Non-lethal methods to reduce predation can help mitigate conflicts with wildlife. This study evaluated the effectiveness of a chemical repellent (capsaicin) combined with an odour (vanilla) in reducing bait consumption by predators, using red foxes (Vulpes vulpes) as a model species. The aim of this pilot study was to determine whether foxes could associate the odour with the repellent through a learned aversion process. Baits were distributed across eight baiting points (four treatment and four control) in two separate zones. The experiment included four phases: pre-repellency (baits without repellent at all points), repellency (capsaicin and vanilla at treatment points), post-repellency (only vanilla at treatment points), and post-repellency-rotation (treatment and control points switched, vanilla maintained at new treatment points). To assess effectiveness, the study compared (1) bait consumption between treatment and control points across phases using Kaplan–Meier survival analysis and generalized linear models, and (2) the time taken by foxes to consume the bait and the frequency of spice-related behavioral responses using generalized linear mixed models and the Cochran–Mantel–Haenszel test. Overall, bait consumption did not differ significantly between treatments or phases. However, foxes took significantly longer to consume baits at treatment points during the repellency, post-repellency, and post-repellency-rotation phases. Additionally, spice-related responses were observed not only during the repellency phase but also in later phases when only vanilla was present. These findings could be used to develop strategies for wildlife management (i.e., crops, livestock, endangered species), which would increase safety and reduce the cost of implementation compared to other conditioned food aversion applications.
Río et al. (Sat,) studied this question.