Population Cycles and Spatial Patterns in Snowshoe Hares: an Individual-Oriented Simulation

The issue of population cycles in mammals is reviewed and focused on the particular case of the snowshoe hare spatiotemporal dynamics. We have tested some hypotheses by means of an individual-orientated simulation. The results suggest that a lagged response to food supply is able to generate cycles, which can be qualitatively very similar to the observed field fluctuations. Surprisingly spatial structures, as target patterns and spiral waves, emerge from the trophic interactions despite the random rules in the simulation. These macroscopic patterns can explain the observed synchronization in hare dynamics over large areas, which has been recently reported. Furthermore, the formation of spiral waves can explain the U-shape pattern in the synchronization vs. distance plot observed by Ranta and co-workers. Population cycles and spatial patterns go together. An increase in the maximum vegetation available acts as a bifurcation parameter, inducing cycles when it is up to a given threshold. Some “simulation experiments” are performed, and the results are discussed in the light of field observations and theoretical predictions.