Restricted-area culls and red fox abundance: Are effects a matter of time and place?

Predators are often culled to benefit prey, but in many cases this conservation goal is not achieved or results remain unknown. The red fox (Vulpes vulpes) is a predator of global significance, and an invasive species in some regions. Red fox culls intended to benefit prey are often restricted to small areas, and effectiveness is rarely sufficiently evaluated. Given the economic, ecological, social, and welfare issues associated with lethal predator control, there is a strong need to assess the effects of spatiotemporal variation in culling intensity on red fox abundance. We surveyed red fox populations in fragmented forests of south-western Germany and related indices of local fox abundance to culling data, predicted landscape-scale fox abundance, and other covariates. We tested whether restricted-area culling was associated with local reductions in fox abundance, and examined how this relationship changed over time. Local fox abundance was temporarily reduced in spring, following winter culls. However, the effect was minor and fox populations had compensated for the reductions at the latest by autumn. Restricted-area culling therefore likely failed to sustain effects on fox abundance throughout the period most relevant for conservation (i.e., the reproductive period of the target prey species). To be effective as a conservation tool, culling will therefore require explicit spatiotemporal coordination matching the biology of predators and target prey.