Behavioral consequences of plant invasion: an invasive plant alters rodent antipredator behavior

Antipredator behavior is an important aspect of predator prey dynamics and prey survival, and invasive species are becoming an increasing threat to ecosystems worldwide. Although these 2 concepts are frequently connected in terms of invasive predators and naive prey, other effects of invasive species, such the creation of novel habitats by invasive plants, may also have indirect effects on animal behavior and community dynamics. We used giving-up densities to examine foraging behavior of Peromyscus leucopus in forest habitats that were invaded or uninvaded by the exotic invasive shrub, Lonicera maackii, which forms a novel shrub layer in hickory oak forests in Missouri. We experimentally manipulated the presence or absence of an artificial cover over foraging trays and predicted that rodents would have less of a preference for artificial cover in invaded sites with high densities of invasive shrub cover. We found that the invasive shrub decreased perceived predation risk, but this effect was contingent on other environmental correlates of predation risk (i.e., clear, moonlit nights) and foraging cost (i.e., warm temperatures). Our results demonstrate that invasive plants can change animal behavior, which may benefit the invasive species by causing apparent competition and promoting further invasion. Our results have implications for further behavioral changes that could affect multiple trophic levels and suggest that plant invasions can have cryptic, interactive effects on animal behavior, aside from their commonly studied effects on other plant species.