Prey exhibit antipredator responses that can influence population dynamics, however understanding the ubiquity of these effects and their importance relative to lethal effects of predators remains an open question. In mammals, processes influencing maternal investment provide an intuitive link between individual traits and population dynamics as maternal investment is sensitive to predation risk and is often related to neonate growth and survival. Field experiments can directly link responses to predation risk, but can be difficult to extrapolate to complex ecological systems, particularly when treatments do not emulate natural processes. Correlative field studies, provide inference regarding how predation risk covaries with population vital rates, however confounding factors can make determining causation difficult. Here, I describe a framework for examining nonconsumptive effects (NCEs) of coyote (Canis latrans) range expansion in eastern North America on white-tailed deer (Odocoileus virginianus), the region's dominant herbivore, by combining field experiments, correlational field studies, and controlled laboratory experimentation.
Results/Conclusions
Field experiments using a series of predator exclosures and paired control plots, revealed that predation risk resulted in decreased foraging and increased diurnal activity in fawn rearing female deer. Correlative field studies demonstrated that this effect extended beyond the experimental treatment and occurred in systems with dynamic spatiotemporal variation in predation risk. Increased diurnal activity exposed fawns to greater thermoregulatory costs. Controlled experimentation using repeated measures on individual captive deer demonstrated that increased thermoregulatory costs results in elevated stress and reduced growth rates in fawns, which can increase time to first reproduction and decrease lifetime reproductive output. This series of studies including field experiments, correlative field studies, laboratory experiments provides a useful framework for examining NCEs in large mammals.