Nest density, nest-site selection, and breeding success of birds in vineyards: Management implications for conservation in a highly intensive farming system

Increasing intensification in vineyards has detrimental effects on biodiversity. Although several studies addressed this topic, the reproductive outcomes of model organisms in vineyards received little attention. We carrie d out the first study on birds nesting in natural nests on vines, focusing on nest density, breeding performance and nest-site selection in organic and conventional systems and in two contrasting trellising systems, pergola (taller, with more spaced rows and a denser canopy) vs. spalliera. We surveyed 228 nests of six species and analysed nest densities and final fates as a function of vineyard management and trellising system by means of GLM(M)s. 51% of nests were abandoned before egg-laying and the probability of early abandonment was positively related to the amount of access farmers had for management activities. The number of nests was four times higher in pergola than in spalliera vineyards, likely due to pergola's complex and tree-like structure. Organic or conventional management did not affect nest density, probably due to reduced differences in terms of management practices between them. Breeding success was low and marginally affected by the interaction of the management and trellising systems, being higher in conventional pergola. Nests were preferentially built on larger vines and were placed at an increasing height on the vine as the season progressed. Nests built at greater heights had greater success. We provide some management recommendations for bird conservation in vineyards: promoting pergola and maintaining older vineyards, limiting grass mowing in April and May, and in compatibility with agricultural management, optimising the amount of farmers' access to vineyards.