General results

Since the beginning of the project, 3,720,184 butterflies belonging to 193 species have been recorded. In 2025, 180 species were detected in the CBMS network and 264,685 butterflies were counted, a 12% increase compared to 2024. In this section, you will find the main results regarding local trends, regional trends, recent changes, and multi-species indicators, updated to 2025. For more information on how each of these metrics is calculated, see the data analysis section.

Local trends

Currently, 15,036 butterfly populations (species–transect combinations) are recorded within the CBMS network, of which 8,008 have sufficiently long time series to estimate local trends. Of these, 899 are in decline (11%), 423 are increasing (5.3%), 3,565 are stable (44.5%), and 258 (3.2%) have undergone local extinction. The remaining populations are considered occasional at the transects where they occur. The figure also shows the five species with the highest number of populations in each category.

Regional trends

In 2025, trends were calculated for a total of 159 species. Overall, 80 species (51%) show moderate or strong declines, 12 (7%) show moderate or strong increases, 37 (22%) are stable, and 32 (20%) have uncertain trends. See species-level results and check the species factsheets to determine their population status. By climatic region, trends were estimated for 140 species in the alpine region, of which 45 (32%) are in moderate or strong decline and 15 (11%) are increasing. In the humid Mediterranean region, trends were calculated for 128 species, with 68 (53%) in decline and 11 (8.5%) increasing. In the arid Mediterranean region, trends were estimated for 59 species, 15 of which (25%) are declining, although 26 species (44%) still fall into the uncertain category. The Balearic Islands have their own regional trends due to their isolation and insular nature. Trends were calculated for 25 species: 9 (36%) are declining, 4 (16%) increasing, 4 (16%) stable, and 8 (32%) with uncertain trends.

Increasing populations The species with the highest annual population growth rate

Declining populations The species with the most negative annual population growth rate

Cumulative change

Cumulative changes in species abundance help quantify population increases and declines for species showing significant trends. A total of 80 species have experienced negative change, with a median of −54%. Among these, 62 species have seen their populations reduced by more than half, and 14 by more than 90% over the studied period. On the other hand, 12 species show positive change, of which 8 have increased their populations by more than 100%. In some cases, these changes vary across climatic regions for the same species.

Recent changes

The last decade

Trends over the past 10 years provide a snapshot of recent changes. During this period, 20 species (12.5%) have shown moderate or strong increases, while 57 species (36%) have declined. As expected, uncertainty is higher with the shorter 10-year time series, with 62 species (38%) included in this category. The remaining species are considered stable. Patterns vary across climatic regions. In the alpine region, 82 species (58%) show uncertain trends, 30 (21%) are declining, 19 (14%) increasing, and 9 (6%) stable. In the humid Mediterranean region, 42 species (33%) are uncertain, 52 (41%) declining, and 11 (8.5%) increasing. In the arid Mediterranean region, 35 species (59%) are uncertain and, unlike the other regions, more species are increasing (13, 22%) than declining (6, 10%).

Last year

In 2025, 180 species were recorded in the CBMS network and 264,685 butterflies were counted, a 12% increase compared to 2024. The change observed between 2024 and 2025 was positive for 82 species (49%) and negative for 84 (51%). In total, 16 species (10%) reached their lowest recorded levels in 2025. Patterns vary across climatic regions. In the alpine and subalpine region, 80 species (56%) increased and 63 (44%) declined. In the humid Mediterranean region, 54 species (41%) increased and 79 (59%) declined. In the arid Mediterranean region, out of 64 species, 36 (56%) increased, 26 (40%) declined, and two showed no change compared to the previous year.

Greatest increase The species with the highest population increase in 2024-2025

Greatest decrease The species with the greatest population decline in 2024-2025

Multispecies indicators

Overall abundance indicator and grassland and woodland indicators

The overall CBMS abundance indicator shows an average decline of 53% over the past 32 years, meaning that currently slightly less than half of the butterflies are being recorded compared to three decades ago. The indicator that weights regional trends according to each species’ habitat preference shows a 68% decline for the grassland indicator and a 21% decline for the woodland indicator.

Catalan Grassland Butterfly Indicator (C-GBI)

The Catalan grassland indicator is calculated using the aggregated trend of 16 of the 17 species included in the European Grassland Butterfly Indicator (GBI). This indicator, based only on data from Catalonia, shows a declining trend of 64%. The selected species span a range of habitat preferences that goes beyond grasslands (indicator range TAO = 0.16–0.80, mean = 0.59 ± 0.26). When the GBI is calculated weighting species by their habitat preference, the result is an 80% decline for the grassland indicator and a 31% decline for the woodland indicator.