The evidence base for ranger patrol effectiveness in conservation and how to improve it

Abstract

Ranger patrols are a cornerstone of wildlife protection efforts around the world and occur across all ecological governance systems. Evidence that patrols reduce threats to wildlife and enable their recovery has not been systematically examined previously. Without evidence of patrol effectiveness in varying contexts, protected area managers risk wasting limited conservation resources and lack information required to improve the effectiveness of patrols. We conducted a meta-analysis evaluating the effectiveness of terrestrial patrols for conserving African, Asian, and Latin American wildlife directly threatened by exploitation. After filtering 57 studies, we calculated effect sizes from each of the remaining 15 studies that included a comparator and measurement of wildlife abundance and calculated standardised mean difference and % change in wildlife species abundance. Results suggest tentative support that areas implementing patrols (alongside other interventions) were associated with higher wildlife abundance levels compared to time periods or locations without patrols. We were unable to confirm causality between patrols and changes in wildlife population abundance because studies were inadequately designed to evaluate and report on effectiveness. Studies commonly lacked a comparator or counterfactual event, temporal or spatial replication, and consistent and/or long-term monitoring of population abundance, and had study designs that confounded conservation actions. Further, of the 15 included studies linking wildlife abundance to patrol efforts, five also reported a reduction in a poaching threat, but only three of these used a comparator in the threat reduction evaluation. Without monitoring threat trends alongside wildlife abundance, it is difficult to be confident that patrols resulted in increases in wildlife abundance. To help evaluate patrol interventions (i.e. not only whether they work but where and under what conditions they work), we identify opportunities to improve future patrol effectiveness research and provide recommendations on how to improve the evidence base.