Demography of fluctuating prairie vole populations: comparison of demographic variables among phases of fluctuations

Author： Getz Lowell L. Oli Madan K. Hofmann Joyce E. Mcguire Betty

Publisher： Mammal Research Institute, Polish Academy of Sciences

ISSN： 0001-7051

Source： Acta Theriologica, Vol.52, Iss.3, 2007-07, pp. : 291-298

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Abstract

We tested for differences in the proportion of reproductively active males and females, proportion of the population composed of young and immigrants, and monthly survival (total, adult, young) among phases (trough, increase, and decline) and among habitats (alfalfa, bluegrass, and tallgrass) of 30 population fluctuations of Microtus ochrogaster Wagner, 1842 over 25 years in east-central Illinois USA. Total population survival and survival of adults and young were greatest during the increase phase, among fluctuations, irrespective of habitat. The proportion of reproductively active adult males and females was lowest during the decline phase, an effect of lower reproduction during the winter. These results suggest that phase-specific changes in survival were the primary demographic factor driving population fluctuations of M. ochrogaster in our study sites. We conclude that small-scale spatially different population fluctuations may be explained by the same mechanisms that explain fluctuations within a population.