| Abstract: | In previous studies we have shown that subordinate swordtail males (Xiphophorus helleri) direct more bites to their mirror image than dominants and, in confrontations with strange dominant males, approach the opponent more often during the pre-escalation period of fights. Consequently, we predicted that fights between two omega-males should escalate faster than fights between two alpha-males. Indeed, in omega-omega fights preescalation periods were shorter and biting rates were higher than in alpha-alpha fights before the fights escalated from the first retaliation bite onward. Another new observation was that in omega-alpha confrontations the first bite in the pre-escalation period was executed more often by the omega-male and there was also a tendency to bite more compared to the alpha-male in that stage of the encounters. We conclude that sub-ordinate males escalate faster and fight more offensively prior to escalation than do dominant males. The results cannot be explained by the “social conditioning principle.” On the ultimate level moderate costs of losing and high benefits of winning a fight, constraints on continued growth after maturing, short life-expectancy, and habitat saturation are probably factors promoting the offensive tactics of subordinate males. © 1993 Wiley-Liss, Inc. |
