Europe 1 with AFP / Photo credit: KLAUS-DIETMAR GABBERT / DPA / DPA PICTURE-ALLIANCE VIA AFP 22:29 p.m., May 15, 2023

While birds in Europe are declining, with an average of 20 million disappearing each year, researchers blame agricultural intensification as the main cause. To do this, they used a dataset unprecedented in its scope with 37 years of observations from 20,000 ecological monitoring sites in 28 European countries, for 170 species.

Agricultural intensification is the main cause of a dramatic decline in Europe's birds, with an average of some 20 million disappearing each year, researchers concluded in a paper published Monday, after amassing an unprecedented amount of data. Many European scientists, who publish in the American journal PNAS (Proceedings of the National Academy of Sciences), have collaborated to find out which human activities are responsible for the decline of European bird populations. To do this, they used a dataset unprecedented in its scope: 37 years of observations from 20,000 ecological monitoring sites in 28 European countries, for 170 species.

800 million birds

"There has been a one-quarter decline in species abundance since 1980," Vincent Devictor, a CNRS researcher and coordinator of the study, told AFP. "In other words, 800 million individuals in 40 years, or 20 million per year, so a systemic, profound decline in European avifauna," says the expert. Some ecosystems are more severely affected than others: the number of forest birds has decreased by 18%, a drop of 28% for urban birds and even 57% for birds in agricultural areas. "We conclude that agricultural intensification, particularly the use of pesticides and fertilizers, represents the main pressure for most bird population declines, particularly those that feed on invertebrates," the scientists write their paper.

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These invertebrates represent "an important part of the diet for many birds during at least some stages of their development," point out the authors. They are thus crucial for 143 species among the 170 studied during the breeding season. For example, a reduction in available food will have a negative effect on reproductive success by changing the behaviour of parents and affecting the survival of the chicks. The decline is marked in species such as the grey flycatcher (-63%) or the famous house sparrow (-64%).

Changing the model of agriculture

To stop this collapse, we would have to start by changing the model of agriculture. But "we continue to be in an industrial vision of the agricultural world", associating massive recourse to mechanization and chemistry, regrets Vincent Devictor. "We are still not out of this paradigm of the post-Second World War," says the researcher, citing the increase of megafarms in France to the detriment of small areas. In addition to agriculture, other factors related to human activity are also affecting bird populations, starting with climate change. Logically, it hits hard species preferring cold (40% decline), such as the boreal, but does not spare either heat-loving species (18% decline).

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Finally, the progression of urbanization also makes victims among swifts or swallows. "We are creating territories that are increasingly hostile, including the interior of the urban environment," says Vincent Devictor, who worked with two colleagues based in France, PhD student Stanislas Rigal and Vasilis Dakos of the CNRS. "Species liked to nest in crevices, to be in places where there are still insects in urban areas. With the modes of concretization today, coupled with the disappearance of insects, it becomes hostile even for them," he says.