Butterflies & Birds: Conservation Slows the Decline—but Is It Enough?

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Europe aims to protect more nature and restore damaged ecosystems. But even if key conservation targets are met, the populations of many bird and butterfly species that are still common today could continue to decline through 2050. A Nature Ecology & Evolution modeling study published in July 2026 reached this conclusion. In none of the future scenarios examined does the average decline of the species studied reverse.

That does not mean conservation is ineffective. The outlook improves especially for birds when conservation targets are given greater weight, with farmland birds benefiting the most. In the models, however, this is not enough to reverse the trend. For butterflies, the additional effect of the conservation measures is even smaller.

The findings of biodiversity researcher Stanislas Rigal and his research team therefore raise a fundamental question: Is it enough to protect more land and make land use more compatible with nature—or are more far-reaching changes also needed in agriculture, resource consumption, and landscape use?

The focus is not on rare species

For the study, the researchers did not focus primarily on highly threatened animals, but on 265 common bird species and 144 common butterfly species. This is important because even widespread species can lose large portions of their populations long before they are considered at immediate risk of extinction.

The study therefore does not investigate whether individual species will go extinct by 2050, but how the populations of species that are still common today might develop under different future scenarios. A projected decline is therefore not a prediction of extinction.

Data from more than 20,000 sites across Europe

The study is based on long-term data from two European monitoring programs. For birds, the researchers analyzed observations from 15,731 sites in 27 European countries collected by the Pan-European Common Bird Monitoring Scheme. The butterfly data came from the European Butterfly Monitoring Scheme and comprised 4,959 transects in 15 countries. Overall, the data span the period from 2000 to 2021.

The researchers investigated how population trends for individual species were related to changes in climate, land use, and land-use intensity. The factors considered included temperature and precipitation, the proportions of agricultural land and forest, landscape diversity, protected areas, and the intensity of agricultural and forestry use.

They combined these relationships with various scenarios for how climate and land use in Europe might develop through 2050. This allowed them to model how populations might develop under different future conditions.

Five possible paths into the future

The current study compared five future scenarios for its projections:

1. Business as usual: Current trends in land use and land-use intensity continue largely unchanged.
2. SSP1 (“Taking the Green Road”): A more sustainable development pathway with a stronger focus on environmental and climate protection.
3. Nature for Nature: Protecting biodiversity is the central priority.
4. Nature for Society: Nature is protected primarily because of the benefits it provides to people, such as climate regulation.
5. Nature as Culture: Human use and conservation are to be more closely integrated, for example through diverse cultural landscapes and more nature-friendly land use.

The last three scenarios are based on the Nature Futures Framework of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) and were previously developed for Europe in an earlier study (Dou et al., 2023).

Farmland birds benefit from greater conservation efforts

The differences between the individual scenarios are particularly pronounced for birds of agricultural landscapes. This group of species has been among the losers of the transformation of Europe’s landscapes for decades. In Germany, too, typical farmland birds such as the northern lapwing, grey partridge, and whinchat are declining sharply in many places. Major causes include the intensification of agriculture, the loss of structurally diverse habitats, and the use of pesticides. A recent study from France, for example, found that common bird species were generally less abundant in regions with greater pesticide use.

The data from 2000 to 2021 analyzed for the current study also show a negative population trend across Europe for numerous farmland birds. It is particularly pronounced for the northern lapwing (Vanellus vanellus), whinchat (Saxicola rubetra), and European turtle-dove (Streptopelia turtur). The Eurasian skylark (Alauda arvensis) also declined; for this species, a larger proportion of low-intensity agricultural land was associated with a more favorable population trend.

In the future models, farmland birds clearly benefit from the scenarios that give greater weight to conservation targets. Less intensive land use, more diverse landscapes, and more land available for nature can improve their trajectory. However, this is not enough to reverse the trend: Even in the more favorable scenarios, the average population trend for farmland birds remains negative through 2050. The decline is therefore slowed, but not stopped.

Forest birds—an important exception

Forest birds fare considerably better in the models than farmland birds. Their combined population index already rose during the observation period and remains comparatively positive in the future scenarios. One possible explanation is the increase in forest area in parts of Europe.

However, not all species automatically benefit. Increasing forest cover can even mean habitat loss for birds of open landscapes. The findings thus show that landscape changes can have very different effects depending on the group of species.

