PATTERNS OF DOMINANCE AND AGGRESSIVE-BEHAVIOR IN BLUE-JAYS AT A FEEDER

We studied interactions among Blue Jays (Cyanocitta cristata) visiting a feeder in south-central Florida over a 4-year period to examine the influence of sex, time of year, and body size on dominance and aggres sion, describe changes in dominance among individuals over time, and t est for the presence of linear dominance hierarchies. Males dominated females throughout the annual cycle, and in all 24 of the male-female significant dyads. We cannot reject the hypothesis that male dominance over females results from the larger body size of males. We infer tha t males also were more aggressive than females because they were invol ved in more interactions than expected by chance. Females became more, and males became less, aggressive immediately prior to the breeding s eason, but fluctuations in aggression did not lead to shifts in inters exual dominance. Dominance relationships among a few high-ranking male s were intransitive and changed over time. Dominance hierarchies, char acterized by reversals, circular triads, and unknown relationships, we re not linear. Whereas linear hierarchies have been shown to exist in New World jays that live in small, stable social groups, we suspect th e variable constituency and instability of flocks precludes the emerge nce of strictly linear hierarchies in the genus Cyanocitta.