specialist butterfly relies heavily on two specific plants: the strawberry tree (Arbutus unedo) and the myrtle-leaved coriaria (Coriaria myrtifolia). Diurnal butterflies, including the Callophrys avis, are considered excellent bioindicators of environmental quality due to their sensitivity to changes in vegetation, climate, and ecological conditions. This sensitivity provides valuable information about the state of urban biodiversity.
Urban Butterflies and Environmental Health
During their larval stage, these species depend exclusively on a small number of plants. If these plants disappear or decrease, butterfly populations also decline rapidly. Butterflies also respond very sensitively to the effects of climate change. Beyond their ecological value, butterflies play a critical role in urban ecosystems as primary consumers and as a food source for many predators and parasitoids.
They also help connect citizens with urban nature, thanks to their easy identification and high educational and aesthetic value. The discovery was made possible by the volunteer network of the uBMS (urban Butterfly Monitoring Scheme) Citizen Urban Butterfly Observatory. This project is coordinated by the CREAF ecological research centre and has operated in the city since 2018, under an agreement with the Barcelona Municipal Institute of Parks and Gardens.
Currently, about 40 volunteers actively participate in weekly butterfly monitoring across 29 parks and gardens in the city. Between March and November, visual censuses are carried out to collect data on the presence and abundance of different species. In addition to the uBMS observatory's monitoring, Barcelona also participates in the Catalan Butterfly Monitoring Scheme (CBMS), promoted by the Granollers Museum of Natural Sciences, which conducts monitoring along two routes in Montjuïc and El Carmel.
Monitoring and Conservation Efforts
The main goal of butterfly monitoring programmes is to obtain data on species presence and abundance over time. This helps understand the diversity of species in the city, analyse population trends, identify urban factors that favour or limit biodiversity, develop ecological management tools, and create indicators of urban biodiversity quality.
Accumulated data shows that, despite an increase in the number of species detected, the five most common species currently account for 64% of all observations. This pattern indicates a community primarily composed of generalist species better adapted to urban environments. Barcelona is promoting various naturalisation strategies aimed at favouring species with more specific ecological requirements.
Key actions include implementing urban meadows and grasslands, low-intensity forest management in natural areas such as Montjuïc, Els Tres Turons, Collserola, and the Sèquia Comtal, and creating biodiversity refuges. These measures aim to improve ecological connectivity, increase habitat quality, and balance the abundance of different species present in the city.
Climate Impact and Future Outlook
Monitoring data has also shown the direct impact of climatic and management factors on butterfly populations. In 2020, coinciding with the lockdown and reduced intervention in green spaces, along with rainier weather conditions, a notable increase in butterfly abundance was recorded in the city. However, the prolonged drought between 2021 and 2023 caused a significant decrease in observed populations. Data from 2024 onwards shows a progressive recovery.
All individuals interested in butterflies who wish to join the uBMS observatory's volunteer network can find more information on the project's website.
