Male lance-tailed manakins (Chiroxiphia lanceolata) cooperate in complex courtship displays, but the dominant (alpha) partner monopolizes mating opportunities. This raises the question of why subordinates (betas) cooperate. ...

In species where males form cooperative alliances for the purposes of reproduction, there may be considerable variation in the strength and size of alliances observed within one population. Male lance-tailed manakins, ...