Within-season use of public and private information on predation risk in nest-site selection

Abstract

Nest-site selection can be an important preemptive defense strategy for songbirds to reduce the risk of predation and is likely most effective when it incorporates both public and private information about predation. We examined the degree to which two songbirds, the Northern Cardinal (Cardinalis cardinalis, n = 160 pairs) and the Acadian Flycatcher (Empidonax virescens, n = 70 pairs), changed nest-site attributes (e.g., nest height, nest concealment, and vegetation density surrounding the nests) between subsequent within-season nesting attempts from 2006 to 2010 in Ohio. Specifically, we asked if birds adjusted nest-sites based upon information such as prior experience with nest predation, predator abundance, and predation risk. We predicted that, in cases where previous nests failed (private information) and/or sites had a greater risk of nest predation (public information), birds would make greater changes in nest characteristics such as nest height, concealment, and the vegetation density surrounding the nest to make presumably safer nest sites. Only cardinals, not flycatchers, showed evidence of using private and public information in changing nest-site attributes. There were greater changes in nest height when previous nests failed, and greater changes in nest concealment at riskier sites compared to those with low daily predation rates. These findings suggest that species differ in behavioral plasticity and use of information in ways that can both reflect and predict their ability to adapt to novel conditions.