Positive effect of power line mitigation on reintroduced red kite ( Milvus milvus ) population in southern Spain

Abstract Electrocution is one of the main causes of unnatural mortality among European raptors and poses a significant threat to vulnerable species such as the red kite ( Milvus milvus ). This study assessed the combined effects of mitigation measures on hazardous power line infrastructure and the red kite reintroduction programme aimed at restoring its breeding population in Jaén (Andalusia, southern Spain), where it had previously become extinct as a breeding species in the early 2000s. Between 2021 and 2025, 186 individuals were released following habitat suitability assessment, of whom 181 were fitted with GPS transmitters to monitor survival and spatial ecology. In parallel, a high-risk power line previously associated with elevated raptor mortality was retrofitted with anti-electrocution devices across 48 pylons located within the release area of the tagged red kites. A total of 80 mortality events of monitored red kites were recorded during the study, of which 72 were assigned a cause. Natural mortality accounted for 54.2%, with predation as the dominant factor (n = 34). Anthropogenic causes represented 45.8%, mainly poisoning (n = 9) and electrocution (n = 8). Notably, 21 reintroduced individuals used the mitigated power line area, generating 802 GPS fixes, with no recorded mortality associated with these structures, indicating effective reduction of electrocution risk. Population recovery was rapid, transitioning from complete absence to three breeding pairs in 2023, six in 2024, thirteen in 2025, and twenty-two in 2026. These findings demonstrate that integrating targeted infrastructure mitigation with reinforcement-based reintroduction can substantially improve survival rates and accelerate population recovery, highlighting an effective conservation strategy for raptors in human-modified environments.