Insectivore diet and abundance determine the contribution of bird species to services and disservices in an agricultural ecosystem.

This article investigates the trade-off between ecosystem services and disservices provided by insectivorous birds in cider apple orchards in northern Spain, focusing on their diets and potential for pest control. Using DNA-metabarcoding of fecal samples from 26 bird species, the study assessed birds’ trophic positions and agronomic quality—defined as the balance between consumption of apple pests versus natural enemies of those pests. Results showed that bird species with higher insectivory and trophic positions tended to consume more natural enemies than pests, indicating potential disservices through intraguild predation. However, the overall contribution to pest control was largely driven by the abundance and insectivory degree of common bird species rather than by species-specific diet quality, suggesting that a few dominant species primarily sustain pest control services in these agroecosystems. The findings highlight the importance of conserving abundant, mixed-diet bird species and managing orchard habitats to support their populations for effective biological pest control.