Leveraging passive acoustic monitoring for result-based agri-environmental schemes: Opportunities, challenges and next steps

Despite over three decades of agri-environmental schemes (AES) in Europe, farmland biodiversity continues to decline. Most AES are action-based, compensating farmers for implementing biodiversity-friendly management practices. In contrast, result-based payments (RBP) are AES that reward farmers for achieving specific biodiversity targets, making them a promising alternative for farmland species conservation. RBP have largely focused on vascular plants due to the difficulty and expense of monitoring elusive or mobile species. Passive Acoustic Monitoring (PAM) offers new opportunities for low-cost, standardised monitoring of soniferous animals’ occurrence, activity and diversity. This study conceptually explores the integration of PAM as a novel monitoring approach within RBP. Using established RBP design frameworks, we examine key considerations for employing PAM in future RBP. We identify appropriate biodiversity targets at species and ecological community levels as well as indicators that effectively represent these targets. We further assess how the use of PAM affects the costs associated with RBP, with a focus on expenses for monitoring. Farmer acceptance is key to the success of AES, so we discuss farmers’ willingness to adopt PAM technology and their perspectives on using ecological communities as targets in RBP. Finally, we propose pathways to implement PAM-based RBP pilot projects, emphasising collaboration with farmers and authorities, and provide an example for the whinchat as a target species. Such pilots can test the feasibility of integrating PAM in practical settings while addressing challenges identified in this study at the conceptual level, such as cost, technical implementation, and farmer engagement.