Effects of Habitat Patch Shape on Population Dynamics of Meadow Voles (Microtus pennsylvanicus)

The geometry of habitat patches may affect population dynamics due to differences in edge-to-area ratios for patches of different sizes and shapes. We conducted a field experiment replicated over 2 years employing four square (40 by 40 m) and four rectangular (16 by 100 m) habitat patches of equal size (1,600 m2) to determine the effects of contrasting shapes of habitat patches on population dynamics of meadow voles (Microtus pennsylvanicus). We tested the predictions that dispersal rates would be higher, home ranges larger, and population densities lower in rectangular patches compared to square patches. The number of dispersers, but not dispersal rates, was greater in rectangular patches than in square patches only when densities of voles were low. Home ranges were of equal area but different shape in the contrasting shapes of patches. Population density, recruitment, body mass of dispersers, body mass of residents, survival, and age structure were largely unaffected by differences in patch shape. Thus, plasticity of behavior (e. g., changes in shape of home range) appears to have prevented differences in population dynamics between the two patch shapes. We conclude that patch shape does not markedly affect the population dynamics of the meadow vole, and that this species appears to be an edge-tolerant species.