Electronic Thesis and Dissertation Repository


Master of Science




Dr. Liana Zanette


Predators kill, but the risk of being killed is also a powerful force affecting survival because scared prey eat less, thereby increasing the likelihood of starvation. Young of most animals are extremely vulnerable to predators and may alter their behaviour to limit detection. I investigated the previously unexplored effects that predation risk has on the behaviour of newly fledged offspring and their parents, and the impact this has on offspring survival. I manipulated predation risk using sound and found that parent song sparrows reduced their feedings, providing 60% less food overall. Critically, not only did this parental response estimate survival of individual offspring, it allowed me to project that the number of surviving fledglings decreased by ~24%, and fear overall reduced the number of offspring produced per year by ~54%. Counter to my expectation, song sparrow fledglings actually appear to be increasing their auditory detectability in response to reduced provisioning due to their parents’ response.