The objective of the project is to develop a new approach to basic research in conservation biology--Species-Centered Environmental Analysis (SCEA)--and to apply it to an extensive analysis of the population dynamics of the endangered Redcockaded Woodpecker (Picoides borealis) in relation to its environment. A graph (envirogram) containing information on extrinsic factors that directly and indirectly affect the reproduction and survival of the population of interest is constructed. These factors include predation,competition, with other species for cavities, quality and amount of foraging habitat,properties of cavities, and the distances among social units. The second step is causal modeling by path analysis using structural equations. In the third step,field data for 160 social units from three study areas in northern Florida and Southern Georgia and additional data from North Carolina is obtained. The fourth step is an explicit interaction among theory, previous knowledge about causal relationships, and statistical data analysis. Finally, the results are simplified into a graphic summary of the covariance structure of factors thought to be limiting the populations. The method, Species-centered Environmental Analysis (SCEA), searches the system of responses of units to their respective environments for the combination of key environmental factors that could support a viable natural population at each site. For the Red-cockaded Woodpecker, this research is crucial. Provision in a modern managed landscape of the specific features of old growth that it requires. We think that the SCEA approach will help researchers develop interpretable descriptions of factors regulating populations. One of its potential applications is in the development of recovery plans for endangered species.
