Proceedings of the Ninth Mountain Lion Workshop - Carnivore ...

Cougar-Induced Vigilance in Ungulate Prey: Does Predator Proximity
Matter?
David M. Choate, Department of Biological Sciences, University of Notre Dame, 107
Galvin Life Sciences, Notre Dame, IN 46556, USA, dchoate@nd.edu
Gary E. Belovsky, Department of Biological Sciences, University of Notre Dame, 107
Galvin Life Sciences, Notre Dame, IN 46556, USA, belovsky.1@nd.edu
Michael L. Wolfe, Department of Wildland Resources, Utah State University, 5230 Old
Main Hill, Logan, UT 84322-5230, USA, michael.wolfe@usu.edu
ABSTRACT Trading foraging time with increased vigilance is widely attributed to the
threat of predation. Numerous studies examining the relationship between vigilance and
other factors (e.g., prey’s herd size, habitat use) suggest that clear patterns are elusive and
that vigilance per se may be highly plastic. If vigilance is costly by reducing feeding
time, prey should reduce vigilance as the distance to a predator (or threat) increases,
resulting in a scaled response even within factors (e.g., specific habitat types). In this
study we used focal sampling of foraging bouts by 3 species of ungulates that differed in
body size and anti-predator defenses (elk, Cervus elaphus; mule deer, Odocoileus
hemionus; and white-tailed deer, O. virginianus), to determine whether proximity of a
stalking/ambush predator (cougar, Puma concolor) influences time spent vigilant while
foraging. For all 3 species males spent less time vigilant than females. There was no
evidence for a herd-size effect on vigilance for any species, but white-tails displayed a
significant decline in vigilance with increasing distance to cougars. Both deer species
responded to the presence of a cougar within the same drainage or “viewshed”, by
decreasing vigilance levels with increasing distance. When cougar were outside of the
viewshed, there was no longer a relationship between cougar proximity and vigilance
levels. Prey-specific anti-predator responses to cougar, a stalking predator, suggest that
generalizations of vigilance to other predator types (e.g., coursing predators) is
inappropriate, and that vigilance as a metric for determining population levels of
predation risk may be less appropriate for communities with low-density solitary felids
such as cougar, except at very small (i.e., within viewshed) temporal-spatial scales.
Proceedings of the Ninth Mountain Lion Workshop
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