Outfoxing the fox: Effect of prey odor on fox behavior in a pastoral landscape

Invasive mammalian predators have had a devastating effect on native species globally. The European red fox (Vulpes vulpes) is one such species where it has been introduced in Australia. A novel but unexplored tactic to reduce the impact of mammalian predators is the use of unrewarded prey odors to undermine the effectiveness of olfactory hunting behavior. To test the viability of unrewarded prey odors in an applied setting we investigated how foxes responded to the odors of three different prey species. We used the odors of two locally extinct native Australian marsupials; the eastern quoll (a smaller carnivore) and eastern bettong (a fungivore), and the European rabbit, an introduced herbivore. Conducting our research over a period of 3 weeks in a pastoral environment in South-eastern Australia, we used video observations of foxes' behaviors, as they encountered the different odors. We found a reduction in the number of fox visits to bettong odors in the third week. In contrast, we observed a sustained number of visits to rabbit odors. Foxes also spent more time investigating rabbit odors and displayed longer durations of vigilance behavior at quoll odors. Our results support the hypothesis that the exposure of wild foxes to unrewarded odors of novel prey species can reduce their interest in these odors, which might translate to a reduction in predation pressure. Our results also suggest, however, that olfactory pre-exposure may not be as effective at reducing fox interest in a competitor species' odor.