Heads up! Variation in the vigilance of foraging chipmunks in response to experimental manipulation of perceived risk

Vigilance is a behavior in which an organism is gaining information about its environment, often used for predator detection. Vigilance is influenced by the risk that an organism perceives. Animals may vary their use of vigilance behaviors by modifying not only the percent time they dedicate to vigilance, but also the duration of vigilance bouts, rate of vigilance bouts, and type of vigilance posture. Assuming these different vigilance tactics come at different costs to the individual, different sources of perceived risk should elicit specific vigilance strategies. Here, we experimentally altered the sight lines of foraging Eastern chipmunks ( Tamias striatus ). We carried out our field work in three locations in Michigan that vary from low (an island site) to high predator pressure. Our results show that chipmunks respond to changes in their immediate microhabitat by altering the rate of vigilance, regardless of predator density. On the other hand, chipmunks at sites with lower predator densities spend less time vigilant when compared to sites with higher predator densities and they utilize vigilance postures that decrease vigilance but do not completely halt feeding. Further research should aim to quantify costs and benefits of vigilance postures and strategies to further our understanding of how individuals balance the trade‐off between mortality and energy gain.