2023-05-31 09:30:33
The number of birds fell by an average of 25% between 1980 and 2016 on the European continent, reveals a new study. Intensive agriculture, in particular the use of pesticides and fertilizers, is the main associated pressure.
In 37 years, from 1980 to 2016, the number of birds has fallen by 25% on the European continent, calculates a new study published in the revue PNAS (Proceedings of the National Academy of Sciences). The figures are dizzying: every year, 20 million birds disappear from one year to the next. This study, conducted by the University of Montpellier and having involved a large European scientific collaboration, nevertheless underlines a certain variability according to the ecosystems. If the fall only affects 18% of forest birds, it affects 28% of urban birds, but 57% for species in agricultural environments.
Thanks to a large dataset covering 20,000 ecological monitoring sites in 28 European countries, for 170 different bird species, the researchers were able to prioritize the major pressures leading to these disappearances. Result: intensive agriculture is the main factor leading to this disappearance. ” We find that the intensification of agriculture, in particular the use of pesticides and fertilizers, is the main pressure for the decline of most bird populations, especially those that feed on invertebrates. “, underline the authors in this study. They thus point to the scarcity of insects due to the use of synthetic chemistry.
Varying pressures depending on the species
For the other pressures, the responses to the changes vary more specifically according to the species. “ Forest cover is associated with a positive effect and increasing urbanization with a negative effect on population dynamics, while temperature change has an effect on the dynamics of a large number of bird populations, including the magnitude and direction depend on thermal preferences of species “, specify the authors. In particular, the global increase in temperatures is responsible for 40% of the decline of species preferring cold temperatures, but also for 18% of species preferring hot weather.
In France specifically, the number of agricultural and forest birds has decreased by 43% and 19% respectively, while the number of birds nesting in urban areas has increased by 9%. Some species are particularly impacted by these developments. For example, tree sparrow, meadow stonechat and meadow pipit populations have declined by approximately 75%.
While birds are involved in fundamental interactions, their disappearance jeopardizes all ecosystems. Their role is indeed essential in the predation and regulation of other species, the dissemination of seeds, but also the resources for other predatory species, recalls the study.
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