Trap use as an indicator of social behavior in mainland and island voles

Abstract

1980: Trap use as an indicator of social behavior in mainland and island voles. Acta theriol., 25, 23: 295-307 [With 4 Tables] The social behavior of a cyling mainland population of Microtus pennsylvanicus and a non-cycling island endemic, M. breweri was studied. Social structure was determined by the spatial distribution of various sex, reproductive, and age classes using a grid arrangement of live traps. The response of voles of given age and sex classes to olfactory cues left by other voles of known age and sex classes in live traps was studied in the field. Differences between the two species in social behavior were looked at as contributing factors in the observed demographic differences between the species. Resident and dispersing sub-populations of each species were compared. The social behavior was also examined in each of 4 distinct phases of a single population cycle of M. pennsylvanicus. It was seen that the intensity of social interactions increased markedly as populating density increased. Dispersers in a cycling vole population (M. pennsylvanicus) show a random social distribution, perhaps indicative of social intolerance. The dispersers in the non-cycling M. breweri do not exhibit this social intolerance, but are less aggressive in comparison with residents of the same species. This difference is suggested as being a factor in the differences in the population dynamics of the two species. Analysis of the response to olfactory cues left in traps reveals that olfaction primarily functions as an aid in reproduction, and is independent of major demographic changes in M. pennsylvanicus. It is not a major factor in the determination of social structure in either species.