Organic farming favours bird communities and their resilience to climate change in Mediterranean vineyards

Abstract

Farmland birds have suffered notable declines in Europe in recent decades, mainly due to agricultural intensification and climate change. Organic farming, which has been shown to enhance biodiversity, is increasingly being put into practice in European vineyards. Nevertheless, no previous studies have reported significant positive responses in avian communities to organic practices. On the other hand, cover cropping is a common practice in both organic and conventional vineyards and is thought to have positive effects on bird communities and, particularly, on insectivorous species that may help control pests in agroecosystems. In this work, we studied bird communities in Mediterranean vineyards in Catalonia (NE Iberian Peninsula) in both the breeding and wintering seasons, and tested the effects of two common management options – organic vs. conventional farming and herbaceous cover vs. bare soil – on bird communities. In particular, we focused on (a) insectivorous birds that may help control pests and (b) avian species negatively affected by climatic warming whose population fluctuations may reflect the resilience of these bird communities to future climate change. Organic farming had a positive effect on vineyard bird communities and, specifically, increased species richness and overall bird abundance. This farming technique also positively affected the abundance of both insectivorous species and species whose populations are declining due to climate change. The presence of inter-row herbaceous cover between vines also had positive effects on bird community parameters, specifically in spring and in organic vineyards, when herbaceous cover favours species richness and the abundance of insectivorous species. However, further investigations are still needed to better understand the effects of different types of vegetation cover - i.e. plant origin and composition (e.g. sown vs. spontaneous vegetation) and proportion of vegetation cover (full vs. partial vegetation cover) - when employed as tools in wildlife conservation. This work provides useful information regarding bird conservation, which will help mitigate the effects of climate change on bird populations.