The Costs of Conspecifics: Are Social Distractions or Environmental Distractions More Salient?



Daniel T. Blumstein, Department of Ecology and Evolutionary Biology, University of California, 621 Young Drive South, Los Angeles, CA 90095-1606, USA.



Animals have limited attention that predisposes them to distraction, but the impact of different types of distraction is relatively unknown. We first conducted a discrimination experiment to ensure brown anoles (Anolis sagrei) responded appropriately to model predators (a rubber snake) and model conspecifics. We found anoles responded to the snake by suppressing looking and increasing locomotion, a marked difference than their response when presented with a conspecific. Next, we designed a prime and probe experiment to test the salience of social and environmental distractions on brown anoles. The social distraction consisted of a conspecific exemplar that was presented to the focal individual. Environmental distractions were vegetation that was moved at different speeds (ambient or vigorous) near the focal individual. Following 30 seconds of distraction with one of the three treatments, we presented the model snake, which was initially moved to within 1 m of a subject, and then moved closer until the subject looked in response to the approaching threat, and then fled. There was no effect of distractor on alert distance, but anoles distracted with the conspecific tolerated a closer approach with the model predator before fleeing than they did to either of the vegetative movements. These results cannot be explained by three other models of risk assessment and suggest that social cues distracted brown anoles more than environmental cues. These results may be generalizable to other social species that must simultaneously monitor conspecifics and assess predation risk.