Heterospecific information about predation risk influences exploratory behavior

Use of socially derived information from other species is common in many types of decision making, but particularly in predation avoidance. In communities with diverse prey that share generalist predators, public information concerning predator location, type, or activity is often used by heterospecifics. Given that exploration and exploitation of the environment is constrained by predator avoidance, exactly how information about predators affects subsequent prey behavior is of increasing interest. In this study, we tested how social information (predation threat encoded in antipredator vocalizations of the tufted titmouse, Baeolophus bicolor) influences the exploratory behavior (movement, vigilance, and space use) of Northern cardinals (Cardinalis cardinalis). Cardinals, placed inside a small flight cage equipped with an array of perches, experienced randomly assigned playback treatments of titmouse antipredator vocalizations that varied in threat level. Exploratory behavior was videotaped during 3 periods—Before (B), During (D), and After (A) playbacks of titmouse calls. When titmouse vocalizations encoding more dangerous and immediate predation threats were played, cardinals significantly reduced active movements but increased visual scanning relative to subjects hearing calls that encoded low threat levels. Furthermore, they were also slower to return to prethreat behavior. Thus, we conclude that cardinals interpreted the antipredator signals correctly and responded accordingly, adjusting their activities to potentially reduce risk (decreasing movement and increasing vigilance). Our work demonstrates specifically how the trade-off between exploration (comprised of both movement and sensory scanning) and predator avoidance is actuated via spatial decision making in the cardinal.