RUI: Incidental Nest Predation in Songbirds: Using Behavioral Indicators to Determine Ecological Processes and Scales

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0089588. Kenneth Schmidt. Predation rates and the subsequent impact of predators on prey are thought to be determined mostly by the population density of predators. Nonetheless, much predation by generalist predators may occur when secondary prey types are encountered coincidentally by a predator while searching for its primary prey. Such incidental predation is determined by the behavioral responses of individual predators to the abundance and distribution of alternative prey types, as well as to features of the predator's environment. Incidental predation may be extremely common in generalist, and to a smaller degree in specialist predators. Because such weak interactions potentially stabilize community structure, they are of considerable importance. More specifically, the rate of incidental predation may be related to amount of enemy-free space (areas unutilized by predators). Understanding this mechanism is critical because of its relationship to the strength of the predator-prey interaction, as well because enemy-free space influences the stability of predator-prey dynamics and the coexistence of multiple prey species.The proposed research examines incidental predation in a community of breeding songbirds, whose eggs and nestlings are preyed on by small mammals, primarily the white-footed mouse (Peromyscus leucopus). It focuses on predation from the perspectives of individual behaviors and population dynamics, as well as their repercussions to community-level phenomena. The approach combines theoretical, observational, and experimental components, ultimately to test explicit underlying mechanisms. More specifically, the research involves (1) monitoring the density of common vertebrates (white-footed mouse, eastern chipmunk, gray squirrel) which are nest predators of songbirds (2) monitoring nest predation rates using artificial songbird nests, and (3) monitoring the success of natural nests of selected songbird species, (4) testing if enemy-free space is a key control of incidental predation, (5) evaluating the utility of giving-up densities as indicators of ecological patterns and processes at multiple spatial scales, and (6) estimating the influence of population density and individual behavioral responses of predators on the survival of nests of songbirds.