Predicting multi-predator risk to elk (Cervus canadensis) using scats: Are migrant elk exposed to different predation risk?
KARA M. MacAULAY ̵̶ Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, CANADAhttps://orcid.org/0000-0003-1001-6906
ERIC G. SPILKER ̵̶ Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, CANADA
JODI E. BERG ̵̶ Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, CANADA https://orcid.org/ 0000-0003-0678-8137
MARK HEBBLEWHITE ̵̶ Wildlife Biology Program, Department of Ecosystem and Conservation Sciences, W. A. Franke College of Forestry and Conservation, University of Montana, Missoula, Montana 59812, USAhttps://orcid.org/0000-0001-5382-1361
EVELYN H. MERRILL ̵̶ Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, CANADAhttps://orcid.org/0000-0001-7737-958X
  1. ABSTRACT: There is growing 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 across a landscape quantify predator space use to estimate potential predator-prey encounters, yet this approach does not account for successful predator attack 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.
  2. 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 spatial predictions of scat-based resource selection functions (RSFs) for bears (Ursus arctos/U. americanus ), cougars (Puma concolor ), coyotes (Canis latrans ), and wolves (C. lupus ) based on surveys with scat-detection dogs with predictions for the probability that a predator-specific scat in a location contained elk. We evaluated our approach by comparing predictions to a model of predation risk 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.
  3. 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.
  4. The scat-based approach we present permits broad-scale inferences on predation risk for prey species that has advantages especially in multiple predator species.