Avian Responses to Predator Communities in Fragmented, Urbanizing Landscapes

Behavioral responses to predators during the breeding season can critically affect the nest success of songbirds. However, the ability of birds to modify behavior based upon perceived and actual predation risk at multiple spatial scales (e.g. local (within-site), site, and landscape) and in novel (e.g., urban) environments remains poorly understood. In this dissertation, I explored how information about predation risk influenced the nest-site selection and nestling provisioning behavior of two species of songbirds -- northern cardinals (Cardinalis cardinalis) and Acadian flycatchers (Empidonax virescens), which are two relatively common forest songbirds of eastern North America with contrasting responses to urbanization. I studied the use of information regarding predation risk and behavioral responses of birds during the 2006-2010 breeding seasons at riparian forest sites within the urbanizing landscapes of central Ohio. Specifically, I investigated the following questions: 1) how do cardinals and flycatchers choose nest locations based on information about local-scale nest predator activity patterns, 2) do cardinals and flycatchers incorporate private (i.e. detectable information only known to the individual) and public (i.e. detectable information known to all individuals) information about predation risk in nest-site selection, and 3) are provisioning rates to nestlings adjusted relative to public information about site-level predation risk? The ways that birds used information about predation risk varied with species, type of behavior, and the scale of information. Cardinals incorporated local scale information about predator activity, previous nest fate, and at times, actual predation risk at the site scale, to modify nest-site selection. They demonstrated sensitivity to information at multiple scales and an apparent ability to adjust nesting behaviors in ways that may allow them to thrive in urban areas. On the other hand, flycatchers used only local-scale predator activity information in selecting nest-sites, were less responsive to site-scale information, but likely recognized and responded to predator information or other cues of habitat quality at the landscape level when making breeding decisions. Both songbird species exhibited more cautious breeding behaviors when faced with certain types of predation risk, but seemed sensitive to the scale of predator information in choosing to do so. Thus, differences in use of information about predation risk may reflect constraints on the relative behavioral flexibility of cardinals and flycatchers. Not only does this study reveal ways in which behavioral plasticity can vary between songbirds with different affinities for urbanizing landscapes, but also illuminates the importance of studying various scales and types of information in evaluating songbird responses to predators.