The social behavior of the prairie vole evolved as an adaptation to habitats with low food availability prevalent in the original range of the species. These behaviors include communal nesting, territoriality, monogamy, and mate guarding. The basic social organization involves strong genetic tendencies that have retained the original behaviors even when populations occupy habitats with high food availability. However, in habitats with high food availability, mate guarding and territorial defense become less effective. In such cases, most females within the communal group are reproductively activated and high population densities result.