Proceedings of the Seventh Mountain Lion Workshop

COUGAR-INDUCED INDIRECT EFFECTS: DOES THE RISK OF PREDATION
INFLUENCE UNUGULATE FORAGING BEHAVIOR ON THE NATIONAL BISON
RANGE?
DAVID M. CHOATE, Ph.D. candidate, Department of Biological Sciences, University of Notre
Dame, 107 Galvin Life Science Center, Notre Dame, IN 46556, USA; and, Department
of Forestry, Range & Wildlife, Utah State University, Logan, UT 84322, USA, email:
dchoate@nd.edu
GARY E. BELOVSKY, Professor, Department of Biological Sciences, University of Notre
Dame, 107 Galvin Life Science Center, Notre Dame, IN 46556, USA, email:
Gary.E.Belovsky.1@nd.edu
MICHAEL L. WOLFE, Professor, Department of Forestry, Range & Wildlife, Utah State
University, Logan, UT 84322, USA, email: mlwolfe@cc.usu.edu
Abstract: Ecologists have long debated whether predators (“top-down”) or nutrients/food
(“bottom-up”) limit prey populations. Evidence supporting the importance of predation is
frequently based on the number of prey killed by predators – a direct effect. By examining only
this direct effect many predation studies fail to consider behavioral changes arising from the risk
of predation - indirect effects. Furthermore, these behavioral indirect effects can be more
important than the direct effect of predator-caused mortality, influencing both top-down and
bottom-up processes. In this study we capitalize on a “natural experiment” on a suite of large
mammalian herbivores, in a system (National Bison Range, MT) where the behavior and
population dynamics of ungulate prey species (whitetail deer, Odocoileus virginianus; mule deer,
O. hemionus; elk, Cervus elaphus) can be compared before and after an increase in risk of
predation by cougar (Puma concolor). We present preliminary data demonstrating that cougars
can influence several aspects of prey behavior. With an increase in predation risk, mule deer and
elk total daily activity time has declined by 35.9% and 31.8% (P