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

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.