Intensive agriculture causes decline in farmland bird diversity in Europe

Cereal-producing countryside of central Spain, where natural vegetation and fall
Cereal-producing countryside of central Spain, where natural vegetation and fallow land elements that favor the functional diversity of bird communities can still be seen / Eladio García de la Morena.

A study led by the Autonomous University of Madrid (UAM) has revealed how the intensification of agriculture is drastically altering the composition and functional diversity of bird communities in cereal agroecosystems in Europe. The research, which analyzes the impact at field and landscape level, reveals a predominance of smaller and shorter-lived bird species, with a reduction in the diversity of parental investment strategies and an increase in generalist species.

A European study, led by experts from the Autonomous University of Madrid (UAM), has shed light on the serious impact that agricultural intensification is having on farmland bird populations in Europe.

The results, published in Basic and Applied Ecology, highlight how intensification in agriculture not only reduces the taxonomic diversity of birds, but also significantly affects their functional diversity, an aspect so far little explored.

The study focused on cereal agroecosystems and examined the response of bird functional diversity to a gradient of agricultural intensification across Europe. Using literature information on life history traits of 30 bird species, the researchers calculated various indices of functional diversity and analyzed their relationship to agricultural intensification, both at the landscape scale and at the crop field level.

The results specifically revealed that greater intensification at the field level favors the assemblage of shorter-lived and smaller bird communities, in addition to decreasing overall trait diversity, including relative brain size.

This intensification also restricts the variety of parental investment strategies. Worryingly, an increase in generalist species, including some introduced or managed for hunting, was observed to the detriment of species typically adapted to croplands and grasslands, which are more associated with the provision of ecosystem services.

"Most studies emphasize the role of non-cultivated landscape elements in maintaining functional ecological communities in agricultural landscapes, but our study indicates, at the European scale, that what is done in each field profoundly influences the composition and functionality of these communities, which also affects the provision of ecosystem services," says co-author Irene Guerrero, a researcher at the EU Joint Research Centre in Ispra (Italy).

Manuel B. Morales, Professor of Ecology at the UAM and co-author of the study, warns: "The increasing intensification of management turns our agricultural landscapes into simplified ecosystems, integrated by impoverished and homogenized communities where the presence of exotic species may increase".

Finally, Juan Oņate, Professor of Ecology at the UAM and signatory of the paper, concludes that "only a less intensive agricultural management based on the ecological processes themselves would avoid reaching this point".

Bibliographic reference:

Guerrero, I.; Duque, D.; Oņate, J.J.; Pärt, T.; Bengtsson, J.; Tscharntke, T.; Liira, J.; Aavik, T.; Emmerson, M.; Berendse, F.; Ceryngier, P.; Weisser, W.W.; Morales, M.B. (2024). Agricultural intensification affects birds’ trait diversity across Europe. Basic and Applied Ecology, 74, 40-48.

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