AUTHORS: Michael E. Egan, Southern Illinois University; Abigail M. Weber, Southern Illinois University; Nicole T. Gorman, Southern Illinois University; Michael W. Eichholz, Southern Illinois University; Daniel Skinner, Illinois Department of Natural Resources; Peter E. Schlichting, Illinois Department of Natural Resources; and Guillaume Bastille-Rousseau, Southern Illinois University
ABSTRACT: Behavioral responses of prey to predation risk have ecological impacts that can be as great as the direct mortality mediated through behaviors including behavioral state changes and spatial avoidance. Theory suggests that prey choose between these behaviors by pairing responses to risks based on the hunting mode of the prey (hunting mode hypothesis), but prey may ignore hunting mode to prioritize responding to the most lethal predators (lethality hypothesis). Furthermore, prey may respond to the spatial distribution of these risks (risky places hypothesis) or respond only during the periods of highest risk (risky times hypothesis).We test these hypotheses using data from 40 female and 29 male white-tailed deer (Odocoileus virginianus) and two mesopredators (coyotes, Canis latrans and bobcats, Lynx rufus) fitted with GPS collars and human sources of mortality (hunting, roads, human modification).We used hidden Markov models (HMM) to determine whether each covariate impacted the probability of transitioning between behavioral states and step selection functions (SSF) to determine whether deer spatially avoided each covariate. Additionally, we evaluated whether these patterns varied daily and seasonally. Generally, deer changed behavioral state in response to both mesopredators, consistently shifting to slower movement states, but avoided human modification. Spatial responses to human modification varied depending on the time of day. Deer selected for human modification during daylight hours but avoided human modification during the crepuscular and nighttime periods. Space use was most strongly related to more lethal humans, providing support for the lethality hypothesis. Despite prioritizing humans, mesopredators impacted deer behavioral state, suggesting that mesopredators still have important impacts on prey behavior. Finally, temporal patterns of avoidance align with other studies that indicate avoidance of predators is time-dependent while further highlighting the complex push-pull relationship of human modified areas on wildlife.
