University of Tübingen: Perennial fallow land provides the best protection for field birds
Fallow land effectively protects field birds – but only if they have existed for at least two years. This is the result of a study by Julia Staggenborg and Nils Anthes from the Institute for Evolution and Ecology at the University of Tübingen. The study, which evaluates a total of 143 previous research papers, is one of the most extensive studies in Europe to date on species protection of farmland birds in agriculture.
In the past forty years, the populations of farmland birds in Europe have fallen by an average of 56 percent, and in the case of individual bird species such as the partridge by as much as 90 percent. Grain eaters such as tree sparrows or yellowhammers can no longer find enough food because when harvesting with modern machines hardly any grain grains are left on the fields. Pesticides and land consolidation have displaced wild herbs and unused habitats such as verges, embankments or grass paths, which are not necessary for agricultural production but are vital for insects and the rearing of young birds.
From January 1, 2023, the next five-year agricultural support period will begin in the EU. According to EU law, farmers then have to reserve four percent of their fields and meadows for the preservation of biodiversity and only receive financial support if they meet this condition. This so-called conditionality is new in EU agricultural policy. “The regulation is a great opportunity for species protection,” says Staggenborg, “but these areas should then also be reserved for measures that, according to scientific knowledge, are actually effective in preserving biodiversity.”
How the areas for species protection have to be treated in detail is regulated by the member states themselves within the framework of a national “strategic plan”. In its draft, which is currently being voted on by the EU Commission, the Federal Government calls for existing fallow land to last a maximum of one and a half years. Farmers in Germany can reduce the period to less than a year through exemptions. “Many insects cannot complete their reproductive cycle in this short time from summer to the following spring and then the breeding birds do not have enough food,” says Nils Anthes. The new research results confirm that farmland birds benefit much more from perennial fallow land than from just annual ones.
The draft of the strategic plan obliges farmers to temporarily set aside land, but allows the greening of fallow land with species-poor mixed seeds, for example clover and mustard, or with “flowering mixtures” containing many non-native plants such as sunflowers, phacelia, dill or Persian clover. Their tall and dense growth suppresses weeds and is therefore popular with farmers. “However, it is much more effective for preserving biodiversity to simply let wild weeds sprout,” says Nils Anthes. “These native plant species are needed by many of our insects and offer ideal breeding grounds for field birds.” Wild growth would result in a diverse coexistence of grasses, flowering herbs or areas that remained completely free. So birds would have enough food, shelter and nesting areas.
In addition to being left fallow for several years, farmland birds can be protected if farmers only mow their meadows late in the year, as the researchers show in their study. Or leave a strip of grain when harvesting, as required by law in Britain, so farmland birds have enough to eat through the winter.