The research proposed seeks to demonstrate the feasibility of testing complex, multifactorial hypotheses regarding the population dynamics and community organization of small mammals. The approach is to conduct a series of fully factorial experiments in the field using penned populations. The proposed experiments will determine if the results from earlier work, in which food and predation had equal and additive effects on the density of prairie voles, apply to meadow voles (a closely related species found in the same grassy habitats in central Illinois). In addition, a third major environmental factor (interspecific competition) will be manipulated to see if factor interaction medicated by behavior influences the outcome of competition. To accomplish these objectives and to test related hypotheses, replicated experiments will be conducted during each of three growing seasons. Each replication will consist of a set of eight different combinations of treatments from the following three factors: food (normal or rabbit chow added), predation (normal or protected from predators) and interspecific competitors (prairie voles alone, meadow voles alone, both prairie voles and meadow voles). If successful, this approach should dramatically improve our ability to understand the effects of simultaneously operating multiple factors on natural populations, which may have implications for many endangered populations worldwide.
