title: Fear of large carnivores causes a trophic cascade.
abstract: 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.
authors.affiliation: Department of Biology, University of Victoria, Victoria, British Columbia, Canada V8W 2Y2.|Raincoast Conservation Foundation, Sidney, British Columbia, Canada V8L 3Y3.|Department of Biology, University of Western Ontario, London, Ontario, Canada N6A 5B7.
authors.forename: Justin P
authors.initials: JP
authors.lastname: Suraci
authors.affiliation: Department of Biology, University of Western Ontario, London, Ontario, Canada N6A 5B7.
authors.forename: Michael
authors.initials: M
authors.lastname: Clinchy
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6.
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Dill
authors.affiliation: Department of Biology, University of Victoria, Victoria, British Columbia, Canada V8W 2Y2.
authors.forename: Devin
authors.initials: D
authors.lastname: Roberts
authors.affiliation: Department of Biology, University of Western Ontario, London, Ontario, Canada N6A 5B7.
authors.forename: Liana Y
authors.initials: LY
authors.lastname: Zanette
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D010872:Caniformia; D002335:Carnivora; D003163:Competitive Behavior; D004285:Dogs; D017753:Ecosystem; D005239:Fear; D020387:Food Chain; D011235:Predatory Behavior; D011821:Raccoons; D014828:Vocalization, Animal