Temporal refuges differ between human and natural top-down pressures in
a subordinate carnivore
Abstract
Animals exhibit variation in their space and time use across an
urban-rural gradient. As the top-down influences of apex predators wane
due to human-driven declines, landscape level anthropogenic pressures
are rising. Human impacts can be analogous to apex predators in that
humans can drive increased mortality in both prey species and
carnivores, and impact communities through indirect fear effects and
food subsidies. Here, we evaluate the time use of a common mesocarnivore
across an urban rural gradient, and test whether it is influenced by the
intensity of use of a larger carnivore. Using multiple camera-trap
surveys, we compared the temporal response of a small carnivore, the
raccoon (Procyon lotor), to the larger coyote (Canis latrans) at four
sites across Michigan that represented a gradient of pressure from
humans. We found that raccoon time use varied by site and was most
unique at the rural extreme. Raccoons consistently did not shift their
activity pattern in response to coyotes at the site with the highest
anthropogenic pressures despite considerable interannual variation, and
instead showed the stronger responses to coyotes at more rural sites.
Temporal shifts were characterized by raccoons being more diurnal in
areas of high coyote activity. We conclude that raccoons do partition
time to avoid coyotes. Our results highlight that the variation in
raccoon time use across the entirety of the urban-rural gradient needed
to be considered, as anthropogenic pressures may dominate and obscure
the dynamics of this interaction. In an increasingly anthropocentric
world, to understand species interactions, it is imperative that we
consider the entire spectrum of human pressures that it may occur
within.