Social Behavior of Microtus pennsylvanicus in Relation to Seasonal Changes in Demography

Abstract

A combined mark-recapture trapping and radiotelemetry study was carried out on a free-ranging population of meadow voles (Microtus pennsylvanicus) during summer, fall, and winter. Social relationships of pairs of neighboring voles were determined by examining their spatial and temporal use of areas of overlap. Relationships between social behavior and seasonal changes in population demography were investigated. During summer, reproductively active (RA) males had larger activity areas than RA females, and their areas overlapped substantially with those of both RA males and RA females. RA females had little or no overlap with other RA females. Neither RA males nor RA females used the overlap area with neighbors differently from random expectation. There was little contact between RA voles except when females were in estrus. Then, RA males approached the estrous female and were aggressive towards other RA males. Nonreproductive (NR) voles in summer and fall were more tolerant socially than were RA voles. In winter, activity areas of NR voles overlapped extensively, and these voles shared nests with each other. The composition of the population changed from predominantly RA voles in summer to entirely NR voles in winter.