Evaluating the summer landscapes of predation risk and forage quality for elk (Cervus canadensis)

Abstract

The recovery of carnivore populations in North American has consequences for trophic interactions and population dynamics of prey. In addition to direct effects on prey populations through killing, predators can influence prey behavior by imposing the risk of predation. The mechanisms through which patterns of space use by predators are linked to behavioral response by prey and nonconsumptive effects on prey population dynamics are poorly understood. Our goal was to characterize population‐ and individual‐level patterns of resource selection by elk ( Cervus canadensis ) in response to risk of wolves ( Canis lupus ) and mountain lions ( Puma concolor ) and evaluate potential nonconsumptive effects of these behavioral patterns. We tested the hypothesis that individual elk risk‐avoidance behavior during summer would result in exposure to lower‐quality forage and reduced body fat and pregnancy rates. First, we evaluated individuals' second‐order and third‐order resource selection with a used‐available sampling design. At the population level, we found evidence for a positive relationship between second‐ and third‐order selection and forage, and an interaction between forage quality and mountain lion risk such that the relative probability of use at low mountain lion risk increased with forage quality but decreased at high risk at both orders of selection. We found no evidence of a population‐level trade‐off between forage quality and wolf risk. However, we found substantial among‐individual heterogeneity in resource selection patterns such that population‐level patterns were potentially misleading. We found no evidence that the diversity of individual resource selection patterns varied predictably with available resources, or that patterns of individual risk‐related resource selection translated into biologically meaningful changes in body fat or pregnancy rates. Our work highlights the importance of evaluating individual responses to predation risk and predator hunting technique when assessing responses to predators and suggests nonconsumptive effects are not operating at a population scale in this system.

Autumn resource selection by female elk in a recently burned landscape in western Montana

“…Thus, elk movements out of areas with increasing snowpack was likely a traditional movement towards winter range, where forage resources were more available. Backcountry rifle model diagnostics suggested a lack of fit, which we attribute to strong inter-individual variation in selection patterns (Paterson et al 2022) and temporal variation in elk selection during that period. Elk began moving from summer and autumn range in the high-elevation mountains to winter range in the valley during the backcountry rifle period (Figure 7), so there was considerable intra-individual variation in selection patterns throughout the period.…”

Multiscale influences on Elk (Cervus canadensis) calving site selection across a fragmented Appalachian landscape

“…Future work should assess the effectiveness of management actions aimed at improving Elk calving habitat in Kentucky, focusing on both spatial and demographic responses to habitat manipulation. We caution that context-dependent effects such as functional responses (Mysterud and Ims 1998) and individual responses to forage and risk (Heffelfinger et al 2020;Paterson et al 2022)…”

“…Future work should assess the effectiveness of management actions aimed at improving Elk calving habitat in Kentucky, focusing on both spatial and demographic responses to habitat manipulation. We caution that context-dependent effects such as functional responses (Mysterud and Ims 1998) and individual responses to forage and risk (Heffelfinger et al 2020; Paterson et al 2022) may mediate variations in calving habitat selection patterns in different parts of the KERZ and recommend managers gain an understanding of how parturient cows behave locally to better inform habitat management in these diverse landscapes, and in other eastern regions where Elk have been recently reintroduced.…”

Behavioral trade‐offs and multitasking by elk in relation to predation risk from Mexican gray wolves

“…To gain a more holistic picture regarding how elk navigate NCEs from predators with different hunting strategies (including humans) and behavioral changes of mothers due to predation risk for calves, future studies could include multi‐predator risk indices (Atwood et al., 2009 ; Eacker et al., 2016 ; Makin et al., 2017 ). Lastly, including all diel periods (i.e., night) and covariates related to individual personalities and nutritional condition could be important for future studies as these time periods/factors likely play an important role in how prey respond to and potentially mitigate the indirect effects of predators (Paterson et al., 2022 ).…”