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Title:Manuscript - Dynamics of sympatric vole populations: influence of food resources and interspecific competition
Author(s):Getz, Lowell L.; Hofmann, Joyce E.; McGuire, Betty; Oli, Madan K.
Food resources
Microtus ochrogaster
Microtus pennsylvanicus
Interspecific competition
Abstract:Abundance of food resources and interspecific competition can significantly influence the dynamics of arvicoline rodent populations. We studied responses of Microtus ochrogaster and M.pennsylvanicus to supplemental food and interspecific competition in bluegrass (marginal food habitat) and tallgrass prairie (low food habitat). Removal experiments were conducted to study reciprocal interspecific interactions between the two species in bluegrass and the effects of M. pennsylvanicus on M. ochrogaster in tallgrass. Mean population densities and patterns of fluctuation of M. ochrogaster did not differ between supplementally fed and control sites in either bluegrass or tallgrass habitats. However, amplitudes of fluctuation and proportion of reproductive females were higher in supplementally fed than in control bluegrass sites for this species. Mean population densities of M. pennsylvanicus were slightly higher in supplementally fed than in control tallgrass sites; the addition of food to bluegrass, however, did not result in higher population densities for this species. Population densities of M. ochrogaster and M. pennsylvanicus in bluegrass were not suppressed by the presence of the other species. Although survival of M. ochrogaster was lower in the presence of M. pennsylvanicus, there was no negative effect on reproduction. Presence of M. ochrogaster did not adversely affect either survival or reproduction of M. pennsylvanicus in bluegrass. Although M. pennsylvanicus appeared to exert a strong suppressing effect on population densities of M. ochrogaster in tallgrass, neither survival nor reproduction of M. ochrogaster was lower when M. pennsylvanicus was present in this habitat. Similar results were observed from interspecific correlations between population densities, survival and reproduction of the two species during a 25-year demographic study in bluegrass and tallgrass. We conclude that food resources and interspecific competition do not play a major role in driving the dynamics of M. ochrogaster and M. pennsylvanicus populations in our study sites.
Issue Date:2004
Genre:Working / Discussion Paper
Publication Status:published or submitted for publication
Rights Information:Copyright held by authors
Date Available in IDEALS:2007-01-03

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