Flying vertebrates provide valuable biocontrol services in olive grove landscapes of the Mediterranean

• The economic value of biocontrol services provided by birds and bats in olive groves remains poorly quantified. • Experimental exclusion of birds and bats significantly increases Bactrocera oleae infestation. • Extrapolation from olive-dominated landscapes in Portugal indicates that vertebrate-mediated biocontrol may represent a substantial economic contribution to the European olive sector. • Biocontrol services have the potential to support conservation and management of insectivorous birds and bats in olive agroecosystems. Olive ( Olea europaea var. europaea ) grove landscapes dominate much of Mediterranean Europe, yet increasing agricultural intensification has raised concerns about biodiversity loss and its consequences for sustainable production. Insectivorous birds and bats are widely recognized as effective pest controllers in agricultural systems; however, the economic value of their biocontrol services in olive production remains poorly quantified, limiting their integration into biodiversity-friendly management strategies. Here, we conducted a two-year exclosure experiment to evaluate the contribution of birds and bats to the control of a major olive pest, the olive fruit fly Bactrocera oleae , and to estimate the economic value of vertebrate-mediated biocontrol across two contrasting production systems (i.e., low- and high-intensity systems). Biocontrol effectiveness was quantified as the proportional increase in fly infestation in the absence of birds and bats, while economic value was estimated as the corresponding reduction in olive oil profits under elevated pest pressure. Birds and bats reduced fly infestation in olive groves across production systems, with maximum reductions of approximately 14%. Assuming this estimate from olive groves in Portugal, and the number of hectares of harvested cropland across Mediterranean Europe, we estimate the value of their biocontrol services to the olive industry is roughly €642.79 million per year, considering only price gains associated with reduced fly infestation in produced extra virgin olive oil. Even under spatial constraints and conservative assumptions, we provide the first experimental evidence that birds and bats can act as effective biocontrol agents against B. oleae, and deliver economically valuable biocontrol services to olive industry. Our results highlight the usefulness of biocontrol services provision as an argument to support the integration of biodiversity management into agricultural practices and policy frameworks.