SOCIAL TOLERANCE AND PROXIMATE MECHANISMS OF DISPERSAL AMONG WINTER GROUPS OF MEADOW VOLES, MICROTUS-PENNSYLVANICUS

Proximate mechanisms for movement among communal groups of meadow voles were examined during two winter seasons. Radiotelemetry and live trapping were used to identify group members and monitor the movement of voles. Paired encounters between individuals removed from the field indicated that aggression neither precipitated nor prevented movement of animals between groups during winter. Dispersal most often occurred in conjuction with loss of nestmates to predation. The removal of nestmates resulted in increased home range size and movement between groups for males, but not for females. With the onset of reproduction, aggression increased toward individuals from other groups, but not toward nestmates. Winter groups did not break up with the onset of breeding, but these groups were closed to the immigration of new members. © 1990.