Predicting multi-predator risk to elk (Cervus canadensis) using scats: Are migrant elk exposed to different predation risk?

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.

Industrial development alters wolf spatial distribution mediated by prey availability

“…Models including other prey species (moose and white‐tailed deer) in relation to block features were not as well supported, which is consistent with previous findings that mule deer and elk are preferred prey for wolves in the Rocky Mountains and foothills regions (Huggard, 1993; MacAulay, 2019; Wasser et al, 2011). Moose occur at a low frequency in wolf diets in Alberta's foothills (MacAulay, 2019; MacAulay et al, 2022), but white‐tailed deer are often a selected prey species. While it is possible that white‐tailed deer do not significantly mediate wolf occurrence on anthropogenic features, the relatively ubiquitous distribution of white‐tailed deer across the study area could have resulted in a limited ability to detect their influence on wolf occurrences.…”

“…Models including other prey species (moose and white‐tailed deer) in relation to block features were not as well supported, which is consistent with previous findings that mule deer and elk are preferred prey for wolves in the Rocky Mountains and foothills regions (Huggard, 1993; MacAulay, 2019; Wasser et al, 2011). Moose occur at a low frequency in wolf diets in Alberta's foothills (MacAulay, 2019; MacAulay et al, 2022), but white‐tailed deer are often a selected prey species.…”

“…Models including other prey species (moose and white-tailed deer) in relation to block features were not as well supported, which is consistent with previous findings that mule deer and elk are preferred prey for wolves in the Rocky Mountains and foothills regions (Huggard, 1993;MacAulay, 2019;Wasser et al, 2011).…”

“…Moose occur at a low frequency in wolf diets in Alberta's foothills (MacAulay, 2019;MacAulay et al, 2022), but white-tailed deer are often a selected prey species. While it is possible that white-tailed deer do not significantly mediate wolf occurrence on anthropogenic features, the relatively ubiquitous distribution of white-tailed deer across the study area could have resulted in a limited ability to detect their influence on wolf occurrences.…”

Beyond the encounter: Predicting multi‐predator risk to elk (Cervus canadensis) in summer using predator scats

“…Global Positioning System (GPS) data are available on the MOVEBANK data repository (associated with Movebank project ID 72264071; data repository https://doi.org/10.5441/001/1.k8s2g5v7, Hebblewhite & Merrill, 2016). Processed datasets used for the scat and kill site spatial analyses are available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.2ngf1vhpv, MacAulay et al, 2022).…”