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Habitat selection by pine voles (Microtus pinetorum) has been attributed to cover density (Goertz, 1971; Paul, 1970) soil condition (Benton, 1955; Fisher and Anthony, 1980), and food resources (Noffsinger, 1976; Paul, 1970). Goertz (1971) reported that pine voles were distributed in diverse habitats, but there was a close correlation with height and diversity of grass. Miller and Getz (1969) found populations in sloping upland woods, Benton (1955) in dry woods, and Paul (1970) in hardwood slopes with a close correlation between distribution and amount of ground cover. Soil type has been examined by Benton (1955) and Fisher and Anthony (1980) and they have shown that pine voles are associated with light soils containing moderate layers of humus. These factors are important to reduce predation, moderate the effect of rain and temperatures, and permit the excavation of fossorial nests and tunnels.
Noffsinger (1976) has demonstrated that the amount of digestible energy and availability of food sources were important factors affecting birth and death rates of pine voles when abandoned and maintained orchards were compared. Behavioral characteristics of pine voles have been associated with decreased meadow vole density as pine voles appear to be a more aggressive species (Smith, 1975). Paul (1970) has shown that pine voles appear to replace meadow voles when they are sympatric in favorable habitats. Trapping and telemetry methods indicate that pine voles have low dispersal capacity and home ranges 100 m2 or less in size (Gettle, 1975).
All these reports are from established pine vole populations and not from the initial colonizing event and subsequent development of a local population. Therefore, this research project is directed at understanding what site qualities permit pine vole colonization in areas where they have been historically absent, but where its competitor, the meadow vole (Microtus pennsylvanicus), is common.