Abstract:
While constrained by endogenous rhythms, morphology and ecology, animals may still exhibit flexible activity patterns in
response to risk. Temporal avoidance of interspecific aggression can enable access to resources without spatial exclusion.
Apex predators, including humans, can affect mesopredator activity patterns. Human context might also modify temporal
interactions between predators. We explored activity patterns, nocturnality and the effects of human activity upon a guild of
carnivores (grey wolf, Canis lupus; Eurasian lynx, Lynx lynx; red fox, Vulpes vulpes) using travel routes in Plitvice Lakes
National Park, Croatia. Humans were diurnal, foxes nocturnal and large carnivores active during the night, immediately after
sunrise and before sunset. Carnivore activity patterns overlapped greatly and to a similar extent for all pairings. Activity curves
followed expectations based on interspecific killing, with activity peaks coinciding where body size differences were small (wolf
and lynx) but not when they were intermediate (foxes to large carnivores). Carnivore activity, particularly fox, overlapped much
less with that of diurnal humans. Foxes responded to higher large carnivore activity by being more nocturnal. Low light levels
likely provide safer conditions by reducing the visual detectability of mesopredators. The nocturnal effect of large carnivores was
however moderated and reduced by human activity. This could perhaps be due to temporal shielding or interference with risk
cues. Subtle temporal avoidance and nocturnality may enable mesopredators to cope with interspecific aggression at shared
spatial resources. Higher human activity moderated the effects of top-down temporal suppression which could consequently
affect the trophic interactions of mesopredators.
