Socio-ecological indicators for effective monitoring of trophic rewilding with medium/large herbivores

Herbivores play a crucial role in ecosystem functioning, modulating resources availability by altering the physical state of biotic and/or abiotic components. The reintroduction or restocking of medium and/or large herbivores in areas from which they have disappeared is increasingly seen as a key tool to restore ecosystem processes. Often referred to as trophic rewilding, these initiatives aim to reverse biodiversity loss, restore ecosystem structure and re-establish trophic interactions. However, trophic rewilding remains a controversial concept due to concerns about its ecological sustainability, potential unintended effects, and variable social acceptance. While limited evidence exists to support its effectiveness at local scales, further empirical research is needed to address these uncertainties. This study employs an integrative review of existing frameworks and case studies to propose a comprehensive approach for monitoring trophic rewilding projects. Indicators were grouped into three categories —population trends, rewilding progress, and rewilding impacts—balancing ecological and socio-economic dimensions. These indicators are designed to ensure transparency, repeatability, and adaptability, enabling the evaluation of ecosystem changes over time relative to a pre-intervention reference status. Additionally, they incorporate measures of local community perception and attitudes, providing essential insights into social acceptance. The implementation of a robust monitoring program, as outlined here, could mitigate controversies surrounding trophic rewilding by generating critical data to assess long-term effectiveness and addressing potential disputes. This approach offers a practical path toward fostering better understanding and acceptance of trophic rewilding, while supporting adaptive management and the restoration of ecosystem integrity.