Brown Thrasher nest reuse: A time saving resource, protection from search-strategy predators, or cues for nest-site selection?

We examined the potential functions of old nests in a population of Brown Thrashers (Toxostoma rufum) nesting on the Konza Prairie Research Natural Area in northeastern Kansas. We determined whether thrashers reuse nests constructed in previous years, and tested predictions of the hypothesis that old nests function to reduce the risk of nest predation by saturating the cues used by search-strategy predators. We also manipulated old-nest densities to test the hypothesis that old nests are used as indirect cues for nest-site selection. Thrashers were found to reuse nests, albeit at low rates (4% of nests monitored). We found no significant relationships between the density of old nests and the success of active nests, and experimentally removing nests did not influence nest-site selection. These results suggest that old nests may only benefit thrashers in this population as a resource to reduce the time spent in nest construction.