The COVID-19 lockdown unmasked the overwhelming impact of human activity on the breeding success of an endangered raptor

Abstract

Understanding how human activities influence wildlife populations is crucial for the conservation of endangered species, yet assessing their demographic impacts remains challenging. This is partly because experimental approaches are seldom feasible in research on threatened wildlife, limiting our ability to effectively identify and manage key threats. Here, we capitalized on an unintentional pseudo-experiment—the 2020 COVID-19 lockdown—embedded within a 31-year monitoring program (1246 breeding attempts from 1994 to 2024) of the endangered Bonelli's eagle subpopulation of southeastern Spain to assess the effects of human activities on its reproductive success. We detected a significant increase in productivity during the lockdown, especially in territories traditionally subject to a higher number of human activities. Partridge hunting with calling lures and traffic—likely facilitating other recreational uses such as hiking and cycling—were identified as the most detrimental activities for breeding success. This study demonstrates how exceptional events, when analyzed within a long-term framework, can uncover the full extent of human disturbance on wildlife, thereby helping to identify priority actions for conservation. It also underscores the limitations of purely correlational studies and highlights the irreplaceable value of long-term monitoring for understanding and mitigating threats to endangered species.