ABSTRACT
High predation pressure has been observed in other studies on noncyclic rodents. In a Polish deciduous forest, the rodents declined markedly during the nonbreeding season every year. The impact by predators was high and estimated at a minimum of 70% of the losses. Experimental studies where predation has been manipulated provide more conclusive evidence. Predation is probably an important agent influencing dynamics of both cyclic and noncyclic rodent populations. The interactions, however, are performed differently in the two cases. In predator-prey systems examined with noncyclic microtine populations, the response of the predators to varying prey densities is mainly functional, i.e., individual predators increase their vole consumption at high vole numbers. Evidence suggests that long-term stability could be achieved by predation; the main prerequisite seems to be that predators should not be depending on rodents but sustained by alternative prey when rodents are scarce.
