Semi-natural habitat surrounding farms promotes multifunctionality in avian ecosystem services

Abstract

Farmland birds can suppress insect pests, but may also consume beneficial insects, damage crops and potentially carry foodborne pathogens. As bird communities shift in response to farming practices, so too do the benefits (services) and costs (disservices) from birds. Understanding how and why ecosystem services and disservices covary can inform management interventions that enhance synergies, avoid trade-offs and promote multifunctionality. We investigated how farmland diversification practices influence the services and disservices provided by wild birds on 21 California strawberry farms. Specifically, we coupled 285 bird surveys, metabarcoding and other molecular analyses of ~1,000 faecal samples representing 55 bird species (mostly passerines) to determine which individuals consumed pests, natural enemies, and crops and carried foodborne pathogens. Then, we explored how farming practices shape ecosystem service bundles, or suites of consistently co-occurring services/disservices. Avian services and disservices were shaped by interactions between local farming practices and landscape context. We found that the amount of semi-natural habitat surrounding each farm was the single most important driver of ecosystem services, with the best outcomes (highest multifunctionality) occurring on farms surrounded by semi-natural habitat. Bundles were primarily influenced by landscape context. Increasing semi-natural habitat around farms was associated with more multifunctional bird communities that maximized services and minimized disservices. However, not all trade-offs were minimized in landscapes with more semi-natural habitat, suggesting that specific farming contexts can exacerbate or mitigate trade-offs as bird communities shift in response to diversification practices. Synthesis and applications. Though growers are often pressured to remove non-crop habitat to reduce food-safety risks, our work suggests that conserving habitat can support bird conservation, mitigate food-safety risks and decrease crop damage from birds. More broadly, by considering the multiple roles that communities play in ecosystems, managers can simultaneously maximize services and minimize disservices to achieve multifunctionality.