Landscapes of nausea: Successful conditioned taste aversion in a wild red fox population

Predation by invasive mammalian species is one of the key drivers of native species' population declines and extinctions. Current management of invasive species focuses on their removal from the landscape. However, total removal can be difficult, costly and even impossible. If eradication is not achieved, reductions in predator numbers are often temporary. New tactics are needed to target predators in situ, to reduce their negative impacts. We test the efficacy of conditioned taste aversion (CTA), a tactic that could reduce the impact of predation on target prey species. By associating nausea with a specific food source, it may be possible to condition an aversion to a target bait, and ultimately to live animals in the wild. To assess if wild invasive red foxes (Vulpes vulpes) can be conditioned to avoid a specific food source, we used baits (fried deboned chicken) containing encapsulated levamisole, an anthelmintic agent known to induce nausea leading to emesis and/or diarrhea at high dosages with no long-term side effects. We buried baits at 30 stations across an open landscape. After treatment, reductions in control baits taken (at least 30%) were observed for 68 days, indicating the use of CTA had successfully reduced bait consumption by red foxes in a wild context. To our knowledge, this study represents the first successful test of CTA to a meat bait in a wild red fox population. Our results suggest that CTA shows promise as a tool to reduce the predation of vulnerable animals providing an alternative tactic to manage the impacts of invasive mammalian predators where eradication is currently impossible.