Spatio-temporal dynamics of attacks around deaths of wolves: A statistical assessment of lethal control efficiency in France
Résumé
Evaluating the efficiency of lethal control of large carnivores such as wolves to reduce attacks on livestock is important given the controversy surrounding this measure. We used retrospective data over 10 years and an intra-site comparison approach to evaluate the effects of lethal control on the distribution of attack intensities in the French Alps. We analyzed 278 legal killings of wolves between 2011 and 2020 and the 6110 attacks that occurred during a period of ± 90 days and within 10 km around these lethal removals. This large number of attacks allowed us to perform an original framework that combined both continuous spatial and temporal scales through 3D kernel estimation. We also controlled the analysis for livestock presence, and explored different analysis subsets of removals in relation to their locations, dates and proximity to other removals. This statistical method provided an efficient visualization of attack intensity spatio-temporal distribution before and after removals. A decrease of the intensity of attacks was the most common result after the lethal removals of wolves. However, this outcome was not systematic for all subsets and depended on the scale of the analysis. In addition, attacks tended to persist after removals while showing frequent interruptions in time after but also before removals. We also observed localized positive trends of attack intensities at varying distances from removals after they occurred. To summarize, our results showed that considering the scale of the analysis is crucial and that effects should be analyzed separately for each local context. As a next step, we recommend to move forward from patterns to mechanisms by linking the effects of lethal control on wolves to their effects on attacks through analysis of fine-scaled data on wolves and livestock.
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