Abstract
There is evidence that prey can perceive the risk of predation and alter
their behaviour in response, resulting in changes in spatial
distribution and potential fitness consequences. Previous approaches to
mapping predation risk quantify predator space use to estimate potential
predator-prey encounters, yet this approach does not account for
successful predator attacks resulting in prey mortality. An exception is
a prey kill-site, which reflects an encounter resulting in mortality,
but obtaining these data can be expensive and requires time to
accumulate adequate sample sizes. We illustrate an alternative approach
using predator scat locations and their contents to quantify spatial
predation risk for elk (Cervus canadensis) from multiple
predators in Alberta, Canada. We combined predictions of scat-based
resource selection functions for bears (Ursus arctos/U.
americanus), cougars (Puma concolor), coyotes (Canis
latrans), and wolves (C. lupus) based on scat-detection dog
surveys with predictions for the probability that a predator-specific
scat in a location contained elk. We evaluated our approach by comparing
predictions to a predation risk model developed from elk kill sites and
applied it to describing spatial patterns in predation risk that were
consistent with changes in the distribution of elk over the past decade.
We found a strong correlation between risk predicted by kill sites and
risk predicted by our approach (r = 0.98, P < 0.001). There
was a spatial pattern to predation risk, where elk that migrated east of
their winter range were exposed to highest risk from cougars,
non-migratory elk were exposed to high risk from wolves and bears, and
risk to elk that migrated west of their winter range into protected
areas was high only from bears. The patterns in predator risk were
consistent with changes in the migratory tactics in this population. The
scat-based approach we present permits broad-scale inferences on
predation risk for prey.