Seasonal Differences in Social Behavior among Adult and Juvenile Meadow Voles, Microtus pennsylvanicus

Seasonal differences in behavioral interactions between wild‐caught adult and juvenile meadow voles, Microtus pennsylvanicus, were measured in paired encounters in a neutral arena. Seasonal differences existed in the adult‐juvenile paired encounters. Early in the breeding season (May—Aug.) paired encounters between adult males and juvenile males were more agonistic than other adultjuvenile pairings. Late in the breeding season (Sep.—Dec.) adult female‐juvenile male encounters were more agonistic than other adult‐juvenile pairings. Odor preferences of juveniles were determined in a Y‐maze olfactometer. Juveniles did not demonstrate seasonal differences in odor preference. Males preferred the odor of adult females to the odor of adult males or their own odor. Females preferred the scent of an adult male to the odor of an adult female, but did not show a preference between their own odor and the odor of an adult male or an adult female. The results are consistent with hypotheses that state in a promiscuous species, females should be philopatric, and males should disperse as a consequence of adult competition. The data suggest that agonistic behavior by adults may regulate juvenile dispersal and recruitment, and define the composition of overwintering groups. 1988 Blackwell Verlag Gmb