still increase in the area of intensive monoculture primarily responsible drop bird populations Europe has suffered in the last 40 years. Specifically, they have been reduced by 25% on average, but in the case of farmland native species the reduction is close to 60%.
According to a study recently published in the journal PNAS, bird populations in each country declined differently depending on the characteristics of their farming practices. For example, western European regions, Where crop areas are often large and pesticide use is high, they are among the hardest hit compared to eastern countries where these practices are not very consolidated.
Another special case is Mediterranean basinwhere the characteristic relief of the terrain makes it possible, at least in certain areas, to preserve a mosaic agricultural landscape with vegetable and stone margins and crops combined with natural habitats. “This has helped reduce bird loss,” explains Sergi Herrando, a researcher at CREAF, the Catalan Institute of Ornithology (ICO), and the European Bird Census Council, one of the paper’s authors.
According to research, With the intensification of agriculture, the use of fertilizers and pesticides has increased.Products that destroy insects and other invertebrates from the soil are a staple food for many birds, “especially during the breeding season when chicks need a lot of protein,” says Lluís Brotons, a CSIC researcher and co-author at CREAF. .
These products also pollute the seeds. and if birds ingest them, toxic substances can accumulate in their bodies and even cause their death.
Extensive landscapes with no plant diversity
On the other hand, monocultures produce homogeneous landscapes. The diversity in the vegetation disappears so that the birds cannot feed on their own. look for plants and various fruits or shelter.
The authors warn that this doesn’t just affect the types of typical breeding grounds. common skylark or yellow buntingThis also applies to other species that go to crops to feed themselves. Among them, Brotons points out, those who have a diet based on invertebrates, such as ordinary swallows or long-distance migrants such as doves, are “the majority of ordinary birds, in short.”
The study analyzed 170 common bird species observed in more than 20,000 locations in 28 European countries over 37 years. According to Stanislas Rigal, a researcher at the University of Montpellier and lead author of the paper, “the results leave no doubt, this is not a local problem, but the harmful effects of large crops, fertilizers and pesticides are spreading all over Europe. We need to accelerate the regulation of agricultural practices. and implementing more sustainable models”.
Climate change, second cause of decline
The research also analyzed the weight of climate change, urbanization and changes in forest landscape on species decline. The results point to climate change as the second cause of the decline, after agricultural intensification. temperature rise In recent years this has meant the loss of 40% of cold endemic bird populations and 18% of warm habitats.
“This difference is probably due to the fact that characteristic birds of high latitudes and altitudes are less adapted to the heat,” explains Herrando.
On the other hand, urbanization positioned as the third factor: “There is less green space and more buildings in cities” and bird populations in urban areas have decreased by 28%. Finally, typical forest birds decreased by about 18%; forest cover in Europe in recent years. According to the authors, this is explained by the lower quality of new forests, that is, the loss of centuries-old trees and the simplification of fauna and flora.
“The four human pressures we describe in the article are collectively already a 25% reduction of all birds in Europewith. The descent continues. To stop this, we need transformative changes in European societies. new political agreements such as European Restoration Law The issues being discussed in the European Parliament can help push them forward, Brotons says.
Reference work: https://doi.org/10.1073/pnas.2216573120
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