Is spacing behaviour coupled with predation causing the microtine density cycle? A synthesis of current process-oriented and pattern-oriented studies

Current ecological information on periodically fluctuating microtine populations are demonstrated to support a hypothesis involving both predation and intrinsic self-regulation as necessary and sufficient factors for explaining the 'microtine density cycle'. The structure of the cyclic time series is largely two dimensional with strong delayed density dependence. Together with recent field studies on rodent demography, our modelling suggests that trophic interaction is a likely candidate to generate the dimensionality observed for northern microtine rodent dynamics. It is shown that the trophic interaction must be fairly strong. This suggests that specialist predation is the most likely one among the classes of trophic interactions. We also argue that some - but not too strong - self-regulation must occur to generate the structure of the available time series on northern European microtines.