Time series analysis of a predator-prey system: Application of VAR and generalized impulse response function

The maintenance of population densities requires information as to how organisms react to intended as well as unintended changes. This paper demonstrates the usefulness of multiple-equation and innovation accounting time series techniques that are well-suited for analyzing the responses of variables to unexpected changes (i.e., shocks) in other variables. The analysis is conducted within the context of a predator-prey system. A vector autoregression is estimated. The time series model characterizes the interactions and dynamics inherent in a system of two freshwater organisms. The recently developed method of generalized impulse response analysis is used to simulate the responses of the organisms to disturbances. The results indicated that there are significant responses of the population density growth rate of the predator (prey) to shocks in the growth rate of the prey (predator) population density that are not captured by standard interpretation of the multiple equation model results. This method provides insight into the transmission of shocks in the predator-prey relationship.