Reaching under the wings of birds in the agricultural landscape

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A characteristic breeding bird of the agricultural landscape: the yellowhammer.
A characteristic breeding bird of the agricultural landscape: the yellowhammer. Its populations are declining, but it benefits from a small-scale, diverse agricultural landscape. Photo: Hans Glader

Research team shows links between agricultural landscape structure and bird populations


The intensification of agriculture has its price: it makes landscapes structurally more uniform and thus contributes to the decline in biodiversity. How should agricultural landscapes be designed in order to promote biodiversity? A new study by researchers from the University of Göttingen, the Dachverband Deutscher Avifaunisten (DDA) e. V. and the Thünen Institute contributes to current discussions on this question. The results clearly show that a small-scale, diverse agricultural landscape is necessary to protect farmland birds. The size of the fields and the diversity of the crops are important factors here. However, one-size-fits-all solutions are not enough: According to the researchers, more attention needs to be paid to the proportion of copses and hedges and the species’ demands on their habitat. The results were published in the Journal of Applied Ecology.

The researchers linked data from the monitoring of common breeding birds for the years 2017 to 2019 with detailed maps of agricultural areas and crops derived from satellite data. For more than 800 areas in Germany, they determined the proportion of copses and hedges, the size of the fields and the diversity of crops and correlated the data with the diversity and abundance of farmland birds such as yellowhammer, lapwing and linnet.

Contrary to what is often assumed, smaller fields and a greater variety of crops do not always lead to greater diversity or abundance of farmland birds, according to the study. Instead, these relationships are significantly influenced by the proportion of copses and hedges in the landscape and the species’ habitat requirements. Claudia Frank, PhD student at the University of Göttingen and DDA employee, emphasizes: -The results illustrate the complexity of the relationships between agricultural management and bird diversity. Smaller fields can promote the occurrence of farmland birds, especially where hedges and copses are lacking in the landscape. A greater diversity of crops, on the other hand, has a more positive effect on farmland birds if many woody structures are already present.

Near-natural habitats are therefore an important component of agri-environmental measures, as Dr. Sebastian Klimek from the Thünen Institute of Biodiversity emphasizes: -The proportion of near-natural habitats in the landscape should be taken into account when developing and implementing measures to reduce the size of fields and increase the diversity of crops. Dr. Norbert Röder from the Thünen Institute for Living Conditions in Rural Areas adds: -It is currently not so easy to implement these new results in support measures, but they should be promoted more strongly in the future.

A distinction must also be made between species groups when designing effective measures: birds that breed on the edges of fields can be encouraged by smaller fields and a high diversity of crops. For species that breed in the fields, this is not necessarily the case, as Frank explains: -field breeders such as skylark and lapwing are exposed to direct cultivation practices in the field. Additional measures that reduce the intensity of cultivation are therefore essential for field breeders.

Original publication:
Claudia Frank, Lionel Hertzog, Sebastian Klimek, Marcel Schwieder, Gideon Okpoti Tetteh, Hannah GS Böhner, Norbert Röder, Christian Levers, Jakob Katzenberger, Holger Kreft, Johannes Kamp. Woody semi-natural habitats modulate the effects of field size and functional crop diversity on farmland birds. Journal of Applied Ecology (2024). DOI: 10.1111/1365-2664.14604