Spatiotemporal risk avoidance varies seasonally, relative to risk intensity, in a reestablishing predator-prey system Ecological Monographs

Cara J Thompson¹Nicole M Tatman²Zachary J Farley¹Scott T Boyle³Allison R Greenleaf⁴James Cain^5*

• ¹Department of Fish, Wildlife, and Conservation Ecology, New Mexico State University, Las Cruces, New Mexico, United States
• ²New Mexico Department of Game and Fish, Santa Fe, New Mexico, United States
• ³Department of Biology, College of Arts and Sciences, New Mexico State University, Las Cruces, New Mexico, United States
• ⁴U.S. Fish and Wildlife Service, Southwest Regional Headquarters,, Albuquerque, United States
• ⁵USGS, New Mexico Cooperative Fish and Wildlife Research Unit, Las Cruces, New Mexico, United States

Predation establishes risk, which can indirectly influence prey behavior and ecology. We evaluated the influence of Mexican gray wolves (Canis lupus baileyi) on habitat selection and spatiotemporal predator avoidance strategies of elk (Cervus canadensis). We fit 866 adult female elk with GPS collars across areas of varying wolf densities within the Mexican wolf experimental population area of eastern Arizona and western New Mexico between 2019−2021. Using step-selection functions we examined relative intensity of elk use in relation to landscape attributes, estimated predator/prey diel activity, and measures of risk. Risk metrics included predicted wolf presence, habitat openness, and predicted risky places modeled from attributes of locations where wolves killed elk. Wolf activity varied across seasons and increased midday and night in fall and monsoon seasons. Relative use by elk was best explained by incorporating an interaction between diel period and predicted risky places across all seasons. Elk utilized risky places more in times of nutritional deficit associated with high energetic demands of motherhood and when forage quality was best, during spring and monsoon season. Particularly, use of risky places increased at less risky times in areas with more established wolf presence, suggesting use of risky places varied relative to exposure to Mexican wolves. These behaviors highlight the importance of temporal avoidance when predators and prey are highly mobile and largely overlap in space. Our research suggests temporally responding to predictable and relatively static environmental characteristics associated with encounter and kill rates may better balance energetic trade-offs than anticipating changes in wolf activity or spatially avoiding areas with higher wolf presence. Thus, elk appear to be more willing to take chances and mitigate cursorial predation risk with a more immediate, reactive approach and make proactive trade-offs during the seasons they can best increase fitness.