Butterflies benefit less from the conservation scenarios

While the future trends for birds improve markedly under the conservation-oriented scenarios, the researchers find only small additional effects for butterflies. In addition to an overall butterfly index, grassland and forest species were considered separately. Overall, the future scenarios differ much less here than they do for birds. On average, there is still no reversal of the trend through 2050; particularly for grassland butterflies, the measures examined are not sufficient to stop the decline.

This does not mean that measures to protect butterflies are ineffective. Rather, the models suggest that the proposed changes are not sufficient to substantially reduce key pressures. Climate change also plays a role. At the same time, butterflies are sensitive to the structure and use of their habitats.

A predominantly agricultural landscape can be large-scale and uniform, or it can consist of a mosaic of meadows, field margins, hedgerows, and fallow land. Such differences can be crucial for many butterflies. A protected status alone therefore does not guarantee suitable habitat.

The overall negative trend also masks very different trajectories among individual species. The small tortoiseshell (Aglais urticae) showed a negative population trend across Europe between 2000 and 2021; in the model, greater fluctuations in spring temperatures were associated with a less favorable trajectory. By contrast, the trend for the meadow brown (Maniola jurtina), one of the species in the European Grassland Butterfly Indicator, was nearly stable.

Other common species even showed positive trends over the same period, including the common brimstone (Gonepteryx rhamni) and small white (Pieris rapae). The negative overall trend therefore does not mean that every individual species studied is declining.

More protected areas do not solve every problem

Many biodiversity strategies aim to better protect land or restore damaged habitats. But common species in particular do not live only in protected areas; they also live on cropland, in grasslands, in forests, and in other managed landscapes. What happens there can be just as crucial for their populations.

Although the conservation scenarios examined improve numerous conditions for nature, they do not fundamentally change Europe’s land-use and economic system. The researchers therefore point out that more far-reaching changes may be needed to reverse the trend—such as less intensive agriculture, more diverse landscapes, lower resource consumption, and more effective climate action.

The study does not determine which combination of such changes would be sufficient. But it shows that even comparatively nature-friendly future scenarios do not automatically lead to a recovery of common bird and butterfly populations.

What the study cannot predict

The future projections are based on how bird and butterfly populations responded to changes in climate, land use, and land-use intensity in the past, namely between 2000 and 2021. These relationships are extrapolated to possible developments through 2050. Ecosystems are complex, however: Species can adapt, shift their ranges, or respond differently to environmental changes in the future.

In addition, only factors for which sufficient data were available at the European level could be considered. The results should therefore not be understood as an exact prediction for the year 2050. The comparison between scenarios is more informative: Under which conditions do populations fare better—and which measures are unlikely to be sufficient to reverse the trend?

The combined population indices must not be applied to every individual species, either. A negative average can include declining species as well as stable or increasing ones. In addition, a population decline says nothing about whether a species faces an immediate risk of extinction.

Conservation must go further

The study’s findings are not an argument against conservation. On the contrary, especially for farmland birds, the models show that more ambitious conservation measures can substantially slow the decline. But a slower decline is not yet a recovery.

If even future scenarios with additional conservation measures do not produce an average upward trend for common birds and butterflies, this suggests that biodiversity conservation cannot remain limited to individual protected areas or isolated measures. What matters is the entire landscape in which the species live.

A Eurasian skylark benefits only to a limited extent from a new protected area if conditions in the rest of the agricultural landscape continue to deteriorate. The same applies to butterflies, which need suitable plants, diverse structures, and appropriate climatic conditions.

The study shows: Conservation measures can make a major difference, but to bring about a lasting reversal of the trend, they may need to be combined with more far-reaching changes in land use, agriculture, resource consumption, and climate action.

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Sources

• Dou, Y., Zagaria, C., O’Connor, L., Thuiller, W., & Verburg, P. H. (2023). Using the Nature Futures Framework as a lens for developing plural land use scenarios for Europe for 2050. Global Environmental Change, 83, 102766.https://doi.org/10.1016/j.gloenvcha.2023.102766
• Rigal, S., Lenormand, M., Tardieu, L., et al. (2026). Predicted decline in common bird and butterfly species even under conservation policy scenarios in Europe. Nature Ecology & Evolution.https://doi.org/10.1038/s41559-026-03139-6
• Rigal, S., Lenormand, M., Tardieu, L., et al. (2026). Predicted decline in common bird and butterfly species despite conservation policy scenarios in Europe [Preprint]. arXiv.https://doi.org/10.48550/arXiv.2509.18227