Fig. 6.

Composite aggression scores (PC1) for Bird 1128 and her opponents calculated from principal components analyses (PCAs) of six aggressive behaviors (attacks, chases, displacements, songs, chip-up and chip calls). Data from Bird 1128 are shown in black, and data from WS and TS birds are shown in white and tan, respectively. Separate PCAs were conducted for (a) short-day trials with WS females (b) short-day trials with TS females (c) long-day trials with WS females, and (d) long-day trials with TS females; thus, aggression scores are comparable only within groups. Bird 1128 was clearly the most aggressive female during long-day trials, but was not distinctively aggressive during short-day trials