Abstract:
Where direct killing is rare and niche overlap low, sympatric carnivores may appear to coexist without conflict. Interference
interactions, harassment and injury from larger carnivores may still pose a risk to smaller mesopredators. Foraging theory
suggests that animals should adjust their behaviour accordingly to optimise foraging efficiency and overall fitness, trading off
harvest rate with costs to fitness. The foraging behaviour of red foxes, Vulpes vulpes, was studied with automated cameras
and a repeated measures giving-up density (GUD) experiment where olfactory risk cues were manipulated. In Plitvice Lakes
National Park, Croatia, red foxes increased GUDs by 34% and quitting harvest rates by 29% in response to wolf urine. In
addition to leaving more food behind, foxes also responded to wolf urine by spending less time visiting food patches each
day and altering their behaviour in order to compensate for the increased risk when foraging from patches. Thus, red foxes
utilised olfaction to assess risk and experienced foraging costs due to the presence of a cue from gray wolves, Canis lupus.
This study identifies behavioural mechanisms which may enable competing predators to coexist, and highlights the potential
for additional ecosystem service pathways arising from the behaviour of large carnivores. Given the vulnerability of large
carnivores to anthropogenic disturbance, a growing human population and intensifying resource consumption, it becomes
increasingly important to understand ecological processes so that land can be managed appropriately.
