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Predicting multi-predator risk to elk (Cervus canadensis) using scats: Are migrant elk exposed to different predation risk?
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  • Kara MacAulay,
  • Eric Spilker,
  • Jodi Berg,
  • Mark Hebblewhite,
  • Evelyn Merrill
Kara MacAulay
University of Alberta
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Eric Spilker
University of Alberta
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Jodi Berg
University of Alberta
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Mark Hebblewhite
University of Montana Missoula
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Evelyn Merrill
University of Alberta
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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.

Peer review status:UNDER REVIEW

11 May 2021Submitted to Ecology and Evolution
11 May 2021Assigned to Editor
11 May 2021Submission Checks Completed
12 May 2021Reviewer(s) Assigned
18 Jun 2021Review(s) Completed, Editorial Evaluation Pending