Meeting Abstract
Animal communication carries the risk of signal exploitation by predators, and thus many species will adjust their behavior to produce signals that range from more discreet messages to conspecifics, to conspicuous anti-predator cues. Although rails (Family Rallidae) are known to use the visual display of tail-flicking as a warning of vigilance towards predators, how these birds will alter their frequent and diverse vocal behavior based on perceived predation risk remains little studied. The calls of owls, which consume a variety of rallid species and can home in on acoustic cues of their prey, have been found to reduce singing in numerous other birds. We applied remotely-activated broadcasts and Autonomous Recording Units to study whether rails in the wetlands of the Lake Calumet region near Chicago would decrease vocal activity rate (VAR) following the broadcast of a known rallid predator, the Great Horned Owl (Bubo virginianus). In our comparison of different wetland sites that varied in the historical presence of owls, neither Soras (Porzana carolina) nor Virginia Rails (Rallus limicola), nor both species combined, showed a significant reduction in VAR in experimental relative to control trials. As the rails at Lake Calumet showed a general trend of higher VAR with the onset of the breeding season, our results indicate that these rallid species may signal alarm despite owl predation risk, or that they employ alternative, currently unknown behavioral strategies to mitigate this risk.
