Kenneth A. Schmidt - US grants

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.

Ecological systems typically include many species that interact in complex networks of connections. We seek to determine the key ecological connections that govern the dynamics of Lyme disease risk to humans. Prior observational and experimental studies in oak forests suggest that risk of human exposure to Lyme-disease bearing ticks may be predictable almost two years in advance based on acorn production. Production of acorns - a high quality food for wildlife - by oaks varies dramatically among years. High abundance of acorns in the fall enhances survivorship, reproduction, and population growth of white-footed mice, resulting in high mouse density the following spring and summer. Newly hatched larval ticks feed more successfully, and acquire the Lyme disease bacterium more efficiently, from mice than from other hosts. Therefore, we predict that the higher the abundance of mice, the greater the expected abundance of infected ticks capable of transmitting disease to humans. Because mice are also voracious predators on eggs of ground-nesting songbirds, these rodents appear capable of regulating population size of species such as Veeries and Wood Thrush. We will test these expectations over the next five years.

Results of this project are used in Ecology and Mammalogy textbooks and for public education (local and regional presentations and newspaper/magazine articles). The proposed research has strong practical implications because it will facilitate the prediction of times and places of high disease risk. As such, it promotes both the realized and perceived utility of ecology for human welfare.

Optimal decision making by organisms relies upon the acquisition of information regarding relevant ecological conditions (e.g., location of predators, qualities of prospective mates). The better informed the individual, the better it can match its behavior to its present or anticipated future circumstances. These adjustments in turn may be important drivers or regulators of ecological interactions. Therefore, to fully grasp ecological complexity, ecologists must understand the sources of information available to organisms (e.g., past experiences, newly acquired information), how information changes an organism's behavior, and the consequences of information use for other organisms. The research to be performed will investigate these questions within the context of how breeding songbirds acquire information about predation risk. It combines long-term observational data on individually marked animals, experimental manipulation of predators in time and space, and computer simulations to explore the role of environmental predictability on information use and, hence, on possible responses to global change.

The proposed research will facilitate undergraduate research that targets underrepresented groups through programs such as McNair Scholars and Howard Hughes Fellows. It will develop a new initiative to provide science education through reflection and active research experience to non-science majors. This initiative will occur within a curriculum designed to groom students for professions that communicate the science of the natural world to non-scientists. Through proposed education assessments, this initiative would represent perhaps the first attempt to quantify the role of reflection and research experience on students' abilities to effectively convey the nature of science through writing.

This research will investigate the ecology of human granulocytic anaplasmosis (HGA), an emerging disease on three continents and examine the effects of species diversity on disease transmission. HGA is caused by a rickettsial bacterium, Anaplasma phagocytophilum, that is transmitted from host to host through the bite of an infected ixodid tick. The research will include a characterization of reservoir competence of wildlife hosts and determine whether host reservoir competence is a function of coinfection with the bacterium that causes Lyme disease. The researchers will build and test models to predict how risk of human exposure to HGA will vary with changes in the diversity and species composition of host communities. They also will experimentally evaluate specific mechanisms underlying effects of variable diversity on risk by manipulating key hosts in natural communities. Finally, they will educate local health-care providers about this emerging disease and expand the HGA surveillance capabilities of the local (Dutchess County, NY) health department. The enhanced surveillance data will be used to test for spatial correlations between ecological risk and human incidence. The project will train more than 40 undergraduates and provide for them an opportunity to conduct independent research. Understanding disease transmission dynamics is crucial for the appropriate management of communities and landscapes to reduce the total burden of zoonotic disease.