To know how they are doing they must be counted, and in Europe they are counted by skilled volunteers. For birds, observers stand at a point or walk a fixed route in the breeding season and record every individual. For butterflies, they walk a transect between two hundred metres and three kilometres long, several times a year, and count those passing through an imaginary box five metres ahead and above them and two and a half metres to each side. The data flow into two continental schemes, the Pan-European Common Bird Monitoring Scheme and the European Butterfly Monitoring Scheme.
Stanislas Rigal, of the French institute INRAE in Montpellier, and thirty-five other authors, among them Mattia Brambilla of the University of Milan, took the counts from 2000 to 2021. For birds that means 15,731 sites in 27 countries and more than six million annual abundance measures, from which the 265 most frequent species out of 450 were chosen. For butterflies it means 4,959 transects in 15 countries, with 144 species out of 318. Italy is among the bird countries, with a few hundred sites. It is not among the butterfly countries.

The authors linked each species’ trend to spring climate, land use and the intensity of land use, measured in one-kilometre cells around each site. The results are not simple. High-intensity farming weighs negatively on 123 bird species and positively on 99, while low-intensity farming disfavours 91 and favours 132. More trees go with fewer birds for 130 of 223 species, and the balance is worse among farmland species. For butterflies a warmer spring has so far been unfavourable to 83 of 135 species, and a more varied landscape has favoured 95.
They then projected everything to 2050 under an intermediate climate scenario that brings global temperature to about two degrees warmer by mid-century. The reference scenario extends past trends and adds climate. The second is the so-called green road among the socio-economic pathways used by the IPCC, the most environment-minded of those in use. The other three come from the Nature Futures framework of IPBES, the intergovernmental platform on biodiversity, and add targets close to Europe’s own. They foresee protected areas on thirty percent of the land, a one percent yearly increase in natural areas between 2030 and 2050, a thirty percent cut in synthetic nitrogen fertiliser and three billion trees planted in towns and less intensively farmed countryside.

In all five scenarios the average decline of common birds and butterflies goes on, neither stopping nor reversing. The three scenarios with more conservation slow the fall of common birds, and farmland birds above all, compared with the green road alone. For butterflies, of the three, only the scenario called Nature as Culture improves on the reference, thanks to a more varied landscape. The trend of grassland butterflies does not change under any of the three.
The past trend is already heavy. On the study’s main figure the farmland bird index falls by more than a third over the first two decades of the century and the grassland butterfly index halves. Forest birds, by contrast, increase, because Europe’s forests are spreading.

The authors explain why policy is not enough. In the scenarios, apart from the nitrogen cut, the farming model stays as it is today, and the share of intensively farmed land grows in all of them. The share of intensively managed forest rises too, even in the greenest scenarios. The green road alone, which spares land by concentrating production, would remove about a third of Europe’s grasslands by 2050. And field abandonment, with scrub closing over meadows, appears among the causes of the past decline alongside intensification.
There are two paradoxes. The first concerns the forest, which grows and rewards forest birds but goes with the decline of farmland birds. The second concerns protected areas, which help most farmland birds while woodland butterflies do worse inside them than outside. The authors attribute this to canopy closure when less timber is cut, since most butterflies live in open spaces within the forest.
The benefit, where it exists, is not evenly spread. Western and northern Europe gain most, though farmland birds there have already fallen far after decades of decline. In eastern Europe, where the decline sharpened with the farming changes brought by the Common Agricultural Policy, the improvement is hard to see. In southern Europe the authors expect declines or weaker increases for farmland and forest birds, as low-intensity farming and forestry give way to more productive methods. On the regional maps Italy belongs to this southern Europe. Forest birds, which grew across almost the whole peninsula, do slightly worse under the scenarios with more conservation than without.

The work has limits that the authors state. The links found are correlations, supported by known mechanisms but not proven as causes. The climate of 2050 may leave the range observed over the past twenty years, and the estimates say which scenario is better rather than how large the decline will be. The confidence intervals of the trends are wide and in several cases include zero.
The authors’ conclusion goes beyond birds. Every scenario used takes for granted a growing demand for food, energy and raw materials. If not even the greenest road, reinforced by conservation targets, halts the decline of common species, different frameworks are needed, ones that question that demand, with more varied landscapes and another farming model.
For Italy a gap remains. Its common birds are counted. Its butterflies, for this study, are not.

For each driver, how many common species showed a negative or positive response between 2000 and 2021, combining significant and non-significant estimates. More low-intensity farming favours most birds, more trees disfavour most of them, a warmer spring weighs on butterflies. ScienceOnline chart from data in Rigal et al., arXiv preprint 2509.18227v2, 2026, section 2.2.

References
Rigal S., Lenormand M., Tardieu L. et al., «Predicted decline in common bird and butterfly species even under conservation policy scenarios in Europe», Nature Ecology & Evolution 10: 1694–1708, 2026. doi:10.1038/s41559-026-03139-6
Rigal S. et al., «Predicted decline in common bird and butterfly species despite conservation policy scenarios in Europe», preprint arXiv 2509.18227, version 2, 2026. arxiv.org/abs/2509.18227
Rigal S., script and data produced, Zenodo, 2026. doi:10.5281/zenodo.20605816
BioAgora, «Predicted decline in common bird and butterfly species despite conservation policy scenarios in Europe», press release, 25 August 2026. bioagora.eu