Effects of predation risk and group dynamics on white-tailed deer foraging behavior in a longleaf pine savanna

Abstract

Costs associated with antipredator behaviors can have profound effects on prey populations. We investigated the effects of predation risk on white-tailed deer foraging behavior by manipulating predator distributions through exclusion while controlling for effects of habitat type. In 2003, we constructed predator exclosures on 4 of 8 approximately 40-ha study plots in southwestern Georgia, USA. We examined the seasonal and sex-specific effects of predator exclusion, and group size and composition on the behavioral state (i.e., feeding or vigilant) of foraging white-tailed deer at baited camera traps during 2011–2012. Predator exclusion resulted in a 5% increase in the time females spent feeding during the summer, concurrent with fawning; and 13.4% increase in the time males spent feeding during winter, while in postrut condition. Males were more vigilant than females and demonstrated a stronger response to predator exclusion. Males showed no response to group size or composition, whereas females and juveniles decreased foraging when males were present during the summer. Our results suggest that white-tailed deer alter vigilance levels in response to predator distributions independent of habitat cues. We propose that expanding coyote populations in the southeastern USA influence white-tailed deer numerically through predation of juveniles, and behaviorally by inducing antipredator responses that likely carry foraging costs. This emerging predator–prey dynamic may have strong nonconsumptive effects on naive white-tailed deer populations that experienced little nonanthropogenic predation risk for decades.