A recent study shows that millions of birds have disappeared from the European continent over the last forty years. The decline is estimated at 25% since the 1980s, corresponding to the disappearance of around 800 million birds.
This trend had already been highlighted by previous studies, and one of the reasons put forward was the pressure exerted by human activities on bird populations, although some of the effects of this pressure were difficult to explain.
To gain a better understanding of this dynamic, a team of scientists led by researchers from France’s National Center for Scientific Research (CNRS) analyzed 37 years of data collected on 170 different bird species living at 20,000 sites in 28 European countries.
The analysis of this data, published on the PNAS website in May 2023, confirmed that birds are suffering from urbanization and changes in forest cover. The study also highlighted two main causes of bird extinction: rising temperatures and intensive agriculture. The data show that birds preferring colder temperatures are particularly affected by the decline in their population, which reaches 40% compared to 18% for bird populations preferring warmer temperatures.
The biggest decline is in agricultural birds, whose population has fallen by more than 50%, mainly due to the intensive use of fertilizers and pesticides, which disrupt the food chain of insectivorous birds, the ones most affected by the decline. In France, for example, the surface area devoted to intensive agriculture is one of the largest in Europe and has risen sharply in recent years.
At the same time, temperatures have risen by around 1 ˚C between 1996 and 2016, and forest cover is below the European average, while the artificial surface area is above average. The population of farmland birds has thus fallen by 43% and that of forest birds by 19%, while the population of birds living in urban areas has increased by 9%. In detail, some bird species are more threatened than others, with declines of up to 75%, such as the European sparrow or the meadow sparrow.
The researchers consider this trend in bird populations to be symptomatic of the long-term trend in environmental degradation. They draw attention to the central role that birds play in the overall ecosystem, helping to regulate other species, disseminate seeds and provide food for larger predators. To avoid further destabilizing this ecosystem, the researchers believe it is essential to reconsider our food production methods.
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