Number of lunges, (b,h) tussling, (c,i) lunges per meter, (d,j) wing threats, (e) circling, (f) wing extensions. All panels show mean and standard error of the mean. (a–d) Octopamine control (tdc2/+) and mutant (tdc2/kir). (e–j) CS male-male, male-female, and Cha-Gal4;UAS-tra (“Cha-Tra”) male-male pairs. (k–m) Ethograms, based on transition matrices. The ethograms show transitions where the interval between a fly’s action and the next lasted ≤ 10 seconds. We count intervals > 10 seconds without action as ‘no action’ nodes (not shown). The transition probability is represented by the thickness of the arrows (normalized over all arrows that exit a node including the arrow into ‘no action’). The arrow stumps represent the transition probability from one action into the same action. Circle diameters (logarithmically scaled) and numbers denote the average action frequencies. (n) Frequency of CS male-fly positions while extending a wing towards a decapitated CS female. Left: group-housed flies (GG, n = 10); right: single-housed flies (SS, n = 10). (o)