Significance of Dispersal in Fluctuating Populations of Microtus ochrogaster and M. pennsylvanicus

Abstract

The impact of dispersal on the population dynamics of Microtus ochrogaster and M. pennsylvanicus was assessed by monitoring the movement of voles through a 1-ha permeable enclosure and employing drift fences to intercept emigrants. Dispersal was not correlated with density nor with rate of increase in either species. Totals of 31 Af. ochrogaster and 10 M. pennsylvanicus dispersers were captured. Losses accounted for by dispersal were estimated at 16.7 and 6.6% for M. ochrogaster and M. pennsylvanicus respectively. Analysis of our data and those of other studies suggests dispersal is an unlikely mechanism of microtine population regulation.