Research: Fear of large carnivores causes a trophic cascade

Raincoast researcher publishes Gulf Island study on the role of fear in maintaining healthy ecosystems

A pair of raccoons in the dark sit in a tree.


Suraci, J.P., M. Clinchy, L.M. Dill, D. Roberts and L.Y. Zanette. 2016. Fear of large carnivores causes a trophic cascade. Nature communications, 7

Download the paper:  Suraci et al 2016 -Fear of large carnivores- Nature Comm


The fear large carnivores inspire, independent of their direct killing of prey, may itself cause

cascading effects down food webs potentially critical for conserving ecosystem function,

particularly by affecting large herbivores and mesocarnivores. However, the evidence of this

has been repeatedly challenged because it remains experimentally untested. Here we

show that experimentally manipulating fear itself in free-living mesocarnivore (raccoon)

populations using month-long playbacks of large carnivore vocalizations caused just such

cascading effects, reducing mesocarnivore foraging to the benefit of the mesocarnivore’s

prey, which in turn affected a competitor and prey of the mesocarnivore’s prey. We further

report that by experimentally restoring the fear of large carnivores in our study system, where

most large carnivores have been extirpated, we succeeded in reversing this mesocarnivore’s

impacts. We suggest that our results reinforce the need to conserve large carnivores given

the significant ‘‘ecosystem service’’ the fear of them provides.

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