General Models for the Population Dynamics of the Field Vole Microtus agrestis in Central Scandinavia

Abstract

Mathematical models have been developed for different aspects of the population dynamics of the field vole. The models are presumed to cover the most essential phenomena influencing the demography and habitat utilization of the field vole in Scandinavia. Their presentation permits a simulation model for the field vole's population dynamics to be developed. The models include: Energy requirement and utilization; a generalized version of the functional response curve; impact on vegetation and scramble competition; reproduction and survival schedules; predation; habitat utilization and contest competition. Our basic hypothesis is that the major features of the population dynamics of the field vole may be understood by analyzing the condition of individual organisms, particularly their nutritional balance. Emphasis is placed on evaluating the models with respect to realism, thus showing that many observations on free-living field vole populations may be explained by these models. Critical areas for further research are indicated. Most important are: To study food acquisition and nutritional effects on demography; to evaluate other factors which have been supposed to affect demography; to study the effects of predation; and to examine the field vole's use of heterogeneous environments including demic structures and dispersal. Any information which may reject particular hypotheses is indicated.