Organic management and landscape heterogeneity combine to sustain multifunctional bird communities in European vineyards

Conserving functionally diverse bird communities in European farmland is becoming critical, with no exception for regions of wine production. Management intensification combined with the loss of semi-natural habitats in wine-growing landscapes has led to a long-term decline not only in birds of conservation concern but also in once common insectivores and seed eaters. These declines are expected not only to threaten key ecological services provided by vineyard birds, such as pest or weed control, but also their cultural significance. We analysed how organic management and landscape heterogeneity affected taxonomic and functional diversity of 334 bird communities from 12 regions of the three main wine-producing European countries (France, Italy and Spain). We further modelled the responses of community-level metrics measuring mean habitat specialization and bird song attractiveness to humans, as well as cumulative abundances of functional insectivores, seed and grape eaters to account for individual avian functions. We found that organic viticulture enhanced bird functional diversity and individual functions, but that its positive effect partially depended on grass cover management in the inter-rows and landscape heterogeneity. Woodland cover and landscape compositional heterogeneity increased both taxonomic and functional diversity of bird communities, as well as functional insectivory. Landscape configurational heterogeneity also increased functional diversity and mean song attractiveness of bird communities. Overall, both bird diversity and functions were enhanced by higher landscape heterogeneity, especially in organic vineyards. However, mean habitat specialization decreased with woodland cover and configurational heterogeneity, meaning that open habitat specialists preferred more even landscapes with high vineyard cover. Synthesis and applications. Our study highlights the benefits of combining organic management and partial grass cover at the field level and promoting interfaces between vineyards and semi-natural habitats at the landscape level to sustain multifunctional bird communities in wine-producing European countries.